PM3000......white noise....help please!

I have a PM3000 and am very disappointed. It is by far the most frustrating bit of kit on my RV4. I bought it because I was told it was excellent but that has not turned out to be the case. To be fair it may of course be the harness.

First off it has been exchanged by PS Engineering for another unit, but it behaves the same. So it is either that is the way the units are, (second rate) or the installation.

What I have done to diagnose the problem is this.

1. Turned everything off on the aircraft so nothing is radiating.

2. Plugged the headset directly to the radio at the diagnostic jacks that PS recommend, and listened to the radio. Between transmissions it is dead quiet.

Turned the radio off.

3. Moved the headset to the intercom jacks (pilot or P2 are the same). Background white noise. Not loud, but enough to irritate, especially after a while.

4. Moved the squelch through its full range. Nothing changes

5. Moved the volume through its full range. Nothing changes except perhaps right at the top end there is a very slight increase. (From this I deduced that the noise is not coming in through the microphone circuit since then it would react to the volume control.)

6. Moved the pilot isolation switch - nothing changes.

7. In desperation I have also pulled the plug from the intercom and put a meter on the pins that lead to the headset earphones. Nothing is shorted to ground.

8. At this point I have pretty much run out of ideas as to where the noise is coming from. The harness is made with shielded cable of course.

Can any audio experts tell me what my next step should be?

Apart from this background white noise it works in all other ways.

Dear Steve:

You and I have worked hard on this issue, and I hope that you found my support to your satisfaction. And at the risk of sounding a bit boastful, having founded PS Engineering, Inc. some 23 years ago in 1985 I believe I could put myself at least into the Intercom Expert Category.

When you returned your unit to us we provided same day warranty work at no cost to you. I decided to send you an exchange unit rather than sending your original unit back so that I could be absolutely certain that the problem is not being caused by our intercom. I believe I can safely say that at this point, I don?t think it is the unit.

The Van?s Airforce is an absolutely wonderful resource for getting support in all sorts of areas of knowledge, the knowledge base here is remarkable. I truly hope that someone here will be able to offer you an insight in your noise problem that I have not been able to do.

However, my last suggestion to you was to build up a small harness (power, ground, pilot headphone audio and return) and see if the white noise goes away, have you done this?

Here?s the work order.

WORK ORDER# 16234
Date In: 7/7/2008 Date Out 7/7/2008
Preliminary Inspection: No Damage
Included Accessories: None
Repair Charge: $ 0
Model: PM3000
Teardown/Hidden Damage: None
Repair Station ID: 33542
Inspector: LR
TD Inspector: A11
Steve Sampson c/o XXXXXXXX
XXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXX
XXXXXXXXXXXX
Background noise in headsets
Corrective Action: Could not confirm. Unit has been inspected, tested to full spec and placed in the exchange pool. Sending customer exchange unit #C05902A-D.
Part Number 11931A
Maintenance Release - The appliance identified above was repaired,
maintained or altered, and inspected in accordance with current
maintenance rules of the Federal Aviation Regulations under 14 CFR 43.9,
and is approved for return to service.
Technician Signature: One File
Check here if unit was condemned, or not RTS as airworthy, note reason above
PSE Document 002-901-0400, Rev. 02, 2/2006
PS ENGINEERING
FAA CRS # P34R133O
Parts Replaced: None
Part Number Serial Number C05823-A
FAA Cert #: 2786461
2:03:58 PM Time out: Time in: 82234 7/7/2008 RA
Quantity
Mod Level XXXX
2:34:36 PM

Again, I?m sorry you are having trouble. I felt compelled to chime in because I would really hate to have other pilots come to the belief that we make second rate equipment, when if fact we have earned a reputation of not only making great intercoms and audio panels but that we provide great after care support.

Sincerely,

Mark Scheuer
Founder and President
PS Engineering, Inc.

Steve Sampson said:

I have a PM3000 and am very disappointed. It is by far the most frustrating bit of kit on my RV4. I bought it because I was told it was excellent but that has not turned out to be the case. To be fair it may of course be the harness.

First off it has been exchanged by PS Engineering for another unit, but it behaves the same. So it is either that is the way the units are, (second rate) or the installation.

What I have done to diagnose the problem is this.

1. Turned everything off on the aircraft so nothing is radiating.

2. Plugged the headset directly to the radio at the diagnostic jacks that PS recommend, and listened to the radio. Between transmissions it is dead quiet.

Turned the radio off.

3. Moved the headset to the intercom jacks (pilot or P2 are the same). Background white noise. Not loud, but enough to irritate, especially after a while.

4. Moved the squelch through its full range. Nothing changes

5. Moved the volume through its full range. Nothing changes except perhaps right at the top end there is a very slight increase. (From this I deduced that the noise is not coming in through the microphone circuit since then it would react to the volume control.)

6. Moved the pilot isolation switch - nothing changes.

7. In desperation I have also pulled the plug from the intercom and put a meter on the pins that lead to the headset earphones. Nothing is shorted to ground.

