PS Audio 4.6 noise floor


#1

Just added a pair of Audeze headphones and when listening through my 4.6 preamp, I notice lots of noise in the phono signal path. Nothing has changed in that path in years – same cables, same cartridge – although the system was just subjected to a complete disassembly, a 5000-mile move, and a reassembly after months in shipping cartons.

The noise goes away when I unplug the turntable, but I realize that that doesn’t mean that the turntable, phono cabling, or cartridge are necessarily the noise source. The circuit may simply not be operating when there are open inputs.

I’m also not certain that there wasn’t some level of noise all along. The Audeze’s are audio microscopes. My gut feeling, though, is that this is something new, since the noise is profound enough that I can’t imagine that I wouldn’t have heard it in the past.

I’ve tried several times to contact PS Audio re: whether they can give my unit an overhaul & return it to factory spec. But so far no reply.

Anybody suggest any direction? I can’t swap cables b/c the turntable cables are hardwired into the table. And I don’t have a second table or preamp to swap in for further testing, which would of course make everything easier.

Any ideas?

c


#2

Welcome, cundare

What are you using to drive the Audeze headphones? They are a bit tricky to drive.

How does it sound with a CD player or other source plugged into the preamp?


#3

The 4.6 is at an age where the capacitors are ready to poop out like they did in my 4.5. The electrolytic caps in the phono section vomited fluids dramatically and the young audiophile I had given it to was horrified. The caps can be replaced by any good repair shop but it might be time for a new piece of gear. These pre’s were a great peek into 1980’s audio nirvana for a sweet price. Is the noise a hum or “white” noise-like?


#4

Yes, exactly, but I am concerned you tried to contact us without any results. Can you tell me how you tried to contact us?


#5

Hi Paul:

Thanks for the personal reply.

I tried multiple times to use the online problem-reporting page on your Web site, but each time, it wasn’t clear that my message was sent. I kept seeing “There’s an error with your submission, please correct highlighted fields”, but no fields were highlighted. So I’d hit the Submit button another time. After a few days of that, with no response, I called & spoke to a support person yesterday who wasn’t familiar with the 4.6 but promised me a quick call back from a more qualified person who had just stepped out to lunch. But no reply. I couldn’t find a direct email address for support.

I’ve always loved the 4.6 and still have a lot of vintage analog gear, so if I can keep it, I would. The functionality is exactly what I need. I hear the noise when the preamp is in passive mode, and only through the phono signal path, so my best guess, if the cause is the preamp, is out-of-tolerance passive components in the phono stage. Other manufacturers provide refurb services for classic gear (Quad UK, e.g., restored my 1950s Quad II valve amps & AM/FM valve tuners to original spec a few years ago), so before I run out to buy a multikilobuck preamp – without really knowing for sure if the 4.6 is my problem – I was hoping that PS Audio might be able to take a look at it and perhaps give it a full overhaul – not a bad idea for an older unit, as one person mentioned, even if the preamp is not my noise source.

Does PS Audio offer such services?

Don


#6

wglenn:

It’s amplitude-fluctuating static, not exactly white noise, but more like the sound you’d hear when turning a dirty pot or, even more to point, like the noise between radio stations on an old shortwave or AM receiver. If the problem is indeed in the phono stage – and there’s not much in one of those circuits to go wrong, I’d suspect a cap. Being an old EE, if I had time and a schematic, I’d take a look myself, but I’d rather let a real service organization do the job, someone who is familiar with the hardware – especially if, without other components to swap, all of this is just a SWAG.

I mean, I’ve never heard of noise like this resulting from a sudden failure of a MC cartridge. Not sure if such a thing is even possible, much less likely.

D


#7

Hmmmm. I will have to check the form. Sorry about that!

Yes, we can refurb most of our products wit a few exceptions. The Lambda transport is one, because we can no longer get parts. The 200CX because we no longer have boards and some of the front panel switches like on the 4.5, 4.6, and 5.0

But circuitry and what you are asking shouldn’t be hard.


#8

Yay! That’s what I was hoping to hear. I had a feeling that PS Audio might offer that service, because PS has already upgraded this unit from a 4.5. Regardless of the source of my noise problem, I’d love to restore this vintage piece of gear to original working order. And the front-panel switches are fine & wouldn’t need work.

Who do I speak to next re: logistics, cost, etc.?

