Regular, Sharp Pops Through Stereo

[avantbored]

You stated that the noise was not present with the Nikko gear, but returned with the NAK device. If the noise is present only when using the Nak PA7II, I'd still suspect the amplifier. If you had the same noise with other amps in the same setup, it could be some other device causing it.

If i'm not missing something in your descriptions, you never reported the same noises present with other amps. You mentioned the NAK PA7II not doing noises for some time, but noises returned always with that same amp.

From here, to me, it sounds like the amp has an intermittent problem, something usual to us who repair amplifiers.

Please , in case I didn't see it before in the thread, let us know if you had those noises using other amplifier.

It's worth summarizing my testing. The underlined and bold result is of note.


Main Room
All driving Yamaha NS1000Ms

Nak PA7AII & CA7A Pre: Pop

Yamaha CR820: Pop (Putting this here for posterity, but I have to discount this component's result because it has its own power supply issue.)

Nikko Alpha 220 & CA7A Pre: Pop.


Office
Driving Yamaha NS100X

Nak PA7AII & Nikko Beta 20 Pre: No pop

Nikko Alpha 220 & CA7A Pre: No Pop

Nak PA7AII & CA7A Pre: No pop



Tonight (5/5/2023; 6pm - 9pm) in main room

I sat in front of my left speaker with PA7AII & Beta 20 pre: No pop

Then, I reassembled the normal set up (PA7AII CA7A): No pop.

 

[avantbored]

It's worth summarizing my testing. The underlined and bold result is of note. ...

Well the pop returned, and I had a flyaway thought that the variable that wasn't replicated between the two rooms was the analog source. Denon DL103S. So, I started searching and found this thread on VE: https://www.vinylengine.com/turntable_forum/viewtopic.php?t=103362.

Same sound!

@elnaldo pointed out the Nikko stack was not producing pops. I didn't have the MC installed when I'd posted.


I am now running my AT150 on the Nak. Well see.

 

[gadget73]

Sounds like a problem not related to the gear since the Nikko works fine in your office. I wonder if you have a noisy device on the same circuit or a problem with the outlet. Have you tried feeding it from another circuit using a heavy extension cord?

 

[avantbored]

Sounds like a problem not related to the gear since the Nikko works fine in your office. I wonder if you have a noisy device on the same circuit or a problem with the outlet. Have you tried feeding it from another circuit using a heavy extension cord?

Thanks for replying. I've had the Nak and Nikko both in the office, which is on another circuit.

I've had the Nak separates back in the main room and on all day with my AT150, not the Denon. I haven't heard a pop (except for a suspect sound, but I was slightly far away so couldn't hear it clearly).

The Nikko and Denon are in the office, also on, but haven't listened closely.

 

[avantbored]

Thanks for replying. I've had the Nak and Nikko both in the office, which is on another circuit.

I've had the Nak separates back in the main room and on all day with my AT150, not the Denon. I haven't heard a pop (except for a suspect sound, but I was slightly far away so couldn't hear it clearly).

The Nikko and Denon are in the office, also on, but haven't listened closely.

I am sad to report that I heard the pop on the Nak PA7/CA7 combo in the main room with the AT150 cartridge, eliminating the Denon as the culprit.



The suspects so far:

1) Noisy transistors in the Nak
2) Outlet
3) Noisy appliance
4) The turntable ?


This is an open-plan space with the living area (main room) and kitchen in one physical space, but on two separate breakers; the pops happen independent of the fridge.

 

[elnaldo]

My vote is still transistors in the NAK, but I've had noises coming from a noise suppressor capacitor at a turntable. I've seen that just once, but it would be easy to spot it: when you are hearing the noises, unplug the TT from the main AC voltage.

 

[jimbofish]

I lost track of your switching rooms and components, but didn't you say this was a townhouse dwelling, meaning you're sharing walls?
If so, it may be coming from one of the other units. You probably have separate meters and service panels, but you all come off the same transformer.
Some years ago we were picking up noise from the neighbor's computer. Their house is over 500' away, but both of us were fed by a single transformer between the lots.

