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Old 17th February 2019, 04:21 PM   #11
Sandy82579 is offline Sandy82579
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Join Date: Feb 2019
Default Wondering About Components for Mod

So I read this thread with interest since I’m about to put together my TU-8200, and I have a few questions:

I found all of the parts and have ordered them except for the Nichicon CS(M) capacitors. Mouser has them listed in their film capicators but they have no stock and you can’t order them. Digikey doesn’t even have them listed. I substituted the Nichicon UCS series electrolytics. Will those work?

I was also wondering why we shouldn’t use “audio grade” caps (+-10%) instead of “general purpose grade” (+-20%), and would it make any difference?

In addition to twisting the power wire that runs from back to front, would it help to shield it somehow to reduce the hum?

Finally, you cannot get the FETs 2N60Z anymore. No one has them. Do you know a good substitute?

Thanks for going through the mods and providing the changes. I just want to build the best sounding TU-8200 I can,and I think these changes will help.
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Old 18th February 2019, 03:18 PM   #12
paczeltf is offline paczeltf  Hungary
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I received this in PM first and replied to that, but now that it has been posted to the thread, here is the summary of what I wrote for those who are interested.

From looking at the respective datasheets, Nichicon CS(M) and UCS are practically identical. You should be fine with either.

I doubt that boutique electrolytic caps would make a big difference in the power supply of this amp, and they also tend to be bigger than regular models. Space is the biggest limitation, unless you want to install these caps to the chassis and connect them to the PCB with wires, which almost certainly will introduce hum.

The biggest reduction in hum was achieved by the bigger C22. Twisting the power wires should be enough, I also recommend twisting the power transformer primary and secondary wires once before connecting them to the respective boards.

I cannot hear any hum with headphones in triode mode (which I do not like), and just a very distant hum in the preferred UL mode, which was not exactly the case with the original setup. The speakers are totally silent in any mode.

If we wanted to reduce the hum even further then we would probably need different PCB layout with separate power transformer secondary windings and grounding for the left and right channels as well as DC heating of the power tubes.

I could not order the FETs online either so I bought 4 pieces from Elekit when a defective "NOS" power tube killed one. Victor may also be able to help. I have not yet managed to find a replacement. The problem here is that Q3 and Q4 are working close to their dissipation limits so we need to be careful here.

Also note that the group of changes that I suggested are kinds of enablers for the driver stage update, which makes the real difference. (This is why I wrote in my post that it was the first part..)

On the other hand, having a more robust power supply with less hum and heater voltages closer to the nominal value should also make a difference.

Regards,
Ferenc
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Old 25th March 2019, 10:03 AM   #13
Unikis is offline Unikis
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I am at "dummy level".

My question is- what would happen, if I use 500V caps instead of 400V; 420V (C22, C23, C24, C7,C8, C11, C12)? Or maybe 350V instead of 400V? Or I should find exactly 400V?
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Old 25th March 2019, 07:56 PM   #14
paczeltf is offline paczeltf  Hungary
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500V caps are bigger and may not fit the board or the space between boards. Be careful as caps in the same product line are usually available with different lengths and diameters. The list that I attached contains caps that you can install without having to modify anything.

350V caps should be fine except maybe for C22, but I tend not to use caps and other components close to their limits in a particular area.
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Old 25th March 2019, 09:08 PM   #15
Unikis is offline Unikis
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I found and ordered all items you have listed in excell document at www.digikey.be

It sounds, that you know what you are talking about, therefore I trust you


It would be interesting to hear any other modifications, if they are necessary. My Elekit TU-8200 will arrive next week and I want to make as you have recommended. Maybe will add some fancy caps later.

Thanks!
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Old 27th March 2019, 08:44 PM   #16
paczeltf is offline paczeltf  Hungary
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Well, if you build the amp with the mods in the first place, you won't know how it sounds with the stock components

The changes I recommended let you use better driver tubes than 12AU7. Send me a PM for details.
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Old 31st March 2019, 07:49 PM   #17
Disque is offline Disque  Netherlands
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I Read all the posts with great interest, because I expect a kit amplifier to show many compromisses. Your sugestions for upgrades are to the point and well designed. So I am very interesten in your ideas about modification of the driver stage. Do you think about ecc99 family or ecc88?

With many thanks for your work so far!
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Old 5th April 2019, 09:15 PM   #18
paczeltf is offline paczeltf  Hungary
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These tubes do not fit the TU-8200 for the opposite reasons.

ECC88 was designed for low plate voltage and relatively high cathode current, it is not really a driver tube. You would also need a socket converter.

ECC99 is certainly meant to be a driver, but it draws too much heating current and is an overkill for this kit.

E80CC is the right tube for this kit from many aspects as long as you use it with 6L6GC (or maybe KT66). I know some kit owners have already installed them but the rectifier upgrade is NOT enough to support these great tubes correctly.
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Old 7th June 2019, 11:25 PM   #19
Sandy82579 is offline Sandy82579
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Two things. On your spreadsheet updates C34-C35 have the same “original value” and “new value”. Should the “new value be the same as C33? 330-470uf/16v

Also you say about the E80CC “the rectifier upgrade is not enough to support these great tubes correctly”. What would need to be done to correct this.
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Old 8th June 2019, 11:26 PM   #20
oface1 is offline oface1
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Here's a headfi post on the TU-8200 and all the posts on tube rolling and modifying.
Elekit TU-8200 DX Headphone/Speaker Amp Review | Headphone Reviews and Discussion - Head-Fi.org

It is pretty lengthy, yet it is active and has great posts on those who have modded and rolled new tubes and their results.
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