Orion and Aleph? - Suggestions please -long

I have the main boards to build a set of Orion speakers by Siegfried Linkwitz, w.linkwitzlab.com/orion_construction.htm and am waiting on SL to finalize the Orion in late Sept or October.

The speakers are designed to be tri-amped. It looks like an ATI 1506, 150 watt per channel 6 channel power supply would be a good off the shelf choice.

My request of those reading this thread is to please offer suggestions as to what I might build to meet this need that would be practical to build in six channels and might realistically be expanded to 10 channels for home theatre.

I am not above building a tower six feet tall 19"by 19" if that's what it takes to get incredible sound. I'm more concerned about being able find enough heatsinks, and concerned about heat output into a 14 by 27 room along with power draw idling. It can be pretty hot here in the summer( I need to look up Grey Rollins sometime, I frequently travel to Columbia)

While new to solid state, I've recently finished a tube preamp using sowter 9335's for attenuators and am currently working on a power amp using 304tl's (high voltage stuff), both to Jim dowdy designs. I'm not saying that I wouldn't ask a bunch of stupid questions, but I am a meticulous careful builder that has recently put together a pretty decent bench.

I do realize that heatsinks will be a major hurdle. I will be unable to start construction on this project till the first of the year or spring, so I figured if I could decide soon that I might trying buying the sinks from the Australian source I saw in another thread that seemed quite reasonably priced. And/or I thought some others might wish to go in with me and we possibly might be able to pool enough purchasing power to make a "Quantity buy" of some sort to enable price/access that would not normally be available.

In closing I would like to thank you for reading this. I would also like to thank Nelson Pass who most graciously allows and supports this forum.

Ken L
Greenville, SC
I'll wait and see what the rest of the board comes up with, but I'd expect that you don't actually need 6 times 150 watts. Linkwitz mentions minimum 100 watts into 4 ohms for the woofers, but you'd hardly need that much into the tweeters and midrange. Just as long as all channels had equal gain.

Just think about it, 6 channels of space heaters, in the summer...:hot:

I am very interested in your progress on the orion, Siegfried and I talked about a more compact speaker than the Phoenix last year, and I even did some sketches to see what he thought. Looks like he came up with something that works ;)

A Possible Solution....

You might consider Hugh Dean's AKSA amplifier kits. While not personally familiar with all the amplifier possibilities out there, these amps firmly trounced my highly thought of Llano's. Incorporating much of the topology of Douglas Self's 'Blameless' Class B amplifiers (a mischaracterization, they are low bias Class AB amps) they barely warm the heatsinks even when driven quite hard. Though incorporating some of Self's 'modern' topology, Hugh discards some of the 'de riguer' must haves, current sources and mirrors after subjecting his designs to that "roiling cauldron of subjective evaluation". Subjectively(IMO), they are marvelous amps. Wonderful bass control and definition that belie its mere 100 watt rating,, a delightful midrange, and a clear and extended top end. None of the expected sand stage grit wiht great resolution. And a wonderful soundstage with imaging to knock your socks off. Two models are offered, 100wpc and 55wpc; mono construction.
As you mentioned Australian heatsinks, the Aksa 100 wpc uses Conrad MF30-1F-75 per channel. And 2 channels of the 55w version share the same heatsink. Each channel requires (for best results) its own transformer and ps. The transformers are easily available from avel-lindberg, plitron, etc... (actually, someone is selling Plitron trannys, on this board for $35/each, perfect for the 100 watt version). Some builders have built the 55watters with lower voltage (and lower output) to optimize for mid and tweet duties. You might even discuss with Hugh, building tri-monoblocs on a single MF30-2F-151.5 heatsink.... housing a 100w channel and 2 55w channels (or a 100, 55, 25 watts).

Thare has been much discussion on this board of these marvelous amps, as well on the HarmonicDiscord boards, which is generally not as technically savvy as here.

Visit Hugh's site-
And give him an email if you've questions.

They really seem a perfect match for your needs.
YMMV, and obviously subjective opinions are just that, subjective...

Apologies to Nelson, I didn't realize I was posting on the Pass board until I was returned to my post. But as you mentioned the heat constraints, and by extention, the bias class of the amp is of importance, I suggested a low bias amp. Obviously one of the 'Class D' amps might also be a solution, but I've not heard them.
Probably should have made that Pass Labs instead of Aleph

Thanks for your comment Transducer - I intend to post results of the Orion under loudspeaker forum when completed - If I can remember I'll send you an e-mail -

A quite appropriate comment about gain - It had occurred to me, I'm not sure how to allow for or if different characteristics of different amps would possibly be a negative factor.

Thanks pmkap for your response. Really, no easy answers here. I appreciate all input and I would also be surprised if it bothered Nelson.

I would prefer to stay with Pass Labs if possible.

I've looked through their website pretty well and read a good many various threads including the 30 plus pages of the Aleph X thread.

