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DIY McIntosh Amp
DIY McIntosh Amp
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Old 14th October 2019, 01:39 AM   #141
6L6 is offline 6L6  United States
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DIY McIntosh Amp
Quote:
Originally Posted by mc240 View Post
... I just wanted to know if anyone has built a worthwhile tube amp yet and I don't see anyone who has done it DIY... maybe a little SE amp with 10 watts, but that's not going to do it for me. I'm looking to build the real deal.

What do you mean by "worthwhile tube amp"?

I'm not asking to pick a fight or argue, I'm looking for clarification and understanding. You've been talking about a MC240 clone, that's not impossible but there's going to be a challenge sourcing the output transformer. The reasons people don't clone McIntosh amps is the transformers. IF you can get them made, seriously, that's awesome, and I'd be interested in a pair myself.


Quote:
I think now I want to look at SE and PushPull quality tube amp kits or quality instructions/schematics that are really good like the MC240 or better specs and sound quality.
Again, asking to clarify, you want a kit and not building it from scratch?




Then you start talking about a 20W SE amp here -

Quote:
I think a really quality SE tube amp with 20 or more watts and super low distortion and great sound quality would be a good idea.
20W SE is a fairly tall order, but not impossible. "Super low distortion" and "tube single ended" do not live in the same universe. This not not to say that there are no 20W SE amps that sound good - there are plenty. But that's not a specification that will ever happen. "Low distortion" in SE amps is 1-5%. (Yes, people will argue with me, but it's not, overall, an in-genuine number.)


Quote:
Or is there a recommended kit for a "more or less" MC240 or MC275 clone with the same or better performance (I like the +/-.1% db of the original MC240 and how it can handle almost any speaker.
In a word, no. There is no easy way to clone the MC amps and there are no kits.


From what you've asked/talked about you seem to be wanting an amp, tube output, SE or PP, 20+ watts output, preferably a kit, with the ability to drive somewhat difficult loads.

Is this correct?




EDIT: (Again for further clarification of mission and also to add some information)

Way back in post 1 you say;

Quote:
Originally Posted by mc240 View Post
I've asked about doing a MC240 clone and it seems like the transformers are too hard to DIY...
Yes, they are.

But more interestingly;

Quote:
So, is it possible to do a CJ clone? How do their designs differ from the MC240?
Are the CJ transformer designs public information?
Ok, let's look -

Click the image to open in full size.

(Image from here Conrad Johnson MV75 )

This is the c-j MV75, a very highly regarded amplifier and still sought after today. Speaking in broad generalities, it's a fairly classic tube amplifier layout, has a simple and effective voltage gain stage, followed by a differential amplifier ("long-tailed") phase splitter, has "fixed bias" (which is actually adjustable, because naming conventions are weird), uses KT88/6550 for good power connected to a completely standard (and easy to source) ultralinear transformer. The PSU is solid-state with a choke and voltage-referenced capacitance multipliers.

This is a very nice design and I'd happily consider it a candidate for cloning. Performance will be dictated mostly by how much money you're willing to spend on output transformers. If you get, for example, Electra-Prints, it's going to sound absolutely incredible.


Now let's delve into the MC240 a little -

Click the image to open in full size.

Look at the output transformer. It's on the schematic where you'd expect it, as well as just below the output tubes.

It's got the "normal", primary windings, the "normal" secondaries, the specific to Mc designs cathode windings, AND a feedback winding. (14 filars in total, that's a LOT)

(and anode chokes, but those are separate...)

Now the circuit design itself is pretty unique as well, as there needs to be a lot of gain in the drivers to overcome the lack of gain in the output, as well as something specific to the design that has to do with feedback. I'm sure George can explain it much better than me. These two things do point to why it's not normally cloned, as we've already talked about - the transformers are difficult to source and probably won't be the right design, and the design is super complicated overall. BUT my experience IF the design is a very good performer and worth the bother, people will figure out a way. It speaks volumes that people don't clone it.



Copy of the Sam's Photofact of the MC240 - Box

Last edited by 6L6; 14th October 2019 at 04:48 AM. Reason: typo
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Old 14th October 2019, 01:51 AM   #142
TonyTecson is offline TonyTecson  Philippines
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mc240, death is permanent, and if you are doing this for the first time project, then i will discourage you...do something less lethal...
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Old 14th October 2019, 02:21 AM   #143
scott17 is offline scott17
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mc240,
Take a look at the "stickys" at the top of the Tubes/Valves forum. There is one named "Safety Practices, General and Ultra-High Voltage", and another named "On Line Tube Learning for newbies...." .
If you read through those it may help you in your understanding of the subject.
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Old 14th October 2019, 02:37 AM   #144
mc240 is offline mc240
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Quote:
Originally Posted by scott17 View Post
mc240,
Take a look at the "stickys" at the top of the Tubes/Valves forum. There is one named "Safety Practices, General and Ultra-High Voltage", and another named "On Line Tube Learning for newbies...." .
If you read through those it may help you in your understanding of the subject.
lol, the lab at college had it's two of it's own power grids, each the size of a city block, just for the lab. The lab is funded by the US dep of energy. You guys sound a little silly. It's not voltage that is dangerous, it's the amperage... even a tiny amperage can kill people, but they make kids toys out of 5000v plasma globes. I seriously just touched a raw wire 120v/15a and it was not something I want to repeat and could kill a weak person, I guess I was lucky but didn't die. However I don't any hi-fi amps have 15a going through them once the power transformer does the work. The power transformer probably ups the voltage and greatly decreases the 15a from the wall to something a lot safer. Again you guys sound silly and what I see is a bunch of people trying to sell stuff and posting links to their own companies or friends companies. You guys must see everyone coming on here as potential fresh meat to trick into buying your stuff.

