Yes thats what I meant. Make the resistors equal rather than pre-adjusted.
If it works then the circuit is more robust since there is no DC carrying pot in the circuit which could fail open at some point.
It might not bring any other benefits, but its where I would apply the servo.
Shoog
Guys, another idea:
If the bias current is set to be 0.6~0.7A, +-14VDC supply, could we just use low noise IC regulator like LT1963/LT3015 (1.5A max) for supply?
Given loaded,say 1.4A, the drop-out voltage is several hundred mV, which seems OK if V input is 15VDC.
Any suggestions? I am also considering the Sigma-22 regulator module.
Thanks,
E
If the bias current is set to be 0.6~0.7A, +-14VDC supply, could we just use low noise IC regulator like LT1963/LT3015 (1.5A max) for supply?
Given loaded,say 1.4A, the drop-out voltage is several hundred mV, which seems OK if V input is 15VDC.
Any suggestions? I am also considering the Sigma-22 regulator module.
Thanks,
E
Attachments
Here is another thought regarding the use of DC servos (in either position), if you use a DC servo to take care of DC bias, you can retain the bias adjustment pot and use it to trim for minimum AC distortion. Of course, in order to achieve this you will need a distortion measuring scope.
Shoog
Shoog
Arg I did not mean both 1. and 2. at the same time, but just one of them.
And my suggestion for the 330 ohms was only for R6 not R7 (yes I suggested them to be asymetrical)
...anyway you have now moved on, and if the increased Idle current does not cause any problems then that is fine. However the increase in THD is not good.
Last edited:
What caps to use?
Hello, looking to restore a Monster that I bought years ago that unfortunately (or maybe it is good, don't know yet) have been messed up with in the power supply.
I am looking to build the power supply according to the pic. and want to start getting material for it.
Could even think about going really wild
cause in principle it is only the size of the batteries that change and the amount of capacitors. Everytning else being the same.
The caps to use, big buggers 68.000 uF each and 40 V, as I understand should be low ESR and high for ripple current and then it come to price also, cheap would be good (there is a lot of them).
Have been looking on both TDK, CDE and RIFA but what to choose and where do I find them for deacent price. I think Mouser is OK but maybe somewone here have other ideas.
Do I dare buy them from China or the quality is too much of a problem?
Also found Nippon caps that are deacent in price but are they ok for this application (that is rather sensitive regarding sound quality, to what you put into it).
If I remember right (middle aged and slightly amnesic) Hiraga himself was using RIFA because of the sound but I can't verify this cause I have lost the notes that I did take somewhere many years ago and now when I want to get started its gone. Maybe someone here have more meat to the bones on this matter?
Any idea that help me on the road would be appreciated.
Hello, looking to restore a Monster that I bought years ago that unfortunately (or maybe it is good, don't know yet) have been messed up with in the power supply.
I am looking to build the power supply according to the pic. and want to start getting material for it.
Could even think about going really wild
cause in principle it is only the size of the batteries that change and the amount of capacitors. Everytning else being the same.
The caps to use, big buggers 68.000 uF each and 40 V, as I understand should be low ESR and high for ripple current and then it come to price also, cheap would be good (there is a lot of them).
Have been looking on both TDK, CDE and RIFA but what to choose and where do I find them for deacent price. I think Mouser is OK but maybe somewone here have other ideas.
Do I dare buy them from China or the quality is too much of a problem?
Also found Nippon caps that are deacent in price but are they ok for this application (that is rather sensitive regarding sound quality, to what you put into it).
If I remember right (middle aged and slightly amnesic
) Hiraga himself was using RIFA because of the sound but I can't verify this cause I have lost the notes that I did take somewhere many years ago and now when I want to get started its gone. Maybe someone here have more meat to the bones on this matter?Any idea that help me on the road would be appreciated.
Hello,
If i remember correctly the shop in France use to sell the Sic safco brand type co38 and co39. For the 30 watt they had some special ones made, But french people usually will go for french manufacturers.
Good caps usually are expensive, The technology did make some progress they say. No need to go for 40 volt ones for LE MONSTRE because dc voltage is below 20 volts. I think l'audiophile did use 25 volts type caps. Later they start using 40 volts caps for most of their circuits to limit their stock.
