Good ~100W amplifier

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What is a good high power (~100W range) amplifier kit/design to consider for building one for listening to music and maybe some HT.

From what I have searched so far looks like the ones that would work for me are (in random order) -

Randy Slone's Optimos
Rod Elliott's P3A or 101
Hugh Dean's AKSA 55 or 100 (although this appears to be over my budget I am not ruling these out as yet).
Gainclone LM3875 or LM4780.

Power is not very critical. If there is a good amp that is 50W or 200W I'd gladly consider it. But of ultimate importance to me is the "Sound" of the amp. Stellar specs have failed to please me so far.
Any others out there that I can consider ?
 
Add the Leach amp to your list to consider. I like mine a lot. - plenty of detail, effortless sounding. Prof Leach has the boards and it is relatively straight forward to stuff them. This was my first amp project, although I had built some things before.

If you can cope with the heat, head over to the Pass Labs forum and find yourself a nice class A amp. Count on 2-3 times your output power in waste heat all of the time. I built an A-75 that I like a better than the Leach - it's a little smoother on top and has a better soundstage. You may find that Class A operation is the key to what you've found lacking in super spec amps.
 
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percy said:
From what I have searched so far looks like the ones that would work for me are (in random order) -

Randy Slone's Optimos
Rod Elliott's P3A or 101
Hugh Dean's AKSA 55 or 100 (although this appears to be over my budget I am not ruling these out as yet).
Gainclone LM3875 or LM4780.

Hi percy,

There are lots of very good amps and you would probably be happy with most of them, especailly when you build them yourself.

However, from your list I have built:

Rod Elliott's P3A
Hugh Dean's AKSA 55 (standard)
Gainclone LM3875

All are good amps but I have a definite preference for the AKSA. It makes me :D

It really comes down to your budget. I would buy a standard AKSA 55 (and get the Nirvana and Nirvana+ updgrade when funds are available) for the main speakers and Gainclone's for the rest. I have built a few of BrianGT NIGCs and can recommend them if you don't like doing point to point wiring. Get more advice from others about subs.

I believe Rod has upgraded the P3A with a new high quality PCB.

Randy Slone's Optimos would also be a nice amp and I have found his amp design books very easy to read and enjoyable. I must build one after I finish my current projects.
 
If I wanted to build a discrete amp from scratch with only a premade board, I'd go for Rod Elliott's 101.

If $$ were not a big concern, I'd go for Hugh's AKSA 100 with all the upgrades.

Best bang for the buck without question is the LM4780 kit from BrianGT.

Another one to consider is the UcD 180, a class D amp module distributed in the US by Adire Audio.

HTH.


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I have built the AKSA 55 and the NIGC with LM3875.

The nice thing about the AKSA is everything is included except transformers and enclosure. I chose AKSA over ESP because parts selection and sourcing seemed too daunting for me at the time.

On the other hand, the LM3875 amp is extremly simple and inexpensive.

I also prefer the sound of the AKSA over the LM3875.
 
Gainclones are the most simple to build with little or no adjustment needed.
Consider the Leach amp at:
http://users.ece.gatech.edu/~mleach/lowtim/
120W into 8 Ohms. More complicated for a first time amp builder. Documentation on the site is quite extensive tho. Many successful builders out there with variations on the original amp layout.

Remember that you will listen to sound, not specs.
Your speakers will influence how the amp sounds.
 
Thank you all. Your responses will be very useful.

I haven't yet done a cost analysis on the other amps but looks like AKSA might not fit the budget :( .
And the UCD180 does not offer much opportunity of 'building'(aka fun, learning etc..). I believe building is a learning process too.
Well anyway, so assuming AKSA and UCD180 are out (with all due respects to both) the final contenders would be (in random order) -

Leach
Optimos
ESP P3A
ESP 101
Gainclone LM4780

Thoughts anyone ?
 
Hi Percy,

The AKSA is not so expensive for what you get; all component selections made, pcbs, including power supply pcb, all filter caps, even the heatsink. Only the transformers, case and binding posts are required, and by the time public domain amps are built and functioning, the costs are very similar.

PLUS you get technical backup with the AKSA! From me no less!

However, gainclones are certainly cheaper, and the digital amps require no heatsink. These decisions are always difficult, and good luck in your quest!!

Carlos, Greg, tg3, Ultrachrome, thank you for your favourable comments. Appreciated!

Cheers,

Hugh
 
By all acounts the Opti-MOS is very, very good but It may be over kill (size and complexity) for 100W. I've done Elliot's P101 and find it quite good. Even for 100W I used two pairs of output devices in order to improve heat transfer - I like my amps cool. Assembly was quite easy.

I also like the configuration of mounting the PCB flat against the heatsink with the MOSFETS sandwiched in between. This makesmounting in the enclosure very space efficient with the result that the rest of the amp internals are easy to layout.

My only criticsm is that the value of the input cap it too low 1uF. Unfortuneatly there isn't space to substitute a significantly higher vale metal film cap. This leaves you only two practical alternatives: no cap (dircet coupled) or a high value (~47uF) bi-polar electro.
 
You could add Crimson to your list. Their latest version 8 board(fully complementary with faster trannys) is even better than their vii which had an excellent reputation in the HiFi press. but spend plenty money on the unregulated PSU, they seem to benefit from stiff rails but the designer does NOT recommend regulation. I'm now thinking leach front end and having just read the bryston thread toying with the idea of quad complementary for the output end ( without the 3 times gain in the pre-pre-driver)
regards
Andrew T.
 
I've built both the ASKA 55 and the ESP P101 and both are excellent sounding amplifiers. The price difference between them is not all that much and the ASKA does have the advantage that all the component choices have been made and you get an amp as the designer intended.

I do prefer the sound of the ASKA with it's superb imaging and ability to convey the emotion of music. It's hard to put into words but those that own ASKA's know what I'm talking about.

I still love the sound of the ESP P101 but I have to say "Vote 1 for ASKA".
 
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