I am sick of failing amplifiers

[DasguteOhr]

You have to proceed systematically, otherwise you're just groping in the dark.
Connect the speakers and put a short-circuit plug on the RCA input of the amp.
This will ensure that the humming is not coming from other devices. Does the humming change when you adjust the volume? Download the audio tool app and hold the cell phone microphone directly to the speaker.
At what frequency is the humming? 50hz or 60hz is usually a grounding problem. Different grounding concepts, bad wiring or soldering points.
Higher frequency humming can be caused by defective rectifiers ,coupling capacitors, srrp whistling (gradual increase in hum). If the volume doesn't change no matter what you set, it's usually a (grounding) problem.

 

[Audiohertz2]

Run Rex , Run ....!

 

[Robh3606]

Wow what are they? Looks like a kluge and the soldering is awful. You do practice the one hand rule?

Taking High-Voltage Readings on Hybrid Vehicles | Fluke

One of the most common measurements of a hybrid vehicle's high-voltage system is the voltage reading taken after disabling the system to verify that it has been properly shut down.

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Rob

 

[Alrainbow]

Old solder or even this is not bad unless it’s loose.
the older Krell’s were not so nice
boards not cleaned up of solder past
back then they used good solder
I use the good stuff too and flux
the plan starts to make it look no one was there lol. not always works.
I just finished a recap of a Krell amp.
man im
Old and it’s heavy worked on the floor amp on a moving dolly.
in my I have a power lift 2000 pounds rated
lifts 36 inches
Here cave man repair , my neck and back are pissed if st me now.
advil helps

 

[Kingrex]

Something is making the input and driver run microphonic in one amp and not the other. I could try and mirror the amps. I don't know how to read resistors to purchase parts and it myself. And I don't have time. How you do Al is beyond me. Don't you have a pretty big business to run. I could try a local guy who does guitar amps. Ask him to only mirror the amp that works as it should.

The tech who did the work ask to see a video of the noise. I will make that today and download the app to measure the type hum.

 

[Alrainbow]

Something is making the input and driver run microphonic in one amp and not the other. I could try and mirror the amps. I don't know how to read resistors to purchase parts and it myself. And I don't have time. How you do Al is beyond me. Don't you have a pretty big business to run. I could try a local guy who does guitar amps. Ask him to only mirror the amp that works as it should.

The tech who did the work ask to see a video of the noise. I will make that today and download the app to measure the type hum.

Rex ill
Help all you need bro.
a question. how many amps of this type do you have ?
did I understand you it’s two pairs ?
have you gone to diy forums ?
they can help but not always lol.

 

[DasguteOhr]

Wow what are they? Looks like a kluge and the soldering is awful. You do practice the one hand rule?

Taking High-Voltage Readings on Hybrid Vehicles | Fluke

One of the most common measurements of a hybrid vehicle's high-voltage system is the voltage reading taken after disabling the system to verify that it has been properly shut down.

www.fluke.com

Rob

Looks a bit like horace pinker repairs tv..sorry bad joke.
Just the way how the dale resistor is attached, it has two screw holes and that is not without reason (cooling screwed tightly to the cooling surface)

P.S
Find an old TV/radio repair shop. These people grew up with tubes and they will repair them for you, it won't cost much.
A little story: when I couldn't repair anything myself, I did the same thing. The older gentleman was really happy. He said, "Finally, something to do with tubes again, he knows about it."

 

[Kingrex]

Rex ill
Help all you need bro.
a question. how many amps of this type do you have ?
did I understand you it’s two pairs ?
have you gone to diy forums ?
they can help but not always lol.

It is one set of monoblocks. The same ones I have always had. The real flame is they are so close. They play very nice. I am enjoying the music they produce very much. But I do not like hum. It was coming and going so I was chasing power as the culprit. I got out my Akiko Corelli. That helped some. I moved power and interconnect cables around. No change. I tried different tubes. That showed me the issue was isolated with one amp. I eventually opened the top and found they are not wired the same. I have 0 technical expertise. I can only assume one amps power supply is wired so that the input and driver run stable and don't allow vibrations to be amplified into the circuit, while the other one does pick up this noise.

I don't see ever personally opening these amps to work on them. Like I said, there is a solder slinger near me that does guitar amps. If he had one amp to mirror, he could at least make them the same. I hope that would work.

I would much rather these go to a competent tube audio technician. One who gets a SET circuit. But that is hard to find. Especially locally.

Here is a fun kicker. The guy who imports Audion and has sent these amps to different technicians is telling me I am a problematic customer. That I won't be happy with any audio equipment. I find that down right insulting. I have given this guy $`10,000 to make these amps correct. When I show him verifiable evidence they were done incorrectly, he tells me I am the problem. What an ASS.

