15w class a power amp

freo · « **on:** 5 Dec 2005, 07:27 am »

Just finished an altronics kit 15 w class a amp with seperate power supply and I am very pleased with it, it was a little tricky to do, instructions were pretty vague but it was woth the trouble, a little bright for the first 3 hours then it settled to a very detailed smoooooooth little amp, runs quite hot 52degrees when running for 6 hours, very quiet no hum or anything like that. My system is a bottlehead valve pre amp, altronics class a amp, ed frias diy speakers, catt 5 diy speaker cables, all my system including the rack is diy now except my $100 harmon kardon cd player and I think it is value for money. I have photographs of the insides of the altronics amp if anyone needs them, they were kindly sent to me by Howard in Queensland. To change the subject, went looking for floorstanders for a friend of mine looking atspending about $2000 there is a lot of very poor speakers around for that amount of money. If only he had the $8000 to spend at war audio, absolutely fantastic.
Regards Roger

Rocket · « **Reply #1 on:** 5 Dec 2005, 10:42 am »

Hi Roger,

Glad to see that you are still around. I really enjoyed the last time i came over your home and demonstrated my aksa amplifier for you. It sounded really good in your system.

If your friend doesn't mind importing a speaker kit i can recommend zalytron. They sell good quality gear at affordable prices. I have a speaker kit which will hopefully be finished in the coming months.

Pat does sell cheaper kits which would sound better than comparable speakers in the local hifi stores.

Regards

Rod

freo · « **Reply #2 on:** 6 Dec 2005, 12:04 am »

Hi Rod
Thanks for the information I will pass it on, I really liked the sound of your aksa, I don't know why you sold it, it was such an involving, musical amp
Regards Roger

Rocket · « **Reply #3 on:** 6 Dec 2005, 09:08 am »

Hi Roger,

Well i guess i've lived and learnt about upgraditis and i regret selling the aksa. I currently have a spread spectrum technologies SOA at home and it sounds very good. Not as musical as the aksa though. I sure liked your ed frias speakers.

Regards

Rod

bluesky · « **Reply #4 on:** 6 Dec 2005, 09:48 am »

Hi guys

I am in the process of building two of these amps (both stereo). One is being built with the standard parts that comes in the kit and the other has been built with "boutique" premium parts such as Caddock 132's and Vishay Dale RN60 resistors and the caps being Elna Cerafines in the amp module and Nichicon Muse in the power supply with high speed soft recovery diodes.

It will be interesting to see what effect, if any, the premium parts have. I figured that as this amp has such low distortion I should be able to find out for myself if all these premium parts are actually worth it.

The other thing I want to try is to be able to try out different cables and connectors to see what effect they have as well. Things such as RCA sockets and the like.

Cheers

Ian

AKSA · « **Reply #5 on:** 6 Dec 2005, 10:03 am »

Hi Ian,

I will be REAL innerested to see how this amp performs!

I've heard them before in a multiamp setup, impressive sound.........

Cheers,

Hugh

bhobba · « **Reply #6 on:** 6 Dec 2005, 12:14 pm »

Quote from: freo

Just finished an altronics kit 15 w class a amp with seperate power supply and I am very pleased with it, it was a little tricky to do, instructions were pretty vague but it was woth the trouble, a little bright for the first 3 hours then it settled to a very detailed smoooooooth little amp, runs quite hot 52degrees when running for 6 hours, very quiet no hum or anything like that....

Is that the amp designed by Leo Simpson? Reading the article on that was a turning point in my views on Hi Fi. It had almost vanishing low distortion that Leo claimed to be able to hear the difference when compared to other amps - if I remember correctly he described the sound as a lot cleaner. He also found the connectors themselves influenced the amount of measured distortion. So much for those who claim they make no difference.

Quote from: freo

To change the subject, went looking for floorstanders for a friend of mine looking atspending about $2000 there is a lot of very poor speakers around for that amount of money. If only he had the $8000 to spend at war audio, absolutely fantastic.

I have a pair of Axis LS88's for sale if you are interested. I have not set them up because they wrecked havoc with my TV so I can not demo them. But they cost about $2500.00 new and sound pretty good. Midrange very sweet - not easy to tell the difference between them and electrostatics.