 

[avantbored]

I lost track of your switching rooms and components, but didn't you say this was a townhouse dwelling, meaning you're sharing walls?
If so, it may be coming from one of the other units. You probably have separate meters and service panels, but you all come off the same transformer.
Some years ago we were picking up noise from the neighbor's computer. Their house is over 500' away, but both of us were fed by a single transformer between the lots.

Thanks for following along; yes, it is townhouse in form though coded as single-family houses. Technically we don't share a wall, but effectively we do -- you are right that my row in the development shares a transformer.

Wouldn't that mean, though, I would've heard the pop in my office? I could not reproduce the sound with all of the combos just in the office

 

[jimbofish]

You have two legs of 110v coming from the transformer. The office may be on a different leg than the open area which is affected by the noise.

 

[avantbored]

My vote is still transistors in the NAK, but I've had noises coming from a noise suppressor capacitor at a turntable. I've seen that just once, but it would be easy to spot it: when you are hearing the noises, unplug the TT from the main AC voltage.

It would take a miracle to unplug just in time, but will try without hurting myself .

I wonder if the Nikko amp/CA7A pre popped in main room, might it be the pre? What would explain that?

 

[avantbored]

To those still tuned in...

The pops appear no matter what input the preamp is on, line or phono.

As identified before, the Nikko Beta 20 Pre/ Nakamichi PA7AII power: pops.

I am sure it is the power amp.

Last year I reached out to Jon at Vintage Amp Repair about doing a refurb/restore on this, but the problem ended up just being a dead resistor in the protection circuit. But now that the bias drifts a lot in a year, cold spot on the left side, intermittent transistor popping, I'm bringing it to him on Friday to do a PCB recap, change the bias controls (which he has recommended twice to me), and investigate the transistor issue. A big investment, but I inherited this amp, so I want it to live!

 

[UncleAng]

Had the same pop in my NAK.... this is what was replaced (last year)

 

[avantbored]

Had the same pop in my NAK.... this is what was replaced (last year)

View attachment 2918964

Great timing, UncleAng, just thought to put an update here for posterity.

Picking up my amp from Jon in July. But he couldn't reproduce the problem on his end. We went ahead with the PCB recap and bias control replacement for security. Also, bias controls.

Are these from your PA7A II?

 

[UncleAng]

Are these from your PA7A II?

Yup.

 

[avantbored]

Yup.

Nice one. Thanks for the pics. I will forward to Jon and inquire further.

 

[UncleAng]

I will forward to Jon and inquire further.

Repairs were done by Chris Bridge who did all the warranty work for NAKs back when here in Canada. BTW: he's never repaired any 5 or 7 series under warranty, they're made that well. If you PM me with your email address I'll send you a copy of the invoice which has all the parts he replaced and part numbers as well as diagnostic comments. Chris also did the warranty work for Thresholds which he states required considerable more TLC to keep them going then the NAKs. Chris is a moderator on DIYAudio and considered the go to guy (with the exception of Nelson Pass himself) regarding anything Stasis.

 

[avantbored]

Fellow travelers,
I have retrieved my amp from Jon Soderberg of Vintage Amp Repair (PCB recap, trimpots replaced). He gave it a clean bill of health and listened to it several times.The problem persists.

My thinking, then: Either it is some other thing on the circuit, the circuit itself and/or the outlet got damaged during the brownouts, or the Nak has some problem that has escaped three people.

 

[avantbored]

I have reproduced the problem in my office, same setup. Though I cannot be sure it is the same phenomena exactly, as static discharged on the volume knob upon operation in my office, but not in my main listening area. A spreadsheet documenting my listening :

STEREO POP LOG

DATE POP? Y/N APPLIANCES? MUSIC? Y/N TIME (24H) 7/27/23 Nak PA7A II | CA7A Y All lamps; AC on (but not active) N Side A just ended; ~1 min. 20:26 N All lamps; AC on (but not active) Y Side B starts; Joy Division Unknown Pleasures 20:49 All lamps; AC on (but not...

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