[breizheau]

Hi there !
just a question : what about 20V as PSU ?

 

[Pars]

Quote:

Originally Posted by breizheau /img/forum/go_quote.gif Hi there ! just a question : what about 20V as PSU ?

I can't think of any reason offhad why +/-20V supplies wouldn't work fine. Make sure the opamps for the DC servos can handle that voltage. Also use a minimum of 25V caps for any electrolytics; I would probably use 35V just for margin. The original Gilmore Dynamic from the headwize article used +/-16.4V supplies, BTW.

 

[bidoux]

Breizheau has some cool project, he wants to mix the "up" a preamp with super simmetry (susy) from Nelson Pass and a Dynalo. If you upgrade the PSU to 20V, change the resistors in the CCS (explained in original article) and maybe parallel more output Z.
I hope you don't mind if I put the schematic here: http://psykok.homelinux.org/diy/Calins/HUGS.pdf

 

[Pars]

Ah,yes, the CCS. I already use 620 ohm paralleled with a 10K trimpot on mine so would be close to being OK without doing anything. I'd increase them to 680 ohm just to be safe.

 

[luvdunhill]

Quote:

Originally Posted by bidoux /img/forum/go_quote.gif Breizheau has some cool project, he wants to mix the "up" a preamp with super simmetry (susy) from Nelson Pass and a Dynalo. If you upgrade the PSU to 20V, change the resistors in the CCS (explained in original article) and maybe parallel more output Z. I hope you don't mind if I put the schematic here: http://psykok.homelinux.org/diy/Calins/HUGS.pdf

yup, the UGS (it's not called the "up") circuit can be used as a headphone amp, it's pretty straightforward. I wouldn't call it a mix at all...

 

[breizheau]

Hi there. First of all, i would like to show you my finished "Dynalo".

 

[breizheau]

As said, i have another project : HUGS (stands for "Headphones UGS").
The UGS is based on Susy, patented by Nelson PASS. My preamp is really great and i thought about a mix with the output stage of the Dynalo.

The prototype is already done, works pretty good and just waiting for a nice enclosure. The 1st one will be a wooden box. When the PCB will be done, i'll think about a real casing.
It's a balanced output amp. The input could be balanced or not, the output will be always balanced.

Here the schematic : http://psykok.homelinux.org/diy/Calins/HUGS.pdf

But i'll let you know. Stay tuned.

 

[Pars]

Very nice! What is the center PCB? Relay-based attenuator?

 

[breizheau]

Thx Pars.

Yes, it's a relay based attenuator bought at Dantimax in Denmark, 10Klog.
I bought the same one but balanced and 50Klog for the "Bijou".

 

[the_equalizer]

Are chinese vendors in ebay a reliable source for the Dynalo FETs?

Also, I'd like to buy a rev. C board. I sent an e-mail to djgardner some three months ago about this but I haven't received any reply. Does anyone have boards available?

Thanks

 

[Pars]

Which FETs? the duals (2sj109/2sk389)? If so, no. If you are planning on using singles (2SJ74/2SK170) then maybe.

Dan can be challenging to get a hold of. You could try putting a WTB ad in the for sale section here and see if you scare anything up.

 

[weibby]

If PCB is so hard to get, is there any equivalent?
I'm interested in dynamic amp after building a Cmoy with an Opa2227.

Now my DIY addiction withdrawal is full blown, itchy to try something like this.

 

[the_equalizer]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif Which FETs? the duals (2sj109/2sk389)? If so, no. If you are planning on using singles (2SJ74/2SK170) then maybe.

Sorry, I only put the FET numbers in the thread title...

yes indeed, I found several e-bay vendors offering (even matched) sets of 2SJ74/2SK170 FETs.

Quote:

Originally Posted by Pars /img/forum/go_quote.gif Dan can be challenging to get a hold of. You could try putting a WTB ad in the for sale section here and see if you scare anything up.

Thanks for the advice. Will do.

One more question, even though I am able to get 2SC1815 transistors where I live, I can only get hold of 2SA1015GR for the complimentary pair. Does anyone have any experience with those in the Dynalo? Would matching those GR to the non-GR work ?


cheers!

 

[Pars]

Sorry, didn't notice your post title.

As for the sc1815/sa1015, matching within grades, might work, might no:
hFE (1) classification O: 70~140, Y: 120~240, GR: 200~400

I personally have not had good luck going between grades for matching (not necessarily these devices). I just noticed that Mouser sells these (Fairchild version 512-KSA1015GRBU and 757-2SC1815GRTE2FT, for example), as well as bdent.

EDIT: also, the Rev. B boards are virtually identical to the Rev. C, so I personally would not restrict your search to Rev. C only.

 

[the_equalizer]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif Sorry, didn't notice your post title. As for the sc1815/sa1015, matching within grades, might work, might no: hFE (1) classification O: 70~140, Y: 120~240, GR: 200~400 I personally have not had good luck going between grades for matching (not necessarily these devices). I just noticed that Mouser sells these (Fairchild version 512-KSA1015GRBU and 757-2SC1815GRTE2FT, for example), as well as bdent. EDIT: also, the Rev. B boards are virtually identical to the Rev. C, so I personally would not restrict your search to Rev. C only.

Thanks for both pieces of advice. Wish me luck hunting parts for my Dynalo!