if not previous history (diddleedee when making an amp) , there is no logical explanation why opto goes Dodo
it is protected as rare bird , simply having that enormous capacitor across optotransistor , so any voltage change is sloooooow and it's never higher than Ugs (of puck) plus voltage across source resistors ....... so , pretty much under 6V
and it's declared 70V c-e
it is protected as rare bird , simply having that enormous capacitor across optotransistor , so any voltage change is sloooooow and it's never higher than Ugs (of puck) plus voltage across source resistors ....... so , pretty much under 6V
and it's declared 70V c-e
to Zen Mod #1082
Hello Zen Mod,
I can't explain what happened? I did not switch nor anything else.
Something else: has anybody tried an input buffer made of J113 like in the
B1-NUTUBE-pre for this amp?
Or has anybody thought about a white-cathode-follower -like Erno Borbely
made it- as input buffer?
Greets
Dirk
Hello Zen Mod,
I can't explain what happened? I did not switch nor anything else.
Something else: has anybody tried an input buffer made of J113 like in the
B1-NUTUBE-pre for this amp?
Or has anybody thought about a white-cathode-follower -like Erno Borbely
made it- as input buffer?
Greets
Dirk
if you did read my musings about Erno's WC follower , used as option in SissySIT and Babelfish M25 , you could see that I found WCF being "better" than regular plain buffer only when heavily loaded
when loaded sanely/lightly , as most is the case , it brings just more THD ........ which is simply too much of good thing when Sissy is in question amd , most likely , even worse case here
try it , to hear do you like it , but I'm sure that I wouldn't
in short - my stance is that one needs gutsy and invisible buffer in front of amp having enough THD per se
when loaded sanely/lightly , as most is the case , it brings just more THD ........ which is simply too much of good thing when Sissy is in question amd , most likely , even worse case here
try it , to hear do you like it , but I'm sure that I wouldn't
in short - my stance is that one needs gutsy and invisible buffer in front of amp having enough THD per se
Hello Soundhappy,
sorry that I can't report you about the change of loudspeaker-out between different resistors. I didn't try yet. But I will for sure...
I tried a lot of preamps the last time - how they work together with the
50W-SE-Schade-amp. I tseems that Single - Ended - Pres are preferable.
All complementary designs had pretty much noise/hum. I had to turn the 10 kOhm trimpot at the input pretty often.
I have no buffer yet between input and autoformer. I was searching and reading a lot about buffers the last time.
I have tested two buffers based on J113 JFets (like in the B1-Nutube-preamp and one white-cathode-follower-buffer). The WCF-buffer isn't working till now. It is on the vero-board.
The simple J113 JFet buffer (from the B1 Nutube pre) worked immediately and measured around 0,06 - 0,08 % THD+N at 1kHz with some tweaking of the supply voltage (I tested from 18V - 24V) and some added resistance at the source of the JFet)
I was thinking about an input-buffer made with IRF610 or IRF9610 similar
like in Nelsons Aleph poweramps. This could be run from the 60 - 70V rails? But I did not try yet.
I think Nelson suggested to use a complementary input buffer with 2SK170/
SJ74 to get that very low output impedance (under 100 ohm).
I also thought about an input stage like the ACP+ preamp (which has a lot
of similarities to the BA-1 input stage).
And I have now 3 PSUs in this amp:
The main 60 V PSU, I made one for the bias voltage (not necessary) and
I made a regulated 24 V PSU for the buffer. The voltage for the buffer could
have been taken from the 60 V PSU via voltage divider.
This is what I am doing at the moment. But I was also busy at 'real world work' the last two weeks.
Greets
Dirk
sorry that I can't report you about the change of loudspeaker-out between different resistors. I didn't try yet. But I will for sure...
I tried a lot of preamps the last time - how they work together with the
50W-SE-Schade-amp. I tseems that Single - Ended - Pres are preferable.
All complementary designs had pretty much noise/hum. I had to turn the 10 kOhm trimpot at the input pretty often.
I have no buffer yet between input and autoformer. I was searching and reading a lot about buffers the last time.
I have tested two buffers based on J113 JFets (like in the B1-Nutube-preamp and one white-cathode-follower-buffer). The WCF-buffer isn't working till now. It is on the vero-board.
The simple J113 JFet buffer (from the B1 Nutube pre) worked immediately and measured around 0,06 - 0,08 % THD+N at 1kHz with some tweaking of the supply voltage (I tested from 18V - 24V) and some added resistance at the source of the JFet)
I was thinking about an input-buffer made with IRF610 or IRF9610 similar
like in Nelsons Aleph poweramps. This could be run from the 60 - 70V rails? But I did not try yet.
