Wellerman,
Your idea of a bad output transistor is very possible. I beat them up badly during the desolder/re-solder process. I'm going to remove and test them. Thank you.
Sorry about any ambiguity regarding R27. The closest I've gotten to decent sound is with R27 = 330R with voltage across R27 at 2.65V.
Dirk,
I'm using the opamps that came with the kit (OPA2604). I'm not nearly savvy enough to attempt substitutions! :->
Ranshdow,
Thanks for the guidance regarding the settings.
Your idea of a bad output transistor is very possible. I beat them up badly during the desolder/re-solder process. I'm going to remove and test them. Thank you.
Sorry about any ambiguity regarding R27. The closest I've gotten to decent sound is with R27 = 330R with voltage across R27 at 2.65V.
Dirk,
I'm using the opamps that came with the kit (OPA2604). I'm not nearly savvy enough to attempt substitutions! :->
Ranshdow,
Thanks for the guidance regarding the settings.
AkimoSD writes:
"The closest I've gotten to decent sound is with R27 = 330R with voltage across R27 at 2.65V."
This is interesting because that computes to 8mA which should be too high. Can this be a clue as to where the problem might be?
"The closest I've gotten to decent sound is with R27 = 330R with voltage across R27 at 2.65V."
This is interesting because that computes to 8mA which should be too high. Can this be a clue as to where the problem might be?
I've ordered new output transistors as I mangled up the existing ones during desoldering.
Craigl59m
Thanks for pointing that out. I'm embarrassed to say I've muddled the appropriate I vs V ranges. Before I put the new transistors in, I'll take the conservative route and put higher value R27's in.
Craigl59m
Thanks for pointing that out. I'm embarrassed to say I've muddled the appropriate I vs V ranges. Before I put the new transistors in, I'll take the conservative route and put higher value R27's in.
Earlier in this thread many have reported success. Am using dual power supplies (one discrete psu for each board) and duplicating the regulators along with the 7815 and 7915s to good effect - less noise. Randy Thatcher offers the pcbs for a flexreg psu that works well with the P3 and allows you to experiment with voltages from 15 to 24 vdc. Give your ideas a try.
@mhenschel:
I have the regulators on my PSU-boards (which is normally not as good as to have them on the amp-board).
You could also use two regulators behind each other (I know this from PSUs for headphoneamps...). One pos. and neg. regulator on the PSU followed by a pos. and neg. regulator on the amp-board. Not necessary, but you can go that 'crazy' route
Give the regulators something to work (that they regulate 3 to 4 volts down).
You could also use a shunt reg followed by the regulators on the PEARL3 boards...
A few members like Mark Johnson and Randy Thatcher offer great PSUs.
Many roads lead to Rome...
Cheers
Dirk
I have the regulators on my PSU-boards (which is normally not as good as to have them on the amp-board).
You could also use two regulators behind each other (I know this from PSUs for headphoneamps...). One pos. and neg. regulator on the PSU followed by a pos. and neg. regulator on the amp-board. Not necessary, but you can go that 'crazy' route
Give the regulators something to work (that they regulate 3 to 4 volts down).
You could also use a shunt reg followed by the regulators on the PEARL3 boards...
A few members like Mark Johnson and Randy Thatcher offer great PSUs.
Many roads lead to Rome...
Cheers
Dirk
@Wellerman
I assume you omitted the on-board regulators. any other associated components omitted? caps etc??
Where did you connect the super regs on the Pearl 3 board?
I assume you omitted the on-board regulators. any other associated components omitted? caps etc??
Where did you connect the super regs on the Pearl 3 board?
Last edited:
@cubicincher : have been interested in the battery option for several years. Can you describe in audiophile terms what difference a battery PSU makes?
Aside from the subjective opinion, the battery supply will have higher impedance and be noisier vs a well constructed/regulated linear
supply, so (IMO) I fail to see any advantage of batteries.
