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Old 22nd June 2012, 01:59 PM   #1
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Default Hybrid amplifier with ECC88(PCC88) + LM3875

Hybrid amplifier with PCC88 (ECC88) + LM1875

Hello all!
Want to make this hybrid amplifier given by the schematic.
Therefore, seek the opinion about this amplifier. Is this pattern should or needed some changes to the schematic?
Please for comment.
thank you!
Attached Images
File Type: jpg LM-1875 Amplifier with ECC88 Tube Buffer.jpg (89.8 KB, 361 views)

Last edited by formula 22; 22nd June 2012 at 02:01 PM.
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Old 22nd June 2012, 02:27 PM   #2
Fenris is offline Fenris  United States
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It's a bit pointless. The cathode follower adds nothing. The strength of tubes is in voltage amplification, not current amplification. The LM1875 has a sufficiently high input impedance that a tube buffer before it is nothing but fashion. Plus, you now have to build five power supplies instead of the two of a normal Gainclone. For a better use of tubes and chipamps, try:

SuperTriodes & Inverted ES Speakers

where a tube provides the voltage gain and the chipamp provides the current gain with a nestled feedback loop.
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Old 22nd June 2012, 02:34 PM   #3
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It reminds me Joe's one
Tube Gainclone for DIY Buffs
Just search for inverted gainclone + tube on the Forum , there must be a thread
about the circuit , though I've never understood the difference between the 1MΩ and 10 KΩ resistor versions ....

Last edited by picowallspeaker; 22nd June 2012 at 02:37 PM.
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Old 22nd June 2012, 03:52 PM   #4
tomchr is offline tomchr  United States
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I'd also suggest using something other than the ancient LM1875, LM3886, etc. You can do much better with the LME-series, such as the LME49811.

Yet Another LME49811 + STD03 Build

~Tom
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Old 22nd June 2012, 04:44 PM   #5
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Hi guys!
I'd offer some more specific design of a hybrid audio amplifier with PCC88 (ECC88) + LM1875.
thank you
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Old 22nd June 2012, 05:49 PM   #6
oshifis is offline oshifis  Hungary
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I just opened my AXL T-15R mini guitar combo, and it has a 12AX7 and an LM1875...
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Old 23rd June 2012, 12:13 AM   #7
Fenris is offline Fenris  United States
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Quote:
Originally Posted by oshifis View Post
I just opened my AXL T-15R mini guitar combo, and it has a 12AX7 and an LM1875...
Another example of why it's not an accurate reproduction amp, but more of an effects amp. Look at the TubeCad article I linked too. About a third of the way down is an example of a better way to combine a Gainclone and tube.
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Old 23rd June 2012, 03:13 AM   #8
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Quote:
Originally Posted by oshifis View Post
I just opened my AXL T-15R mini guitar combo, and it has a 12AX7 and an LM1875...
If you are unable to insert the schematic.
thank you
P.S.
Check out this web site:
http://www.tubecad.com/2008/04/blog0140.htm

Last edited by formula 22; 23rd June 2012 at 03:20 AM.
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Old 23rd June 2012, 03:52 AM   #9
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Hello!
What do you think of this design: in this schematic the amplifier with LM1875 to add this to the input buffer with PCC88?!
Or someone has a better solution?
thank you
Attached Images
File Type: jpg Amplifier with LM1875.jpg (41.4 KB, 214 views)
Attached Files
File Type: pdf Buffer with PCC88 (complet).pdf (28.4 KB, 63 views)

Last edited by formula 22; 23rd June 2012 at 04:20 AM.
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Old 24th June 2012, 01:07 PM   #10
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Weak activity, ...
It seems everyone went on vacation?!
While a reconstruction, people do not leave ... ha,... haa,....
Cheers!
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