8. At this point I have pretty much run out of ideas as to where the noise is coming from. The harness is made with shielded cable of course.

Can any audio experts tell me what my next step should be?

Apart from this background white noise it works in all other ways.

Click to expand...

Steve, these guys at PS Engineering are great and really know their stuff. Take the time to do what they ask you to do and I'm sure you'll find your problem. I've been using their products in all of my airplanes and have never been dissappointed. Mark and his team will find the answer for you. At this past Oshkosh Mark himslef was walking the flightline and thanking customers for using their products, and even answering technical problems! He solved one of mine on the spot actually!
In reading your description of your particular problem, I think you have a wiring issue or a bad jack. It really shouldn't take too long to figure out. I don't know where you live, but if it's anywhere near Atlanta, drop into Mallards Landing (GA04) on the week end and we'll figure it out together.

Vic

PM3000 noise

I went through the same scenero when I installed the PM3000, having been a stereo/electronic buff in my younger days the white noise seemed excessive to me as well. After trying a second unit and having the same results I made a little harness and plugged the unit in outside the airplane with just power and headphones with the same result.

So... after talking to a few folks I decided to just ignore it for the time being and see how it was when flying. Well as soon as you start the engine the noise is totally unnoticable and I cannot tell it's there at all.

So IMO, it's normal and not at all noticable under actual conditions, so forget it and move on

Me Too

Steve,
I've got a RV-9A that has had a PM3000 in it for the last 18 months. It has the exact set of symptoms that you describe.
1. White noise as background.
2. Not volume dependent or squelch dependent

This occurs with only the master and the intercom and the comm. No engine, No transponder, No lights, No GPS, nothing. I have an RMA to send it back for checkout but maybe I'll do a bit more debugging first.

I've been flying it and just ignoring the noise for a good while, but its starting to bug me during low engine operations.

Questions, but Walt is onto something

Walt said:

Well as soon as you start the engine the noise is totally unnoticable and I cannot tell it's there at all.

Click to expand...

I don't have a PM3000, but a quick search on the web got me to the install manual. Look on page 5 where the manual clearly states that the input voltage must be at least 13.75 volts in order for the supply to attenuate noise. This would explain Walt's findings. Have you tried this yet with then engine running? What is your alternator outputting? Will it quiet down with the alternator switched off with the engine running? (Don't turn the alt on and off with the engine running to avoid damaging your regulator.) Did you use individually shielded wires per the manual? Could you have induced ground loops by not grounding everything in your plane at a common point under the panel? In other words, did you run only power wires to anything in your plane and then ground to the airframe at that point? This will cause you all kinds of nightmares later on. Are your mike and phone jacks floating or did you leave out the insulators?

Edit... If you hear the problem with the engine running does it follow rpm changes?

To those who have replied, thanks. Also, Vic, thanks for the offer of help in Atlanta, but the UK is rather far away! To Walt, when I start the engine it remains an irritation to the point that if I am on my own I plug directly to the radio jacks. It is loud enough to spoil music so just becomes dead weight.

Mark, I guess I turned here because after several months it is not working and I am frustrated. The problem as I see it, is we have two different agendas. I as a customer want a working system, radio, a mess of wire, intercom and a couple of headsets. You appear to me to be concerned mostly, to be able to say it is not the PM3000. I really do not want a public spat, just a working system.

Up until this point I have done it your way which has cost me quite a bit of money and achieved nothing. As you can see from my post at the start of this thread I am more than aware it may well not be the intercom itself. There is a huge amount of experience on Vansairforce (who view the intercom as a system component) and I wanted to harness that. I hope that experience is not now frightened off.

Yes you did ask me to start the construction of a second harness. If I had the d plugs pins and jacks, I probably would have, but I couldnt see the point and therefore didnt start ordering the bits. What would be the point? Either, 1) the noise would go away, and you would reasonably say 'the problem is in the external wiring its not the PM3000'. To which I would reply 'the system isnt working', or, 2) The noise would still be there.

Up until now I had assumed since two units behaved identically it was a problem to do with the external wiring. I presume it is reasonable to assume that the noise is entering the system AFTER the amplifiers since if it was upstream of there it would react to volume. If that is a reasonable assumption I would have thought for someone experienced in audio that there would be few possible sources of the noise, and only a few checks (beyond 1-8 above) to make. But then I am not an audio engineer.

Reading the above posts though, I wonder if my assumption is wrong and that I am expecting more for my $400 than you can provide, and that 2) above is the correct answer. When I turn my engine on it remains as a tiresome irritation, similar to the level of the radio carrier after the speech has finished before the radio squelch cuts it out. I dont need that continuously.

So Mark, please tell me what the steps are after I make a second harness depending on result 1 and 2. Also Mark, or anyone, please advise how else to debug the system.

PS I am not quite sure what the point of copying your paperwork onto Vansairforce is. You enclosed a copy when you returned the unit.

Bryan , thanks for your input. It crossed with my very recent post. I have embedded the answers. Please keep the queries coming. Something will trip in my brain..

