Attachments
Last edited:
second channel
Rise time 1.2us (second channel)with 270pf compensation capacitor.
Rise time 1.2us (second channel)with 270pf compensation capacitor.
Attachments
Last edited:
sx
Hi Bonsai ,is there any reason that is not used bc550c,560c(low noise) instead of bc547c,557c in sx-amplifier?
Thanks.
Hi Bonsai ,is there any reason that is not used bc550c,560c(low noise) instead of bc547c,557c in sx-amplifier?
Thanks.
Thimios,
You can use 550 c and 560 c also.
Normally for a power amp you don't really need low noise transistors.
Your rise time is a bit longer than mine, but I guess that's because you are using 270 pF for your comp
You can use 550 c and 560 c also.
Normally for a power amp you don't really need low noise transistors.
Your rise time is a bit longer than mine, but I guess that's because you are using 270 pF for your comp
Today first channel was tested again(220pf compansation cap.)
Same results(1.2us),then this same channel was measured before L out. Rise time=520ns.
BTW I want recommendations about volume potentiometer value(ΚΩ)
Attachments
Last edited:
Ok - that sounds more like it - my measurements were before the inductor
For the potentiometer, I would suggest 10 k is the max.
The input is a diamond buffer and you do get partial cancellation of the input bias currents. However, you may still get pot scratch noise which means you should capacitively couple the pot to the amp input.
For the potentiometer, I would suggest 10 k is the max.
The input is a diamond buffer and you do get partial cancellation of the input bias currents. However, you may still get pot scratch noise which means you should capacitively couple the pot to the amp input.
Ver2 isolates the DC effect of the vol pot from the amplifier input.
Does that isolation affect the input bias?
Does that isolation affect the input bias?
Here is how to wire a pot to the input without causing problems.
If you do not use a DC blocking cap as shown in the diagram, you will get 'pot scratch' noise after a while. And the DC source resistance will change as you adjust the pot.
If you do not have a bipolar cap, just use two electrolytics back to back - use a minimum value of ~50uF.
If you do not use a DC blocking cap as shown in the diagram, you will get 'pot scratch' noise after a while. And the DC source resistance will change as you adjust the pot.
If you do not have a bipolar cap, just use two electrolytics back to back - use a minimum value of ~50uF.
Attachments
Last edited:
Yes - that's correct.
I always prefer the lower value of 10k for my power amps. But because you are actually loading the pot wiper, it needs to be higher.
I always prefer the lower value of 10k for my power amps. But because you are actually loading the pot wiper, it needs to be higher.
Not a Lot of choices for NX PT..
I want to go with Piltron 500VA.. They have a min Charge or $250 so need 2 PT's.. possible I can pick up..
So my question is What other amp can I build? Then I can buy the PT for it..
The NX is so well Documented and with the PCB's, should make things easy😎
Bonsai, I like to go for the works, and build matching preamp, Symphony? looks like the PT's are on the boards.. Or can it be separate Toroidal? What Spec
Any suggestion?
Is symphony ready, what about SCA-1
I want to go with Piltron 500VA.. They have a min Charge or $250 so need 2 PT's.. possible I can pick up..
So my question is What other amp can I build? Then I can buy the PT for it..
The NX is so well Documented and with the PCB's, should make things easy😎
Bonsai, I like to go for the works, and build matching preamp, Symphony? looks like the PT's are on the boards.. Or can it be separate Toroidal? What Spec
Any suggestion?
Is symphony ready, what about SCA-1
Last edited:
Is it not cheaper to buy a transformer from Mouser or Digikey? I bought a single 500 VA off the shelf for about $100 excl. shipping. It had split secondaries ANC split primaries 34-0-34 from Triad Magnetics.
Re the pre, both the Symphony and SCA-1 are complicated and I would need to generate a lot of documentation to be able to make them build able by someone else.
I won't make promises, but might find some time in the future to revisit the Xaltra Mini and make that build able. It does have a very good sound and I use it ( currently driving my sx-Amp and fed from my Pioneer SACD player)
Re the pre, both the Symphony and SCA-1 are complicated and I would need to generate a lot of documentation to be able to make them build able by someone else.
I won't make promises, but might find some time in the future to revisit the Xaltra Mini and make that build able. It does have a very good sound and I use it ( currently driving my sx-Amp and fed from my Pioneer SACD player)
Last edited:
A HOUSE FROM RECYCLED MATERIALS.
Preparing a house for sx amplifier from recycled materials and what i have on hand now.😀
A Faraday shield from an old monitor ,a big transformer from an old UPS ,two new cap banks ....
Preparing a house for sx amplifier from recycled materials and what i have on hand now.😀
A Faraday shield from an old monitor ,a big transformer from an old UPS ,two new cap banks ....
Attachments
Last edited:
Xaltra looks nice.. Maybe one day then, Thanks!
The only PT I can come up with, is Piltron or Acme..
Acme is 600VA 33-0-33 - $165
Maybe the 400VA unit on ebay is a good choice.
I've sourced some parts form china, including spec wound tube transformers.. The quality was good.. I'll see what they can do for the Toroidal for NX.
Bosai, I could, possibly help out, for getting the PCB's manufactured, for a preamp..
The only PT I can come up with, is Piltron or Acme..
Acme is 600VA 33-0-33 - $165
Maybe the 400VA unit on ebay is a good choice.
I've sourced some parts form china, including spec wound tube transformers.. The quality was good.. I'll see what they can do for the Toroidal for NX.
Bosai, I could, possibly help out, for getting the PCB's manufactured, for a preamp..
Last edited:
