Mini A vs.

I want to make a 5 channel amp, budget of course. And I was thinking about building a 5 channel mini A, all 60w per channel, but I'm worried about cost.

I was asking Brian about costs and with my budget if it would be worth it to DIY or go commercial in my case.
He said the big issue would be heatsinks. Since class A amps produce so much heat it would cost me a lot to get heatsinks and cool the amps properly.
I said I could stick a small fan inside, run slower than normal so it wouldn't make as much noise and he mentioned that this would cut down on heat a lot.

Questions:
What do the mini Alephs compare to commercially? McIntosh?
How would a Leach amp compare to the mini Alephs and a McIntosh?
How much do you all think a 5 channel mini A would cost (60wpc)?
Is there anything I should know before trying to do this kind of project?


Thanks,

Josh
 
Mini-A is only 10 to 15 Watts. Aleph 5 is 60 watts. Five channels of Aleph 5 will heat your house. Five channel mini-A is possible. 750 VA min(12 to 15 volt dual secondaries) $110 to $150 . 8 x 11 heatsink with 2 1/2 inch fins for each channel $30 each, cheaper if you get them suplus. Lots of Caps. The good thing is lower voltage are cheaper. Peter D. had some 230000 uf. 25 volt for $12 plus shipping. May need some plates to bolt everything together. Try low cost metals. Boards and electronics $125-200. Good luck, Mike

Sound Of Alephs are much better with voices and midrange. The ten watts are very surprising.
 
I understand SPL and efficency, but my speakers are pretty inefficient. They are about 85db 1w/1m and 79db 1w/1m. I'd like 60w because That gives me PLENTY of room when I turn up the volume, and the power for different speakers.

For example 1 amp will be driving a wr125 and a tweeter. The speakers are only going to be half active, the woofer will have a seperate 80watt amp, while the mid and tweeter share an amp.

I thought that Brian had designed his mini aleph boards to act like an Aleph 5 when, I believe 3 components are removed so that it can be 60wpc.

My Denon claims 90wpc rms, but I doubt it can get that high, but the amp starts at -70db and goes all the way up to 15db. I'm not sure, But I was guessing that 0db is actually 90wpc. During movies I often turn up the volume to 11db and keep it there, I've brought the volume all the way up during action scenes, but it normally stays at 11db. I'm a teenager and I enjoy good music and movies loud, as long as they are not really distorted. I was guessing that 60wpc I could achieve that same volume as I can with my Denon.

What would you all say the mini aleph compares to in sound quality?

Thanks,

Josh
 

Dennis Hui

Member
Paid Member
2002-08-27 7:19 pm
Toronto, Canada
Mike is our resident Mini-A expert since he's built
quite a few of them.

I'll just add that the key to doing this on the cheap
is finding surplus heatsinks and transformers.
If you can find them locally, so much the better, since
they're heavy and shipping costs can add up.

For example, instead of ordering a couple
of 2x12VAC toroidal transformers in the
300-400VA range, I ended up getting
four 250VA 13VAC transformers for 46CAD from
a local surplus store. OK, so they're not as
nice as the toroidal ones but they will
also work in my application and the price
certainly was right. :)

Good luck.

Dennis
 
I understand now, sorry.

Let me rephrase my topic, Aleph 5 vs.
Sorry for the confusion.

Well maybe I could go with less power, maybe 30w.

I understand I can build the Aleph 3 or the Aleph 30. It says that the reason why people would make the aleph 30 (with 2 more output devises) is for lower distortion. I'm new to solid state and I'm sure this is all common knowledge to everyone else.

Is it worth the money to add two output devises to build the Aleph 30, or will I not knowtice much diference with the Aleph 3.

Brian wants me to build an aleph before I decided to build a 5 channel, so I think I will build a mini Aleph. If I like the sound quality I'll build another aleph, and if I think that 10-15w is enough power than I'll just build a 5 channel mini aleph.