Bryan Wood said:

I don't have a PM3000, but a quick search on the web got me to the install manual. Look on page 5 where the manual clearly states that the input voltage must be at least 13.75 volts in order for the supply to attenuate noise. This would explain Walt's findings. Have you tried this yet with then engine running? What is your alternator outputting? Will it quiet down with the alternator switched off with the engine running? (Don't turn the alt on and off with the engine running to avoid damaging your regulator.)

Click to expand...

Prior to starting the engine the volts are normally 14.3 or 14.4. (Everything is new.) In flight It sits very steady at 14.5 to 14.6. (I have reams of data streaming off an ACS3400 and have just back through past logs.) I have to say as I start the engine I am more concerned about other things, but a very similar noise is there before I start up and once I am flying. WRT to the question at the end, no its a white noise not an alternator related hum. Absolutely steady.

Did you use individually shielded wires per the manual? Could you have induced ground loops by not grounding everything in your plane at a common point under the panel? In other words, did you run only power wires to anything in your plane and then ground to the airframe at that point? This will cause you all kinds of nightmares later on. Are your mike and phone jacks floating or did you leave out the insulators?

Edit... If you hear the problem with the engine running does it follow rpm changes?

Click to expand...

I have one of those 'Forrest of Tabs' things and all the radio and intercom grounds go back to that with two exceptions. Those are the grounds for P1 and P2 PTT. They ground locally. Sometime ago I asked Mark if they could be the culprits but he said no. Since the problem is there all the time though, not just when you push the PTT, I cant see that as an issue, since they are of course open. They are not shielded either beyond the jacks to the PTT buttons on the stick, but with everything off where could the noise come from? I mentioned that to Mark also. Everything else is shielded.

The insulators are all in place. I checked again visually today. My check at point 7 (first post) would presumably have shown this up as the problem. I have to say I check both mike and phone side but do concentrate on the phones because if it was noise in the mike cct it would be controled by the volume control wouldnt it?

Is there a chance that you grounded the shielded wires shields at the jacks by mistake?

Steve Sampson said:

.....Prior to starting the engine the volts are normally 14.3 or 14.4. (Everything is new.) In flight It sits very steady at 14.5 to 14.6.

Click to expand...

Steve,

Could you confirm that you actually have over 14V prior to starting the engine. Most 12V batteries, when fully charged, will provide you with about 12.7 or 12.8 volts. Once the charging system kicks in after engine start, you should see anywhere from 13.8 or higher (depending on how the charge regulator is set).

If you are indeed seeing such a high voltage before startup, you may have a defective device measuring your voltage, and therefore your charging voltage may not actually be in the 14V range (since you are using the same device to measure your battery voltage after the engine start.

Another possibility is that you just measured the battery voltage right after having applied an external charger. A higher voltage would be measured over some period of time, but not 14V.

Then again, it may have just been a typo on your part.

Dear Steve:

Your comment “You appear to me to be concerned mostly, to be able to say it is not the PM3000”, is correct, but that is just part of my concern. My team and I are dedicated individuals in making EVERY customer happy. Over the past 23 years we have come close to 100% but clearly are missing the mark with you, and I’m sorry.

The steps you need to follow to test the intercom’s white noise on a bench is

1) Find a clean power supply that can supply 13.8 volts DC or more, but not to exceed 28.5 volts DC. You might consider using your aircraft battery to assure there is not conducted noise that may be coupled from the AC power supply.
2) Connect power and ground
3) Connect pilots left and right headphone audio to tip and ring of a stereo jack per installation drawing
4) Connect audio low to barrel of the stereo jack per installation drawing
5) Plug headphone into the jack
6) Turn power supply on
7) Turn Intercom on
8) Listen
a. Is the white noise the same?
b. Is it lower

If the white noise appears to be as loud on the bench as it is in the airplane, then the white noise you hear is normal and wouldn’t be loud enough to be heard in an operating aircraft. If the white noise is lower, then you will have to reevaluate your harness.

Just as a reference, the Bose Corporation has been using our PM3000 at their display booths at AOPA, Sun ‘N Fun and AirVentures airshows almost 10 years. The audio experts at Bose have never complained about white noise. In fact, they appreciate our audio fidelity so much that they display our logo at their booths.

The reason I copied some of the information from your repair order was I wanted to demonstrate that we were diligent and systematic with the care of your unit. It was probably my thin skin reaction to your comment about “second rate” that made me want to demonstrate our commitment to customer satisfaction during our post-sale support.

Steve, don’t worry about me scaring anyone from wanting to help you, I trust the members of Van’s Airforce realize that I want you to be a happy customer and any and all suggestions that could possible help you would make me happy.

Sincerely,

Mark Scheuer
PS Engineering, Inc.

I have the PM1000 II and it also has a very high background noise level. This was the case from first test with my wiring harness on the bench using a 12V bench supply.

It is now in the panel and with the radio on, noise is no different. I can reduce it by increasing the audio levels (radio and intercom) and reducing the headset sensitivity via their volume controls. Same for co-pilot and pilot.

