Zen Revisited Vs Anthony Holton A/B amp

Hi guys, new poster here ;)

I've been into audio for about 3 years now, and my system has ended up with a MF X-Ray front end, Pass Zen revisited amp and some home made two way's. (use Audax HM170Z0 aerogel woffers and Scan 9500 tweeters, around 89db/w)
I've only recently discovered this forum and have a first question for all the Pass fanatics ;)
Has anybody had experience with the 200wpc Symmetrical output MOSFET amp designed by Anthony Holton http://www.vision.net.au/~anthony/symmetric.htm and how it would compare with my Zen?

I'm fairly sure the sound wouldn't be as good (GREAT amp btw NP :D ) but I want more welly than the (around) 15wpc my Zen produces (less heat would be nice too, I already have central heating).

If the Anthony Holton amp doesn't compare, does anyone have any suggestions on a class A/B design around 100-200wpc that I could try? Nice and simple plz, I like to be able to try a nice 'rats nest' prototype first, only poss with reasonably simple circuits, the Leach isnt simple enough for my liking.

Thanks in advance ;)
Richard
 
Hi Give it a go I don't think you will be disappointed..

regards

Anthony Holton
http://www.aussieamplifiers.com

FullThrottleRic said:
Hi guys, new poster here ;)

I've been into audio for about 3 years now, and my system has ended up with a MF X-Ray front end, Pass Zen revisited amp and some home made two way's. (use Audax HM170Z0 aerogel woffers and Scan 9500 tweeters, around 89db/w)
I've only recently discovered this forum and have a first question for all the Pass fanatics ;)
Has anybody had experience with the 200wpc Symmetrical output MOSFET amp designed by Anthony Holton http://www.vision.net.au/~anthony/symmetric.htm and how it would compare with my Zen?

I'm fairly sure the sound wouldn't be as good (GREAT amp btw NP :D ) but I want more welly than the (around) 15wpc my Zen produces (less heat would be nice too, I already have central heating).

If the Anthony Holton amp doesn't compare, does anyone have any suggestions on a class A/B design around 100-200wpc that I could try? Nice and simple plz, I like to be able to try a nice 'rats nest' prototype first, only poss with reasonably simple circuits, the Leach isnt simple enough for my liking.

Thanks in advance ;)
Richard
 

dexter

Member
2001-04-16 4:04 am
Aussie amplifier please respond

I'm interested in buying the pcb
however, I'd to ask your kind favour to spare yr time
answering my questions.

First: Is the current pcb reflects the changes you made for the
biasing scheme and o/p stage?

Second: can I use toshiba SK2915 instead IRF 240?
Can I use only 2 pair for each channel as I only have 4 pairs tr?
can I use (45V ct 45v)x-fer?

Third: what is the chances for me to succeed in building yr amp?
it seems quite difficult for a novice like me,will the instruction in
assembly as detailed as the aksa kit (printedelectronics.com)?
 
reply from aussieamps

Hi Dexter

I am not sure which amplifier you are refering to but I assume you are talking about the n-channel amplifier.
The changes to this design only require the addition of some degenerative resistors in the o/p stage which are easyly fitted to the existing pcb design. The other changes are only component value changes.
You should have no problems completing this amplifier, as it is no harder to build that any other amplifier.
I see no problem using the 2SK2915 devices, provided they have a Drain Source voltage rating of at least 150 volts.
4 pairs should not pose a problem as you would be operating it from a lower supply rail. As you will have no problem using the 90v ct transformer...

If you want to have a look at the construction manual for the n-channel or the other designs. then have a look at
http://www.aussieamplifiers.com and click on the link called Construction manuals Online. They you will find some PDF files...

I hope this helps you..

Warm regards

Anthony Holton
http://www.aussieamplifiers.com
 

hifi

Member
2001-03-06 3:07 pm
sweden
How about rising the supply rail voltage? ...i got an old denon POA6600A monoblock witch seem imposibly to repair.... (its operated to close to SOA so the transiotors just break down too often) so im looking for a nice project to rebuild it around...the nchanel amp looks quite intresseting esspecially since i got a lot of irfp240 but i believe the denon amps supply deliver around +- 70-90 volt not quite certain but i have the schematic so i can check it upp.. how much can yhe n channel amp take before it needs to be redesigned?


/micke
 
reply form aussieamps

G'day

The n-channel design should have no trouble handling supply rails as high as +-95 volts. The only thing that needs to be checked is the thermal stability of the o/p stage and perhaps a small heatsink on the pre-regulator ccT for the bias control...
The other thing would be the use of more powerful devices if 4 Ohm loads are to be used at higher power levels around 300 watts or higher...
Advanced Power Technology or APT make most excellent devices with case power dissapation as high as 500 watts..

warm regards

Anthony Holton
http://www.aussieamplifiers.com
 

Moby1998

Member
2001-05-15 10:42 pm
Holton 200w MOSFET Amp

I've looked at the Holton schematic for an N-channel amp. It's very attractive. My guess is that it probably sounds great at high volumes, but a little mushey at low sound levels. Has anyone heard it?

