good for you
me - after years of playing , fallin' in all usual audiophool mine-holes , decent buffer combined with decent AVC is way to go
everything to avoid resistive attenuator ..... and I tried them all - TKD, P&G ,Alps = all conductive plastic , old Pro series Preh , wirewound from WW2, modern wirewound,Black Beaty , numerous stepped attenuators made with most expensive and cheapest parts ............ of them all - best bang for the buck is white-blue rotary Chinese one from EBay , made with smd resistors
that about attenuators ;
do you need gain stage - it's always best when you don't need it
however , one can be surprised , connecting decent buffer after pot ..... I believe that was also Pa's idea , when he brought B1 ( all iterations) to Greedy Boyz eye .......
me - after years of playing , fallin' in all usual audiophool mine-holes , decent buffer combined with decent AVC is way to go
everything to avoid resistive attenuator ..... and I tried them all - TKD, P&G ,Alps = all conductive plastic , old Pro series Preh , wirewound from WW2, modern wirewound,Black Beaty , numerous stepped attenuators made with most expensive and cheapest parts ............ of them all - best bang for the buck is white-blue rotary Chinese one from EBay , made with smd resistors
that about attenuators ;
do you need gain stage - it's always best when you don't need it
however , one can be surprised , connecting decent buffer after pot ..... I believe that was also Pa's idea , when he brought B1 ( all iterations) to Greedy Boyz eye .......
Ok
After checking it is the second of ZenMods pictures that works. looking at the terminals this is the wiring. (for 2 : 1 gain)
After checking it is the second of ZenMods pictures that works. looking at the terminals this is the wiring. (for 2 : 1 gain)
Last edited:
Thanks. I actually tried that 🙁. Could be a wiring issue as now I have a hum problem. Will strip down and rewire.
Sent from my iPad using Tapatalk
Sent from my iPad using Tapatalk
Finally got it to work 🙂. Thanks Zen Mod and ColinA. Lesson learnt - multistranded hookup wires are a nightmare - should stick to thin solid core. My eyes are too old!
Sent from my iPad using Tapatalk
Sent from my iPad using Tapatalk
zero specimen of Balanced AVC finished
thorough technical testing day after tomorrow
(rotary switches stuck in Customs for two weeks already)
got them ...... (switches) ...... finally , after 18 days in Custom
each will get proper treatment with vaseline
just inside
Attachments
nice pic , custom bobbins , ABS plastic , 0.8mm thickness
better than original bobbins - too much slack , so waste in Rdc, coupling and space generally
also - with them can't squeeze two coils on core, for balanced AVC , without sacrifice in Rdc (thinner wire)
better than original bobbins - too much slack , so waste in Rdc, coupling and space generally
also - with them can't squeeze two coils on core, for balanced AVC , without sacrifice in Rdc (thinner wire)
Attachments
Last edited:
Looks fantastic ZM and constant level across all frequencies! What does a square wave look like?
good enough 
I didn't posted sweeps and squares simply .....from two reasons :
- Rout of generator is somewhat wimpier than needed , so will wait** for that measurements with my own gear , where Rout of gen is confirmed and trusted ;also probes (ultragigamegaexpensive) are having some incompatibility with calibration at used levels (my friend working in service center for veeeeery high freq. gear)
-sweeps are just compressed tests already shown on pics
anyway , this pic will say enough - you can see in upper traces that gene output is showing some sweat and tears , driving 10H per coil
whatever , thingie is , as always must be the case , optimized for my Diamond Buffer ....... and "even" Toshiba complementary JFet buffer is driving it with ease
so , to reach desired plateau of performance , I didn't go to make Swiss knife AVC , rather entire package - buffer in front of AVC , as pretty special Swiss knife
(and , as always , proof is in da pudding 🙂 )
**edit - no need to wait - I already measured SE ones at my place and conducted thorough listening tests ...... as Bal AVC is "nothing more" than two SE coils on one core .... things are more than easy and logical to decipher
I didn't posted sweeps and squares simply .....from two reasons :
- Rout of generator is somewhat wimpier than needed , so will wait** for that measurements with my own gear , where Rout of gen is confirmed and trusted ;also probes (ultragigamegaexpensive) are having some incompatibility with calibration at used levels (my friend working in service center for veeeeery high freq. gear)
-sweeps are just compressed tests already shown on pics
anyway , this pic will say enough - you can see in upper traces that gene output is showing some sweat and tears , driving 10H per coil
whatever , thingie is , as always must be the case , optimized for my Diamond Buffer ....... and "even" Toshiba complementary JFet buffer is driving it with ease
so , to reach desired plateau of performance , I didn't go to make Swiss knife AVC , rather entire package - buffer in front of AVC , as pretty special Swiss knife
(and , as always , proof is in da pudding 🙂 )
**edit - no need to wait - I already measured SE ones at my place and conducted thorough listening tests ...... as Bal AVC is "nothing more" than two SE coils on one core .... things are more than easy and logical to decipher
Attachments
Last edited:
Nice work! The square wave is very impressive given the restrictions on the equipment. Well done ZM!
A bit bright now - will play around with some audio caps to tune as i switched to radial epcos pp to minimise component interactions. Bass seems to be a bit light.. either that, or it needs to run in 🙂
Generally happy with it 🙂
Sent from my iPad using Tapatalk
it is possible to conduct mono test : you can try running two buffers in parallel , feeding one Telefunken ( then feed both amplifier channels from it)
then disconnect one buffer , leaving just one to drive telefunken
if you have better bass with two in parallel , buffer Rout is issue and you need at least B1 V2. , meaning - complementary JFet buffer
that way you can go with proper dual polarity PSU , avoiding any cap in signal path
then disconnect one buffer , leaving just one to drive telefunken
if you have better bass with two in parallel , buffer Rout is issue and you need at least B1 V2. , meaning - complementary JFet buffer
that way you can go with proper dual polarity PSU , avoiding any cap in signal path
Bass is better now i have changed the input caps. It is still a bit brighter than my arcam pre out. I will let it run in and monitor. Dont really want to do the test now as I am using ls3/5a equivalents - not known for bass 🙂
Sent from my iPad using Tapatalk
Sent from my iPad using Tapatalk