[gunz_drawn]

hi

Is it absolutely imperative that we should use the ultra reg power supply with the dynolo....cause getting any opamp like 548 (the reason i chose dynalo...only op27 is available) is impossible in this part of the world...also the op27 has a very low slew rate to be used instead of the 548..

So could i use a STEPS and use something like this

for the virtual ground...



thanks in advance

 

[Garbz]

well firstly the opamp in the dynalo doesn't actually form part of the audio chain. It's a servo unit only and can be any opamp that fits.

You could use that virtual ground circuit on the dynalo, but you'd be butchering a very good amp with a medicore psu. If possible an ideal alternative would be to build 2 STEPS. On one use Pins 11 and 12 on the transformer instead of 11 and 14. Then replicate everything on that side of the transformer a second time and put it to pins 13 and 14. This will give you 2 independant power supplies You can join the GND off the top one to the +ve of the bottom to get a dual supply with a proper ground.

The other option instead of using 2 LM317s and tieing the output together is to just build the first half of the dynalo PSU. Leave out the OPA548. Set the LM317/LM337 to output 16.4V and take that. It should still provide sufficient supply, and once again an actual ground.

 

[DigiPete]

Quote:

Originally Posted by Garbz well firstly the opamp in the dynalo doesn't actually form part of the audio chain. It's a servo unit only and can be any opamp that fits.

Good point. I have had much better performance with the TL071A op amp in the Dynalo and Dynahi amps, than either the op27 or opa227, and it's much cheaper.

 

[Pars]

I agree with the previous posters. Kevin Gilmore himself has said that he does not believe in virtual grounds. As noted the OPA27 in the original has nothing to do with the PSU. Check ebay for OPA548Ts... there are usually some up there for really good pricing.

I would recommend doing the entire Gilmore supply. Another option would be to by a Dynahi PSU board (current group buy on headwize, or from SFT) and configure it for a Dynalo (see dgardner's site for details). Of course then you would have to source OPA541s, which are not available on ebay. But you would have a commercial PCB...

 

[gunz_drawn]

Hi

Thank you guys.

I was actually referring to the opamps in the power supply when i said they are impossible to get...I can get the op27 here..no problem.

Secondly i think i will go for 2 TREADS instead of 2 STEPS as that would be way too expensive.. I could connect them in this fashion

Is it OK...or the TREAD is too mediocre

 

[Garbz]

That is much better work, but one of the secrets to the Gilmore Dynalo is his overkill powersupply. It leaves a good upgrade point in the system.

I say go for it.

 

[eVITAERC]

I remember that there used to be some one-IC dual tracking regulators floating around somewhere. A bit low on the current thought. Are they still around?

I sometimes wonder what will happen if you chain enough doides to drop a +15v supply 30v to -15v. Will it even work like that?

 

[Garbz]

Diodes voltage drop just like resistor dividers depend on a bottom. You can't drop +15V to -15V unless you have -15V to begin with. My guess is the circuit would break down. Plus the heat of a 30V drop and then a 250mA load would be painful.

 

[Gontran]

Sorry guys, I'm lost.

I'm an electronics tech, but I have no idea what a STEPS and a TREAD is.
Please enlighten me.

 

[DaKi][er]

http://www.tangentsoft.net/elec/teps/
http://www.tangentsoft.net/elec/tread/

Just lm317 based voltage regulators, made for people who need premade PCB's for everything

 

[Gontran]

Good enough, thanks!

 

[gunz_drawn]

Hey should each "half" of the tread supply be giving the EXACT voltage...??Cause i also plan to build one for my friend to power his M3 and....Can he bypass the capacitance multiplier (i honestly didnt understand what this does) on the pcb?? (TLE is a problem to get) OR

use the same thing ie

for M3

 

[Garbz]

I can't give details because I do not know the design of the M3 very well, but as far as I know that virtual ground circuit is useless there, as the M3 has an actual ground channel.