Don


#9

Send alexp@psaudio.com and email and he’ll hook you up.


#10

Let us know how it works out!

I have had a phono cartridge fail over time, but it wasn’t sudden. It also did not become noisy, it became quieter and shrill.


#11

Thanks, Paul!

I’ve owned numerous PS Audio products over the decades and, even at my advanced, quasi-retirement age, I’m still knocked out by their quality & value, but even more impressed with the company itself. I greatly appreciate your personal attention to my concerns.

Don


#12

…however, after sending an email to Alexp yesterday, I still have not yet received a reply. Starting to feel like a rat in a maze…

I’d just like to send out my preamp for repair/upgrade and have it back in my system as soon as possible. After nearly a week, I feel as though I’m getting closer, but still don’t even know how much such a job would cost or how long it would take.

D


#13

Odd. PS Audio is typically very responsive. Perhaps there is something in your email addy/email content which is flagging it as spam.

Have you tried the, admittedly old-fashioned, phone?


#14

Yes, of course. When I did get through, I was promised a callback when the appropriate tech returned from lunch. But that was, I think, on Monday.

I posted on this blog only after exhausting all other avenues I could think of. Paul (the CEO!) is the only person who has responded, other than one fellow who initially picked up the phone and apparently was unfamiliar with my preamp.

D


#15

I dunno, Elk, maybe I should just pop the cover and look for something obvious, like a burnt area of a circuit board or, as I think you described in horrific detail, a capacitor that is actually leaking into the chassis. Brrr.

The symptoms you mention with your cartridge make sense to me. Assuming that a cantilever hasn’t been banged around, the most likely thing to fail in a cartridge would be any elastic components of the suspension. If they start to stiffen or otherwise lose compliance with age, that might well be what you hear, a tilting of the frequency response curve toward the lower-excursion, higher-frequency registers.

If PS Audio made an analog preamp similar to the 4.6 today, I’d buy it in a second. But I don’t know of any products in the current product line that would provide the functionality of my 4.6. I’m switching a bunch of analog sources, turntable, tape decks, tuner, etc. And finding a better phono preamp for three figures would be pretty tough even today. So if there’s a way I can keep the 4.6 by restoring it to original spec at a reasonable cost, I’m all for it.

It’s just frustrating that it’s been so hard to find anybody at PS Audio, other than Paul, willing to talk to me. Like you, I just don’t understand it, based on my consistently great experiences with PSA in the past. The spam-filtering idea seems unlikely, but who knows? Regardless, based on Paul’s comments, I’d think that the right people would already be aware of my problem as it’s been discussed here, even if they somehow never received my email.

Well, I’ll just keep trying. Maybe tomorrow will be the charm. Part of the problem is that I’m on Hawaii time, so the time difference is an obstacle. Tomorrow, for example, I’ll be in conference calls from 7:30 AM to 10:00 AM, which is 4PM NY time. So by the time I can get to a phone half the day is gone on the Mainland.

D


#16

Hehe, Alex is probably digging around for that old schematic right now… He may have been out yesterday. I got his voicemail when I called.

P.S. I put in a service request through the generic service email link and Paul answered it back on the weekend!


#17

It shouldn’t be that hard and I apologize for the lack of communication. I will try and give the lad a nudge today - that just isn’t right.


#18

Paul:

I did hear back, but apparently, the unit can’t be fully restored. Alex offered to evaluate it & replace the caps for $250, but that’s about all he can do. So now I have a harder decision.

Does PS Audio make any product that would provide a fairly compatible upgrade path? I don’t know of any personally, but you’re the expert.

Don


#19
cundare said

The symptoms you mention with your cartridge make sense to me. Assuming that a cantilever hasn’t been banged around, the most likely thing to fail in a cartridge would be any elastic components of the suspension. If they start to stiffen or otherwise lose compliance with age, that might well be what you hear, a tilting of the frequency response curve toward the lower-excursion, higher-frequency registers.


I think this is exactly what it was.

While I can’t do anything about it, I am really sorry you have had such issues contacting PS Audio. They truly are typically very good and I am certain Paul will be on top of it. While in other contexts it sounds corny, he and his group really do care - it matters to them that they provide exemplary service.


#20

Here’s what we can do - despite what Alex may have said. We can replace the input transistors as well as the caps - and that is likely to address the problems you’re experiencing with noise.