DIY tube buffer

Audiolab 6000CDT Dedicated CD Transport

gobble

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Hello Folks

I need a volunteer to build this so I can try it between my CDP and SS amp.

http://www.shinjo.info/frank/sheets/106/7/7754.pdf

I can provide the parts. I think the transformer-less version will have less chance of introducing unwanted distortion to SQ correct?

Will pay a small fee for time spent and labour. :)

Any volunteers?
 

kaushik

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Hmm ..bigg improvement for small fee .. :mad:!

seems simple one you can try your self...

after dac build done , i can help.
I am sure many people can do it .
 

gobble

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Hmm ..bigg improvement for small fee .. :mad:!

seems simple one you can try your self...

after dac build done , i can help.
I am sure many people can do it .

Okie, I pay you more. :)
I will even sell my amp and speakers and CDP to help pay your fees :D

If you can give me a parts list to buy that will help me procure them.

Regards
 

iaudio

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Okie, I pay you more. :)
I will even sell my amp and speakers and CDP to help pay your fees :D

If you can give me a parts list to buy that will help me procure them.

Regards

And I will buy your amp, speakers and cdp for a 'small fee'?:p
 

kaushik

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Okie, I pay you more. :)
I will even sell my amp and speakers and CDP to help pay your fees :D

If you can give me a parts list to buy that will help me procure them.

Regards

ok small fee ,tea n cookies... and free audition after build
will do ,

i dont want to read valve theory and go back to engineering days..some clear valve buffer ckt are here from cavali

The Cavalli OCL Buffer
all parts available except mr.valve..some ppl in india sell
circuit seems ok
so take home work now :
>get valve source
>check the feasibility of the buffer

i never played with valves ,cant answer ,"will it improve questions"....
 

gobble

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ok small fee ,tea n cookies... and free audition after build
will do ,

i dont want to read valve theory and go back to engineering days..some clear valve buffer ckt are here from cavali

The Cavalli OCL Buffer
all parts available except mr.valve..some ppl in india sell
circuit seems ok
so take home work now :
>get valve source
>check the feasibility of the buffer

i never played with valves ,cant answer ,"will it improve questions"....

Hey Kaushik

I was particularly interested in the design of the link I posted originally.
I dont understand circuits - can you peek into it and tell me if it is a complete design by itself? I don't want any transformer and related hum problems. Just want a cheap toy to soften my SS amp and play/experiment.

What do you mean by valve source?

TIA
regards
 

aks07

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I don't understand why the TS would want to use a medium power tube as a preamplifier/buffer? Maybe I'm missing something here?
I am eagerly awaiting how this pan out. Always willing to learn a new trick ;) Oddball tubes, innovative ideas, enthusiastic builders. :licklips:
 

kaushik

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i have not touched valves.. some times i read the valve theory ..left halfway as i do most of the times.

so gobble, get me a proper design ..i will join wires and make it real.

the sylvania circuit seems a push pull power amp.. one fellow i have seen online made a buffer by modification ... if that is the case i am unreliable person at this time for a design.

cranky ,aks ..some one just give us technical insight here..
gobble,
valve source meaning ..valve vendor
 

stevieboy

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gobble methinks you want a tube buffer. what you've posted the sylvania link is for a single ended/push pull amp. two completely different things :)

a tube buffer is what you'd use between a cd player and an integrated amp, the buffer doing its buffering to the output from the cd player to the amp.
 

kaushik

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If you've not worked with tubes before you should not even attempt it. The voltages are very dangerous, and one wrong connection will fry the tube. Or you. Probably you first, then the tube. I mean it, these things are hot and hard to get right for the DIY'er as it is. It cannot be made by joining wires. Biasing up a tube circuit is not for the faint of heart, it's not plug and play. I would suggest trying a few simple discrete circuits to get a feel for building point-to-point, and then going for the tubes.