Thanks
Bill

freo · « **Reply #7 on:** 6 Dec 2005, 03:56 pm »

Hi Ian
I would also like to hear what differences you find between the stock amp and the upgraded version. I have found changing my capacitors to auricaps has made a huge difference in my valve pre amp.
I used larger transistors in the power supply of the altronics as the voltage was a little eratic with med to high volume
Regards Roger

Howard G · « **Reply #8 on:** 17 Dec 2005, 02:07 pm »

Well done Roger,

I am pleased you found those pictures useful. It is such a completely satisfying hobby when you build your own stuff. I would love to see a picture of your amp sometime. I am considering powder coating the casework of my. I recently built a pair of SE KT88 amps which I had powder coated and I like the look.

http://www.eastmarinedrive.com/contents/images/audioprojects/tweak/lights.jpg

If you are interested in finding out more on this amp (two box version) then visit my website at eastmarinedrive.com

http://www.eastmarinedrive.com/contents/images/audioprojects/syren/amp.jpg

I would say that mine also runs just as hot, particularly the power supply. I would advise anybody considering this project to really over engineer the supply heat-sink. This amp requires a bit of drive to get it going and it does not work with passive preamps particularly well.

OTHERWISE ITS A CRACKER

Howard
http://www.eastmarinedrive.com

[url]

Greg Erskine · « **Reply #9 on:** 9 Feb 2006, 10:09 pm »

Roger and Ian,

Any more news?

Howard,

I'm curious about your PSU running hotter than the class-A amp. What voltage is the 300VA toriod?

I was considering 2 separate mono blocs with one amp and a separate PSU per case. The toriods I have are custom screened Harbuch ones especially designed for this project. These are 21-0-21 160VA but nearly as big as a normal 300VA toriod. I am now a little concerned about fitting the 150 mm heatsink for the PSU inside of the case. The amp heatsink was going to be exposed at the back of the case.

regards
Greg Erskine

freo · « **Reply #10 on:** 16 Feb 2006, 01:32 am »

Hi Greg
My only news Is the amp sounds better and better the warmer it gets, I have the opposite problem to Howard, my amp runs twice as hot as the power supply. Again I am very happy with this set up, the bottlehead pre seems to work really well with the class a mabeye because the pre has quite a lot of gain
Great album to listen to, Coles Corner by Richard Hawley (what a voice and great laid back guitar playing, perfect for late nights with a glass of wine)
Regards Roger

Greg Erskine · « **Reply #11 on:** 16 Feb 2006, 11:18 am »

Hi Roger,

Thanks for the info. I would expect a class-A amp to get hotter than the PSU. I wonder what the difference between your setup and Howard's, voltage drop I'd guess.

Hmmm...interesting comment on the bottlehead pre, mine has a gain of less than 1 so it looks like I'll have to finish one of my pre-amp projects with higher gain.

regards

bluesky · « **Reply #12 on:** 9 Jun 2006, 11:17 am »

Hi Everyone

I have just revisited this post after a long abscence and thought I should just post a note to say that I am (finally) getting closer to finishing the two 15 watt Class A amps. The PCB's are all done and test out fine.

I recently bought some cases from Altronics (on special of course) and have acquired a couple of heatsinks. I am now drilling the various holes in both the chassis and heatsink and can then assemble everything and start listening.

I think (to me at least) that it will be a very interesting comparison betwwen "standard" and "premium" parts. I shall give my impressions as soon as I have A/B'ed the two amps after a decent burn in time. Lastly the speakers used for this exercise are Hugh's Aksonics which I find excellent.

Bluesky

Rocket · « **Reply #13 on:** 9 Jun 2006, 11:31 am »

Hi Ian,

Your package is on the way.

Regards

Rod

bluesky · « **Reply #14 on:** 9 Jun 2006, 09:54 pm »

Hi Rod

The item in question is being built into an audio system for my Dad who had become quite depressed after recent heart bypass surgery.

So......this is what I am building for him. We got a Technics SP10-MKII and a Syntec tonearm off Ebay (at a bargain price!), the cosmetics were a bit rough but I am polishing up the case and the tonearm with various calico polishing mops with my drill and bench grinder. I will then make a new plinth and base for it from salavaged sink cutouts.

The amp will be one of Hugh's 55 watt Aksa's, just the standard as it is all I can afford and as Dad wears a hearing aid it will be more than enough for him. The phono stage will be the Bugle and preamp is the new Studio Series from Silicon Chip along with their headphone amp as Dad asked for this because of his hearing loss (and to not annoy my Mum).

I think it should turn out to be a darn good system on a tight budget and Dad has brightened up enormously just by taking some time to do it for him and he has been really interested in the progress. So it has proved to be really worthwhile all around as I get to build more audio stuff and keep learning more as I go.

Thanks heaps Rod, your generosity has made a couple of people very happy!

Bluesky