[steve k]

It looks like a great value for the money. I was wondering if anyone here has heard one and has any thoughts.
Thanks,
steve k

[avta]

I'm going to buy one soon. I'll keep you posted.

Guy

[steve k]

I have one on the way too. It's supposed to be delivered tomorrow. A friend of mine bought one and really likes his. His came with EH tubes. More later.
steve

[steve k]

The Norh ACA 2B arrived yesterday and I got about 4 hours listening on it yesterday. Keep in mind that my previous preamp was a Bottlehead Foreplay that I'd done all of Doc's mods to. I've used other preamps in my system temporarily such as an ARC SP-9 and an Aronov but I'm most familiar with the sound of the Foreplay so that's the baseline.

Just out of the box, the ACA was much better. It definitely has more gain and dynamics than the Foreplay. The noise floor is much lower and therefore there's more detail and space in the sound. The bass is not as full as the FP but much tighter and better controlled. Overall the bass is more balanced with the rest of the frequency spectrum. The Foreplay was a bit bass heavy in my system. The separation between instruments and vocalists is much more distinct across the soundstage and the timbre of each instrument in a group of violins e.g. is much more distinct now. Massed strings sound like individual string players, not just a "string" sound. The high frequencies are silkier and more refined with the ACA, singers less sibilant.

I don't care for the stock EH 6922 tubes that came with it but that's no big deal. The bass had a lot of authority on the EH's but the treble was too crunchy IMO and the highs were too hard sounding. I swapped them with my pair of Amperex PQ USA gold pins that were in my Seduction phono pre and the difference was quite large. The sound is much more refined now on top, lusher and richer, more subtle. The bass seems a little lighter though with the PQ's. I may look into some Tungsrams or Siemens.

Overall, I'm really impressed with the ACA. It is a very musical, quiet, and dynamic preamp that works very well in my system. It's a beautiful, compact unit, solidly built with a heavy gauge chrome plated case and black face. It has a soft start feature, mute switch, 3 inputs, two outputs plus a tape output. It shipped here from Thailand in 2 days! For $399.95 shipped, nothing can touch it that I'm aware of.

Back to the listening couch.

[avta]

Thanks Steve. I ordered mine a few days ago. I was wondering about changing the tubes too. Where would I get the ones you mentioned? Are there other tubes that you or anyone else knows about that would be worth considering and if so where would I get them?

Guy

[steve k]

I've had good luck on ebay over the years. A good source for info about various brands' sounds is Joe's Tube Lore on Audio Asylum BTW. I've found his descriptions of the sound of tubes to be spot on.
http://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html

Other good NOS sources are www.tubeworld.com, upscale audio and antique electronics supply. Good luck,
steve

[avta]

Thanks again Steve. What does NOS mean?

Guy

[steve k]

"new old stock". It's kind of a misnomer because most "NOS" tubes are used. But they're also better built than most new tubes built today so they last longer (especially small preamp tubes like the 6922).
s.

[avta]

Thank you. I can't wait for the preamp to arrive. I'll send a post when I've listened to it for a while.

Guy

[avta]

Have been listening to the ACA 2b for a few days. I've got it hooked up to a Pass Aleph 3 which is an old class A amp. and  Magnepan 1.6's. I'm using the stock Sovtek tubes. The sound is the best I've heard from my system. More open and natural and with plenty of detail. The soundstage is much bigger as well which gives a more lifelike quality to the music. I've listened to a variety of cd's but especially enjoyed the Chesky demo disc. I'm quite impressed with the unit considering it's price. I'll be getting some Amperex tubes soon so that should be fun.

Guy

[steve k]

Glad you're liking what you hear, Guy. I've found that it just keeps getting better as it breaks in and the tubes break in. I found the bass response continued to increase all last week to the point I've turned it down a bit on my crossover.

The ACA 2B is a perfect preamp for maggies. Dynamic, detailed, liquid and smooth.

Have fun.
steve

[maryland111]

Got mine this morning. (230v)
After a few modifications: Replacing the original mains inlet fuse by a Xindak 2a silver one,replacing the original cheap powercord by an audiophile one and including a matched pair Jan/Nos 6922/E88c Philips ECG, i'm now running in.
 First impressions:
 
Beautyful open sound,fluid,and open wide soundstage.All musical information is reproduced at it is; with precise details in
the high and medium range and with deep and dry (no soft at all) bass.
 
After the running in i will give you more details.
 
But one thing is sure :You can't buy a better preamp for the money.

[steve k]

It sounds like your initial impressions are like mine. I've found with breakin the bass becomes deeper and the dynamics improve too. You mentioned tube dampers as an upgrade--have you had any issues with microphonics? After trying the stock EH's and some Amperex PQ's, I've settled on Ei Elite Gold 6DJ8's in mine. I love their overall sound the best of all three but I've had problems with intermittent microphonics even with Herbie's Halo dampers.

I also isolated the PC Board from the 4 steel standoffs with rubber washers in an attempt to decouple the board and tubes from the case but this doesn't seem to help much either. I'm wondering if it's just the tubes?

The PQ's would get microphonic occasioinally but no where near as often as the Ei's. The EH's were the quietest but I just don't like their sound.
A penny for your thoughts.
Thanks,
steve

[maryland111]

Hi Steve
First mine is a 230v, maybe due to the other voltage i have really no problems wirh microphonocs.
Since i have improved a couple of  months ago the inhouse electrical system and mainly the electric cables leading from the fuse panell to the plugs of my hifisystem there's a really amazing improvment.
No emf's anymore,no interferences,no microphonics a thighter and much clearer and cleaner sound.
Improvment consists of 2 separate shielded electrical cables one for the digital  and the other for the analogue components both a also fixed on their own fuse .
So maybe you can check your  home electrical system.
I don't believe either that's only the tubes which create the microphonics problem.

All the best maryland111

[Cazza]

I have had the ACA for around 2 years - really excellent product. A while back someone suggested the JJ/Tesla tubes. I tried two versions, a NOS gold pin version which I got off ebay and the currently available versions(silver pin, go for about $US10 each). They a alot better that the Sovteks - much better soundstage and very good in the highs. If you are tube rolling then it would be worth giving these a go.

[maryland111]

Hi all

After running in now for one week my verdict:

Bass is tight,present , powerful and deep.
Medium: clear,balanced and warm.
High :exact,smooth(no hiss)and neutral.
Its a preamp that puts every music in the right mood,no addition,no effects,no enhancement the music is just transported at it is.
Wide open flowing soundstage,any compression,but precise and with"an emotionnal kick".The tone spectrum is covered in a neutral way with a precise and accurate presentation.



The Aca was listen using Cardas Crosslink interconnects.
Sources: Michell Mycro/Wilson Benesch Act 2 Tonearm/ Ortofon Jubilee Mc/Acurus P10 Phono preamp
Original Leonardo 9.3 MkII Cdplayer
Classic 8.0b transistor poweramp
Soundright LF Silver Loudspeakercables
Spendor S100 Loudspeakers

Maryland111