Is the noise level unacceptable? - at this stage I don't know. I suspect it will be below the cabin background noiselevel. But ... everyone who tries a headset (Bose) in my intercom remarks on the noise.

My intercom is wired correctly iaw 11902 wiring diagram, with the aux jacks.

I plan to use it as is and see if the noise is a real issue. If necessary I will take the unit to work to measure the s/n. For now my priority is getting my RV in the air.

By the way - my day job is as design authority for military sonar systems. I do know the domain. The noise level is much higher than it need be and pretty disappointing when it is not expected.

Perhaps what would help are some specs for these parameters, including s/n, dynamic range, mic sensitivity, open mic noise level and AGC capture range and power supply noise supression to name a few.

I suspect there is good reason for the noise level but it does need some explanation.

Doug Gray

"I bought it because I was told it was excellent but that has not turned out to be the case... "

"it has been exchanged by PS Engineering for another unit, but it behaves the same. So it is either that is the way the units are, (second rate).."

Not fair. You've asked for their help. They tested the unit and determine all functions are normal. They made recommendations you chose not to follow, and then you respond by criticizing them for posting useful information on this forum. My recommendation would be that you request a refund, purchase another brand, and do the same debugging with the new unit. Please continue to post your findings, as I am sure many are curious to find what the root cause is.
Terry

Hey Mark

I recently requested an RMA number for exactly this issue. The unit works really well as far as the intercom functions (vox, etc...) go, but the background hiss has always been higher than I would have expected. Its high enough that its noticeable during taxi and during cruise at lower power settings.

I am going to try to do a little debugging this weekend before pulling the unit and shipping it back to you, but my experience is that I have a very "quite" electrical system, no whine, pops, etc... The noise is present with "only" the master intercom and com powered. Direct to the comm jacks is dead quite.

This noise is constant and I suspect that it is the background noise floor of the output amp stage. I'm just surprised that its that high. I'll try to do some experiments to isolate the unit, I've got enough stuff to make an external harness if need be.

One possible issue is that I'm using increasingly good headsets that are killing the ambient noise and leaving the audio with the hiss. So its getting more annoying.

PM1000II (

Dear Doug:

You have raised some good points and some questions for me and generated some questions that I have.

First, please know that the unit you have was built on or before July of 1998, and was discontinued at that time. That was a result of our FAA TSO certification of the then new, 11922. The 11922 does comply with TSO C50c requirements, which does include THD specifications. (and the system white noise does factor into the THD calculations)

So here we go:

Doug said:

I have the PM1000 II and it also has a very high background noise level. This was the case from first test with my wiring harness on the bench using a 12V bench supply.

Click to expand...

As you can imagine, what you perceive (and your friends) as high background noise level is subjective. And what I'm hoping that I can assure you is, that if the unit is working properly and installed correctly, the white noise you hear would not be heard in the environment the intercom was designed for.

Also, using a 12 Volt supply prevents the linear regulator in your 11902 from working in its regulation zone. Until the regulator is regulating, the regulator will not able to provide the 50dB of noise attenuation that it is capable of. You will need to supply at least 13.5 volt DC. And the supply needs to be as clean as your battery.

Doug said:

Is the noise level unacceptable? - at this stage I don't know. I suspect it will be below the cabin background noise level. But ... everyone who tries a headset (Bose) in my intercom remarks on the noise.

Click to expand...

This point is worth bearing out again. There is white noise, and while I would love making our intercoms with no background noise, there would more cost associated in parts and the design. The intercom market while an important part of our core business, is very price sensitivity. Price/Performance is something we always have to wrestle with. How much more improvement are pilots willing to pay for.

Could we sell an intercom with very low white noise? Sure. Would it be more expensive than our current intercoms? Yes. Would customers be willing to pay for this capability when in fact, the white noise is not an issue in a properly operating and installed intercom while operating in the environment it was designed for? Probably not.

Doug said:

Perhaps what would help are some specs for these parameters, including s/n, dynamic range, mic sensitivity, open mic noise level and AGC capture range and power supply noise supression to name a few.

Click to expand...

All of our product specifications (including Pilot Guides, Installation Manuals, Technical Data Sheets) are available on our web site. www.ps-engineering.com/downloads.shtml

Unfortunately, I do not have a copy of the 11902 Installation Manual so I do not have it available on our site. If you wouldn't mind, could you email me a copy of yours and then I could post it on our Product Support pages products.

Doug said:

I suspect there is good reason for the noise level but it does need some explanation.

Click to expand...

White noise is based upon Black Body Radiation. All matter has energy. Resistors, capacitors, ICs, diodes, transistors, the universe, etc all of inherent energy. This energy is very wide band and as you increase gain of the circuits that these parts are a part of, the white noise is amplified as well. White noise can be reduced by using high grade components, but they are expensive and there still will be some white noise. Because I believe the amount of white noise our current intercoms are at a level that would not be noticed while the units are being used in a noisy environments, I don't believe that the majority of pilots would be willing to pay more for a PS Engineering intercom when the actual benefit would not be realized.

