Re: reflections and questions pt 2
Having changed my power supply unit to the voltage regulator quite recently, I have removed the current limiting (R21 and R22 too). The sound has been improved, not in warming-up, but in others.
ST70 . . . Dynaco . . . ?
Cheers,
🙂
rob lenk said:
Having changed my power supply unit to the voltage regulator quite recently, I have removed the current limiting (R21 and R22 too). The sound has been improved, not in warming-up, but in others.
ST70 . . . Dynaco . . . ?
Cheers,
🙂
Re: Re: reflections and questions pt 2
He says it's a ST70 Heathkit, but I cannot find anything in the Heathkit museum
http://www.heathkit-museum.com/hvmhifi.shtml
for ST70.
I believe he meant the EICO ST70. I have one and all the trannys are larger than those on my Dynaco ST70s. Also the input is a 12ax7 and driver/spliter is a 6sn7
to the output tubes 7591's.
Babowana said:
He says it's a ST70 Heathkit, but I cannot find anything in the Heathkit museum
http://www.heathkit-museum.com/hvmhifi.shtml
for ST70.
I believe he meant the EICO ST70. I have one and all the trannys are larger than those on my Dynaco ST70s. Also the input is a 12ax7 and driver/spliter is a 6sn7
to the output tubes 7591's.
reflections and questions pt 3
yes yes dynaco not heathkit-
there not enough coffee in the world.....
So- Babowana- R21 & R22 out also-thanks for the info-
could you further describe the sonic improvements from removing the limiting
thanks for your thoughts
rob
yes yes dynaco not heathkit-
there not enough coffee in the world.....
So- Babowana- R21 & R22 out also-thanks for the info-
could you further describe the sonic improvements from removing the limiting
thanks for your thoughts
rob
As I briefed, the improvements come from the combination of the new installation of the regulated power supply and the removal of the limiting.
Improvements are here:
Cutting off the listening-fatiguing aspects . . .
All subjective . . . 😉
🙂
Improvements are here:
- In clarity: If you recall the FM TR radio of the battery instead of the wall wart . . .
- In bass end: It goes deeper and wider with definition
- In dynamics
Cutting off the listening-fatiguing aspects . . .
All subjective . . . 😉
🙂
Nice work, Babo. I have seen your thread about the new PSU.
I think that makes the difference.
I never use current limiters in output stages but can it change anything at low level?
I think that makes the difference.
I never use current limiters in output stages but can it change anything at low level?
Hi All,
I know I'll get shot for this. If sound is too clinical or clean, stay away from metal film resistors. Do not go for low ecr caps for power supply. Contrary to popular belief that low ecr is best, I feel that it's a mix & match thing. Lastly belief it or not an EI transformer will provide a different sound to toroids. To me, EI sounds better.
I know I'll get shot for this. If sound is too clinical or clean, stay away from metal film resistors. Do not go for low ecr caps for power supply. Contrary to popular belief that low ecr is best, I feel that it's a mix & match thing. Lastly belief it or not an EI transformer will provide a different sound to toroids. To me, EI sounds better.
JC951t said:
Quite possibly.
I have built another set of boards with no limiting or thermistors and with carbon film resistors. I have yet to swap out the fairly default boards. I will report on the sound. Still trying to get down different transformer sounds myself.
I think the F5 sounds much warmer on a hot day with the bias sitting about 650mv.
JC951t said:
Alternatively, you can increase the value of the Source resistors to 1 ohms,
and increase the value of the feedback resistors from 2 X 100 ohms and 10
ohms to 1 X 100 ohms and 22 ohms.
The lower amount of feedback will warm the sound up, and you can keep
increasing proportional values in the feedback loop if you wish.
😎
Nelson Pass said:
Thanks for the encouragement, Papa.
Pressing down to the 2nd harmonics zone . . . ? I would give a try in the near future.
>🙂<
From personal experience from other projects,
I've notice that by decreasing feedback, the sound
will become mellower & not so tightly focus & at the
same time image size would increase. Again it's about
adjusting the R values to get to what you like.
I've notice that by decreasing feedback, the sound
will become mellower & not so tightly focus & at the
same time image size would increase. Again it's about
adjusting the R values to get to what you like.
Hi Nelson
I would really love to build this amp, however I would like to build it with a quasi-complimentary (two N channel mosfets) output stage.
Could you show us what the circuit would like with any necessary changes to incorporate quasi complimentary output stage.
Thank you in advance.
I would really love to build this amp, however I would like to build it with a quasi-complimentary (two N channel mosfets) output stage.
Could you show us what the circuit would like with any necessary changes to incorporate quasi complimentary output stage.
Thank you in advance.
I had some time and made the changes to the feedback as Mr Pass suggested. It's not a subtle change, maybe a little too far, time will tell.
Bill
Bill
Bill Fuss said:
Bill, very interested in your listening report.
Do you have an 'normal' set of boards to swap back in for comparison?
I only etched one set of boards when I built it.
I agree with a previous poster, the pinpoint imaging is traded for a much warmer, more diffuse soundstage. I have to move the amp to another room that is more listener friendly to really make a judgement.
Still, this is just my opinion and you know what they say about opinions, everybody has one. YMMV
I'll post again later after I get a chance to listen critically.
Bill
I agree with a previous poster, the pinpoint imaging is traded for a much warmer, more diffuse soundstage. I have to move the amp to another room that is more listener friendly to really make a judgement.
Still, this is just my opinion and you know what they say about opinions, everybody has one. YMMV
I'll post again later after I get a chance to listen critically.
Bill
Hi, just a couple of quick questions...
Can I use thermal past under the power mosfets or should I use something else?
How closely does the thermistor need to be next to the mosfet ?
Lastly, what are people using for R35 (I believe it's next to the diode power indicator)?
Thanks,
JG
Can I use thermal past under the power mosfets or should I use something else?
How closely does the thermistor need to be next to the mosfet ?
Lastly, what are people using for R35 (I believe it's next to the diode power indicator)?
Thanks,
JG