Hi pbtoko,
It sounds like you live in Japan. Are you able to read Japanese? I'm wondering because it sounds like there has been a lot of forum activity on the TU-879S in Japan so it would be really great if someone were able to tell us what kind of ideas and discoveries people there have made about improving the amp.
Best regards
It sounds like you live in Japan. Are you able to read Japanese? I'm wondering because it sounds like there has been a lot of forum activity on the TU-879S in Japan so it would be really great if someone were able to tell us what kind of ideas and discoveries people there have made about improving the amp.
Best regards
unfortunately no i do not speak or read japanese but google translate helps a lot I beleive Vicktor of VK music posted a couple of threads and essesentlly i've been rolling tubes and caps upgradeing resistors basically trying to understand what i got here before i start another project. i will post any i find later but i think basically this forum seems to have the tweeks down a lot is local availability and what fits! damn those 100uf 400+V foil caps... i am finding more each day
a company Amtrans sells a couple of upgrade kits on Amazon.co.jp they seem make their own high end audio componites such as resistors and foil caps i have bout a few resistors and some better electrolyc caps but not tried their kits which go for 30 or 4 $ plus shipping. Not sure if they ship out of japan through amazom but the do via the website, oh i guess i shoudl say i am a total newbe at this (more dangerous then i know)
a company Amtrans sells a couple of upgrade kits on Amazon.co.jp they seem make their own high end audio componites such as resistors and foil caps i have bout a few resistors and some better electrolyc caps but not tried their kits which go for 30 or 4 $ plus shipping. Not sure if they ship out of japan through amazom but the do via the website, oh i guess i shoudl say i am a total newbe at this (more dangerous then i know)
Although everyone seems busy with the successor of this little amp, I tought I'd share my latest upgrade. While thinking about a nice coupling-C, I ended up using the Intertechnik Audyn True Copper. Just two of these, leaving out the first pair of coupling caps (c1 & c2).
The difference is simply amazing! So much more detail and space. Now I know that the old plastic caps really sound plastic... Highly recommended!
Next will be the power cap. And I know that the Mundorf is the save way, but I'm thinking of the Audionote Standard capacitor. Might even fit under the pcb...
The difference is simply amazing! So much more detail and space. Now I know that the old plastic caps really sound plastic... Highly recommended!
Next will be the power cap. And I know that the Mundorf is the save way, but I'm thinking of the Audionote Standard capacitor. Might even fit under the pcb...
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Amazing little beast
I am glad to see someone else loves the 879 as much as i do, my only regret is not buying two when i had the chance.
i recently had the opportunity to test my build in a audiophiles sound room, comparing it to a pair of marantz 2's the 879 held it own (within limitations 8 watts vs 34) and a few other things)) witnessed by Stig & Jon the "Lyra Guys" of course passing it through a vintage Lyra Connoisseur 4-2L SE pre amp and phono stage was not wasted. lets put it this way i was not embarrassed, even a little impressed it held up so well.
aside form a pair of v-caps i have upgraded resistors added a TKD stepped Attenuator (outside the box disconnecting the original built in one) , i did upgrade the power caps with some slightly better ones of the same design)
the next phase is to do a point to point re wire in a case big enough for some good old school caps. Mumfords, would be great but for now i woudl give something else a try if i can find some that fit.
see pix little beast on the floor next the marantz 2 (with Phillips el34's xf1's and without tubes infront of the speakers.
keep in touch let me know how your power caps fit and more importiany sound.
I am glad to see someone else loves the 879 as much as i do, my only regret is not buying two when i had the chance.
i recently had the opportunity to test my build in a audiophiles sound room, comparing it to a pair of marantz 2's the 879 held it own (within limitations 8 watts vs 34) and a few other things)) witnessed by Stig & Jon the "Lyra Guys" of course passing it through a vintage Lyra Connoisseur 4-2L SE pre amp and phono stage was not wasted. lets put it this way i was not embarrassed, even a little impressed it held up so well.
aside form a pair of v-caps i have upgraded resistors added a TKD stepped Attenuator (outside the box disconnecting the original built in one) , i did upgrade the power caps with some slightly better ones of the same design)
the next phase is to do a point to point re wire in a case big enough for some good old school caps. Mumfords, would be great but for now i woudl give something else a try if i can find some that fit.
see pix little beast on the floor next the marantz 2 (with Phillips el34's xf1's and without tubes infront of the speakers.
keep in touch let me know how your power caps fit and more importiany sound.
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Yesterday finally the second converter arrived. But they have sent me one lokking different from the first one...
At least it works... Bit smoother already than the stock tubes. And quite heavier on mid bass. Which is good, as this amp is used for a 8" fr to play from 150hz up. The bass is taken care for by two OB Eminence Alpha's 15". The transition from woofers to FR is a lot better now!
At least it works...
Bit smoother already than the stock tubes. And quite heavier on mid bass. Which is good, as this amp is used for a 8" fr to play from 150hz up. The bass is taken care for by two OB Eminence Alpha's 15". The transition from woofers to FR is a lot better now!Attachments
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I know you can change this amp to triode mode. But I do not know exactly how...
Has anyone done this? I understand that its successor has a bit less bass, but great mid range in triode mode. And since I'm using it from 150hz up, I can imagine that this could be the way to go for me.
Viktor, could you tell a bit more about the differences in triode mode vs its standard penthode mode? Would be much appreciated!
Oh, and these 807's start to sound better and better!!!
Has anyone done this? I understand that its successor has a bit less bass, but great mid range in triode mode. And since I'm using it from 150hz up, I can imagine that this could be the way to go for me.
Viktor, could you tell a bit more about the differences in triode mode vs its standard penthode mode? Would be much appreciated!
