Slow Blow pre?

[Kingston]

stating the obvious here but those PSU caps are stupid-large!  

the question is, why?

would think anything between 100-300uF would be enough already, but then we even have the choke? And then more filtering at preamp end!

Looking at the different schematic versions I don't see a dramatic difference to any ol' preamp B+ line.

Why the need for such excessive filtering and the choke? Has someone simply gone bruteforce PSU mad? or does this excess have some real justification?

 

[toffifee]

toffifee, I'm so glad you've posted, I stumbled upon your fantastic build pics in the gallery prior to reading this thread. I have a few EM80 and am looking for a compact way to drive them. Would you please be willing to share your EM80 driver schematic?
Impressive work, inside and out!

EM80 driver, with FET frontend which runs directly off B+:

http://www.jogis-roehrenbude.de/Leserbriefe/Anzeigeplatine/Anzeigeplatine.htm

Cheers, Toff

 

[andrew_k]

Thanks!

 

[electrocutioner]

toffifee, nice work! 

 

[DaxLiniere]

Hey Ole!

How'd you go with drawing us up those plans "last weekend" ??

 

[shuchoco]

apologies if i've missed something,  but what's wrong with the schematic on the Don Hicks site?
http://www.hicksorganservice.net/misc/stuff.html


i need to hear this beast.

 

[Kingston]

but what's wrong with the schematic on the Don Hicks site?

Absolutely nothing.

As probably has been said before, there is no definite slowblow. There are simply preamps with various basic SRPP stages combined and built, with a plethora of transformer options available, with even more PSU possibilities. None of the variants are going to sound bad. Just pick parts most easily available to you.

 

[DaxLiniere]

Ole,
How is your beautiful baby? I can imagine this is why you spend no time here anymore

 

[FotisGR]

hi friends...many people send me emails searching slowblow information...sorry for not be so active at the forum...but...i have 3 kids now...1 woman : , a soldering iron always on
and a bike to run at the hills ;D ... i have plenty of fotos and infos...so you can ask me for ...
everythind is free here for old and new friends...

you can download the first slowblow version from here : http://www.qsl.net/sv3eao/1/slowblow1.zip

and my slowblow version from here : http://www.qsl.net/sv3eao/1/MySlowblow.zip

if you want something just tell me to upload.

 

[FotisGR]

and some pics from the past here :  http://www.qsl.net/sv3eao/1/slowblowpics.zip

 

[Bluzzi]

Thanks for taking the time to do this! I had some of these and I filed it. Right now I am also very occupied (and pre-occupied) with other things. I look forward to the day I can build one or two channels of this pre.

Jim

 

[DaxLiniere]

but...i have 3 kids now...1 woman :

Ahh, congrats friend, those are noble reasons to not spend time here

Can your cousin(?) still make the iron for us? (chokes and PSU)

 

[FotisGR]

hi my old friend...i am glad to see old friends here again...my cousin has a big trafos production factory here...he makes quality toroid trafos and ckokes for all around the country but the real problem is that these items are heavy and the international shipping cost, too...

 

[DaxLiniere]

Yes, but there's nothing that meets the exact specs that's made in Australia anyway, so if I buy a product in Australia, it's already been imported, but it costs me more because I have to pay the middleman (the importer).

Besides, AU dollar is quite good this week, over 0.61euro to the AU dollar.

What do you say, will you look into it please? I know that having these parts will finally get me motivated to start my build.
(In the meantime, I have bought Pendulum MDP-1, Atlas Juggernaut Twin and SSL VHD! )

 

[FotisGR]

ok Dax...tomorrow morning i will look it...
by the way MDp-1 is a beautifull pre...but slowblow is an orgasm machine 
if well constructed...it will stay at the top of your rack, forever...

 

[DaxLiniere]

Oh reallllly??

I liked the sound of MDP-1 so much I thought it might actually be Sismofyt's SRPP! This will be interesting to build (and hear!)

 

[FotisGR]

hi, Dax.
the price for 100VA toroid transformer is 50 euros each...it can be custom made at rating you need...for slow blow i use 100VA (270V - 13V - 48V ).
The 10H/200mA choke costs 33 Euros each
Main transformer plus choke weights ~2.5kgr. EMS shipping for 2.5kgr to Australia is 81.90 Euros.

 

[DaxLiniere]

Sorry for not getting back to you sooner, Fotis, I've been house-hunting.

Wow, that shipping's a killer! I really didn't want to use 3 separate trafos, but at that price, it makes more sense.
What a pity.

Thanks verey much for looking into it, mate.

 

[ricothetroll]

hi,

what about this trafo :
http://www.jukebox-revival.nl/catalog/product_info.php/cPath/282_291_295/products_id/3978?osCsid=9315f6bd17ad58d979cefb57bc4bf135
it's 325V instead of 320, but I don't think this matters so much, the quiescent current will be slightly higher.

mouser sells them also.

has anyone tried that kind of double srpp design with 12ax7 ? they're much easier to find than 5687, and you can obtain a 70db gain. has the 5687 a particular sound compared to 12ax7 ?

[EDIT] I think I understand the reason for the 5687 : its plate resistance is 3k, compared to 80k for 12ax7. Zout with 5687 is then 631 Ohms, against 20k1 for 12ax7.

sorry ! :-X

 

[DaxLiniere]

Thanks Rico, but that's even more expensive and it doens't have the 48v required for phantom. Thanks anyway!