I am sick of failing amplifiers

[Kingrex]

I had Mcinsosh issues too. At the beginning of my journey I bought a Mcintosh preamp. When you turned the volume knob, the right channel would rise 3 clicks and get louder but the left would not change. On the 4th click, the left would jump up to match the right. I sent it back 3 times. It was going to a local shop that sold Mac and.was a repair shop. They told me it was fine. I dumped it on Audiogon.
Years later, at a show, I approached a Mcintosh employee in a showroom and told him my experience. He apologized and said he was familiar with the issue with the volume control on the one I had.

When I sold my Dartzeel. The guy who bought it said his friend tested it, and the output was not equal on both channels. 6 db down. I said no way. I would have known. How did he test it? I asked. No response to that. Just that he was sending it to Europe to be.fixed. I wrote Herve and asked to know what was up as this guy would be in his right to ask for shipping and repair cost if it was not working to spec. Herve wrote me and said the amp was working perfectly. He did include they were going to ask for some amount of money from the owner to resolder some loose connections and clean up some other small stuff. So, technically, those loose points could have come apart on me at any time. And yes, it would suck to have that happen today. The owner has it back now and says it plays great.

 

[Another Johnson]

When you consider the size of the McIntosh installed base, and the fact that 2024 marked their 75th anniversary, it’s not surprising that there are some clunkers out there.

Vintage McIntosh can bring two digit multiples of the original selling price, even with known issues.

I used to trade old McIntosh… the last piece I sold off 10 years ago. Two Chinese eBayers, each with thousands of feedback points as buyers and no feedback points as sellers duked it out at the end of the auction for the right to buy my “working” MX110. I’m sure it was going in a container to be shipped to the Far East.

This guy got me started.

McIntosh Home Audio For Sale, McIntosh Labs Used Audio Equipment

He’s still at it.

 

[Republicoftexas69]

Not a hickup (knock on wood) out of my SPL, Gold Note and LessLoss eq... Put my tube gear up today and thinking of selling...

 

[Kingrex]

When you consider the size of the McIntosh installed base, and the fact that 2024 marked their 75th anniversary, it’s not surprising that there are some clunkers out there.

Vintage McIntosh can bring two digit multiples of the original selling price, even with known issues.

I used to trade old McIntosh… the last piece I sold off 10 years ago. Two Chinese eBayers, each with thousands of feedback points as buyers and no feedback points as sellers duked it out at the end of the auction for the right to buy my “working” MX110. I’m sure it was going in a container to be shipped to the Far East.

This guy got me started.

McIntosh Home Audio For Sale, McIntosh Labs Used Audio Equipment

He’s still at it.

Awe come on. We were about to get on a good bash fest!!!!!

 

[Kingrex]

In all truth my gut says McIntosh is probably one of the better more reliable audio brands. There is a lot out there.

 

[Charles S]

I hear you Charles.
At some time I want to shrink my speakers. I'm probably selling the house we bought and building a new one on a differerent propery. I will have a living room system again. I don’t want that pile of stuff.

As far as new and improved. I don't fully believe top of the line multi hundred thousand gear is always better. I doubt most people have the electrical power or room to really appreciate it. And I wonder, is it really better. Every reviewer will tell you it is. Every forum member that bought it will say so too. But is it????? Better power and a better room with tuning what you have would probably take you further.

I have a past client that has dirty utility power. He bought a Puritan. He still hears the power fluxuate durring the day. He just bought a Goal Zero home back up power supply. Basically a 4kVH lithium battery in a pretty package with a built in charger and a pure sine wave inverter. About $2700. He plugs his putitan into this and has his front end gear powered by Puritan feed by battery. Here is what he says.

I'm pretty good and quickly sizing up sonic differences. I’m less good at being able to tell which I prefer - this can take months. But here’s what I found:

-On the GZ everything is gains a massive transient punch. And I mean punch, like I’ve never heard before (my current system already leans this way and the GZ seems to have let it go even further this way)

-Increase in clarity and all traces of bloom seem to be removed.

-Vocals and mids are moved up more forward and are noticeably clearer and prominent. But somehow it seems at the same time there is no change in tonal balance vs the wall (great!)

-More detail retrieval

-Even though there seems to be no tonal change the sound feels cleaner and a touch lighter - I think this is due to the loss of bloom. Bass is just as present but is more defined and detailed with less bloom.

-Images are rock solid - when connected to the wall I always have the sense that the sweet spot is continually shifting and morphing. Always thought it was my imagination and OCD. With the GX that feeling has totally, utterly vanished.