You need to imagine a regulated linear supply whose raw DC input comes from batteries. Among other advantages, Line Rejection is infinite.
My opinion on PSUs in phonopreamps is, that it has to be as silent as possible.
Why? - A phonopre has to amplify very tiny signals in the mV -region. And the amplification factor is very high (often anywhere
between 40 and 70 dB). The most extreme case is, if you use low output Moving Coil cartridges with a 0,2 - 0,5 mV outputvoltage.
Is a battery power supply or a regulated power supply better?
My opinion is, that it can't be answered clearly. Both variants can be extremely good. For me it is more about the efforts and the effects on the sound. Is it audible? Hmmm.
I think that more than 95% of the PEARL 3 -builders will be more than happy with the PSUs offered in this forum.
If you want to experiment - buy four 9V - batteries and make a nice symmetrical +-18 V DC 'PSU' out of them. It is easy.
Cheers
Dirk
Why? - A phonopre has to amplify very tiny signals in the mV -region. And the amplification factor is very high (often anywhere
between 40 and 70 dB). The most extreme case is, if you use low output Moving Coil cartridges with a 0,2 - 0,5 mV outputvoltage.
Is a battery power supply or a regulated power supply better?
My opinion is, that it can't be answered clearly. Both variants can be extremely good. For me it is more about the efforts and the effects on the sound. Is it audible? Hmmm.
I think that more than 95% of the PEARL 3 -builders will be more than happy with the PSUs offered in this forum.
If you want to experiment - buy four 9V - batteries and make a nice symmetrical +-18 V DC 'PSU' out of them. It is easy.
Cheers
Dirk
I have built a battery- PSU followed by adjustable regulators for a variable outputvoltage. Those are two AGM-batteries (12 V / 7,2 Ah) in series. So I get 24 V DC out. The adjustable regulators can deliver the desired voltages. For symmetrical voltages you can use four 12 V batteries to get +-24 V DC out.
The batteries are pretty big and heavy! But they last very long. Longer than any of my listening sessions...
Greets
Dirk
The batteries are pretty big and heavy! But they last very long. Longer than any of my listening sessions...
Greets
Dirk
Attachments
Right now I am severely constrained on my ability to build due to the baby sleeping beside my desk in the bedroom.
So whilst I can't solder I've been cooking projects up for the future. A friend of mine has requested a phono stage be built next year. Pearl 3 is of course the perfect candidate.
Him being a frugal sort, he won't want to fork out for the full store kit which means I have to do it the old fashioned way since there are no pcbs available.
Since I have to design a pcb anyway. Why not upgrade the power supply!
Thus we get something like this:
The pcb will of course have to be a bit bigger to fit the denoiser but I think it will be worth it.
As much as I know the stock regulators are perfectly good. I know I can do better and therefore I must.
Careful selection of junkbox parts, salvaged Iron, Steel and Aluminium I should be able to keep the cost down and the quality up.
So whilst I can't solder I've been cooking projects up for the future. A friend of mine has requested a phono stage be built next year. Pearl 3 is of course the perfect candidate.
Him being a frugal sort, he won't want to fork out for the full store kit which means I have to do it the old fashioned way since there are no pcbs available.
Since I have to design a pcb anyway. Why not upgrade the power supply!
Thus we get something like this:
The pcb will of course have to be a bit bigger to fit the denoiser but I think it will be worth it.
As much as I know the stock regulators are perfectly good. I know I can do better and therefore I must.
Careful selection of junkbox parts, salvaged Iron, Steel and Aluminium I should be able to keep the cost down and the quality up.
sadface,
what's with 'the thing with the cheap friend in the place'? I don't know the kind of premium 'junkbox' you got going on, whatever the motivation, it is not saving money. Please try again.You can get a phonostage for 25 USD on ebay.
what's with 'the thing with the cheap friend in the place'? I don't know the kind of premium 'junkbox' you got going on, whatever the motivation, it is not saving money. Please try again.
You can get a phonostage for 25 USD on ebay.