Hi,
That's certainly true but it's not the regulation that's at fault but the design.
I ran a MC headamp from a battery and from a properly designed solid state regulator and the regulator had the edge.
Note these are very low current demand class A circuits with very high input sensitivity.
I find battery supplies aren't ideal either and not worth the effort and maintenance expense most of the time. YMMV.
Guess I just had to "chip" in.
Cheers,
That's certainly true but it's not the regulation that's at fault but the design.
I ran a MC headamp from a battery and from a properly designed solid state regulator and the regulator had the edge.
Note these are very low current demand class A circuits with very high input sensitivity.
I find battery supplies aren't ideal either and not worth the effort and maintenance expense most of the time. YMMV.
Guess I just had to "chip" in.
Cheers,
0.1uf poly
I have just listen to my GC for the last half hour. Now I can live with these GCs actually I found tonight that I am turning the volumn higher and higher which I do not normally do with the JLHs. This is good. May be the regulated PSU will prove to be better, I will see..cos I do not have time to do that yet but in my drawer I have 8 little japanese caps left so I just stick them in the GC right after work and finished reading the app. notes of the chip. The soundstage is really clean up now. I wonder why Brain did not put it in his design to bypass the panasonic cap with these 0.1uf polys. This is a much cheaper and quick solution until may be a proper designed regulated PSU can be realised.
The hair in the back of my neck and goose bum are reactivated tonight.
Regards,
Chris
I have just listen to my GC for the last half hour. Now I can live with these GCs actually I found tonight that I am turning the volumn higher and higher which I do not normally do with the JLHs. This is good. May be the regulated PSU will prove to be better, I will see..cos I do not have time to do that yet but in my drawer I have 8 little japanese caps left so I just stick them in the GC right after work and finished reading the app. notes of the chip. The soundstage is really clean up now. I wonder why Brain did not put it in his design to bypass the panasonic cap with these 0.1uf polys. This is a much cheaper and quick solution until may be a proper designed regulated PSU can be realised.
The hair in the back of my neck and goose bum are reactivated tonight.
Regards,
Chris
Re: 0.1uf poly
What type/brand of caps are you talking about here?
I was never really using Panasonics and with BGs, I didn't find a need for any additional bypasses. Actually I tried some, but they always did something not desirable to the sound.
And question to Carlos:
What are the exact areas of improvement with regualted PS?
Also notice that Carlos is using inverted configuaration, which is not exactly same sounding to non inverting
Those amps take up to a month to completely break in.
chris ma said:
What type/brand of caps are you talking about here?
I was never really using Panasonics and with BGs, I didn't find a need for any additional bypasses. Actually I tried some, but they always did something not desirable to the sound.
And question to Carlos:
What are the exact areas of improvement with regualted PS?
Also notice that Carlos is using inverted configuaration, which is not exactly same sounding to non inverting
Those amps take up to a month to completely break in.
Re: Re: 0.1uf poly
Me?
Oh.
I was regulating another one I have.
A buffered NIGC with LM4780.
Peter, I tried them all.
My house is full of amps.
BTW, my regulated BIGC on my main system is playing music non-stop for some two weeks now.
Improvement?
Let's say that on some extreme bass recordings I had some "room resonances" (I thought!), and when I regulated they completely vanished!
I suppose that you know that when you get a good, tight bass (I mean, a bass to for) everything gets better: mids, treble, detail...
Soundstage got bigger, higher, deeper.
That's why I say this seams like a Krell: finally my difficult speakers have what they like.
Seriously Peter, I don't have the money to have a system like this if I was to buy commercial products.
I'm used to listen to high-end for many years (not at home) and the sound I have at home now, in my system, is high-end.
Peter Daniel said:
And question to Carlos:
What are the exact areas of improvement with regualted PS?
Also notice that Carlos is using inverted configuaration, which is not exactly same sounding to non inverting
Those amps take up to a month to completely break in.
Me?
Oh.
I was regulating another one I have.
A buffered NIGC with LM4780.
Peter, I tried them all.
My house is full of amps.
BTW, my regulated BIGC on my main system is playing music non-stop for some two weeks now.
Improvement?
Let's say that on some extreme bass recordings I had some "room resonances" (I thought!), and when I regulated they completely vanished!
I suppose that you know that when you get a good, tight bass (I mean, a bass to
for) everything gets better: mids, treble, detail...Soundstage got bigger, higher, deeper.
That's why I say this seams like a Krell: finally my difficult speakers have what they like.
