I have tried emitter degeneration in first stage, it sounded worse. (for my taste ?)
I have not tried degeneration in vas.
Mike
I have not tried degeneration in vas.
Mike
MikeB said:
Mike, I believe that it was because of rise high order harmonics. Using class A and FETs makes lowering those harmonics?
Re: Symassym is a guarantee of satisfaction.
What you think about a nice tube phase splitter !?
destroyer X said:
What you think about a nice tube phase splitter !?
Hi nando,
Also, you may want to run the signal through a tube for both the inverting and non-inverting. The idea is that the signal should be identical, but 180° out of phase.
-Chris
A waste. This thinking of the extra supply needs to run the tube(s). If you try it, watch out for large spikes on power up / down heading for the Symasym's input transistors. You will need to short the inputs for a time and short them again on power down.
Also, you may want to run the signal through a tube for both the inverting and non-inverting. The idea is that the signal should be identical, but 180° out of phase.
-Chris
You could probably modify the feedback network and make an inverting input, but this requires measures to make the amp unity gain stable, which is what will happen if the input is disconnected. Connecting the inputs of a normal and modified amp togetehrm, would then give you antiphase outputs you could use for bridging.
Ok... Bridge idea is out. 😱
If I buffer the Symasym with an OPA2134, would I loose dynamics, soundstage... ?
If I buffer the Symasym with an OPA2134, would I loose dynamics, soundstage... ?
-_nando-_ said:
I can't tell, but i think the opposite might happen. It should be a good idea to have buffer between volumepot and amp.
Mike
Yeah, I think so, but if the buffer isn't very good (such TL072, NE5532), for sure the dynamics and everything will fade away. For example, a RC4558 (horrible damn think), have 0,9v of slew rate, and also sound awful with a horrible mid and highs. 😱
The OPA2134 have 20v/s of slew rate, the same as symasym, so I think it's ok. And also is a good sounding buffer.
Cheers !
The OPA2134 have 20v/s of slew rate, the same as symasym, so I think it's ok. And also is a good sounding buffer.
Cheers !
Try the LM4562? Very positive reviews on the sonics and neutrality of this one -
http://www.diyaudio.com/forums/showthread.php?s=&threadid=86276&highlight=
Cheers
http://www.diyaudio.com/forums/showthread.php?s=&threadid=86276&highlight=
Cheers
Maximum Supply Voltage?
Hello,
After searching this thread and the forum for over 1 hour I decided to post my (dumm) question.
I do already have a wonderfull torodial powertransformer with a secondary of 2x28,5V~, This would give aprox. 2x40VDC....
Is this too high to drive a Symasym?
Would be a shame, not to use this Pt.
Greetings
Black from Germany
Hello,
After searching this thread and the forum for over 1 hour I decided to post my (dumm) question.
I do already have a wonderfull torodial powertransformer with a secondary of 2x28,5V~, This would give aprox. 2x40VDC....
Is this too high to drive a Symasym?
Would be a shame, not to use this Pt.
Greetings
Black from Germany
Would be a shame, not to use this Pt
Hi Black, the voltage is OK, but it also depends on the current or VA rating.
I would use at least 200VA /channel.
Loek
Hi Black, the voltage is OK, but it also depends on the current or VA rating.
I would use at least 200VA /channel.
Loek
Hello,
Thank you for your answer.
Nice to hear, the torodial should have at least 450VA, I think thats enough.
I definately do not need more power than the symasym normally delivers.
But its a really a nice Pt, covered with a metal-can (against hum, caused by the magnetic field of the PT)
Thanks a lot.
Thank you for your answer.
Nice to hear, the torodial should have at least 450VA, I think thats enough.
I definately do not need more power than the symasym normally delivers.
But its a really a nice Pt, covered with a metal-can (against hum, caused by the magnetic field of the PT)
Thanks a lot.
Hi voltage Symasym
Hi all,
High voltages for Symasym could be a great idea except you have many transistors which can't accept this one.
Hi all,
High voltages for Symasym could be a great idea except you have many transistors which can't accept this one.
Higher voltage for symasym is mainly limited by power dissipation of the small TO92 transistors and voltage rating of input transistors. MPSA18/bc550c/bc547 have all max 45v.
The 2n5551/5401 would allow up to +/-70V, but with an additionally increased vas current to make the higher power usable, these devices would smoke.
Black Chicken, 40v is fine, but you should replace mpsa18 with something having higher voltage rating, maybe bc546. You can also use 2n5551 here.
Mike
The 2n5551/5401 would allow up to +/-70V, but with an additionally increased vas current to make the higher power usable, these devices would smoke.
Black Chicken, 40v is fine, but you should replace mpsa18 with something having higher voltage rating, maybe bc546. You can also use 2n5551 here.
Mike
Loek, for 36v the mpsa18 is ok, it's just with 40v the safety margin gets too small. Assuming 10% supply fluctuation, a 1v input signal could already drive the mpsa18 into its death.
With 36v supply this would be 5.4v, unlikely to reach.
Mike
With 36v supply this would be 5.4v, unlikely to reach.
Mike
Thanks Mike!
Hello,
Yes, I also thought that the main limit of an increasing supply voltage was the max. VCE Voltage of the smaller transistors.
Probably you should make a note on your Symasym-HP, so everybody knows wich power supply voltage range is usable.
Shame, I intended to use the Mpsa, because imo they have better quality than the bc5xx-types (you have to buy up to 20 to find some good matching ones).
I'll try the Bc and the 2n (preferred) - types in the input stage.
What about the BC639? (VCE 100V), I already use it as a good working replacement for the mpsa56 in other projects.
Thanks a lot for your support (auch nach seite 300, bemerkenswert!!!)!!
Good night!
Black
Hello,
Yes, I also thought that the main limit of an increasing supply voltage was the max. VCE Voltage of the smaller transistors.
Probably you should make a note on your Symasym-HP, so everybody knows wich power supply voltage range is usable.
Shame, I intended to use the Mpsa, because imo they have better quality than the bc5xx-types (you have to buy up to 20 to find some good matching ones).
I'll try the Bc and the 2n (preferred) - types in the input stage.
What about the BC639? (VCE 100V), I already use it as a good working replacement for the mpsa56 in other projects.
Thanks a lot for your support (auch nach seite 300, bemerkenswert!!!)!!
Good night!
Black
Hi Black, the bc639 should work, but i would prefer the 2n5551 here.
The sc2240 would be best choice, but does not fit because of pin out.
Mike
The sc2240 would be best choice, but does not fit because of pin out.
Mike
2sc2240
Hello,
since "segor" also sales the 2sc2240 transistors, I'll try these too.
The different pin-layout is imo not an enormous problem. It requieres a bit more work to bend the pins in the right way.
Greetings
Black
Hello,
since "segor" also sales the 2sc2240 transistors, I'll try these too.
The different pin-layout is imo not an enormous problem. It requieres a bit more work to bend the pins in the right way.
Greetings
Black