But if the sound is as good as the excellent graphics on his web-site, then it should be great!

I think I'm still going to build it. Has any one heard it demo'd?
 
Reply from aussieamps

The mosfets only have to be matched per bank.
meaning the + voltage rail bank and the -voltage rail bank.
With regard to the sound quality. It has a very detailed sound stage at any SPL. It would probably be the sweetest sounding amplifier I have heard anywhere. Including the Passlabs amplifiers. Excluding the X-series however...
I haven't got around to building one yet, But I will...

regards

Anthony Holton
http://www.aussieamplifiers.com
 
You can get the 2SC3298 from MCM electronics:

http://www.i-mcm.com/welcome.jhtml

Motorola also makes a version of this transistor, the MJL3298, which is available widely.

From what I understand of the schematic, that transistor is just a series pass transistor for the bias regulator circuit, so any decent power transistor should be usuable in that application with minimal changes.

The IRF610 is very widely available. Digikey has them, for instance.

-Jon
 

Moby1998

Member
2001-05-15 10:42 pm
Sir Grey - I've reviewed the last several e-mails, and I have not seen any reference to commercial transactions.

Inquiries about technical components and sound quality, yes. But no commercial talk. I think you may have read something into those e-mails.

Sorry if we ruffled any feathers... :)

Rich
 
Rich,
More towards the top than recently...
Just wanted to raise the possibility that people wanting to buy circuit boards etc. could contact Anthony directly since Jason provided the means to do so. Some places are more sensitive than others about that sort of thing. Plus, it could get a bit raucous if several people were touting their wares, all at the same time.
Ask Jason...it's his site.

Grey

N.B.: None of this is to be interpreted as criticism of Anthony's circuits. I haven't built any of them, but they all look quite reasonable. Just looking them over, I'd say they should provide as good--if not better--sound than some other circuits that have garnered far more attention.

[Edited by GRollins on 05-20-2001 at 06:22 PM]
 
transistor alternatives

Thanks Jon for helping Dexter out... I had not got back to him in time.
You are right of cause the transistor is only used as a pre-regulator for the bias ccT. and almost any power transistor in the TO220 package will work. Its worth noting that a power Mosfet will work here as well. IRF610, IRF710, IRF530 etc.
The main reason the 2SC3298 was used here was for its case dissipation capability of 30 watts.
As this device has to drop over 60 volts across its self.
The IRF610 can be subbied for IRF710. Harris also make this device as well.

regards

Anthony Holton
http://www.aussieamplifiers.com
 
Zen Revisited v/s Anthony Holton A/B amp

Hai guys,

I just followed this thread on becoming a member and straightaway would like to post the following:

The thread was started as Zen Amp (revisited) v/s Anthony Holton's SYMMETRICAL AMPLIFIER but along the way due to a reference to the use of 2SK2915 Mosfets instead of IRF240s, the attention got diverted to Anthony Holton's N-channel Amplifier. Be that as it may, I built the N-channel amplifier without incorporating the most recent changes for thermal stability that Anthony posted on 4.4.01. I should say that it is indeed a great amplifier. The detailing, dynamics, low end slam and musicality of the amplifier are indeed exceptional. To say the least, this amp does not have the usual `blur' of Mosfet amplifiers.

About two years ago, I also built Giovanni Stochino's Ultra Fast Amplifier (I haven't yet had a look at the thread on this subject) and it was easily the best amplifier that I had ever heard. It outperformed every commercial amplifier (real Hi-End ones) within my reach. The detailing was exceptional throughout the audio spectrum; especially, the quality of reproduction of stringed instruments was live. The overall sound stage reproduced by this amplifier was very `forward'. Though I now have both the above mentioned amplifiers (in addition to many others), I have not yet done an A-B test between these two greats. I hope to do so soon and will keep you all posted.

Finally, I have not attempted the various flavours of Zen Power amplifiers, as I made the Bride of Zen preamplifier and found it to be a good sounding circuit, but the sound was very `dry'; eg., violin strings sounded too metallic and flute lacked real air(iness). This single Hexfet preamp was outperformed by a basic version preamp using OPA204 and both were bettered by a Class A discrete preamp using MAT02 and MAT03 in the input stages. This rather discouraged me from building the Zen amps.

I hope to also report on a comparison of the N-channel amp with a 30 watt Class A amplifier, Power Follower that can be found at http://www.geocities.com/researchtriangle/8231.

Whoever wants to build the N-channel amplifier, just go ahead and do it; it is very easy (take precautions in the handling of Mosfets) and definitely worth listening.

Thanks and hope to hear from some enthusiast.



[Edited by Samuel Jayaraj on 05-28-2001 at 03:28 AM]