I hope this answers some of your questions, but I'm sure you might have more. To go into more details I would really appreciate you giving me a phone call. I ask you this in order to make myself available to you as well as to help me from getting carpal tunnel.

My phone number is 865-988-9800 X31, I'd very much enjoy talking with you and I'll bet I could learn lots from your SONAR expertise. Who knows, you could help us make a better intercom! And that would be great!

Sincerely,
Mark Scheuer
PS Engineering
www.ps-engineering.com

The ever increasing environment

Dear David:

My assumption here is that everyone on this thread is concerned about white noise, not background noise one would hear when the VOX is opened in an aircraft that is running.

You may be onto something David. Some of the posts here have been from pilots who have not flown with the unit and are testing in a quite environment. In your particular situation, you have a very quite system that would also not mask the white noise.

If in fact that white noise is at a level that would be distracting, fatiguing, annoying, a real simple solution is to turn the headset volume down just a little bit.

The peak to peak voltage of the noise floor at the headset output is about 37 mVolts (0.037) peak to peak (P-P). The entertainment, intercom, and aircraft radio voltage levels at the headset can be as high as 8.5 volts P-P.

That's why by turning your headset volume down just a little will have a major effect on the white noise.

You are welcome to send the unit it to me personally and I will take it to our test bench and verify the noise level is the same as our standard. Be sure to put your RMA number on the outside of the shipping box.

I hope that this is of some help.

Sincerely,
PS Engineering
Mark Scheuer
9800 Martel Road
Lenoir City, TN 37772

dedgemon said:

I recently requested an RMA number for exactly this issue. The unit works really well as far as the intercom functions (vox, etc...) go, but the background hiss has always been higher than I would have expected. Its high enough that its noticeable during taxi and during cruise at lower power settings.

I am going to try to do a little debugging this weekend before pulling the unit and shipping it back to you, but my experience is that I have a very "quite" electrical system, no whine, pops, etc... The noise is present with "only" the master intercom and com powered. Direct to the comm jacks is dead quite.

This noise is constant and I suspect that it is the background noise floor of the output amp stage. I'm just surprised that its that high. I'll try to do some experiments to isolate the unit, I've got enough stuff to make an external harness if need be.

One possible issue is that I'm using increasingly good headsets that are killing the ambient noise and leaving the audio with the hiss. So its getting more annoying.

Click to expand...

Some progress today.......

Alfio (aka Lycosaurus). - Thanks for picking me up on that. You are absolutely right in that just prior to starting the engine I do not have 14 Volts. I was typing that at 2:30 am so perhaps a little tired. Thats my excuse! All my debugging in the hangar has been done with the float charger connected so then I do have the voltage I talked about, and also in the air. The point that you picked up on is not, it turns out, germane to the problem (see below), but it might have been.

Terry - if you want to quote me please quote whole sentences. You wont endear yourself to anyone by distorting what was said by selective editing. Relations between myself and Mark are admittedly fragile, and yes I am at the end of my teather, but we have both remained polite. You are not party to the close to 40 email that have already passed between us and I intend to keep it that way. You stirring things up will not help.

Mark/others - so as the heading says I have made some progress. I wont take you through the blow by blow logic of how I deduced what I have, but the upshot was I went and got my stereo headset and plugged that in. Without being in a position to start the engine the problem would appear to have gone.

The reason I did this was looking at a mono headset plug and a jack socket it became clear that plugging it in would have the effect of shorting pin 22 to ground, and introduce one of the dreaded ground loops (thats right isnt it?). Thats on P1's jacks and similarly pin 21 on P2's.

I do need to run the engine up, but sitting in the hangar listening to passing aircraft, when they stop talking it gets eerily quiet! Great!! The loudest noise is, I think, the very slight hiss of the noise canceling logic in the headset.

Now the reason I havnt been using the stereo headset is because the mono ones I have are so comfortable and nice. It knocks the socks off the PA1779 (or similar #) stereo/noise cancelling one I have. I doubt you will know my monos. It is a very small British company called Comunica. They do a lot of work for the police and military (money is no object/quality everything) and only sell a very few sets to 'friends' in the commercial sector at unprofitable prices. The headsets must be close to 14 years old, but I have never met anything I prefer. Also, here ATC is mono, but I cant imagine how ATC can usefully be otherwise, but thats another issue. Reading your FAQ on this page http://www.ps-engineering.com/faq.shtml#4 at #5 "Can I use a mono headset in my stereo intercom?" it says effectively 'no problem'. so now I am puzzled. #5 appears to run across the fact that plugging a mono headset introduces a ground loop if I understand your wiring diagram correctly.

So where do I go from here? Do I have to buy another stereo headset and give up on my Comunica, or is there something wrong with my harness that is stopping the mono sets working? Can we yet agree that I don't have to make up another harness outside the aircraft and that is pointless in view of the above?

grounds?

Mike,
I'm sitting at work so I can't check this .... but ... is the case grounded?

I'm just wondering if there is a ground loop issue due to the instrument panel being grounded through the airframe, yet the intercom sensing ground through the connector that is on the aircraft single point ground system. However; I'm not sure how this would impact the noise floor. The noise isn't modulated or anything like you would typically get with ground loops.