 

[Atmasphere]

Something is making the input and driver run microphonic in one amp and not the other. I could try and mirror the amps. I don't know how to read resistors to purchase parts and it myself. And I don't have time. How you do Al is beyond me. Don't you have a pretty big business to run. I could try a local guy who does guitar amps. Ask him to only mirror the amp that works as it should.

The tech who did the work ask to see a video of the noise. I will make that today and download the app to measure the type hum.

Rex, I recall silencing the buzz in an amp you had that was based on an old Eico circuit. Too bad it wasn't all that great musically. You might have kept it and this thread might not exist.

What I don't understand is that somehow you persist working with amps that look messy inside, that are (unsurprisingly) prone to buzz. FWIW, I can tell you that if the amp looks orderly and neat inside it has a much greater chance of also being reliable and low noise. One of the reasons for this is simply the fact that you know the person who built the amp took pride in their work. But it also points to care in the layout on the part of the designer. A rat's nest is no way to build an amp

I know this says nothing about the sound. But there are amps out there of nearly all persuasions that aren't a mess inside, hold together and sound great.

I think you could do a lot better without spending so much and it really wouldn't matter what kind of amp you got as long as it is musical in your system.

 

[MarkusBarkus]

...Rex you have posted pics of your panel boxes, wires landed in boxes, etc. and you're a honcho in the electrical world. That's how I learned to do it in the '70s myself. When I see a rat-nest in a panel, it makes me wild.

The EE world is similar for components, PCBoards, etc. IMO.

Some stuff you see and know: F-inA, those folks know what they're doing. The detail is primo. It's how you would do it, Rex.

A lot of folks can get stuff to work, but working well and using best practices to ensure longevity/performance is a level up.

Not everyone is up to the task. And similarly, in the electrical world, a guy can loop wires, hook up breakers and make the lights come on, but mama-mia, pull back the drapes, and it might be a monster.

There are problem customers, for sure, but knowing how things are supposed to be is different.

About 10 years back, I had a company renno our kitchen. Full gut. Their local guy did the custom veneer work for odd-ball panels to match the manufacturer's cabs. They pimped him hard. He's the man.

Well, he delivered multiple panels with issues. Small junk under the veneer, so I know he doesn't have a clean room to spray finish/adhesive.

Another panel with the wrong % of reflectivity in the clear. It's obvious. He wants to re-spray. I tell him no. You will fill in all the grain if you do that and it will not look the same.

He does it...and of course it looks different. Same sheen, but now it's a texture issue.

He sez I'm a problem customer. He's been doing this for 30 years. So I say: I've been driving for over 50 years, does that qualify me to run at Talladega? Whoah, I thought he was coming over the island at me.

So I asked him: is this the best you can do? He sez yes. That's acceptable, professional work.

So I said: great. Now we solved our problem. You are not the right person for this job. Can't ask a guy to do a job he can't do.

Found a different guy, and it was fine. Sorry... is that story too long?

Knowing what's right, doesn't make one a problem customer. At least, in my view. Good luck out there, fellas.

 

[DonH50]

@Kingrex Do you have a schematic of the amps? May only be a start since it looks like each is a one-off wiring job. Lots of poor solder joints and questionable wiring dress visible but impossible to say from behind a keyboard the actual cause.

I find it interesting he uses finned power resistors but mounts them upside down in free air, restricting air (heat) flow and obviating the heat sinking from mounting them to a panel as is usually done. Not necessarily a problem, but interesting.

In any event, I am pretty sure everyone on this thread agrees that you are not the problem. My guess is he knows there's an issue and is looking for a way out without having to fix it.

 

[Kingrex]

No one wants to see a customer again unless they have their wallet.

He's just weird. All high on its the best thing ever, till its not. Then offened you said something.

I put white tack putty around the case. It damped enough vibration I'm not getting feedback. The tubes are still hyper sensitive. I would prefer they not be. As long as they play quiet I'm good for now.

 

[Lagonda]

I did not insinuate anything , i said i have not had one fail on me in 40+ yrs ..!

Your friend operating his amplifier deficiently or having a faulty amp does not negate my comment ..

I have also owned many toobs , some failed so didn't, all had some issue Or the other and required more maintenance .

Toobs require more maintenance than their SS counterparts , this is not even debatable..

BTW never had a krell fail on me , tell your friends to monitor the temps on those high bias amps , if you can’t touch the sinks they are too hot turn it off or cool momentarily with a fan ..

Last forever really ..!