Why do I bring this up. What he said is the same language use to describe changing your $60,000 DAC into a $300,000 DAC. The guy spent $2700. He is tuning what he has. Yes you can chase your tail buying tweeks.
I have been pondering battery power for some time. I was looking more at large high output inverters. Like 30,000 watt for whole.home. Then a bank of batteries. As much amp hours as you want. Then a Torus attached to the output of the inverter. I figgured I could make something far more robust than 2 x Stomtank S5000 for about $22,000. And it would not be in your room. In a garage somewhere. Anyhow, I never got to it.
I may become a Goal Zero distributor and create a package of GZ plus Torus. It would include a special power cord to attach the 30A output to the 20A IEC of the Torus. There is also a way to open the GZ and access taps that were a future way to chain batteries in parallel. That would provide limitless current. That output could go into a device like a subpanel or one of my integrated power panels that have breakers and duplex all in 1 enclosure. Set it behind your rack.and have massive battey current for whatever gear.

Kingrex, unless I am mistaken you are still on your journey for better sound and will be for some length of time. I totally agree that the "light pole" whether it be a battery, whole house generator, solar, or regular utility company makes a huge difference that power conditioners cannot compensate for. A quality fuse box with dedicated 20 amp lines is preferable. Every line that I have is a dedicated 20 amp line, no.10 wire, coming straight out of a 440 amp fuse box. I also have a Transguard TG60 surge protector between my the transfer switch of my whole house GE generator and the light pole. It has a noise filter on it that is amazing. It removes the kind of noise that you don't realize is there until it is gone. It's very good to meet you.

 

[Charles S]

I recently bought a MC2.1KW An. I waited patiently for 20 years for this amplifier. It is a thing of beauty, weighs 415 pounds, and has 526,000 microfarads (1,720 joules) of capacitance. For 50K IMO it is an excellent value. It is surprising how much better it controls my Thor than my previous amp which was an MC1.25KW. I can't speak for anyone but me, but I have had excellent reliability (not perfect) over the course of many decades with McIntosh. Recently the original tubes of the Mc3500 MKII, the blue and red output tubes, were of very poor quality. However, Mac got right on it, and the green labeled tubes are quite reliable driving my XVX.

 

[Kingrex]

 

[Kingrex]

Here are the potentiometers. I can see in the hole. I can also see in the large crack. In the crack I can see the swiper moving over what I assume is the steps. Through the hole I think I am seeing the back where I would assume the resistors are.
I was told Caig Deoxit G spay should be fine. Its supposed to be a cleaner and then leaves a thin film that is not conductive. As in it wont arc from point to point. The Caig D series is more a cleaner for oxidation. I am kind of torn what to use. If I have oxidation, I guess I should use the D.

I never opened these when I got them back. I paid a guy over $6000 to fix these. Of course I heard the shit talk about Mu metal being used to quiet noise. I also heard crap about a couple pieces of wood under the output transformer. I have no idea why the other tech put the wood there. Anyhow, upon opening the unit, the Mu metal is still there. As well as the wood under the output transformer. It makes me shake my head. The input transformer that was one of the issue was replaced. That it what the Mu metal was wrapped around. So if it was such a laughable item, why did the tech put it back. Maybe it wasn't such a stupid idea. And why is the transformer still on wood. I included some very high tech NASA damping rings that could have gone in the place of the wood for better vibration control. That type of work is just not me. When I get into something, If I am laughing at what the last guy did and I am crapping on his work, I change it. I make it the way I believe it should be. I also see a wire that is coming off the 845 from the hum pot. No sure what it does. But its pressed up tight against a choke or small transformer. Stuff like that bugs me I would love to have the time in my life to pull these amps from the under sized enclosure they come in and put them in a better box. Make some space. Try and quiet them just a little more. I don't have the skills or the time.

And, per what I was writing on the SET thread. They do sound very pleasing and nice. I am actually enjoying them more than I thought. Once I was a few days away from the Blade I was able to take off my audiophile hat and just enjoy the music. A 845 plays nice. Its very full and organic. Nice body. My transformer coupled, differential design KT88 PP amp with a lot of Monolith is way more clean, articulate and fast. These amps don't snap a snare near the same. They don't have the body of the stand up bass expressing the wood character and hearing the buzz of the string. But they have more body and flesh. They are liquid and easy to digest if you sit back and just listen to the songs because you enjoy the music. I am glad they finally work and in my collection to enjoy.
Rex

 

[Kingrex]

 

[Kingrex]

I was told the following

• 12 minutes ago

• 
  
• Add bookmark
• #3,915

Have you signal sources that dc coupled?e.g dac
You often see these days that there are no coupling capacitors in front of the volume pot on tube amps. That's high-end today, unfortunately DC voltage destroys contacts and sliding tracks over a longer period.
If there isn't one, just solder 0.1-0.15uf into the signal path. Just try it out and see if there is no more noise when switching. A photo of this would be helpful.
Do it the old school standard.

