• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). There are daily reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Why did Class H amps never really catch on?

restorer-john

Master Contributor
Joined
Mar 1, 2018
Messages
9,131
Likes
25,788
Location
Gold Coast, Queensland, Australia
I think that John @restorer-john might remind me if there was a commercial amplifier (Crown? edit: Technics SE-A1 ) based on this principle.

Yamaha B2-X also is somewhat similar, except they do it the other way around. A super accurate low power, low voltage rail +/-3V (fixed not floating) and a high powered AB stage +/-70V to absorb power loss.

1631867228499.png


Service manual is on HiFi engine. I have an original brochure if you want a copy. (I'll scan it over the weekend and upload it to HiFiEngine)
 
Last edited:

chelgrian

Member
Joined
Jul 27, 2020
Messages
97
Likes
127
Sure it didn't catch on... the Crest 4801, 6001, 7001, 8001, 9001, 10001, 10004, CA4, CA6, CA9, CA12, CA18, just didn't exist. Hell, Crest, QSC, Camco and a whole bunch of others just don't exist.

Class H caught on in the pro world, but big amps really aren't that common in an audiophile setting. Usually you only see Class G and Class H in amps that are more than 300 WPC.

Indeed it was the only way to make high power amps with a 'reasonable' PSU However a crest CA18 still weighs in excess of 20Kg.

The pro world has now largely moved to class D with switching PSUs due to the weight advantages either with flown active cabinets or flown amp racks.
 

restorer-john

Master Contributor
Joined
Mar 1, 2018
Messages
9,131
Likes
25,788
Location
Gold Coast, Queensland, Australia
Last edited:

JSmith

Major Contributor
Joined
Feb 8, 2021
Messages
2,627
Likes
5,742
Location
Algol Perseus
It never caught among audiophiles on because Class H is like Class A, but a bit too open in the top.
Class type is irrelevant and your comment makes no sense... it comes down to design and implementation, not amp class type. If two amps measure the same, they measure the same.



JSmith
 

pma

Major Contributor
Joined
Feb 23, 2019
Messages
3,047
Likes
6,178
Location
Prague
Class type is irrelevant and your comment makes no sense... it comes down to design and implementation, not amp class type. If two amps measure the same, they measure the same.



JSmith
If you go in deep, you never get absolutely same set of measurements from two different amps.
 

Hapo

Active Member
Joined
Jan 11, 2022
Messages
225
Likes
97
Class D is not ready for prime time, plus the decent sounding ones cost a lot.
...all of this is so far above my head I should not be posting but class D reminds me of digital photography...initially eschewed by professionals...

...who uses Kodachrome today...???...
 

Goodman

Active Member
Joined
Jun 1, 2021
Messages
182
Likes
69
Did I already say this is completely wrong and you are to the very least uninformed?
Seriously, class D amps costing thousands are trying to catch up to near state of the art class AB amps you can pick up on the used market for three to 400 hundred, Euros. Have a listen.
 

mocenigo

Addicted to Fun and Learning
Joined
Dec 8, 2018
Messages
965
Likes
702
Seriously, class D amps costing thousands are trying to catch up to near state of the art class AB amps you can pick up on the used market for three to 400 hundred, Euros. Have a listen.

Seriously, you can have a < 2K USD Purifi build with Neurochrome buffers that beats any state of the art Class AB amp even if you spend tens of thousands of dollars on them. Have a listen.
 

Chr1

Active Member
Joined
Jul 21, 2018
Messages
213
Likes
100
Seriously, you can have a < 2K USD Purifi build with Neurochrome buffers that beats any state of the art Class AB amp even if you spend tens of thousands of dollars on them. Have a listen.
I think that the point is that for 400 Euros there are a lot of very good A/B amps available second hand. This is not the case with Class D (yet).
 

Chr1

Active Member
Joined
Jul 21, 2018
Messages
213
Likes
100
Picked up one of these in mint condition for £100 a couple of years ago. Haven't actually used it as yet. It is built like a tank.

Perfect subwoofer amp, I reckon.

LD Systems LDPA1600X

IMG_20190907_125530.jpg
 
Last edited:

mocenigo

Addicted to Fun and Learning
Joined
Dec 8, 2018
Messages
965
Likes
702
I think that the point is that for 400 Euros there are a lot of very good A/B amps available second hand. This is not the case with Class D (yet).

I realised that, but I think we should be close. A NC502MP based amp can be found for about 800€, so the used price should be as low as 500€.


A NC252MP based amp should be in the target range.

EDIT: in fact, this one was sold for about 400€ https://www.canuckaudiomart.com/details/649669840-vtv-amplifier-hypex-ncore-nc252mp-stereo-amp/
 

mhardy6647

Master Contributor
Joined
Dec 12, 2019
Messages
5,995
Likes
12,049
...all of this is so far above my head I should not be posting but class D reminds me of digital photography...initially eschewed by professionals...

...who uses Kodachrome today...???...
Well... no one, since it's no longer made.
Some folks do still use film, though -- just as some folks do still use vacuum tubes.
 
Top Bottom