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Old 19th April 2011, 08:56 AM   #1
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Talking Choices, choices, decisions, decisions!

Hello all,

I am VERY intreagued by these Pass designs, the symmetry simply rings true in my mind, so wouldn't mind having a bash as constructing my own amp based on these wonderfully simple designs (something else which rings true, the simplicity). Hence I like the designs that use simplicity plus super-symmetry (am I right in assuming the Aleph-X?)

But! Where to start, so many long threads, so many options, so please allow me to ask the question of where to start!

My aim is to produce a 30Watt amp, that will drive some full-range speakers I built (thnx Planet10). I wouldn't mind implementing the Lightspeed attenuator idea into the design too.

Hence what PSU / pre-amp / amp combo should I be looking at & where can I find some 'finalized' schematics?? Getting hold of PCBs would be useful too as this would ease the construction pain somewhat.

Thanks in advance,

Andy
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Old 19th April 2011, 09:28 AM   #2
h_a is offline h_a  Europe
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Quote:
am I right in assuming the Aleph-X?
An Aleph-X is not for the faint of heart

Better start with something simpler and more final, like the super-popular F5. Less symmetrical but nevertheless cute are the Burning Amps BA1 or BA2.

If it has to be an Aleph, the Aleph30 is a good option to start with.

As preamp the B1 is favoured by many.

F5/BA1/BA2 boards you get from the DIYAudio-store, Aleph30 boards maybe from someoneelse in Swap-meet.

Have fun, Hannes
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Old 19th April 2011, 10:49 AM   #3
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An Aleph-X is not for the faint of heart
can I ask, why do you say that?

Andy
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Old 19th April 2011, 11:30 AM   #4
h_a is offline h_a  Europe
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Sure!

First of all, the circuit itself is not series production level mature and might need tweaking (e.g. to get acceptable DC-offset) depending on actual circuit and power level. There exist also a number of variations, like with jfet frontend, that have other potential issues as well, like limited number of output fets due to little drain current of the jfet LTP.

Also thermal design (thermal coupling of mosfets) plays a role to get stable dc-offset, so good mechanical and thermal construction is well advised.

The X'ed amps are also a little sensitive on the impedance at their inputs, so dc-offset might become a small issue depending wether they're driven balanced or single ended.

Last, as there exists quite a number of variations, it might be difficult to get professionally made boards for the variation you're interested in, as most do their own board design at this level.

Hannes
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Old 19th April 2011, 11:35 AM   #5
Itsmee is offline Itsmee  England
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Quote:
Originally Posted by underwurlde View Post
can I ask, why do you say that?

Andy
This is the sort of thing you could end up with, not cheap, a project for the dedicated builder. If you are a member of the fearless amp builders, go for it.

Pic is from the AX thread.
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File Type: jpg ax_twins_small.jpg (78.0 KB, 272 views)
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Old 19th April 2011, 11:37 AM   #6
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Very nice build!

Hannes
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Old 19th April 2011, 01:14 PM   #7
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Just so's you's know's my profession is electronics engineer (high power controllers at Penny & Giles, so using & clamping MOSFETs is my bag, baby ).

So not much is putting me off the actual 'doing' side of things. I have much kit and bits available to hand as one would expect being in such an industry. Having said that, amps are one of those things I lack experience in, so I take on board what you guys mention re: tuning & matching etc.... Hence the thread question!

Cheers,

Andy
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Old 19th April 2011, 01:34 PM   #8
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In your case I think your best bet is find the original X-amp thread by Grey Rollins and review the progression and development. You will find that a very simple approach will yield over 30 watts per channel, enough for med. efficiency full rangers.

Best, Bill
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Old 19th April 2011, 01:54 PM   #9
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"The Aleph-X" is the original thread.
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Old 19th April 2011, 02:29 PM   #10
6L6 is offline 6L6  United States
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I would suggest a look at the F5. It 'checks the box' of your requirements, namely power, simplicity, and symmetry. It is a very popular amplifier right now, and justly so... Everybody who builds it is very pleased with it's performance and quality.

Boards are available from 2 legitimate (and authorized) sources, and there are stolen, pirated rip-offs from that auction site. Many people have built the amp on this forum, so you will find plenty of resource and help.

Here is the manual, written my Nelson Pass. It is in 2 parts, the 'owners manual' in the beginning, and the 'how-to' after that.

http://firstwatt.com/pdf/prod_f5_man.pdf
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