It's kinda all blurring together at the moment.

Just trying to sort it out - hopefully some of the Pass Labs Forum folks that are familiar with the zen variations, etc, will point towards a similar solution to yours from within the Pass family.

Ken L
Hi Mr. Pass -

ummmm - I take it that means that none of your current or previous designs available to diy wouldn't meet my needs?

Actually, when I redid the heat/AC I made sure that this particular room is on a thermostat and zone of it's own.

So, I could take some heat if it wasn't a great deal. When another poster on a home theater thread commented that five Aleph 2's would draw roughly thirteen amps, I knew I needed to start looking at heat and current.

I don't think I would want say ten amps idling all the time, or say a 15 amp draw - (six channels operating )

Is there any reasonable combination of your designs that wouldn't be stretching too far??

I am quite sincere in my appreciation of your genorosity and support for this forum.

Thank you

Ken L

Nelson Pass

The one and only
Paid Member
2001-03-29 12:38 am
No problem by me if you go Class A. It's just that
a lot of heat seems to be a barrier for quite a few

I like to tri/quad/quint amp, and usually I allocate the
heavy power to the bottom end, where no matter what
the sensitivity rating is, it's taken at higher frequencies,
and getting down to 20 Hz chews up the watts. Usually
100 watts is enough.

Above that I usually run very efficient drivers, 98+ dB/watt,
and give them 10 to 30 watts each.
Can we expect >1kW AB monster from you published as a project? I think there are a lot people that would like to build it (including me), there are many other designs, but theyre not so stable, have load limitations (min. 4ohm - no bridging:( ), anyhow, id like to see that kind of amp made by you so we could shake a disco/house/hamster:D
Mr Pass, my apologies for being so slow on the uptake pertaining to AB

Must be the OCD kicking in.

At first I thought you were kidding, but am now hopeful you were at least partly serious.

More homes now have multichannel and that market should continue to increase as formats evolve and mature. And it really is hard to do six channels of class A, not only the heat and space, but current draw also becomes an issue.

Were you kidding?? or is there hope for AB from the one and only NP?:yummy:

As always, I sincerely appreciate your generosity by allowing, supporting and participating in this forum.

Ken L
Heat really can be a big barrier. I used to live in Canada, and quite enjoyed the heat of my tubes (I'm not a Pass owner yet), but down here in California, I often find myself reluctant to switch on my amps. All that heat also means big power draw, and the power supply and heatsink components start to really drive up the cost of the amp. The budget for my Aleph-X project is overwhelmingly dominated by power supply and heatsinks. The actual circuit components seem almost trivial by comparison.

For me, DIY is largely about economy. Probably because I got started in it when I was still in high school, and $40 was a big deal. DIY means I can afford to own the audio system I really want, instead of having to put up with mass market junk. It's fun and educational too, but shouldn't have to be expensive.

Ken L:

Have a peek at the ESP Project 3a. It's a nice simple little design that purportedly sounds very good. I've seen the ciruit, and it looks quite agreeable. It should be quite inexpensive and quick to build, at least relative to most other circuits, allowing that multi-amped multi-channel dream to be a lot less expensive... About the only thing the P3a lacks is output short circuit protection, but that should be a simple addition - I'm sure someone out there has done it already.
Ken L

Here is the Passlabs URL to the Aleph owners manuals


All the Alephs seem to have 20 dB gain
The Aleph 5 has 60watts/ch and consumes 300watts for 2 channels. Thats only ;) 1200 watts for 8 channels.Maybe it is better to use one amp for both woofers on each side. Mr. Linkwitz says it would be a 2 ohm load then. The Alephs can handle this, but I'm not completely clear what the ouput would be.The Aleph 4 would certainly handle it with one channel.It draws 250 watts/ch So four channels of A5 plus 2 of A4=1100 watts total
Thanks mark for your response

Variac - appreciate your thoughtful reply.

Gets me much further down the path.

Really a wealth of info there - I had looked for that more than once but kept missing it.

And your very useful analysis relating to my actual useage clarifies somewhat more.

Really a great example of this forum and others like it and what they can mean to us all.

Real Life has intruded to the point that all "fun" projects will be on hold for a good bit longer than I would like.

I'll let you and this forum know how things turn out.

When I get time, I'll see if I can get together an order for heatsinks if anyone else is interested.


Ken L

As always, I am very appreciative of Nelson Pass for not only allowing but supporting this forum
Thanks for the link thylanter

I'll check it out.

The 6 channel 300 watt may be the trick.

Or who knows, Nelson may have been more than half-serious about designing an AB

Basically, I've been a tube guy - but when you get into tri-amping or 6 channel, tubes become pretty unwieldy.

So your link and the others have been a big help to me.


Ken L

As always, I am very appreciative of Nelson Pass for not only allowing but for supporting this forum.