Seriously Peter, I don't have the money to have a system like this if I was to buy commercial products.
I'm used to listen to high-end for many years (not at home) and the sound I have at home now, in my system, is high-end.
Neal, the circuit is the same, the PCB is the same, components are the same, PSU diodes are the same.
What I was hearing was not LF instability, it was simply related to the unregulated PSU's low capacitance (1000uf), and it's inability to deal with this extreme dynamics and transients.
As you can't go much higher in capacitance with this chips (sounds bad), no solution here.
Voltage variations, as little as it may be, affects bass performance IMHO.
What I was hearing was not LF instability, it was simply related to the unregulated PSU's low capacitance (1000uf), and it's inability to deal with this extreme dynamics and transients.
As you can't go much higher in capacitance with this chips (sounds bad), no solution here.
Voltage variations, as little as it may be, affects bass performance IMHO.
Peter?
Take a look at this:
http://www.diyaudio.com/forums/showthread.php?s=&postid=420456#post420456
Take a look at this:
http://www.diyaudio.com/forums/showthread.php?s=&postid=420456#post420456
Hi Carlos,
I am not doubting you the only reason I asked is because that's exactly what I have heard with the unregulated supply and when checking with 'scope and sig gen identified the LF instability on the PSU rails, cap value had no effect, I observed it with just 1W o/p into my ‘speakers.
Further messing with cap values again today on the regulated supply (trying to find the best sound) I again detected a bass whooph with one cap value and sure enough on the 'scope the LF instability was there again. It's simple enough to measure, drive a 50HZ sine wave into the amp for a 1W output into your 'speakers and look on the 'scope at the PSU rails.
Neal
I am not doubting you the only reason I asked is because that's exactly what I have heard with the unregulated supply and when checking with 'scope and sig gen identified the LF instability on the PSU rails, cap value had no effect, I observed it with just 1W o/p into my ‘speakers.
Further messing with cap values again today on the regulated supply (trying to find the best sound) I again detected a bass whooph with one cap value and sure enough on the 'scope the LF instability was there again. It's simple enough to measure, drive a 50HZ sine wave into the amp for a 1W output into your 'speakers and look on the 'scope at the PSU rails.
Neal
Neal,
Cap values after the LM338 regulator make a huge difference in sound, I made plenty of tests with that.
I stoped testing when I've got the sound that made me .
So, that was a 47nf polyester cap between reg output and ground (NEAR the reg), and 33uf/40v Philips electrolythics on the LM3886 PCB.
I bypass the LM3886 on the PSU pins with 0.1uf ceramics (as I always do with op-amps).
I can't say that this is definitely the ideal, as even the cap's type, quality, etc. can probably make a difference.
But what I have now is definitely another league ahead of the unregulated GC.
Can we still call this a GC?
Cap values after the LM338 regulator make a huge difference in sound, I made plenty of tests with that.
I stoped testing when I've got the sound that made me
.So, that was a 47nf polyester cap between reg output and ground (NEAR the reg), and 33uf/40v Philips electrolythics on the LM3886 PCB.
I bypass the LM3886 on the PSU pins with 0.1uf ceramics (as I always do with op-amps).
I can't say that this is definitely the ideal, as even the cap's type, quality, etc. can probably make a difference.
But what I have now is definitely another league ahead of the unregulated GC.
Can we still call this a GC?
Hi Carlos, yes that's what I am finding also.
I have tried .47uF, .22uF, .1uF, .047uF & .022uF
I can see (hear! ) why you like .047uF. Very open and detailed, however, I prefer the .22uF. Could not get the amp stable with .1uF as mentioned before and .047uF worked depending on volume level, low level was OK but as I turned it up the sound became strident and spitty. .47uF was bass heavy with apparent detail missing and lack of 'air'. I have got to see why .1uF causes me problems, might add a resistor in series with it to see if damps down the instability.........
Neal
I have tried .47uF, .22uF, .1uF, .047uF & .022uF
I can see (hear!
) why you like .047uF. Very open and detailed, however, I prefer the .22uF. Could not get the amp stable with .1uF as mentioned before and .047uF worked depending on volume level, low level was OK but as I turned it up the sound became strident and spitty. .47uF was bass heavy with apparent detail missing and lack of 'air'. I have got to see why .1uF causes me problems, might add a resistor in series with it to see if damps down the instability.........Neal
Neal, where do you join the output of one reg with the ground of the other reg to make the ground?
I do it on the board, near the regs.
I think it's better than run two wires and join them on the amp(s).
