choky said:
not so small -and discrete regulation........
no stinkin' chips here-please!
Zang's reg boards and this toroid from Steve @ apex.jr:
Avel-Lindberg Inc
Input: 2 X 120Vac 50-60Hz 3 1/4" Dia X 1 1/2" Tall
Output: 2 X 25V @ 2 Amps 100Va $17.95ea
Middle in the picture.. Although I have all 3... I might use the large....
Attachments
rabstg said:
with chip regs you can't achieve what is possible
if your plan is to have regs only to input (voltage and predriver stage) without drivers,best way is discrete shunt reg
for drivers seral discrete reg
or-as some medium solution-serial discrete reg for input and drivers together
it's my opinion 😀
rabstg said:
Why ? Class A designs won't benefit much from regulated power supply. I mean, it won't hurt, but I think that $$$ and effort is better spent elsewhere (more devices, more capacitors, bigger toroids, bigger heatsinks, nicer looking case).
Anyone aware of any Nelson Pass power amp design (Threshold, Aleph, X, J ...) that use regulated power supply ? I know others are doing it (Krell Reference) but it looks to me more of a marketing excercise that anything really useful for a class A amp. If its good for a Master ...
Bratislav
Bratislav said:
400VA, 25 x 2 per channel
CLC, 68K uF 1.8mH 68KuF (then bypassed with Wima polypropelyne)
16 inch wide 8 inch tall 2 inch thick heat sinks (8 wide x 3 tall = .5K/C)
1/2" alum front, 1/8th inch top back and 1/4" bottom
Hypex soft start
Silver plated wire w/ Teflon insul through out
I'm game for descrete regs, design a PCB and BOM and I'll build.
jacco vermeulen said:
Thank you for the explenation Jacco.
I have attached a schema of what I would like to do for the PSU (mainly what Pinkmouse suggested on page 434). From what I understood, I won't get the benefit of a greater headroom since the voltage is the same for drivers and outputs, but it would enable me to have the "always on" front end without the outputs, and I would also be able to add regulated voltage to the front end which does sound beneficial. My question is, would this work if the relay was to be powered only when the amp would be in use?
And thank you for pointing me to the discussion GeWa. Have you applied the idea in your amp?
Paul
Attachments
Bratislav said:
The Pass/Thagard A75 uses a regulated front end with rails higher than the MOSFET output stage. The Aleph and AX designs need a single supply to work.
Why ? Class A designs won't benefit much from regulated power supply. I mean, it won'
There are designers who think that regulating the voltage amplifier board in class A does give benefits.
Borbely does in his class A designs and in Australia look at the Silicon Chip 15 Watt class A amp that is fully regulated. The distortion figures are very low.
The ripple current in a class A will be higher than others and would benifit with a regulated power supply in the front end.
My 2 cents.
Regards
Harry
There are designers who think that regulating the voltage amplifier board in class A does give benefits.
Borbely does in his class A designs and in Australia look at the Silicon Chip 15 Watt class A amp that is fully regulated. The distortion figures are very low.
The ripple current in a class A will be higher than others and would benifit with a regulated power supply in the front end.
My 2 cents.
Regards
Harry
Re: Why ? Class A designs won't benefit much from regulated power supply. I mean, it won'
Harry,
of course regulating everything will make figures better. The question is "can we really hear the difference" ? That's what I was alluding to. And that's what Pass seems to think is not necessary. At least in his commercial designs (some of which are widely recognized as state of the art ).
Bratislav
Harry3 said:
Harry,
of course regulating everything will make figures better. The question is "can we really hear the difference" ? That's what I was alluding to. And that's what Pass seems to think is not necessary. At least in his commercial designs (some of which are widely recognized as state of the art ).
Bratislav
JoeyDD said:
How long would you like this to work ?
Such a relay should be pretty fancy, is my guess.
I think a regulator can be constructed that does.
Integrated regulators have become a lot better, LM3xx style regulators do not deserve to be called stinkin.
Mr Pass has made simplicity his goal when he started Pass Laboratories, he does like constant current sources.
Aleph amplifiers are popular among the diy people because they are so easy to build. imo, they are not a good match with just any kind of loudspeaker, i sometimes wonder how many who built Aleph amplifiers have the right ones.
Same goes for class A amplifiers in general, easier to construct for diy-ers than an outstanding class AB.
NP was the only one to have succes with his stasis designs, all others who tried floating bias on their designs never quite made it to audio heaven.
Guys like Peter Daniel are the few on this forum who constructed Mark Levinson designs, those are complex and it requires someone with the experience of PD to make it through with honors. ML designs from the KSA50 era leaned heavilly on regulation.
Take away the output stage of a class AB amplifier, and there isn't much of a difference with the front end of a class A design.
There's an abundance of class AB amplifiers with regulation for the front end.
You can not go faster with bigger wheels, but you can with ABS and suspension control.
My 2 cents next to Harry's.
jacco vermeulen said:
For some time, but it can be 4 single relays, or a switch instead of that quad. Would there be any long term problems?
Paul
A relay on the primaries or the secondaries of a transformer makes quite a difference.
If the bias setting of the amplifier remains unchanged there would be very high currents going through the relay contacts because the capacitors will be totally empty.
Bare in mind that with a single PS the front end of the amplifier acts as a soft starter.
With the front end working 100%, the output devices will be fully open when you hit the relay switch.
