Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Pass Labs This forum is dedicated to Pass Labs discussion.

Amp Camp Amp - ACA
Amp Camp Amp - ACA
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 21st June 2018, 11:36 AM   #4671
Spencer Brandsen is offline Spencer Brandsen  Netherlands
diyAudio Member
 
Join Date: Mar 2018
Location: Amersfoort
I have an ACA 1.3 here at the moment with only a 'dumb pot' in front of it. Sounds okay. So why do people say it's not a good solution? How much better will it sound with a B1 buffer or an active preamp?
  Reply With Quote
Old 21st June 2018, 12:05 PM   #4672
Zen Mod is online now Zen Mod  Serbia
Official Court Jester
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Amp Camp Amp - ACA
try, and let your ears decide , not mine or anyone else's

I did some writing regarding that , mostly in What's wrong with the kiss,boy ? and Iron Pumpkin(s) and other smaller vegetable animals threads
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa...© by Mighty ZM
  Reply With Quote
Old 21st June 2018, 12:06 PM   #4673
MEPER is offline MEPER  Denmark
diyAudio Member
 
Join Date: Nov 2017
Location: Copenhagen
The ACA is the first amp I have tried where an active pre-amp made a relative big improvement compared with a passive pre-amp. It probably has something to do with the construction. When you add a serie resistor (pot) you change the amount of NFB. But yes....it sounds ok with passive pre-amp but more silky treble (not as hard) and better defined bass using an active pre-amp. At least that was my conclusion after trying both.
  Reply With Quote
Old 21st June 2018, 12:11 PM   #4674
rnjorge is offline rnjorge  Brazil
diyAudio Member
 
Join Date: May 2016
Location: Campinas SP
This weekend I built the B1 to test it against Schiit Audio Saga (passive preamp).
The result: "WOW! How could I live without it for so long? "
And this without any fancy parts, just what I had at home.
But do as Zen Mod says and try it for yourself.
  Reply With Quote
Old 21st June 2018, 02:56 PM   #4675
Spencer Brandsen is offline Spencer Brandsen  Netherlands
diyAudio Member
 
Join Date: Mar 2018
Location: Amersfoort
I struggled through 25 pages of posts before I gave up.. I understand that a certain preamp (of which I don't know what it is) gives more and better bass. And that I will probably need an active preamp to get the best out of an ACA (more silky treble and better defined bass). But what active preamp?
  Reply With Quote
Old 21st June 2018, 03:05 PM   #4676
Soundhappy is offline Soundhappy  France
diyAudio Member
 
Soundhappy's Avatar
 
Join Date: Oct 2012
Location: Montpellier near Mediterranean Sea France
Quote:
Originally Posted by Spencer Brandsen View Post
....But what active preamp?
Line stage ( non phono ) active preamplifier without feedback example :

The BA-3 as preamp build guide

Enjoy
__________________
class A amplifiers with full range speakers
sings like angels in heaven
  Reply With Quote
Old 21st June 2018, 03:39 PM   #4677
johnnycamp5 is offline johnnycamp5  United States
diyAudio Member
 
Join Date: Jun 2013
Location: NJ
Quote:
Originally Posted by Spencer Brandsen View Post
I struggled through 25 pages of posts before I gave up.. I understand that a certain preamp (of which I don't know what it is) gives more and better bass. And that I will probably need an active preamp to get the best out of an ACA (more silky treble and better defined bass). But what active preamp?

I agree with this.
I am building a DIY preamp “kit” for this purpose called the “Forewatt” .

Meper- how much negative feedback does the ACA have...three or four DB?
I was under the impression this circuit had 0 NFB.

Last edited by johnnycamp5; 21st June 2018 at 04:04 PM. Reason: Additional info.
  Reply With Quote
Old 21st June 2018, 04:39 PM   #4678
MEPER is offline MEPER  Denmark
diyAudio Member
 
Join Date: Nov 2017
Location: Copenhagen
Quote:
Originally Posted by johnnycamp5 View Post
I agree with this.
I am building a DIY preamp “kit” for this purpose called the “Forewatt” .

Meper- how much negative feedback does the ACA have...three or four DB?
I was under the impression this circuit had 0 NFB.

The NFB resistors are R11 (10k) and R12 (39.2k). So if you have 5 V out then approx. 1 V will be returned to the input. R11 and R12 are the dividers for the NFB.
NFB is an integrated part of the ACA design. It would nok work very good without NFB. I think bass control would be bad and response not very linear. Nelson Pass has open loop curves at FirstWatt pages for the ACA.
The first ACA version had less NFB. You can play with the amount of NFB to find out the difference in sound. Gain will be higher if you have less NFB and damping factor lower.
  Reply With Quote
Old 21st June 2018, 04:57 PM   #4679
Spencer Brandsen is offline Spencer Brandsen  Netherlands
diyAudio Member
 
Join Date: Mar 2018
Location: Amersfoort
Thanks. The BA-3 looks like something I could use. But I suppose I can't buy it as a kit with a good manual?
  Reply With Quote
Old 21st June 2018, 05:34 PM   #4680
ernesternest is offline ernesternest  Europe
diyAudio Member
 
ernesternest's Avatar
 
Join Date: Oct 2007
Location: Cologne
Doesn't have BA-3 pre part have enough oomph to drive F4? This would be way too much for ACA. Use something with about 3x voltage amplification. It does sound pretty good with simple tube Pre, with Salas HPA used as a Pre. Whammy works.... One of Juma pre's. Lots of options for really good sound. There is not the one preamp for ACA.

Cheers, Ernst
  Reply With Quote

Reply


Amp Camp Amp - ACAHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Amp Camp Amp #1 Nelson Pass diyAudio.com Articles 54 8th May 2018 03:13 AM
Amp Camp! Jason Site Announcements 2 30th June 2012 02:57 PM
Best D camp config for Tweeter amp Zero One Class D 0 24th February 2010 04:57 AM
better the Pass camp? rick57 Tubes / Valves 6 26th March 2005 06:04 AM


New To Site? Need Help?

All times are GMT. The time now is 03:05 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki