I've bought a Audioromy 828 about 2 years ago, and so far I'm very pleased with this thing; Great sound for an afordable price.
Lately I've been thinking of changing the tubes, or at the very least get some spare ones if (or when...?) the existing ones burns out.
I have some experience with electronincs, but vacuum tubes is a whole new world to me, i know very little about them. I've done some reading and as far as I can tell either the american 829b or the russian GU-29 will work as output tubes in this amp?
This particular amp is the m828-A model and it has four identical JAN 5670-W driver tubes, they appear to be made by General Electric, green text. Will either the 5670, 2C51 or the russian (Not chinese) 6N3P work as driver tubes, or have I been mislead?
Does anyone know how different types/makes of tubes will perform in this amp in regard to sound quality and general durability and life time, and what (If any) adjustments that should be done?
It appears to be many of theese kinds of tubes on ebay from both Russia and the States for decent prices.
I want to do a well educated decision here so I don't break anything
Oh, and if it makes any difference, my speakers are the Klipsch RF-82.
Lately I've been thinking of changing the tubes, or at the very least get some spare ones if (or when...?) the existing ones burns out.
I have some experience with electronincs, but vacuum tubes is a whole new world to me, i know very little about them. I've done some reading and as far as I can tell either the american 829b or the russian GU-29 will work as output tubes in this amp?
This particular amp is the m828-A model and it has four identical JAN 5670-W driver tubes, they appear to be made by General Electric, green text. Will either the 5670, 2C51 or the russian (Not chinese) 6N3P work as driver tubes, or have I been mislead?
Does anyone know how different types/makes of tubes will perform in this amp in regard to sound quality and general durability and life time, and what (If any) adjustments that should be done?
It appears to be many of theese kinds of tubes on ebay from both Russia and the States for decent prices.
I want to do a well educated decision here so I don't break anything
Oh, and if it makes any difference, my speakers are the Klipsch RF-82.
829b's are two tubes in a bottle just like the 5894, but the big difference
is that the 5894 used just one cathode, unlike the 829b's....
section balance is better with the 5894 ...
downside here is that 5894 is a 40 watt tube while the 829b are 60 watt tubes
there are cases where replacing the 829b, one side would red plate....
so you need to get several to find one that matches, or you have to rebias your tube....
in order to balance out your sections, you need to install 10 ohms resistors at the plate side and monitor plate current from there,
otherwise, tube balance can be a pain...
they are the same tubes...if you ask me, i wouldn't bother replacing them as long as they work...
As far as I can tell, the FU-29 is just a chinese ripoff of the russian GU-29, right?
If this is correct, it would imply that the FU-29 is also a 40W tube, and the amp is really a 2x20W rather than the specified 2x30W or am I mising something here?
Is it true that older american and russian tubes in general are better than the chinese ones, despite the fact that the chinese tubes are new and made with modern equipment?
Anyhow, I think I'll just leave the driver tubes the way they are, and if changing the output tubes I should go for some 829b's rather that GU-29 am I right? Are there any difference at all between them?
If this is correct, it would imply that the FU-29 is also a 40W tube, and the amp is really a 2x20W rather than the specified 2x30W or am I mising something here?
Is it true that older american and russian tubes in general are better than the chinese ones, despite the fact that the chinese tubes are new and made with modern equipment?
Anyhow, I think I'll just leave the driver tubes the way they are, and if changing the output tubes I should go for some 829b's rather that GU-29 am I right? Are there any difference at all between them?
Yes.
Well, the 40W vs 60W is what each plate can dissipate. These tubes have two plates, so you get 80W of dissipation or 120W of dissipation. The mfg says 30Wx2 class A, which I find (very) unlikely. Based on my experience with similar amps, I think you probably will get 8-12 usable watts at the speaker posts.
Much has been written on this. I've had some wonderful Chinese DHTs last a long time, and at the same time I've had Chinese KT66s die in a month or two. There was a lot of competition back in the day when most of the US tubes were made. Crappy tubes could be financially damaging to a brand. For the Chinese, crappy tubes (Guiguang) just mean that you need to make a new brand name (Psvane).
The 829B will loaf along in a circuit properly designed for the GU-29; there's certainly nothing wrong with using them.
I have one of these amplifiers, and you need to be cautious about replacing the output tubes. You will need to rebias and rebalance the output tubes at replacement and there are multiple versions of the amp out there.
The amplifier will actually make 30W per channel, you cannot directly equate output power capability with plate dissipation as efficiency and operating points also enter into the equation.
There are lots of variants, mine is about 2 years old and is another Williamson variation. It also has a resistor directly in series with the plate of each half of the 829 (some have 1 ohm resistors and others are 10 ohm) I did a lot of mods on it, and it is easily improved.
There are several threads discussing these amplifiers you might want to search for them. I've forgotten some details of the amplifier design since it sits languishing on a shelf most of the time.
The amplifier will actually make 30W per channel, you cannot directly equate output power capability with plate dissipation as efficiency and operating points also enter into the equation.
There are lots of variants, mine is about 2 years old and is another Williamson variation. It also has a resistor directly in series with the plate of each half of the 829 (some have 1 ohm resistors and others are 10 ohm) I did a lot of mods on it, and it is easily improved.
There are several threads discussing these amplifiers you might want to search for them. I've forgotten some details of the amplifier design since it sits languishing on a shelf most of the time.
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