srpp question Update and news

[kambo]

it seems, srpp stage gives 18-20db of gain... as i read from some old pages.
would this mod below work as line driver for some tube color in summing mixer line input modules....

also, what srpp stands for?

Update and news : i have finally managed a stereo version of srpp circuit on soldered bredboard ( its called something else, i dont know the exact name of it) . i didnt even have a spare tube socket, so i had to solder the wires on second tube ;D
as i have no patience for bloody tube sockets to arrive in  10 days time to hear them in stereo

some mods...
i have first used Cinemag tranies on the output
God, it Rocks...
placed a trim pot on the output resistor, as 2k2 is too much... i need to find the best fixed value...
2k2 is cutting some top end, and narrowing the stereo image...

this is my first tube diy... and worked very nicely... its all on my bench, in a kind of messy way...




thank you
kam

EDIT : i realize i have been asking a lot lately re tube line amp stages... but will be over soon
this design seems very simple to diy and make small print PCB's with tranies on it,

 

[Nele]

http://www.tubecad.com/may2000/:

Just what "SRPP" means is uncertain; maybe it stands for Series  Regulated Push-Pull amplifier or Single-Ended Reflexive  Push-Pull amplifier.

 

[kambo]

thanks for the link Nele.... way too technical for me... (extremely new to tubes)
so, i still dont have a clue from the readings, that if this would work properly or not...

kam

 

[kambo]

i bredborded it, and it works very nicely indeed... no noise what so ever... very clean amp stage.
but those lundahl transformers are the most confusing tranies i have ever used.
i mixed the pin outs, on input stage, and had a bad cable, took couple ours to figure all out.
need to sort out stepped gain control, for stereo... etc... i will update, how it goes

kam

 

[Nele]

cool!
good luck with those lundahls

ps: any pictures?

 

[kambo]

i dont have a digital camera
only laptop camera, and its a really crap quality...
may be seen my 2254c pictures,,, doesnt worth the hassle... i better buy one tho... i am building so many things lately

i will chain this with EZ1290 line in modules, see how they sound when they chained up
combination of neve kind a saturation with single stage tube output...

 

[kambo]

this is fully working temp. version for more modding....

edit:  white stuff : masking tape for avoid shorts , no socket on sec tube... powered from single power supply,of gyraf's design.
lundahl 5402 input, cinemag cmoq-2s output. matched 6DJ8 tubes.

Edit II :  changed the tranies around... cine on input, lundahl output... sounds more natural... cine on out is more colored

 

[gemini86]

you're a brave man...

 

[EEMO1]

what gemini86 said.

 

[Matthew Jacobs]

Very nice...

18-20dB of gain...

I'm thinking of using something like this in my PRR comp?
I'm building one and looking for ways to mod it.

J

 

[radiance]

Nice!

 

[kambo]

this is the very early single channel( fully working ),  with lundahl in/out. friend took this pic with his phone, along with some Igor's 2254C pics...

EDIT : masking tapes are from 2254C built... the one on right hand with numbers on it, were my diode matching stuff... 2 big grey caps are 2x2u2/250V

 

[kambo]

Very nice...

18-20dB of gain...

I'm thinking of using something like this in my PRR comp?
I'm building one and looking for ways to mod it.

J

actually it should work nicely... it has balanced/unbalanced input option with tranie... sounds good without any mod. if you use cinemag on the input output poly cap needs to be around 6u6/250 to make low end more flat. otherwise you get big bump at very low end....
i tried different values there, and you can actually make a Tube HPF with this circuit, with lorlin on the output with some different cap values. rest of the frequency band is pretty much flat. i can post some RMAA files if anyone wants...

kam

ps: i know i was little brave, i admit

 

[Nele]

Nice!
BTW I also read that some claim SRPP to stand for Shunt Regulated Push Pull...

adios,
corneel

 

[maxheadroom]

i can post some RMAA files if anyone wants...

that would be nice! especially the THD

 

[kambo]

i have added a 600ohm attenuator to the output...
resistor values is not perfect... made them with what i had in stock... but close enough for testing purpose...
circuit still on  test jig... not complete...
test specs are little better without the attenuator...

comparisons :

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max gain min att :

EDIT : i checked with the scope, on max gain 1khz sine wave doest square off....
....
....
med gain med att :

...
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min gain max att:

EDIT : some gain L/R are not accurate due quick test... its not the circuit fault but mine

 

[sheadstedford]

Hello? Anyone there?? Great thread, ive been looking at tube amp stages to feed into my gssl for some added colour if needed.
Would this work ok?