I guess I'm just going to have to tear this out a piece at a time to find it. There is currently more noise than I suspect is your bench check norm. And if several of us are hearing it, it surely is an install issue of SOME sort.

I'll try to dust off my EE degree and do some systematic debugging before sending it to you.

mscheuer said:

The peak to peak voltage of the noise floor at the headset output is about 37 mVolts (0.037) peak to peak (P-P). The entertainment, intercom, and aircraft radio voltage levels at the headset can be as high as 8.5 volts P-P.

Click to expand...

Mark,
First, thanks for your contact details and thanks for discussing this openly.

1. I am surprised that my unit was manufactured pre 1998. I purchased the unit new in late 2006 from Mendelssohn in Australia (http://www.ozpilot.com.au) who still have the PS1000II listed in their advertisements.

My unit is in fact the 11922 without the CREW function (SN8889) I received only the 11902 circuit diagram packed in the box, plus the panel template. No install manual.

I was able to download a manual (Rev3 dated August 2003) from the PS Engineering website. I had to remind myself of this by checking through the file - hence my delay in replying.

2. From the figures above we are talking about a 47dB dynamic range. This fits with the noise I hear in the headset. It compares with the d/r of a digital telephone channel (8bit codec has 48dBd/r) . CD audio has a dynamic range of 96dB. Audio electronics can easily match the 96dB with budget components.

3. Power Supply rejection should be much better than 47dB with even an average design. Noise from the power supply (or from an earth loop) is very unlikely to be white. That said I will retest my Intercom when I can get to it (busy on the canopy right now) with a 14V supply.

I will give you a call to discuss this further.

Doug Gray

Again...I'm late to the party and just read this thread. All I can sayis WOW!

In the interest of full disclosure I should say that we are PSE dealers and have dealt with them (and Mark) for years. I have wired, installed, serviced and flown behind most of their products and can attest that you'll likely not find a better group of people or products for audio systems.

Just as an FYI to everyone who has or thinks they have a problem with the PSE product. While is is possible a unit could have a problem out of the box, it's not probable.....and highly unlikely that 2 of them would. That means we troubleshoot these issues like all avionics - asking what is more likely than not - and what are the knowns and unknowns. In this case the PSE equipment is a known. The installation was the unknown.

So, that brings me to my next point. Most of you know this, but as a customer you'll always get more with honey than with vinegar. Starting out a new thread (no matter how frustrated you are) and using words like "2nd rate" are not nice. Especially when the mfgr already replaced your unit for free, and when testing your old one found NFF/CND (meaning no problem with the unit).

In this case I know I'll get flamed, but I think Steve owes PSE and Mark an apology. The problem was 14 year old non-standard mono military headsets.....and Mark sort of got dragged across the coals a couple of times - and unfairly so. I mean, a new unit, 40 emails and other communication is going awfully far to try and fix a problem that wasn't. The originating poster ranted about it costing him money. Well, I'll guarantee you that PSE lost a LOT more money trying to fix this issue than the customer did and erased any hint of profit they made from the original sale. It was a $400 unit to begin with, and they did do a LOT of things to try and rectify it. Try and get that kind of service for your computer, TV, car, or other comparably priced products. Ever call the Dell or Gateway or Microsoft support lines to try and get help with your computer?

I'm just a bit sensitive to things like this so I apologize in advance if I came across wrongly, harsh or if I offend anyone. I just felt a little bit dissapointed to see that the original poster never bothered to come back and say "OOOPS, the problem was mine, not PSE's, sorry for the mis-understanding" - after making some comments that weren't really fair to either the product, company, or people. Given the tone of the original post, as well as some of the follow up comments, I'd expect a gentleman to at least come back and tell everyone they were wrong, or at the very least that some of the comments were perhaps not fair. It's easy to throw stones when you're frustrated, but it's also just as easy to just drop everyone a quick line to know what the end result was. In this case, readers of this thread may have left thinking there was still a problem with the customers unit, when in fact there wasn't. I waited and extra day to see if the originating poster would come back and let everyone know what the deal was - but he didn't so the thread was just kind of left hanging - complete with some negative connotations that shouldn't have been there to begin with.

That's all I'm trying to say. Nothing personal, just trying to make sure that the end result of this issue is fairly communicated, because the first page or two wasn't. Mark and PSE are one of the few top notch companies/people who still take a very personal interest in their customers (similar to TruTrak, AFS, GRT, etc..)...so I'm just trying to make sure things get evened out fairly in threads like this. These guys go above and beyond what almost any other business in our lives do. It's only fair to give them positive credit when it's deserved - and to repudiate negative publicity when it's not deserved.

My 2 cents as usual!