Oh, and these 807's start to sound better and better!!!
TU-8233 can use 2A3 or 300B. The stock tube is 2A3
If you want headphone feature, you need to consider TU-8200. TU-8233 is more powerful than TU-9200
The shipping weight is 14 KG. I have just lower the price to $895.
The shipping via FedEx is around $155.00
I have amtrans upgrade parts for TU-8233
If you want headphone feature, you need to consider TU-8200. TU-8233 is more powerful than TU-9200
The shipping weight is 14 KG. I have just lower the price to $895.
The shipping via FedEx is around $155.00
I have amtrans upgrade parts for TU-8233
Someone asked about converting TU-879S to triode or ultralinear.
Ultralinear: the OPT's supplied with my TU-879S do not have ultralinear taps. It is not possible to convert the amp to an ultralinear configuration without replacement of the OPT's. When I was building my amp, it appeared to me that the 10 watt open frame Edcor transformer looked as if it would be an exact fit on the TU-879S chassis. These OPT's do have ultralinear taps. I have not tried this, your mileage may vary.
Triode: Going from memory from the time I converted my TU-879S to use 6V6 tubes, the screen grids of the power tubes are connected to the power supply through resistors that are used to span some traces on the PCB. These resistors would need to be lifted to isolate the screen grid from the power supply, then the screen grid (pin 4) would need to be connected to the plate (pin 3) through a low value resistor between 100 (typical) and 1000 ohms. I am going from memory as my 879S is at my second house and it has been several years since I have been inside it. Should be easy, but I have not tried this either, as I am perfectly content with my amp running 6V6's in pentode on the rare occasions I get to go to my lake house.
In my opinion, neither an ultralinear configuration or a triode configuration should cause any problems with hum or instability.
The 879S has a large global negative feedback loop and if I were doing this, I would almost certainly disable that loop, as ultralinear provides its own local negative feedback, and triode mode should not require negative feedback, or not much, if at all.
Anytime you do something that is not what the designer intended, you have to understand that there is potential for adverse consequences, and be prepared to work through that.
Win W5JAG
edit: see post #25 in this thread where I converted my amp to 6V6; I still haven't gotten around to building that TU-875 preamp, and have since bought one of the discontinued (?) 6BM8 amps that I also have not got around to building. I like the Elekit amps, but I think the new styling is a step in the wrong direction. That's why I got one of the 6BM8 amps when they were still available.
Ultralinear: the OPT's supplied with my TU-879S do not have ultralinear taps. It is not possible to convert the amp to an ultralinear configuration without replacement of the OPT's. When I was building my amp, it appeared to me that the 10 watt open frame Edcor transformer looked as if it would be an exact fit on the TU-879S chassis. These OPT's do have ultralinear taps. I have not tried this, your mileage may vary.
Triode: Going from memory from the time I converted my TU-879S to use 6V6 tubes, the screen grids of the power tubes are connected to the power supply through resistors that are used to span some traces on the PCB. These resistors would need to be lifted to isolate the screen grid from the power supply, then the screen grid (pin 4) would need to be connected to the plate (pin 3) through a low value resistor between 100 (typical) and 1000 ohms. I am going from memory as my 879S is at my second house and it has been several years since I have been inside it. Should be easy, but I have not tried this either, as I am perfectly content with my amp running 6V6's in pentode on the rare occasions I get to go to my lake house.
In my opinion, neither an ultralinear configuration or a triode configuration should cause any problems with hum or instability.
The 879S has a large global negative feedback loop and if I were doing this, I would almost certainly disable that loop, as ultralinear provides its own local negative feedback, and triode mode should not require negative feedback, or not much, if at all.
Anytime you do something that is not what the designer intended, you have to understand that there is potential for adverse consequences, and be prepared to work through that.
Win W5JAG
edit: see post #25 in this thread where I converted my amp to 6V6; I still haven't gotten around to building that TU-875 preamp, and have since bought one of the discontinued (?) 6BM8 amps that I also have not got around to building. I like the Elekit amps, but I think the new styling is a step in the wrong direction. That's why I got one of the 6BM8 amps when they were still available.
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Great info! Thanks. might be worth a try, although I still like the sound of this amp with 807 tubes even more than the stock tubes.
About the nfb: if I would change it to triode mode, I also think that no nfb would work fine. But what I understand from the info I can find about the 807 tubes, in pentode mode they need some nfb, about 7db. Noe this amp has 9db nfb. This is done by R7 and R8, which have a value of 120ohm. Do you know how to calculate the resistance to get 7db nfb?
About the nfb: if I would change it to triode mode, I also think that no nfb would work fine. But what I understand from the info I can find about the 807 tubes, in pentode mode they need some nfb, about 7db. Noe this amp has 9db nfb. This is done by R7 and R8, which have a value of 120ohm. Do you know how to calculate the resistance to get 7db nfb?
The 807 tube is the original 6L6 with different basing, including its lower plate dissipation and screen grid ratings, some shielding around the input, and the plate lead brought out to a top cap for easier use in RF installations so that the RF output network can be above the chassis, and the RF input can be below the chassis for stability purposes.
Some later production 807 tubes may have later production 6L6GC components inside, I have some like this, but they are not all that common in my experience.
I wouldn't worry about the difference between 7db and 9 db, personally.
Win W5JAG
Some later production 807 tubes may have later production 6L6GC components inside, I have some like this, but they are not all that common in my experience.
I wouldn't worry about the difference between 7db and 9 db, personally.
Win W5JAG
I think you are so right about the styling. The old styling is what made them stood out of the crowd, imo.
And probably also about the 2db difference in nfb.
What do you think: would it be worth it to run the 807 in triode mode? I dont need much power, as the amp works from 120hz upwards in my set...
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