Back to the topics if the OT from NL doesn't have the right wires, then I'll tell them to make one that has the right wires. Seems simple enough. It's not rocket science, but I could work for NASA if I wanted to.

And you guys kept saying that the OT are so expensive, since when is $200 euros expensive? You guys have to really read the stuff you type.
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Old 14th October 2019, 02:51 AM   #145
6L6 is offline 6L6  United States
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mc240 -

I'm putting on my moderator hat and suggesting that you very carefully and seriously take the voltage warnings that are being offered to you in good faith. You have an education in electronics, figure out how much energy these PSUs have at 500V stored in the caps and choke. These amps can bite hard if you're lucky, and have the potential to be easily (and quickly) lethal.

People here in this thread are very knowledgable and experienced in the making of building tube amplifiers. They are trying to help you, because this is what the forum is all about. We honestly want you to succeed.

If you make another comment with the tone being completely caviler about HV safety, I.E., about how this stuff is safe and I know what I'm doing, and you guys don't have a clue, don't worry, I've been shocked before, etc... I will close the thread.


Last edited by 6L6; 14th October 2019 at 02:57 AM.
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Old 14th October 2019, 02:59 AM   #146
SpreadSpectrum is offline SpreadSpectrum  United States
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Quote:
Originally Posted by Tubelab_com View Post
Look it up, as I did.....it does not have the required cathode windings.
I'm not sure where you looked it up, but the VDV-1070-UC should be the same as the Plitron PAT-1070-UC (Both are the Vanderveen Unity-Coupled transformer made by different companies). They should both have bifilar primaries with plate and cathode windings.

Wherever you looked it up probably gave you bad info.
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Old 14th October 2019, 03:22 AM   #147
smoking-amp is offline smoking-amp  United States
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The earlier link in this thread (post 53) gives this:
Specialist: VDV-1070-UC-PPS

and the page 2 pdf there gives this:
https://www.mennovanderveen.nl/cms/i...atasheet-2.pdf

Seems to be showing two screen windings instead of the cathode winding. Maybe it works as either? Would be a different primary Z for the two cases. I think the pdf has the wrong diagram or is labeled incorrectly.

Last edited by smoking-amp; 14th October 2019 at 03:38 AM.
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Old 14th October 2019, 03:36 AM   #148
indra1 is online now indra1  Indonesia
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Quote:
Originally Posted by mc240 View Post
... I ... have a Physics degree from a top 20 university, I'm the CEO of more than one scientific company, I helped record my first album at age 10 or 11, I've been playing with the big toys since I was a kid. ... nothing I didn't already know in 1993.
Now you told us your qualification. You had been a no name avatar with no location, country nor qualifications, and you may as well turn out to be the actual legitimate emperor of China.
Quote:
Originally Posted by mc240 View Post
Ok, I looked up the "Monolith Magnetics"... those kind of shops charge a lot for something that costs them a little, definitely not DIY friendly. The best place to get cheaper transformers is from a place like this, since in my previous post I've shown where a unity coupled transformer to the original McIntosh specs cost just $36 to build DIY. ...
Forgive us Your Royal Highness, perhaps I could interest Your Royal Highness to help President Trump a little bit by starting a DIY friendly transformer shop in the good old US of A? You seem to possess qualifications much higher than any transformer maker that we know of worldwide. Let me contribute to the great effort by placing a firm order of 4 (four) pieces of MC240 transformers. Kindly have pity on our limited resources we can draw from and charge us no more than US$ 54 for a 50% profit from your firm claim of a US$ 36 cost of production. 6L6 also mentioned an interest to acquire 2 (two) pieces. I and 6L6 will promote the DIY friendly transformer shop here in our lowly DIYAudio forum and every other way we can think of as soon as Your Royal Highness notify us that the great effort has been put in motion.

Last edited by indra1; 14th October 2019 at 03:46 AM.
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Old 14th October 2019, 04:00 AM   #149
smoking-amp is offline smoking-amp  United States
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Some Twin Coupled Amps for reference:

1) Norman Crowhurst's 2nd version with EL34

2) J Stewart's Twin Coupled version with 6LU8

3) article on N. Crowhurst Twin Coupled
DIY: EL34 Twin Coupled Stereo Tube Amplifier - Stellar Vintage Electronics of California
Attached Images
File Type: png Crowhurst-twin-coupled-EL34.png (61.0 KB, 111 views)
File Type: png Twincoupled-Amp-B_J_Stewart.png (18.7 KB, 112 views)
File Type: png el34-twin-coupled-tube-amp.png (56.7 KB, 110 views)

Last edited by smoking-amp; 14th October 2019 at 04:05 AM.
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Old 14th October 2019, 04:36 AM   #150
6L6 is offline 6L6  United States
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Please note that this thread has been merged with mc240's thread "diy conrad johnson clone".
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