And I use 1.5mm multi-core copper wire for + and -, and 2.5mm multi-core for ground.
From the regs to the amps goes around 10~15cm of wire.
What cable do you use?
I do it on the board, near the regs.
I think it's better than run two wires and join them on the amp(s).
And I use 1.5mm multi-core copper wire for + and -, and 2.5mm multi-core for ground.
From the regs to the amps goes around 10~15cm of wire.
What cable do you use?
Neal?
This is on the LM138/338 datasheet, page 5:
"Although the LM138 is stable with no output capacitors, like
any feedback circuit, certain values of external capacitance
can cause excessive ringing. This occurs with values between
500 pF and 5000 pF. A 1 µF solid tantalum (or 25 µF
aluminum electrolytic) on the output swamps this effect and
insures stability."
The values that National recommends sound bad, so adjust by ear.
I like 47nf on the output.
Oh, I bypass on the input with 0.47uf poly, because the electrolythics are big and are a little far from the reg, it's always better to bypass near the reg.
This is interesting too, same page:
"An input bypass capacitor is recommended. A 0.1 µF disc or
1 µF solid tantalum on the input is suitable input bypassing
for almost all applications. The device is more sensitive to
the absence of input bypassing when adjustment or output
capacitors are used but the above values will eliminate the
possiblity of problems."
This is on the LM138/338 datasheet, page 5:
"Although the LM138 is stable with no output capacitors, like
any feedback circuit, certain values of external capacitance
can cause excessive ringing. This occurs with values between
500 pF and 5000 pF. A 1 µF solid tantalum (or 25 µF
aluminum electrolytic) on the output swamps this effect and
insures stability."
The values that National recommends sound bad, so adjust by ear.
I like 47nf on the output.
Oh, I bypass on the input with 0.47uf poly, because the electrolythics are big and are a little far from the reg, it's always better to bypass near the reg.
This is interesting too, same page:
"An input bypass capacitor is recommended. A 0.1 µF disc or
1 µF solid tantalum on the input is suitable input bypassing
for almost all applications. The device is more sensitive to
the absence of input bypassing when adjustment or output
capacitors are used but the above values will eliminate the
possiblity of problems."
GC pwr miss-hap
Hi All-
I just powered on my first GC without spkrs for testing purposes and heard a buzz sound. I switched it off and then tried again with the same results.
After investigating, I realized that the PG+ and V+ wires were crossed from the rectifier board to the amp board.
I corrected that issue and turned the switch on again.
This time the 2.5 amp fuse blew immediately.
Questions:
1) 2.5 amp fast blow fuse big enough?
2) Did I kill the 1500uF caps? They were what were buzzing.
3) Did I kill the LM3875?
4) Which is easier to test, caps or chip? I have a Fluke 87 and I believe it measures capacitance, but I'm not sure if it will reach 1500uF.
5) Anyone have spares they want to sell?
By the way, I KNOW, I'M AN IDIOT!!! Such a simple screw up.
Thanks in advance for your assistance,
Troy
Hi All-
I just powered on my first GC without spkrs for testing purposes and heard a buzz sound. I switched it off and then tried again with the same results.
After investigating, I realized that the PG+ and V+ wires were crossed from the rectifier board to the amp board.
I corrected that issue and turned the switch on again.
This time the 2.5 amp fuse blew immediately.
Questions:
1) 2.5 amp fast blow fuse big enough?
2) Did I kill the 1500uF caps? They were what were buzzing.
3) Did I kill the LM3875?
4) Which is easier to test, caps or chip? I have a Fluke 87 and I believe it measures capacitance, but I'm not sure if it will reach 1500uF.
5) Anyone have spares they want to sell?
By the way, I KNOW, I'M AN IDIOT!!! Such a simple screw up.
Thanks in advance for your assistance,
Troy
Re: GC pwr miss-hap
Troy,
Try using a 3A slow blow fuse, as the fast blow will probably die from the inrush currents.
The LM3875 might not be dead. As for the capacitor, if you don't see the top domed up, or leaking fluid, they might be fine for now also.
Give it a try again with a slow blow, and if you are still having problems, I can mail you some new components.
--
Brian
rabstg said:
Troy,
Try using a 3A slow blow fuse, as the fast blow will probably die from the inrush currents.
The LM3875 might not be dead. As for the capacitor, if you don't see the top domed up, or leaking fluid, they might be fine for now also.
Give it a try again with a slow blow, and if you are still having problems, I can mail you some new components.
--
Brian
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