Greetings, Edward
If i remember correctly the shop in France use to sell the Sic safco brand type co38 and co39. For the 30 watt they had some special ones made, But french people usually will go for french manufacturers.
Good caps usually are expensive, The technology did make some progress they say. No need to go for 40 volt ones for LE MONSTRE because dc voltage is below 20 volts. I think l'audiophile did use 25 volts type caps. Later they start using 40 volts caps for most of their circuits to limit their stock.
Greetings, Edward
What to choose ESR or Ripple?
OK, quick search on 25 V caps give me the oppertunety to choose from either low ESR or high ripple resistence.
Question, what to prioritize?
Since the ripple, according to Hiragas own explenation, is reduced by approximately to the power of ten for each capacitor stage in the power supply this should be of minor importance when choosing the capacitors. The priority then has to be made to low ESR to keep a stable working condition....
AM I RIGHT???
Is my conclusion correct here?? I need a second opinion on this. I do thinkt that my thought is correct and then I shuold favour low ESR instead of looking for lowest possible ripple current value.
OK, quick search on 25 V caps give me the oppertunety to choose from either low ESR or high ripple resistence.
Question, what to prioritize?
Since the ripple, according to Hiragas own explenation, is reduced by approximately to the power of ten for each capacitor stage in the power supply this should be of minor importance when choosing the capacitors. The priority then has to be made to low ESR to keep a stable working condition....
AM I RIGHT???
Is my conclusion correct here?? I need a second opinion on this. I do thinkt that my thought is correct and then I shuold favour low ESR instead of looking for lowest possible ripple current value.
Why low esr, why not ultra low esr? Class A - ultra high frequency device.. as motherboard.
Hew Damon,
I did H20W out, any comment?
BTW, the power supply in my mind would be LT1963/3015, but they can only supply 1.5A, should I use parallel topology to increase its power? Or do you recommend PSU that don't need so many caps? I want it small, no room for such a large monster
I did H20W out, any comment?
BTW, the power supply in my mind would be LT1963/3015, but they can only supply 1.5A, should I use parallel topology to increase its power? Or do you recommend PSU that don't need so many caps? I want it small, no room for such a large monster
Attachments
Last edited:
Hi DC Servo Fan. On original schematic of 1985 was 1,456F (summary filter) 68000 uF+0,22R 25W+2*330000uF per rail. Maybe better CLC, or CRCLC. Maybe 2*33000uF+0,25R 30W+4*33000uF+L+16*33000uF per rail (as example).
In my Hiraga's 20W (1980) I used small CRC filter with summary 0,885F.
http://www.diyaudio.com/forums/solid-state/193-hiraga-20w-class-95.html#post4568258
http://www.diyaudio.com/forums/solid-state/193-hiraga-20w-class-97.html#post4612234
On original schematic of 1985 was 1,456F (summary filter) 68000 uF+0,22R 25W+2*330000uF per rail. Maybe better CLC, or CRCLC. Maybe 2*33000uF+0,25R 30W+4*33000uF+L+16*33000uF per rail (as example).In my Hiraga's 20W (1980) I used small CRC filter with summary 0,885F.
http://www.diyaudio.com/forums/solid-state/193-hiraga-20w-class-95.html#post4568258
http://www.diyaudio.com/forums/solid-state/193-hiraga-20w-class-97.html#post4612234
Last edited:
Hi guys,
About PSU, can LDO reduce the usage of Caps?
I found this design: parallel LT1963, very low noise, 3A output.
But the max Input is 20V, while we need 21V, not including dropout voltage.
What if I add voltage reference to increase the output voltage?
Can it work on this?
thanks
About PSU, can LDO reduce the usage of Caps?
I found this design: parallel LT1963, very low noise, 3A output.
But the max Input is 20V, while we need 21V, not including dropout voltage.
What if I add voltage reference to increase the output voltage?
Can it work on this?
thanks
Attachments
A small bank of caps (say 10Ku) followed by a capacitance multiplier and then a bigger bank of caps (say 33Ku) is a good cheap arrangement for the Hirage. Having the big caps on the output of the cap multiplier will minimise the sound of the multiplier.
I don't really hold with the original brute force approach to the power supply advocated by Hirage.
Shoog
I don't really hold with the original brute force approach to the power supply advocated by Hirage.
Shoog