 

[Kingrex]

I would assume this cap needs to be high quality.

I was told there is an autoformer substitute. Would that fix any DC issue? Would I still need a cap before that?

 

[Ampexed]

I would assume this cap needs to be high quality.

I was told there is an autoformer substitute. Would that fix any DC issue? Would I still need a cap before that?

Autoformers pass DC.

 

[DasguteOhr]

You need only mkp cap for test like e.g wima what you use later is up to you
Exsample pic

With autoformer no problem just pay attention to what the maximum input voltage of the autoformer is.

 

[Kcin]

Here are the potentiometers. I can see in the hole. I can also see in the large crack. In the crack I can see the swiper moving over what I assume is the steps. Through the hole I think I am seeing the back where I would assume the resistors are.
I was told Caig Deoxit G spay should be fine. Its supposed to be a cleaner and then leaves a thin film that is not conductive. As in it wont arc from point to point. The Caig D series is more a cleaner for oxidation. I am kind of torn what to use. If I have oxidation, I guess I should use the D.

I never opened these when I got them back. I paid a guy over $6000 to fix these. Of course I heard the shit talk about Mu metal being used to quiet noise. I also heard crap about a couple pieces of wood under the output transformer. I have no idea why the other tech put the wood there. Anyhow, upon opening the unit, the Mu metal is still there. As well as the wood under the output transformer. It makes me shake my head. The input transformer that was one of the issue was replaced. That it what the Mu metal was wrapped around. So if it was such a laughable item, why did the tech put it back. Maybe it wasn't such a stupid idea. And why is the transformer still on wood. I included some very high tech NASA damping rings that could have gone in the place of the wood for better vibration control. That type of work is just not me. When I get into something, If I am laughing at what the last guy did and I am crapping on his work, I change it. I make it the way I believe it should be. I also see a wire that is coming off the 845 from the hum pot. No sure what it does. But its pressed up tight against a choke or small transformer. Stuff like that bugs me I would love to have the time in my life to pull these amps from the under sized enclosure they come in and put them in a better box. Make some space. Try and quiet them just a little more. I don't have the skills or the time.

And, per what I was writing on the SET thread. They do sound very pleasing and nice. I am actually enjoying them more than I thought. Once I was a few days away from the Blade I was able to take off my audiophile hat and just enjoy the music. A 845 plays nice. Its very full and organic. Nice body. My transformer coupled, differential design KT88 PP amp with a lot of Monolith is way more clean, articulate and fast. These amps don't snap a snare near the same. They don't have the body of the stand up bass expressing the wood character and hearing the buzz of the string. But they have more body and flesh. They are liquid and easy to digest if you sit back and just listen to the songs because you enjoy the music. I am glad they finally work and in my collection to enjoy.
Rex

That looks like a Khozmo attenuator.

They have a reputation of turning noisy. Nothing can fix them except for replacement unfortunately.

 

[Kingrex]

So I am hearing. $15k of upgrades and repairs, and I get a crap POT.

 

[Kingrex]

If I take the four screws off the back, will it fall apart.

 

[DasguteOhr]

If I take the four screws off the back, will it fall apart.

You shouldn't do that, it's the best volume pot you can buy. Also, your Khozmo is shunted with 56k, so it's not in the direct signal path. I've been using them for 10 years and have never had a fault.

 

[Atmasphere]

View attachment 140471

I hope that circuit isn't in the power amp! If its really being fed by 150V, its starving. The B+ should be quite a bit more!! 350V would be a better B+...
There should be a resistor between the pot and the input of the tube. Not a bad idea to also have a high resistance to ground at the grid like 1M. The series resistance can be about 5K or so; its called a 'stopping resistor' and prevents oscillation, which can make the attenuator pop, BTW.

The attenuator won't be damaged by DC from the preamp. That's a non-issue. Even if the tube fails it won't be damaged. So no need for the input coupling cap.

 

[Kcin]

The Khozmo attenuator can be very neutral- however, they have had models that had a reputation for going electrically noisy as a result of their mechanical design. You can find these issues on the web. Any cleaning lubrication has been temporary to fix this in my experience. Fader lube as suggested will give a better feel and buy some time if this is the case.