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Class AB Amp(s) for my 3 way system

Printed From: Speakerplans.com
Category: General
Forum Name: Amp Forum
Forum Description: The 'Stopping Jake Fielder moaning constantly' forum description...
URL: https://forum.speakerplans.com/forum_posts.asp?TID=108217
Printed Date: 27 March 2026 at 2:15am
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Topic: Class AB Amp(s) for my 3 way system
Posted By: 270829
Subject: Class AB Amp(s) for my 3 way system
Date Posted: 07 December 2023 at 12:24pm
Hi fam,

I am about to build a 3 way system and i am looking to buy some amps for the system. 

System will be 

Sub: 18 sound LW2400
Mid Bass : B&C NW100
Hi Freq : BMS 4450 compression driver

I've noticed i prefer the sound of a Class AB amplifier over any Class D or H or whatever.

I'm looking at the Matrix XT amp series but i would love some recommendations from you guys. 

I've read that Class AB also do way better on Vocals than digital amps. 

I would love to read more about it and hear all your thoughts about choosing the right amp for my system.



Replies:
Posted By: Earplug
Date Posted: 07 December 2023 at 4:07pm
What's your budget? Can you afford Bryston?  LOL LOL LOL







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Earplugs Are For Wimps!


Posted By: levyte357-
Date Posted: 08 December 2023 at 1:39pm
Needing a Class AB amplifier, for good sound quality maybe desirable for home hifi, but not necessary for PA/Soundsystem.

I used to use JBL MPX 1200 (Class H), on my home hifi, and being Dolby certified, it provided all the sound quality, and low distortion, and plenty of headroom I needed.

Same with Peavey GPS 3400.

Well built, quality amp, Class H/Class D, with plenty of headroom, is an alternate route.

I previously used QSC CX1102 and QSC PL2.0, to drive 12" Mids, and sounded great.

Also previously used CX1102 to drive 2" Comps.
Powersoft X8/X4 also sound great on Mids, High Mids, Sub.

QSC PL380, Void Infinite 8MK2, Crest CA18 and Powersoft K20, can all sound very smooth on sub, with right processing.



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Global Depopulation - Alive and Killing.


Posted By: Meat Substitute
Date Posted: 08 December 2023 at 2:02pm
Typical efficiency of a class AB would be around 50% or so...

...given those nice high power modern drivers and assuming that you're going to power them at or above their AES ratings you're gonna have a nice toasty party and a leccy bill like the national debt if you go down this road.LOL


Posted By: levyte357-
Date Posted: 08 December 2023 at 2:09pm
Originally posted by Meat Substitute Meat Substitute wrote:

Typical efficiency of a class AB would be around 50% or so...

...given those nice high power modern drivers and assuming that you're going to power them at or above their AES ratings you're gonna have a nice toasty party and a leccy bill like the national debt if you go down this road.LOL


Funny thing is, take a look at Turbosound docs going back 15 - 20 years, and IIRC, you will see class H amplifiers specified, albeit with plenty of headroom.


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Global Depopulation - Alive and Killing.


Posted By: Conanski
Date Posted: 08 December 2023 at 2:40pm
Class H is typically a class AB amp with a tiered/stepped output rail setup, same applies to those manufacturers that use a continuously variable output rail design(class G) like Yamaha, Powersoft, and a few others. These designs sound the same as a pure AB amp but usually generate more power and have much better electrical efficiency.

IMO the only thing that matters for subs is having enough raw horsepower on hand to deliver the sub performance you want, this is what class D excels at and sound quality doesn't really come into it at these frequencies, so nothing wrong with using a class D amp here. For everything else a class G, H, or AB amp will deliver the SQ you are looking for.


Posted By: Earplug
Date Posted: 08 December 2023 at 4:16pm
Yes, definitely nothing wrong with a well made Class G or H - or even D.

It's definitely in the ear of the beholder. One DJ type I know bought one of these:-

https://www.madridhifi.com/p/skytec-spl-2000mp3-amplificador-178774/" rel="nofollow - https://www.madridhifi.com/p/skytec-spl-2000mp3-amplificador-178774/

and swears that it's one of the best amps he's ever had - or used!  Confused

Edit:- He uses it to drive a couple of old JBL M Series cabs I sold him. 15" & 1".

Out of  curiosity - and it's low weight, I took a look inside expecting a SMPS/Class D. Instead there's a small, maybe 200VA toroidal and typical crap (maybe 200W/channel) board. A complete joke.

And this DJ regularly plays at some of the best/biggest clubs around here. Unbelievable...   Dead





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Earplugs Are For Wimps!


Posted By: 270829
Date Posted: 08 December 2023 at 6:55pm
Oke thanks for the answers, thats very helpfull. 

Yeah power supply can be problem so maybe just a small Class AB for the compression driver and some high end Class H or G for the bass and mid bass.

Gonna look into the amps you all suggested.

Any more good Class H / G recommendations. 

Budget is around $3000 in total.

So i guess 1 small class AB
and maybe 2 others because i won't run them parallel.


Posted By: Earplug
Date Posted: 09 December 2023 at 6:59am
There are quite a few decent amps you could look at that would do the job, like Lab Gruppen, Dynacord - or my favourite Crest.   Smile





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Earplugs Are For Wimps!


Posted By: Lucasdude
Date Posted: 12 December 2023 at 11:15am
If you dont mind a lot of fan noise, the old Cloud VTX range are really good and often go cheap on the Bay. 1200/1500 aren't hugely powerful, but are bridgable.


Posted By: Lucasdude
Date Posted: 12 December 2023 at 11:19am
Crest Audio CA are also great amps. CA2 and 4 are AB, 6 9 12 and 18 are H. I use a 9/4 biamped for my main speakers.


Posted By: ceharden
Date Posted: 12 December 2023 at 1:20pm
I can fully understand not wanting to use Class D for compression drivers, even some of the higher end ones can still have a noticeable noise floor.

What your best option is really depends on where you are, what's commonly available second hand (assuming you're looking at used amps).

Personally I'm currently using Yamaha amps on my mids and highs. P7000, P5000 etc.  They are a tracking rail design but essentially a linear output stage. For a non-class D design, I think the efficiency is excellent and they sound very good.



Posted By: fat_brstd
Date Posted: 12 December 2023 at 10:13pm
I use QSC CX902 on compression drivers and the difference between that and cheaper, particularly class D, amps is massive. Also keep an eye out for the DCA range from QSC, exactly the same as the CX but marketed to the Cinema world and can sometimes be found very cheap.

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Adrians Wall Sound System
Melbournes Rootical Warrior
Roots - Dub - Steppers

http://www.facebook.com/adrians.wall" rel="nofollow - facebook page



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