Cheers,
Stein

PS - quick little story. An RV-10 builder (who is on this forum) finished his plane some time ago. After flying the 25 hrs off, the first ride was to some friends. The friends in the back seat couldn't hear anything. We spent literally sozens upon dozens of hours on the phone troubleshooting and much to my chagrin determined the problem couldnt' be wiring, it HAD to be the unit - which was a PSE PMA-8000B. We overnighted the customer a new unit and this time the backseaters could hear, but barely. So, during the next round of troubleshooting, we started from scratch...had the customer power everything down and go about it one step at a time. When I asked him to turn up all the volume knobs on the intercom there was dead silence on the other end....they then said "we have the volume knob turned all the way up" to which I said "how about the rear seat volume - again - dead silence. The customer then quietly said "we didn't know there was an adjustment on the audio panel for the rear seaters". Guess what, when the turned it up everything worked peachy. Of course I made fun of them for never having read the manual, and they promptly apologized and bought pizza for my entire crew! We ended up good friends after the deal. I use it as an example of how much time/money can be spent chasing a problem that doesn't exist, but in my case the customers were true gentlemen and in the end none of us felt upset - quite the opposite! I have dozens of such stories....so when you call and can't get hold of us, just remember that many times we're on the phone troubleshooting these types of issues. Also remember that before you call with such issues!

STEIN:
BRAVO. I was planning on writing Mark a personal message to let him know that his is the type of Company I love doing business with. It's evident that his goal is not only making an excellent product, but is willing to back it up to the extreme. I think this is one of the wildest threads that I've run across since Doug began this site. Kudos to Mark. His patience is unbelieveable.
Terry

PS Engineering products

To be fair it may of course be the harness.

Steve, I've been using a portable PS intercom in a C-172 I sometimes fly, for over 7 years now. I have a PMA 4000 in my -4 that is working wonderfully. I had Pacific Coast Avionics make my harness. How about trying someone else's harness??

I just hate to see you so frustrated. Have been following your work for a long time now. Really wish ya well.

Deal Fair
RV-4 (N34CB)
George West, TX (8T6)

Point products or systems.....

Stein, I started this thread so as far as I am concerned I will put the last entry on it. There are only two people who know the full story, myself and Mark.

On the 16 Jan 08 I put this message to Mark. The only editing is I have changed two bits to bold.
--------------------------------------
"I have been reading your web site but am not much wiser. Can you sugest which intercom I should buy please?

The environment is this;

VANS RV4
2 headsets, different types.
1 radio
Inputs from a) ACS3400 EFIS and b) Garmin 496 GPS
Music input is a nice to have though not essential. Similarly stereo.
As I change power the speed of the alternator will change and terefore the voltage. I do not want to have to adjust the intercom.

I think that is it except to say I dont want to spend more than I have to.

Also, do you have a standard harness/jacks for your proposal? Can I buy it through 'Spruce? (I am in the UK it makes consolidation of shipments easier.)

thanks, Steve."
--------------------------------------
While this does not have the formality of specifications I have had to meet throughout my career from the US and British Government and others, it does specify what I want to do reasonably accurately.

The reply I got was this:
--------------------------------------
"Good morning and thanks for contacting us.

RV4 - GREAT AIRPLANE. (Actually, I really don't think that Mr. VanGrusven has ever designed a bad one!

Since you have an audio from the EFIS, I really have only one solution, but it is really a good one though. It's our PM3000A.

It is stereo so you'll appreciate not only the hi-fi sound of the music but you'll appreciate our "Karaoke" mode as well.

What this intercom also brings to the table is the two (2) unswitched inputs. It's the only intercom in the world that I know of, that has this. This would be were the audio from your EFIS would go.

Of course, your 496 also as terrain warnings so that is where the second unswitched audio would go.

You can purchase a custom wire harness from us. Just go to www.ps-engineering.com/pm3000.shtml and then download the "Worksheet." Complete it and FAX it to us. We'll need your credit card (master/visa) and then within 2 days we'll ship it to you. Alternately, you can send the worksheet to Aircraft Spruce and purchase the harness from them.

The harness will keep your warranty in tact.

The Minimum Advertised Price is $419.95 and the part number is 11931A"
--------------------------------------

Now I would have thought several things might be clear from that, one mono was not unimportant, and two purchase through Spruce was preferred for the reason stated. Also, if you think about it I am trying to buy it as a system in both a technical and commercial sense. On the mono point I will pick on one thing you said. While the headset is nearly 14 years old it is no way that I know 'non standard' unless you consider its quality to be non standard. It works fine elsewhere. I had no reason to believe a mono headset would be a problem - see PSEng FAQ #5.

From here on things went spectacularly wrong. I ordered from Aircraft Spruce on Mark's harness order form. Unknown to me 'Spruce did not pass the harness part of the order form to PSEng but had some contractor make up the harness. Personally I think this is quite dishonest and as a result have so far managed to place no further orders with 'Spruce. But to put things in time sequence I had no way of knowing that Mark's dealer had done this. I was in Mark's commercial system for getting this stuff.

When, from a photograph I think, PSEng realised that they had not made the harness it was a big surprise to me. From that point on I have never really felt that PSEng supported my installation as a system. They have only ever focused on the intercom. Without it explicitly being said I have always felt that PSEng feel I ddi something wrong and any help is a favor.