Though you may think that both me and aks were going for your jugular, the fact is that you shouldn't be touching tubes unless you're very, very sure of what you're doing. There are very few DIY'ers around, and it would not be good to have that number reduced by one, due to them trying something they should not have. Not good for the hobby.

As to the circuits, both the posted ones are unsuitable, and the second one is incomplete. If you're looking to 'soften' the sound, try the Pass B1, it's a well-documented SS unity gain buffer projected with tons of support on DIYA. If you still want to push ahead with tubes, try this for size:

.

Practically, getting linear response from a single active device in one stage is extremely difficult, though a cathode follower built around a ECC83 or 12AX7 (shudder!) should work. This should be pretty easy to locate on Google with just the keywords.

Viren's Lyrita is extremely competitively priced. I don't really see the need to venture into the wild unknown when a known product is available at a price like that. But anyway, you guys know best.

Good Luck. I am not responsible for any injury caused as a result of this post. Have a nice day.
cranky ,
thanks for the warnings...
following is not to make gobble just to give the task to me ..

but i refuge to step back ;), so far i have played many times with 230V during my school days making capacitor power supply, during my engineering i showed people how to hold a live mains wire at the third floor of my hostel .. i experimented with powerline data transmission during final year of engineering

Those buffers take 150v low current asfar as i see. By joining wires i meant assembly with all due precautions..do you think i will go fry the tubes and walk out ?

As per biasing is concerned i have seen here some very entry level Diy people here in india building tube buffer ,preamps...
and the net is an unimaginably powerful resource for info , only thing stopping me reading valve circuits now a days i am busy with DACs and some product design(non audio)...

blowing my own trumpet ! well i like to reveal the truth..

i respect Viren's Lyrita ...
in case gobble gets confident with
a design , i hope Diy route is not that difficult... of course grounding etc we can figure out with email exchange with
people all over the world.

after all we need your rich technical know-how to support diy here at hifi vision ,cranky
 
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gobble

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Thanks Guys for all the responses. The purpose of this is just to plug it in between cdp amp and check out how a budget nad 325 integrated improves in tonality or acquired tube like qualities therein. I was actually daydreaming that if it succeeds at a cost effective price, many budget SS owners on this forum would have loved to acquire one as a quick "tube sound" plugin.

I thought it would be a very easy weekend job looking at the original circuit diagram, now the clarification has emerged from the experts that it is incomplete.

And yeah Viren's pre is cost-effective no doubts about that.

Here is the thread I was browsing that led to this passing thought

Tube Buffer Success - AudioKarma.org Home Audio Stereo Discussion Forums

"Buffer amps give a solid state amp that tube sound. SYLVANIA designed a tube just for this job . The tube is 7695. If you have a copy of the SYLVANIA tube manual they even give you a single ended push pull transformerless circuit. I have built a number of them useing the SYLVANIA design and they work extremely well . Also the tube is cheep. The tube uses a 50 volt filliment so insert a 100ohm resister at 5watts in series, and no filament transformer. Here is a link http://www.shinjo.info/frank/sheets/106/7/7754.pdf "

Wow Stevie you read a circuit diagram and figured that out! I didn't know you were an electronics expert!!

Cranky, will the pass B1 lend a tube sound to an SS setup?

And once again Cranky has succeeded in scaring the wits out of me :D
Guess thats what happens when one remains a novice at most things ... :rolleyes:

The trouble is I wouldn't be able to judge if a circuit design I find on the net is good or not, but I will try and locate one then post.