Just a quick question, what is max size toroid needed for max output on a mini Aleph?
I'm guessing 12v secondaries are what Is typical? like this??

Or is that the wrong toroid?

Thanks for all the help,

Josh
 

Dennis Hui

Member
Paid Member
2002-08-27 7:19 pm
Toronto, Canada
edjosh23 said:
I understand now, sorry.

Brian wants me to build an aleph before I decided to build a 5 channel, so I think I will build a mini Aleph. If I like the sound quality I'll build another aleph, and if I think that 10-15w is enough power than I'll just build a 5 channel mini aleph.

Just a quick question, what is max size toroid needed for max output on a mini Aleph?
I'm guessing 12v secondaries are what Is typical? like this??

Or is that the wrong toroid?

Thanks for all the help,

Josh

Try a mini-a...then decide. Good advice from Brian.

For a standard +/-15VDC rail mini-A, a 250VA 2x12 transformer
will work nicely:

http://avellindberg.com/transformers/y23_range_specs.htm

This will give you room to crank up the bias a bit.

Dennis
 
Hmmm, being the guilty party who foisted the Mini-A upon an unsuspecting world, I thought I'd drop in a word.
The concept for the Mini-A was as a...well, a miniature Aleph. Note the word miniature. My original prototype was built to deliver 10W. 60W from a Mini-A? Unh-uh. Don't do it. Build a real Aleph. Trying to get more than about 20W or so from a Mini-A is going to lead you into heat dissipation problems. That's not to say that it can't be done, just that you'd better have your wits about you if you're going to push a single pair of devices for much more than that in a class A amplifier.
If you want to build a Mini-A as a practice circuit, be my guest. The power supply requirements are minimal; a 120VA transformer will do nicely for a stereo amp. You might want to go back and read the original thread as a warm up.
If you want 30W, build an Aleph 3 or Volksamp (also an Aleph) 30. If you want 60, build a 5 (wasn't that the 60 watter? I just got in from hearing Pictures at an Exhibition and I'm distracted) or Volksamp 60. MikeW was kind enough to adopt the Mini-A and built a number of them. He had boards available at one time. Whether he still has them, I do not know. There are numerous boards available if you want to build a full scale Aleph. I try not to take sides as to who makes the best boards. I do boards one way, others do them other ways. As long as the amp works properly, you'll have music and that's the name of the game.

Grey
 
Dennis Hui said:
I'll just add that the key to doing this on the cheap
is finding surplus heatsinks and transformers.....OK, so they're not as
nice as the toroidal ones but they will
also work in my application and the price
certainly was right.

I can certainly relate to that... my ZEN 4s are coming together like that... just waiting for all the pieces to fall into place.... last Sunday at the local swap-n-shop i picked up a CLC supply that served duty on the DEW line (ie Mil-Spec). The tag says 48 VDC 10A -- just about right. $5 :)

And just yesterday the heat sinks appeared -- surplus to jason's project and a prize for helping him move.

Next i need some MosFETs....

dave
 
planet10 said:


I can certainly relate to that... my ZEN 4s are coming together like that... just waiting for all the pieces to fall into place.... last Sunday at the local swap-n-shop i picked up a CLC supply that served duty on the DEW line (ie Mil-Spec). The tag says 48 VDC 10A -- just about right. $5 :)

And just yesterday the heat sinks appeared -- surplus to jason's project and a prize for helping him move.

Next i need some MosFETs....

dave

I can arrange Mosfet's..
 
GRollins,

I understand Mini Aleph's now. When I was reading on BrianGT's website I saw his Mini A kit and it said with more output devices and certain components removes it would have 60watts, but what I didn't realize was that that was an Aleph 5 and no longer called a Mini Aleph.

kilowattski,
I think 60watts will be enough because my GC can power these speakers. I'm going to try building a Mini A and if it doesn't have enough power it will run my B&W 602s, which are seperated from my HT.

jleaman,
you have mail

Thanks,

Josh