I think Nelson suggested to use a complementary input buffer with 2SK170/
SJ74 to get that very low output impedance (under 100 ohm).
I also thought about an input stage like the ACP+ preamp (which has a lot
of similarities to the BA-1 input stage).
And I have now 3 PSUs in this amp:
The main 60 V PSU, I made one for the bias voltage (not necessary) and
I made a regulated 24 V PSU for the buffer. The voltage for the buffer could
have been taken from the 60 V PSU via voltage divider.
This is what I am doing at the moment. But I was also busy at 'real world work' the last two weeks.
Greets
Dirk
Connected to D can be fantastic with B1Korg test points T7,T8 at ~ 9.5V
Music presentation is different
It's been awhile, but progress has been made. Both monoblocks are almost at the same stage of completion with the left channel a bit closer to the finish.
Yesterday, I built the current source for the left channel and the big test was today. The good news is that my workspace is still a non-smoking environment.
I will be using the THF-51S as the output device and based on Zen Mod's tests, I used 6 x 0.1 Ohm resistors in the current source. The results of the test are:
Input: 65V
Output: 35V
Current: 2.2 A
Load Resistance: 16 Ohms
Device Temperature: 36 C
Ambient Temperature: 21 C
Next up is to add the THF-51S. The bias supplies are finished and I have built input buffers for each channel as well.
Yesterday, I built the current source for the left channel and the big test was today. The good news is that my workspace is still a non-smoking environment.
I will be using the THF-51S as the output device and based on Zen Mod's tests, I used 6 x 0.1 Ohm resistors in the current source. The results of the test are:
Input: 65V
Output: 35V
Current: 2.2 A
Load Resistance: 16 Ohms
Device Temperature: 36 C
Ambient Temperature: 21 C
Next up is to add the THF-51S. The bias supplies are finished and I have built input buffers for each channel as well.
Attachments
I will try...this amp
Hello members,
today I had the time to change my speaker output-connection at the 50W-SE-Schade-amp from the midpoint between the four 0.1 Ohm-resistors to the point one up / three down 0.1 Ohm resistors = node 'D' (in the 2SK77B 50W VFET-schematic).
I listened to vinyl (Thorens - XONO - B1 NUTUBEpre - 50W-SE- Schade amp)
and also to flacs from my musicserver. Speakerpolarity inverted.
I listened for circa 2 hours. My impresssion in short words is:
in this configuration it seems to sound more 'precise'. This is the best word I can find for my impression. Especially in the mids and highs.
All the musical information appears - nothing is missing. Bass is really good and controlled. But the mid to highs seem to be more accurate/precise.
The other difference to me is the soundstage and impression of room has changed (seems downsized). It seems no more so 'airy' and completely 'uncoupled' from the loudspeakers anymore.
But these are first impressions. And I did not play at the settings of the B1 NUTUBE pre.
But I can definitively say: this amp is very special!
Nothing for the normal user. My ones need 20 - 30 minutes to really turn on and
reach full bias (at the moment I reduced to 307mV over res. = 3.07 A).
But if they have heated up - sound is really fantastic.
And I should sling the solder iron and make my input-buffers...
till now i only had them on the test-board.
Greets
Dirk
Hello members,
today I had the time to change my speaker output-connection at the 50W-SE-Schade-amp from the midpoint between the four 0.1 Ohm-resistors to the point one up / three down 0.1 Ohm resistors = node 'D' (in the 2SK77B 50W VFET-schematic).
I listened to vinyl (Thorens - XONO - B1 NUTUBEpre - 50W-SE- Schade amp)
and also to flacs from my musicserver. Speakerpolarity inverted.
I listened for circa 2 hours. My impresssion in short words is:
in this configuration it seems to sound more 'precise'. This is the best word I can find for my impression. Especially in the mids and highs.
All the musical information appears - nothing is missing. Bass is really good and controlled. But the mid to highs seem to be more accurate/precise.
The other difference to me is the soundstage and impression of room has changed (seems downsized). It seems no more so 'airy' and completely 'uncoupled' from the loudspeakers anymore.
But these are first impressions. And I did not play at the settings of the B1 NUTUBE pre.
But I can definitively say: this amp is very special!
Nothing for the normal user. My ones need 20 - 30 minutes to really turn on and
reach full bias (at the moment I reduced to 307mV over res. = 3.07 A).
But if they have heated up - sound is really fantastic.
And I should sling the solder iron and make my input-buffers...
till now i only had them on the test-board.
Greets
Dirk
Hello pinholer,
good progress! Continue with your good work.
Do I see an input buffer with a single JFet?
Greets
Dirk
Thanks, Dirk.
My input buffer uses 2SK170 / 2SJ74 like the B1 R2.