You would need some kind of softstart circuit for the output stage, and heavy duty relays.
The small surplus toroids i have for the KSA i got for a dollar each, how much relay, big toroid or capacitor does 1 dollar buy ?
You need the bridge rectifiers and capacitors anyway, the money spent on a small transformer is saved on relays, even a 10VA board mount transformer can do.
If the bias setting of the amplifier remains unchanged there would be very high currents going through the relay contacts because the capacitors will be totally empty.
Bare in mind that with a single PS the front end of the amplifier acts as a soft starter.
With the front end working 100%, the output devices will be fully open when you hit the relay switch.
You would need some kind of softstart circuit for the output stage, and heavy duty relays.
The small surplus toroids i have for the KSA i got for a dollar each, how much relay, big toroid or capacitor does 1 dollar buy ?
You need the bridge rectifiers and capacitors anyway, the money spent on a small transformer is saved on relays, even a 10VA board mount transformer can do.
If I do add a transformer for the front end, will I not also need to take in account that the outputs are open?
Thank you for your help with all these questions Jacco; I really appreciate it.
Paul
Thank you for your help with all these questions Jacco; I really appreciate it.
Paul
jacco vermeulen said:
Ummm... can you please give an explanation how could a regulator (even a 'stinking' LM) make things worse in perfectly static conditions that are prevalent in a class A design ?
I'm no fan of regulated anything in power amplifiers , just want to learn about mechanisms involved.
Bratislav
quote:
Originally posted by Harry3
There are designers who think that regulating the voltage amplifier board in class A does give benefits.
Borbely does in his class A designs and in Australia look at the Silicon Chip 15 Watt class A amp that is fully regulated. The distortion figures are very low.
The ripple current in a class A will be higher than others and would benifit with a regulated power supply in the front end.
My 2 cents.
Regards
Harry
Harry,
of course regulating everything will make figures better. The question is "can we really hear the difference" ? That's what I was alluding to. And that's what Pass seems to think is not necessary. At least in his commercial designs (some of which are widely recognized as state of the art ).
Bratislav
the 15watt reg boards are very useful, increase no of the transistor to up the current put trimmer pot for adjust voltage
when two kits are less than half the price of one 68000uF cap.
harry3 that "Silicon Chip 15 Watt class A amp" is a sweet sounding little amp, up the voltage and bias to add more base control!
allan
Originally posted by Harry3
There are designers who think that regulating the voltage amplifier board in class A does give benefits.
Borbely does in his class A designs and in Australia look at the Silicon Chip 15 Watt class A amp that is fully regulated. The distortion figures are very low.
The ripple current in a class A will be higher than others and would benifit with a regulated power supply in the front end.
My 2 cents.
Regards
Harry
Harry,
of course regulating everything will make figures better. The question is "can we really hear the difference" ? That's what I was alluding to. And that's what Pass seems to think is not necessary. At least in his commercial designs (some of which are widely recognized as state of the art ).
Bratislav
the 15watt reg boards are very useful, increase no of the transistor to up the current put trimmer pot for adjust voltage
when two kits are less than half the price of one 68000uF cap.
harry3 that "Silicon Chip 15 Watt class A amp" is a sweet sounding little amp, up the voltage and bias to add more base control!
allan
BTW, Silicon Chip Ultra Low Distortion amp (as well as 15W class A mentioned by Harry) does use 'stinking' LM 317/337 to regulate front end ... so what gives ?
Bratislav
PS I don't think there's anything wrong with LM3xx application in properly designed power amp; with decent PSRR and steady load (class A) they almost could work without any regulation. And guess what ? Many do !
Bratislav
PS I don't think there's anything wrong with LM3xx application in properly designed power amp; with decent PSRR and steady load (class A) they almost could work without any regulation. And guess what ? Many do !
BTW, Silicon Chip Ultra Low Distortion amp (as well as 15W class A mentioned by Harry) does use 'stinking' LM 317/337 to regulate front end ... so what gives ?
Bratislav
PS I don't think there's anything wrong with LM3xx application in properly designed power amp; with decent PSRR and steady load (class A) they almost could work without any regulation. And guess what ? Many do !
I gather you have something against the LM317/37's?
i do have some questions though.
1-what is the ppsr like in the Ksa50?
2-How much ripple or noise on an uregulated line?
3-How much ripple or noise on a LM317/37?
4-Unregulated or reg'ed, easiest way of dealing with ripple/noise?
Ps I didn't like the sound of the (Silicon Chip Ultra Low Distortion amp)
too clinical, steril.
pps I'am not interested in reg unreg debate(war).
Just the price of the big caps!
and i have a couple of spare regs for a ksa50
allan
Bratislav
PS I don't think there's anything wrong with LM3xx application in properly designed power amp; with decent PSRR and steady load (class A) they almost could work without any regulation. And guess what ? Many do !
I gather you have something against the LM317/37's?
i do have some questions though.
1-what is the ppsr like in the Ksa50?
2-How much ripple or noise on an uregulated line?
3-How much ripple or noise on a LM317/37?
4-Unregulated or reg'ed, easiest way of dealing with ripple/noise?
Ps I didn't like the sound of the (Silicon Chip Ultra Low Distortion amp)
too clinical, steril.
pps I'am not interested in reg unreg debate(war).
Just the price of the big caps!
and i have a couple of spare regs for a ksa50
allan