Small Tube/SS hybrid amplifier design 9V - Page 2

porkchop61 · 24th September 2010, 07:12 PM

I've already agreed that the schematic in the first post is not good for what I'm looking to do. I was now focusing on the second schematic in post #4. Since this is a headphone amp, I would think it would have to be halfway decent to listen to. I'm just thinking of coupling that to some sort of small chip amp for a compact stereo amp that has a nice tube sounding front end to it. This approach also has the added benefit of being able to use it with a pair of headphones and bypassing the power amp section altogether.

Glenn

DF96 · 24th September 2010, 07:35 PM

But it still has far too low a supply voltage, so the only "tube sound" you will get is distortion. If you want to use a valve then you need 30-40V minimum; even then you will get some distortion. Valves don't magically wipe away "SS sound" - like any other component they either add/subtract very little (when used correctly) or add their own distortions (when used badly).

M Gregg · 07:57 PM

Quote:

Originally Posted by DF96

But it still has far too low a supply voltage, so the only "tube sound" you will get is distortion. If you want to use a valve then you need 30-40V minimum; even then you will get some distortion. Valves don't magically wipe away "SS sound" - like any other component they either add/subtract very little (when used correctly) or add their own distortions (when used badly).

I know I thought the same thing so I built it! How can a tube run on such a low voltage. However in the link the guy refers to the tube being used in low voltage applications in the battery circuits in the military! Not with an inverter!

So I built the circuit out of curiosity and I have to say it sounds quite good even when amplified at party levels! OK it's not hifi, however it gives mini systems a run for their money! You can hear people breath as they sing and the wood on acoustic guitar!

Regards
M. Gregg

M Gregg · 08:17 PM

The sound reminds me of an old HMV record player with better high frequency response!

I thought about ECC83 ECC81 etc however this seems only true for the 82. I have an old RCA 82 playing kate bush as I type this!

porkchop61 · 24th September 2010, 08:16 PM

Thanks for the review, probably worth building since it's a pretty simple circuit.
I'll post pictures when I complete the prototype. Thanks for all the input everyone!

EDIT:
Here's the full explanation of the circuit http://diyaudioprojects.com/Solid/12...LM317-Headamp/

M Gregg · 08:27 PM

You must treat it as a hifi project all the same things apply. Built mine on tag board and mounted the tube socket on it!

All the Best!

M Gregg · 09:30 PM

It was done as a fun project!

Just for fun I built mine in a cigar box!
LOL couple of hours after work!

DF96 I have now put an LED under the tube, because it annoys people!

Bigun · 25th September 2010, 12:22 AM

Looks very nice - some photos of the inside ?

soro · 25th September 2010, 04:28 AM

How about this one?
I made it.
B+ 12V bettery supply.

dovla · 25th September 2010, 07:42 AM

There is a $20 pre-build buffer board with 12AU7 intended for Tripath amps so it may work with LM as well. I have one with TA2020 and it does make a difference ('rounding' the sound). It's fed off 12V but the tube gets 43V (3ma) which is a more realistic level. You can see it at
Special for Tripath! 12AU7 Buffer Amp for smooth sound - eBay (item 260658637265 end time Sep-30-10 20:25:26 PDT)

24th September 2010, 07:12 PM	#11
porkchop61 diyAudio Member Join Date: Aug 2004 Location: Mansfield, Connecticut	I've already agreed that the schematic in the first post is not good for what I'm looking to do. I was now focusing on the second schematic in post #4. Since this is a headphone amp, I would think it would have to be halfway decent to listen to. I'm just thinking of coupling that to some sort of small chip amp for a compact stereo amp that has a nice tube sounding front end to it. This approach also has the added benefit of being able to use it with a pair of headphones and bypassing the power amp section altogether. Glenn __________________ "Imagination is more important than knowledge"

24th September 2010, 08:01 PM	#14
M Gregg diyAudio Member Join Date: Jun 2010 Location: UK	The sound reminds me of an old HMV record player with better high frequency response! I thought about ECC83 ECC81 etc however this seems only true for the 82. I have an old RCA 82 playing kate bush as I type this! Last edited by M Gregg; 24th September 2010 at 08:17 PM.

24th September 2010, 08:16 PM	#15
porkchop61 diyAudio Member Join Date: Aug 2004 Location: Mansfield, Connecticut	Thanks for the review, probably worth building since it's a pretty simple circuit. I'll post pictures when I complete the prototype. Thanks for all the input everyone! EDIT: Here's the full explanation of the circuit http://diyaudioprojects.com/Solid/12...LM317-Headamp/ __________________ "Imagination is more important than knowledge"

24th September 2010, 08:20 PM	#16
M Gregg diyAudio Member Join Date: Jun 2010 Location: UK	You must treat it as a hifi project all the same things apply. Built mine on tag board and mounted the tube socket on it! All the Best! Last edited by M Gregg; 24th September 2010 at 08:27 PM.

25th September 2010, 12:22 AM	#18
Bigun diyAudio Member Join Date: Jan 2009 Blog Entries: 2	Looks very nice - some photos of the inside ? __________________ "The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.


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24th September 2010, 07:35 PM	#12
DF96 diyAudio Member Join Date: May 2007	But it still has far too low a supply voltage, so the only "tube sound" you will get is distortion. If you want to use a valve then you need 30-40V minimum; even then you will get some distortion. Valves don't magically wipe away "SS sound" - like any other component they either add/subtract very little (when used correctly) or add their own distortions (when used badly).

25th September 2010, 07:42 AM	#20
dovla diyAudio Member Join Date: Mar 2010	Ready-made for T-amp There is a $20 pre-build buffer board with 12AU7 intended for Tripath amps so it may work with LM as well. I have one with TA2020 and it does make a difference ('rounding' the sound). It's fed off 12V but the tube gets 43V (3ma) which is a more realistic level. You can see it at Special for Tripath! 12AU7 Buffer Amp for smooth sound - eBay (item 260658637265 end time Sep-30-10 20:25:26 PDT)

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