The other idea I had was that it should be a very light-weight PCB kinda thingie (displaying my naivety again :rolleyes:) with a male RCA plugs at one
end and female at the other so I can just plug it in to the CDP and avoid another interconnect and more noise in the system etc etc :cool:

er.. did that sound stupid? :sad:

Regards
 

kaushik

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Reckless and dangerous. Totally not recommended under any circumstances.

just added to tell that high voltages dont scare me..
as i have dealt it them over the past .. :yahoo:

ok i see lott of smiling faces reading this ... but thats the
way i am...
That is a statement of the problem, not an indication that it is an easy task.
nothing is easy ...as a common effort we can do it ...
in a movie joker said "why so serious son?"
in diy i will say "why so negative son?"


coming to the build , i will just put one question:

Can we not make a valve buffer( i hope a very simple of the valve circuits) successfully stable one,how do other people
do it ?
 

aks07

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Can we not make a valve buffer( i hope a very simple of the valve circuits) successfully stable one,how do other people
do it ?
1000% yes. Anybody with basic knowledge of electronics/electricity, soldering skils and a bit of common sense can do it. No doubts about that.

However, Cranky ji couldnt have put it more eloquently. Tubes have dangerously high voltages and one need to follow highest caution. I am sure he did not mean to discourage you.

For all the reverence attached to tubes, they are not something extraordinary or out of this world. Just use proper common sense and electrical care when fiddling with them. And do read up all you can on safety, wiring etc.

People have been dabbling with them for ages and many present day DIY started off with tube projects because of the simple nature. But as Cranky ji very rightly said there is more to just building a tube project. It is only the 1st step. Optimising a design, long term biasing etc will need a little more expertise but eminently doable over a period of time.

Out of box tube voltages really start getting dangerous when you are in 845 triode territory, though I must add that even 100volts can kill you if applied in the right place ;)

Coming back to the subject, you can certainly try a simple tube buffer by using a low voltage tube like the 6DJ8. Do a google 6DJ8/E88CC/6922 tube buffer and I am sure you will find plenty for plans. Decide on which suits you and we can tweak it further. The 6DJ8 (or the similar /E88CC/6922/ECC88) can work down to 30volts and its characteristics are ideal for a buffer stage particularly if in cascade mode.

Kaushik-ji

You sound a dangerous but fun-to-know type of person ;) There was a time I used to do all sorts of experimentation with household power supply. The highest point of my career was the moment when the entire mohalla was deprived of power for 2 days following one of my misadventures. Later I graduated to experimenting with gun powder (baarood) while also earning money making Deepawali Anaars for paying public ;)
 

kaushik

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aks07
thats a positive ion filled air coming , needed for my ideas 2 breathe ..
gobble ,

" who brings the cake eats the cake "

your call now, if now afraid of ending life with valves ..
6DJ8/E88CC/6922 tube buffer or whatever grab your design
 
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stevieboy

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Wow Stevie you read a circuit diagram and figured that out! I didn't know you were an electronics expert!!

Regards

errr no man. it just sounded like a proper amp so was quite confused at you wanting something like that to go with your integrated. always heard of them referred to as 'tube buffers' or tube buffer stage never as a tube buffer amp. hence my confusion as to the design. didnt realize tube buffers could be built single ended or push pull...

it also mentions beam power pentode and 'features remarkably high power sensitivity as a power amplifier' and the two graphs below that show power outputs, so not too sure how that connects to a tube buffer...

i proudly claim complete ignorance as far as electronics goes.
 
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aks07

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See this. Costs 85 Eur. Uses 12 V. DC which won't [may not?] fry you.
Interesting!

But prima facie looks highly compromised. Quoting Technical specifications

- 12V DC power supply: no high voltages
Both HT & heater from same 12V supply? I can understand voltage multiplying the 12v till you reach about 250VDC (good op point for the 6SL7), but does it also taps the heater from same supply? If yes than I wont touch it.

- 6SL7 double triode
A great tube but worst for this specific application. Its a high gain triode typically used to amply low level signal such as phono pickups. There are more suitable tube for a unity gain buffer.

- Adjustable tube operating point
Wah wah ! And how does one sets the op point? Using ones golden ears?

- Low output impedance
How? They are using just a single half of a triode?

Using tubes just for the sake of it is pathetic. I could be all wrong too and it actually might be a very pleasant addition, but from where I come it looks all crap.
 

keith_correa

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