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Old 26th June 2003, 08:17 PM   #1
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Default tube/SS hybrid (low power)- need tube help

Hi all. I attached the schem of a tube/SS amp I have been working on. It would be used for headphones... I just want some comments from tube-minded folks. Values:

C1- 1uF
C2- 4.7uF
P1- 100k
Q1, Q2- 2N5484
R1- 1M
R2- 330
R3- 200k
R4- 100
R5- 820
R6- 1k
R7- 1k
R8- 200k
R9- 1k
R10- 18k
R11- 1k
R12- 100
R13- 10

gain of opamp=10... biased into "class a", and all that stuff. I understand that... just wonder about the tube section. Opamps will run on either +/-12V or +/-15V... lost my good tranny so I may have to settle for 12V.

The tube will be run at +/-42V, probably. Does everything look ok?

How do you think it would sound? I haven't really heard many good things about tube/SS hybrids, but some peopl use them... so I thought I'd check them out. Thanks
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File Type: jpg tssampschem.jpg (18.8 KB, 773 views)
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Old 26th June 2003, 08:26 PM   #2
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But what's the purpose of the valve? It's clearly redundant in this circuit. It would probably have some justification if you had a valve amplification stage followed by a buffer to match the load, but as shown it only adds noise and distortion. This is not what valves are meant to do.
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Old 26th June 2003, 08:35 PM   #3
SY is offline SY  United States
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And why use a bipolar supply if both the tube input and output are capacitively coupled? If you wanted to use a much simpler single-ened supply, the redundant R1 can be snipped out.
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Old 26th June 2003, 08:58 PM   #4
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The tube is just supposed to put in its 'tube sound' and not do much else- add a tiny amount of gain. How bad of distortion? Hmm...
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Old 26th June 2003, 09:04 PM   #5
SY is offline SY  United States
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Quote:
add a tiny amount of gain.
I doubt that. It's a cathode follower.
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Old 26th June 2003, 09:56 PM   #6
zobsky is offline zobsky  India
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i'm interested in this too, kinda ....

suppposed i wanted to use a tube pre-amp with a solid state power amp i have to inject some "tube flava", would i not use something like trespasser_guy, ..except maybe tap off with a bypass cap at the anode, as opposed to the cathode?

i already did this when testing the pre-amp section of a simple 6bq5 triode strapped amp i built last week. ..but is this the correct way to do this

questions from a newbie
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Old 26th June 2003, 10:21 PM   #7
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Hi,

Quote:
i'm interested in this too, kinda ....
One word: forget.


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Old 26th June 2003, 11:02 PM   #8
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So, more or less, there really is no way to implement it and achieve a suitable result?
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Old 26th June 2003, 11:07 PM   #9
zobsky is offline zobsky  India
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well for headphones only / preamp use, there are several excellent tube-only designs. headwize has some good info
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Old 27th June 2003, 12:01 AM   #10
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Yes... but they all cost a fortune... if done right. And, this way, I would be able to build something I know how to build (the SS part) so in the event that the tube thing didn't work out, I still had a good SS headphone amp. Plus, I'd get to use up my OPA637s and BUFs. I would love an all tube, and was about to order the parts a few days ago... but talked myself out of it because I have never done it before, and the amount of money I'd sink in it is a lot to lose...
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