PS: If your friend is throwing out those
worthless mono Bloc’s I can arrange a PU , what are they BTW .. ?

Oh please, Krell breaks a lot, had 3 different Fpb amps and a Kps 25sc, they went down about every second year, the Krell failures where always easy fixes by my "local" tech, even when transistors went bad. Tube gear is much worse in my opinion, the people that claim tube gear is reliable are often the ones with a lot of knowledge doing constant maintenance and tube monitoring.

 

[Kcin]

Well they are definitely not identical. I am not sure how the noisy amp is getting power from the one board unless there are jumpers and things going on underneath it. It looks like a timer for a delay on circuit with a relay.

Sorry to say ,but the layout looks experimental- not a commercial product. It looks like something I would do before I figured out how to layout with a DIY project

Kind of like my frankenstein bench

before and after. . I bet if a really thoughtful local guy saw both -- he could put two or three hours in and prove if the layout was at fault through swaps or clean up.

 

[Audiohertz2]

Oh please, Krell breaks a lot, had 3 different Fpb amps and a Kps 25sc, they went down about every second year, the Krell failures where always easy fixes by my "local" tech, even when transistors went bad. Tube gear is much worse in my opinion, the people that claim tube gear is reliable are often the ones with a lot of knowledge doing constant maintenance and tube monitoring.

Never had a solid state amp fail on me , whats your point? As to your Krell Debacle what other SS amps failed on you ...?

Amps failing due to misuse doesn't count, not applying this to your situation but most of the time when they do its because of misuse ...!

 

[Alrainbow]

Regarding Krell amps failures , I’ve not had one fail but I am one who observes and does recap amps before the explosion occurs.
I think heavy class a amps work the caps harder due to bias
I just recapped my ksa200b
after I measured the caps I removed.
I can’t say I did all but they did Measure ok except the ESR
the date codes are circa 1990
I can see someone did not recap but did replace the heat conductive paste

 

[Alrainbow]

My 750 cx is newer but I recapped them anyway
they had brown nichicon caps
They were replaced with united chemicon
three driver caps were exploded yet the output transistor was ok.
when I re capped my ML no 33 I was shocked the main psu caps measured way above there rating. I was told this happens with age of caps and more complex testing is needed to determine correctly.

 

[Legolas]

Well they are definitely not identical. I am not sure how the noisy amp is getting power from the one board unless there are jumpers and things going on underneath it. It looks like a timer for a delay on circuit with a relay.

Sorry to say ,but the layout looks experimental- not a commercial product. It looks like something I would do before I figured out how to layout with a DIY project

Kind of like my frankenstein bench

before and after. . I bet if a really thoughtful local guy saw both -- he could put two or three hours in and prove if the layout was at fault through swaps or clean up.

I am confused, is this an actual audio company making these amps, or a DIY project? The wood chassis and wiring look very DIY to my eyes.
My advice is buy from an actual audio brand, USA based would make sense. Then you have company history, a warranty and service backup. A company making low volume DIY type products can't survive for long. Maybe selling kits but not finished product.

 

[Kingrex]

The tacky putty is working. These amps do sound good. I enjoy the SET sound. I don’t like bubble gum and duct tape as a solution. At least one was done right. I have a template for someone to follow when I want the other correct. I can hear the incorrect amp has a low level hum slightly higher than the more functional one. I'm sure vibration is slipping through.

Maybe one day my life will settle down and I will find the time to match the circuit on my own.

The US distributor for Audion agrees his tech cut corners not matching the amps to the schematic he was given. He wants to do good by me as he too thought they were complete. He wants me to hear a well functioning prodect as he believes they perform at a high level. And I agree they are very nice amps with the hum shut down. I don't have enough experience with SET to know where they stand in that regard. As far as a tube amp goes, It's its own thing. Its not a CJ. CJ has balls. Its better than the Rogue and Ampsandsou. It's definitely not a Blade. Its not near the resolution. But it has nice body and good resolution. It's very tube dependent. But many tube amps are.

 

[Ampexed]

Regarding Krell amps failures , I’ve not had one fail but I am one who observes and does recap amps before the explosion occurs.
I think heavy class a amps work the caps harder due to bias
I just recapped my ksa200b
after I measured the caps I removed.
I can’t say I did all but they did Measure ok except the ESR
the date codes are circa 1990
I can see someone did not recap but did replace the heat conductive paste

It is mostly heat which degrades electrolytic capacitors. The temperature rating you see on the cap is the temperature at which it will give it's rated number of hours of service (usually something like 5000 hours). As temperature goes down, the life of the capacitor increases proportionally. Caps right next to hot heat sinks will last less time than one far away from a source of heat.