Full Range Amplification - A Revelation

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Well, if you put a 6N3 (which is like the cheapest triode in the world) on 12 or 24 volts, no good things can happen. Do a little search on the Tubes/Valves forum.

Think of the stated distortion figure as "chinese watts"

So your answer is no. You've never heard this pre-amp.

But for clarification, the tube I am running is a 6N3P (Russian) which is affordable due to supply and demand, not because it doesn't sound good. Look at what 5670 and 2C51 NOS are going for on e-bay. Often times more than the equivalent 12AX7 or 12AT7. Supply and demand.

Maybe the Chinese 6N3 that came with the board sounds like crap. I don't know, as I haven't even tried it yet. I'll reserve my comments on it untill I have actually heard it.
 
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Well I consider a lot of the people over at the tubes section very knowledgeable, there are schematics and analysis of that pre over there. You should take a look,
was trying to be helpful, oh well.

I highly recommend evaluating any particular component with music and your ears rather than blindly following the measurebators.

Also, rather than have me go searching for "evidence" that my pre-amp sounds terrible, why don't you simply post a link?

Your approach certainly does not indicate that you are attempting to be helpful at all.
 
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Well, for anyone who is interested, the thread is here http://www.diyaudio.com/forums/tubes-valves/174281-6n3-tube-preamp-dc-dc-converter-7.html

I read the whole thread and I found that the vast majority of people like the way it sounds. In fact, it seems that only one person in that thread has a real problem with it and complains about clipping and 50% distortion. That must be a joke. The same person refers to Chinese 6N3P tubes, which do not exist.

It is far from perfect, but I will tend to agree with the majority of people in that thread that it sounds great, all things considered (the price in particular).
 
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The 6N3 tube buffer preamp appears to show some mods that can improve the performance (usually with any $20 amp, there are easy mods out there to improve performance as lowest price parts is usually par for the course). But there are some who say it sounds great, and some who say it sounds like a "tube" - meaning it adds distortion. So not sure which way to believe. The mods seem to say adding another 1n004 diode in series with existing one on 7805 regulator to bring filament voltage up to 6.3V. Boosting tube voltage with another stage of caps/diodes in voltage multiplier or use your own voltage source. Replace input and output audio caps (a usual suspect - which I am not fully a believer in when it comes to difference between XR7 grade ceramic smd vs polyester film thru-hole). Looks like a cheap and fun base to start mods with though to get that "tube" sound. For $20 you can't really go wrong...
 
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The 6N3 tube buffer preamp appears to show some mods that can improve the performance (usually with any $20 amp, there are easy mods out there to improve performance as lowest price parts is usually par for the course). But there are some who say it sounds great, and some who say it sounds like a "tube" - meaning it adds distortion. So not sure which way to believe. The mods seem to say adding another 1n004 diode in series with existing one on 7805 regulator to bring filament voltage up to 6.3V. Boosting tube voltage with another stage of caps/diodes in voltage multiplier or use your own voltage source. Replace input and output audio caps (a usual suspect - which I am not fully a believer in when it comes to difference between XR7 grade ceramic smd vs polyester film thru-hole). Looks like a cheap and fun base to start mods with though to get that "tube" sound. For $20 you can't really go wrong...

Indeed. Good summary. I might even tinker with some of the mods, in fact. Just a couple of notes:

1) There are many versions and iterations of this one basic design. For example, my input and output caps are already polyester film (not ceramic) so the quality of components will depend a bit on which actual board you buy from which seller.

2) Saying it sounds "great" and saying it sounds "like a tube" are the same thing to many. Not everyone is hung up on distortion (as I am sure you understand). Perhaps the distortion of this pre-amp is an order of magnitude higher than stated in the specifications, which would make it .05% - in my opinion, that is still nothing. My tube amp distortion is rated at 1% for dog's sake! Can I hear it? Not a chance! I am confident that in the setup that I am running, the TA2020 amp will hit distortion and/or clipping well before the pre-amp will introduce its own distortion to the mix in any audible way. Furthermore, neither of the devices get anywhere close to this point even at "reasonably loud" volume, and that is with speakers that are a mere 86-87dB efficient.
 
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One thing I found funny in that other thread was someone's answer to the question "What is the point of it?" The answer was "to sell more crap Chinese tubes", or something to that effect.

Funny because it is so wrong. If that was the plan:

a) The board would be designed to over-power the tube, not under-power it

b) A tube would not be included in the purchase price

Oh, and regarding the 5.6v filament supply; I suspect that is by design due to the fact that the board is only pushing ~60V through the tube, and the tube is not being used as a gain device in this circuit. Ramping the filament up to 6.3V seems to offer no logical benefit. From what I understand about tubes, there should be a balance. If you run one parameter under spec, then it seems logical that the other parameter(s) be scaled accordingly. Otherwise you just have a lot of extra excited electrons hanging around on/near the cathode doing nothing at all.
 
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