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Old 11th January 2001, 08:23 AM   #11
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Wow !
Yeah it looks good. I donīt know thow if putting everything on the bottom of the box to cool is a good idea. It would be better i think on the heatsinks directly.
Anyway it does look cool. I have never seen heatsinks like that anywhere.
I canīt find the Hoffman schematic anywhere. I donīt think he is a registered member here.
If itīs easy to send a pic of it thanks.
(btw. I am not in a hurry I will be away a few days).
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Old 11th January 2001, 09:30 AM   #12
FYC is offline FYC  Hong Kong
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I think the current source in Aleph series is the patented dynamic current source of Pass. To build it as a DIY object might not infringe his patent. But worthwhile to give Nelson Pass a email to confirm?

Intellectual Property right should be observed.
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Old 11th January 2001, 09:31 AM   #13
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I've also seen the Aleph 3 service manual for a few months. I believe that from the circuit, the Aleph 3 is not featured with balanced input and the first -stage is the normal differential amplifer, similar but not exactly the balanced line stage (Super symmetric without the folded cascoded..see Pass's patent page).
The Aleph 3 is simply the Zen amp augmented with
1) differential input stage (probably to isolate output from input in the feedback loop and thus allow high input impedance and lower output impedance than the Zen)
2) 2 output sections in parallel for higher current drive
Probably some more that I don't see.
A good amp to try to make, however.Thanks for the generousity of Pass Labs.
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Old 11th January 2001, 09:42 AM   #14
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You can modify it to have balanced input like the rest of the aleph amps because they all share the same design.
The output isnīt a Zen because the Zen has gain and the output section of the aleph is a power follower.
Apart from that the aleph has no change in phase.
The pair in the input is better the balanced line stage because of the current source. Apart from that it has the same function.
btw does anybody have a real schematic of the super symmetry circuit. I have seen the patent posted but it would be more usefull to see the real thing in practice.
Thank for your reply.
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Old 11th January 2001, 02:00 PM   #15
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Default the link

Refering to the link. I think he says somewhere on the web page the case is a 3phase motor controller case. Very good idea anyone with a friend in an industrial/electrical job??
I think if you look closely you will see the fets are mounted on the sides of the heatsinks.
I was also wondering about any patents and rights etc when looking at building the Aleph. But wouldn't this only apply if you were sell the amp. As to make money off some elses ideas?? What do you guys think?

VDI_Nenna The subs for the A-40 outputs I have heard about so far are MJ11016, MJ11015 let me know if you find anything different. So far I have PCB's etched and some components mounted. Still waiting for a shipment from DigiKey (2 dats late) BTW I posted looking for Silver Micas a while back they can be found at the Digi web site it seems not everything is listed in the catolgue.
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Old 11th January 2001, 03:02 PM   #16
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Wow thatīs why the case looks strange...
Oh yeah you are right the transistors ARE on the heatsink.
I was not paying attention to all the pics in the site. I think the case is only two parts that you screw together.
There is no problem to make an amp like aleph with a few mods. Itīs just for DIY or else Pass wouldnt publish it.
The main reason he published the service manual is because they stop producing the aleph series since they have the x series with new circuits and the parts for the aleph wont be around long or too expensive to buy.
Are the mjīs for the A40 expensive ?
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Old 11th January 2001, 04:41 PM   #17
Eric is offline Eric  United States
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Default Cost for the MJ's

The suppliers I have found for the MJ output devices seem to run $9-12 for the MJ11015 and $7-9 for the MJ11016.
Web-Tronics has them at and you can also find them at DC Kits or ACK Electronics

I'm in the process of sourcing the components for the Pass a40, but probably won't build it for a while yet - I have some other open projects that I need to finish that aren't as much fun...

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Old 11th January 2001, 05:56 PM   #18
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The Aleph 3 is single ended, but the 4 is both balanced and single. It's also 100w into 8 ohms. From what I could see, the schematic is more clear in the Aleph 4. It shows the intersections of connections. I need that to be able to build it correctly. The 3 doesn't have this.

Dok, I'll get the A-40 subs. tonight. But what you have sounds simular. I'll check anyway.
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Old 12th January 2001, 02:38 AM   #19
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An implementation of super symmetry is in the SOZ circuit and the Balanced Line Stage projects, as well as X series of Pass Labs amp and some Aleph preamp (Aleph P 1.0 and 1.7 ... service manuals are on the web as well).
The major different that see (although not fully analyze yet) between Balanced Line Stage circuit and normal differential amp are
1) the coupling resistor between the two MOSFET source pins
2) the separate current sources for positive and negative sides.
So the Balanced line stage looks more like two single-ended connected to each other via the coupling resistor, rather than the differential amp. The Aleph 3 input is, however, exactly a normal diffential amp because it has a common current source connected to both the source pins of the two MOSFETs. According to Pass's patent page on super symmetric topology, the coupling device plays the major role in sharing the distortion to be approxiamately the same on both positive and negative sides, thereby cancelling each other out at the output.
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Old 12th January 2001, 06:54 AM   #20
FYC is offline FYC  Hong Kong
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The output stage of the Aleph is similar to a Zen, it is NOT a power follower.

It is non-inverting because it has 2 stages with both inverting, hence net result is non-inverting.

I guess a good starting point for DIY is to make first following the Aleph schematics. Later changes can be adopted to see how these can improve the sound.
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