The harness has never been a problem in an electrical sense. It was appalling untidy workmanship and there is another whole long story there but this is long enough without me going into that.

The installation of the harness into the aircraft which I did was never a cause of fault.

In summary there were two problems:
a) I wanted to buy a system that would work from the start. Mark's commercial channels did not provide for that, and yes i do expect OEM manufacturers to take some responsibility for their channels to market. I have been doing it half my life.
b) When a customer indicates stereo is a 'nice to have but not essential' there is a clear indication mono might not be unimportant.

Stein, two last thought:
How you can say it has cost PSENG more than me defeats me unless you have no value for my time. The cost is the same for both to write an email. To run a test on a unit and send an exchange from the pool is hardly huge. I wont detail the extra bits I have had to go out and buy. Shipping costs, double duty charges etc.. Oh! And I guess now I have to buy another headset. "Oh well, thats just another customer expense because the product does not meet his original spec.!"

And secondly, no I don't see the problem as mine. From beginning to end mono has been in the frame, and FAQ5 seems to support this as OK. "In the pilot or copilot positions, nobody will notice." I could have put out my spec in the format of a government request for quotation I suppose! A little comment along the lines that plugging a mono headset in is going to be problematic would have been a big help. I cant be the first.

I didn't put anything here yesterday because I was waiting for an answer as to how to best to support the mono headset I have indicated I might use from the start. On that I am no wiser.

Huhh!!!

Ok, I cannot stand it any longer. WOW!!

Having had my share of problems such as described in this thread I had some sympathy for Steve, but come on now. Enough is enough.

You have tracked down the cause of your problems. It turns out not to be the manufacturer's unit that caused the problem. Now you still want to blame them for not providing you with a system that works with your outside sourced older mono headset? You are now saying they should have known what you had intended to use with their system when they sold you their $400 unit.

I for one am glad for manufacturers with this much integrity. I am very surprised at the level of restraint shown by this manufacture and by the fact that they were willing to post comments on such a public forum. If you worked in the computer industry as I do you would know this ABSOLUTELY WOULD NEVER HAPPEN WITH MICROSOFT!!! You should consider yourself extremely fortunate that you had the level of support you did have rather than publicly bashing the manufacturer even after it was determined the problem did not lie with their unit.

It is time to change your focus dude! How about looking at your experience in a more positive light? We should be building our airplanes with the idea that doing so is for Recreation & education. So think of your problems faced and the troubleshooting you ended up doing as the education you gained when dealing with this intercom system. Learning is fun but sometimes it can also be frustrating. Even so, the frustrations we all face in our builds are still very powerful educational opportunities that we should, if not cherish, at least accept as powerful learning opportunities.

I hope you will put this experience behind you soon and over time consider it a valuable experience you would have never dealt with had you not gone down the road you did.

Live Long and Prosper! And maybe perhaps take a chill pill with a pint while you move onto the next learning experience.

Steve Sampson said:

I didn't put anything here yesterday because I was waiting for an answer as to how to best to support the mono headset I have indicated I might use from the start. On that I am no wiser.

Click to expand...

Could you just disconnect the (L) headphone wire from the jack either perm or add a stero/mono switch to the panel at the jack location to disconnect it when using a mono headset plug to prevent the grounding out of that signal?

Also it would be very easy to make up a "jumper" with a male stereo plug on one end and a female mono one on the other. Simply do not connect the (L) signal wire to anything at the female jack.

Hi Steve,

I sense your frustration, and in this case it's obvious there is a huge amount of mis-understanding. Mono headsets have and do work fine. But if I'm not mistaken the Communica Headsets are Tactical/Military headsets. That's a huge flag to me because often times those are different electronically than commercial general aviation grade headsets. I'm afraid in the end you're best bet is to either toss the headsets or try a different audio product (but I do know you'll find none better than PSE), and I also know that you're not likely to find any other company that will go to the extremes Mark and PSE did in your case. You have to admit they have done quite a lot to try and help you.

I don't think there is any more they can tell you regarding your headsets. They simply do not work in this installation, the intercom product is fine - so therein lies the stalemate. If you need to use those headsets and are not satisified with the way they perform with the PSE product, either get rid of the PSE product or get rid of the headset. You surely can't expect them to try and modify the product to meet those headsets? What else would you have them do at this point?

As far as Spruce goes, I wouldn't necessarily call them dishonest....perhaps a bit misleading, but not outwardly dishonest. We do a lot of business with them and aside from a common lack of technical knowledge, they do ok. But this may be yet another place where I can say again price doesn't always equal value when it comes to purchasing technical products. Mark has more than supported his commercial channel here - you have to give them that.

I know you're frustrated, but at this point there simply isn't a solution to this issue that you'll be satisified with in regards to keeping your "unique" headsets and using the PSE product. If you had bought it from me, I'd just simply say at this point sent it back - but I have NO other product that I could recommend as being any better. I can say my patience would have been severely limited as compared to Mark's in this case - then again I'm the Devil compared to his Angel!

Just my 2 cents again...

Best Regards,
Stein

Per request, the end.