Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 5th February 2007, 04:09 PM   #1
same is offline same  Italy
diyAudio Member
 
Join Date: Jan 2006
Location: genova
Default Rails voltages for A30

Hi,
for the A30 PSU I can only find transformer with 18+18V or 22+22V secondaries.
With 18+18V i have 23-24V DC rail, this seems to me a bit low.
With the 22+22V transformer, must use a CRC filter with 1,5-2 ohm resistance, for +25V/-25V standard DC rails (for monoblocks).
What's the best solution? The standard 25V/-25V DC rails are critical?
  Reply With Quote
Old 5th February 2007, 05:41 PM   #2
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Default Re: Rails voltages for A30

Quote:
Originally posted by same
Hi,
for the A30 PSU I can only find transformer with 18+18V or 22+22V secondaries.
With 18+18V i have 23-24V DC rail, this seems to me a bit low.
With the 22+22V transformer, must use a CRC filter with 1,5-2 ohm resistance, for +25V/-25V standard DC rails (for monoblocks).
What's the best solution? The standard 25V/-25V DC rails are critical?

it's not critical, few volts up and down
__________________
my Papa is smarter than your Nelson !
tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; Mighty ZM's Bloggg;I'm dumb
  Reply With Quote
Old 5th February 2007, 05:53 PM   #3
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
Default Re: Rails voltages for A30

Quote:
Originally posted by same
What's the best solution? The standard 25V/-25V DC rails are critical?
They are not critical at all, heatsinks capability to dissipate heat is more critical. So if your heatsinks are a bit shy, go with lower supply voltage, if they are large you may consider higher voltage rails.
__________________
www.audiosector.com
Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it. - JC
  Reply With Quote
Old 6th February 2007, 10:11 AM   #4
diyAudio Member
 
wuffwaff's Avatar
 
Join Date: Aug 2001
Location: Ingolstadt Germany
Hi,

you could also have a look at the speakers you want to use. For lower impedance (4 Ohms) use the lower voltage and a bit more bias. For higher impedances and better efficiency (>90dB) use the higher voltage with a bit lower bias.

William
__________________
een ooievaar is geen konijn want zijn oren zijn te klein!
  Reply With Quote
Old 30th May 2007, 02:40 PM   #5
EsE is offline EsE  Norway
diyAudio Member
 
Join Date: Apr 2005
Location: A cold place..
What?
I though one of Nelson's own top mods for Alephs was full bias, regardless of the speakers.
  Reply With Quote
Old 30th May 2007, 03:26 PM   #6
h_a is offline h_a  Europe
diyAudio Member
 
h_a's Avatar
 
Join Date: Sep 2006
Location: Graz, Austria
Bias+Voltage values give different power into different loads.

So if your speakers have 4 Ohm you obviously want full power into 4 Ohm, and if they are 8 Ohm...you know the game.

Higher bias gives more power into lower loads.
Higher voltage gives more power into higher loads.

There's no such thing as an optimum that fits all.

Cheers, Hannes
  Reply With Quote
Old 30th May 2007, 04:04 PM   #7
Formerly "jh6you". R.I.P.
 
Babowana's Avatar
 
Join Date: Jul 2006
Quote:
Originally posted by EsE


What?
I though one of Nelson's own top mods for Alephs was full bias, regardless of the speakers.

So did I.
Papa and many people here confirm that more bias current gives us better sound regardless of the speakers.

In addition, I think William is just advising on how we could use the voltages and currents in efficient way for the different speakers . . . in case we want it . . .


  Reply With Quote
Old 30th May 2007, 06:18 PM   #8
diyAudio Member
 
wuffwaff's Avatar
 
Join Date: Aug 2001
Location: Ingolstadt Germany
True,

but most of the time we cant dissipate as much power as we want because somehow the heatsinks are always too small

Im also building a pair of Aleph 30s for a friend and will use a 2x18V transformer for around 24V power supply voltage. This way I can set the bias to 3A (with 6fets per amp) and have enough power for his 4 Ohm speakers.

William
__________________
een ooievaar is geen konijn want zijn oren zijn te klein!
  Reply With Quote
Old 15th June 2007, 06:08 AM   #9
diyAudio Member
 
Join Date: Nov 2004
Location: Taiwan
I have the similar question: how many ampere of the transformer should we use for Aleph 30?

Does anyone try to use switch power?

Very thanks,
  Reply With Quote
Old 20th June 2007, 02:15 AM   #10
diyAudio Member
 
Join Date: Nov 2004
Location: Taiwan
Is one set of DC 24v 6.3a, DC -24v 6.3a enough for A 30?

Thanks,
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
LM4780 on 40V rails zdr Chip Amps 25 29th April 2008 06:35 AM
P3A on +/-12V rails 00940 Solid State 6 5th March 2008 12:44 PM
from +/-80v to +/-70v rails leander Solid State 14 13th September 2005 11:26 AM
filament rails resident Tubes / Valves 2 22nd October 2004 12:48 PM
Cap across rails? MikeW Pass Labs 12 24th August 2004 01:35 PM


New To Site? Need Help?

All times are GMT. The time now is 09:58 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2