Are there someone that has this HK-730 schematic, or link to it.
I would be happy to take a look at the schematic.
panzertoo@yahoo.com
regards,
Carlos
I would be happy to take a look at the schematic.
panzertoo@yahoo.com
regards,
Carlos
sajti said:
no.
It is much more likely that PNP are chosen for the input LTP, due to their reputation for lower noise.
Mike,
your recollection of -12mV (or -27mV) is not wrong. It came from as built measurement, see post2515.
phew bias touchy with 1k pot.... while 24mv across top of the two 0.22 resistors targeted and read that below 20mA means crossover distortion, how much can it be increased to?
Without installing a pot, whats prefered way to make less sensitive to my source which has it's own output level capability but sym's 32db a little jumpy in my application, especially when use my higher efficiency speakers. Get tempted to touch 2k - 22k input side.
Lastly, how low can voltage rails be before have problems?
Without installing a pot, whats prefered way to make less sensitive to my source which has it's own output level capability but sym's 32db a little jumpy in my application, especially when use my higher efficiency speakers. Get tempted to touch 2k - 22k input side.
Lastly, how low can voltage rails be before have problems?
Hi traw,
The bias control was changed to a 500R control. I find that just about right.
Your rails should be around 35VDC with this design. Higher voltages will require more output transistors to maintain safety margin, different Vas and some other transistors. Add some heatsinks to the Vas as well.
There are other threads on the SymAsym that you should pick through. Other members have gone to higher power by modifying the design. I find the original SymAsym to be very good.
-Chris
The bias control was changed to a 500R control. I find that just about right.
Your rails should be around 35VDC with this design. Higher voltages will require more output transistors to maintain safety margin, different Vas and some other transistors. Add some heatsinks to the Vas as well.
There are other threads on the SymAsym that you should pick through. Other members have gone to higher power by modifying the design. I find the original SymAsym to be very good.
-Chris
currently running on 36-37volts... curious if would encounter problems at 33 volts, maybe even 32.
will changing 2k/22k input to 10k/47k have bad impact? (like built in voltage divider attenuation).
yes, very good sounding amplifier one of the clearest and open i've heard.
will changing 2k/22k input to 10k/47k have bad impact? (like built in voltage divider attenuation).
yes, very good sounding amplifier one of the clearest and open i've heard.
Hi traw,
-Chris
No, the amp works great "down there".
Yes. Don't play with that. It will affect the DC offset for sure. To correct the offset you will need to mess with the feedback network. That's where everything will go sideways on you.
-Chris
traw said:
Which board did you build? If you've built the 5.3, you have the option to install r16/19 and change the feedbackdivider to reduce gain.
Mike
i built the 5_3 version... took gerber files verbatim and sent off to get fabbed rather than etching or tweaking. r16/19 where the jumpers were? if wanted to shave maybe 4-6 db (overall 26 or so) any recommendations?
There are instructions on my page:
"If the gain is too high because symasym is driven from preamp, R30 can be increased from 499ohms to 1k, but in this case R16/19 (22 or 33 ohms, not on schematic, REs to Q1/2) are required to keep feedback at same level and symasym stable."
If you increase r30 to 1k, you can also reduce c19 to 220µf or even 100µf.
Mike
"If the gain is too high because symasym is driven from preamp, R30 can be increased from 499ohms to 1k, but in this case R16/19 (22 or 33 ohms, not on schematic, REs to Q1/2) are required to keep feedback at same level and symasym stable."
If you increase r30 to 1k, you can also reduce c19 to 220µf or even 100µf.
Mike
yeah, i smacked myself in head as i had just now reread the page noticing that. hmm, ok. 1k, the put 22 ohms in r16 and likewise for r19 (have more 22 around than 33).
thanks
thanks
Hi,
I see Pavel used a XLR in his review : “with XLR connectors, pin 2 live input, pin 3 input GND, pin 1 Shield.”
Is balanced input possible for SymAsym5-3? With or without modifications?
Is there somewhere a schematic with XLR connection?
Thanks, Laurent
PS : Is it possible to print every 330 pages of this Thread or only one page by one ?
I see Pavel used a XLR in his review : “with XLR connectors, pin 2 live input, pin 3 input GND, pin 1 Shield.”
Is balanced input possible for SymAsym5-3? With or without modifications?
Is there somewhere a schematic with XLR connection?
Thanks, Laurent
PS : Is it possible to print every 330 pages of this Thread or only one page by one ?
Have you assembled and listened this buffered VAS into Symassym?
I suppose not.
I am asking.. have you listened?
Have you?.... well... i have made it and listened...into Symassym...the old model 4
regards,
Carlos
I suppose not.
I am asking.. have you listened?
Have you?.... well... i have made it and listened...into Symassym...the old model 4
regards,
Carlos
Not yet, Carlos. For me the symasym is the closed chapter.
But a friend of mine is doing several symasym mods and I am helping him. He will build the buffered VAS and I will certainly hear it.
He goes at higher power, and the current VAS is a weakpoint of the symasym.
But a friend of mine is doing several symasym mods and I am helping him. He will build the buffered VAS and I will certainly hear it.
He goes at higher power, and the current VAS is a weakpoint of the symasym.
All rigth...i wish you and your friend good luck
Into future listening tests.
regards,
Carlos
Into future listening tests.
regards,
Carlos
PMA said:
How is stability? I tried a triple darlington version but discarded it...
Which distortions are lower? 2nd harmonic or the higher ones?
(i have no spice installed yet on my new computer)
Yes, higher power for symasym is difficult because of quite low current in vas, that's the price for using cheap and available to92 here.
Mike
MikeB said:
Hi Mike,
2nd, 3rd, and the higher order content as well.
Regarding stability - you can see one capacitor added in the second diff stage. Value of Cfb changed.
Let´s wait for the built modification, this would say more.