My first pass Labs project was an Aleph L back in about 2002. I had the service manual on one of my computers but lost it at some point. I want to go back to the L for a while and possibly do some mods to it and wanted to know if anyone here could send me the service manual. I moved everything Pass Labs related over to my server a few years ago and I literally have everything Pass Labs except for that. Not sure what happened to it.
Thanks in advance!!
Mark Gulbrandsen
Thanks in advance!!
Mark Gulbrandsen
Aleph L is a nice preamp, a lot of gain if you need so. Though if you want to go for a little batter the Alph P 1.0 is similar but more relaxed, extended and smoother sounding. Regarldless of the volume control (usuallu any 5K or 10Kat the output will do a job). The input and output caps quality is critical as alwyas in any preamp.
Kind regards
Kind regards
Cool, thanks for the pdf and mentioning the existence of an 'Aleph L' 
I still have to read the whole article, but I particular liked this part:
"The Aleph L is a simple Mosfet stereo preamplifier having four single-ended inputs and two outputs. Its controls consist of an input selector and a level control. The volume control is passive up to the 3:00 o’clock position where the gain is unity. At 3:00 o’clock, the connection from input to output is direct, with no components in the signal path, and past the 3:00 o’clock position the unit becomes an active preamp"
Maybe I can implement something like that in my preamp/ volume control ...
Walter
I still have to read the whole article, but I particular liked this part:
"The Aleph L is a simple Mosfet stereo preamplifier having four single-ended inputs and two outputs. Its controls consist of an input selector and a level control. The volume control is passive up to the 3:00 o’clock position where the gain is unity. At 3:00 o’clock, the connection from input to output is direct, with no components in the signal path, and past the 3:00 o’clock position the unit becomes an active preamp"
Maybe I can implement something like that in my preamp/ volume control ...
Walter
Hi Mike W!
Yes you did and I still have it here. I am getting back into this after a grueling eight years of living, breathing and eating Digital Cinema conversions 24/7. I'd like to take your board design and modify it for better coupling caps that are physically much larger. I never felt the small electrolytics were quite up to the task and I wired larger Multicaps with .01 bypasses to the boards. The problem is there are three of them on the output in parallel so more board real estate is needed there. Both at the input and the output.
The other option is building an Aleph X preamp which I have the service manuals for. Those have balanced supplies and shouldn't need output caps.
P.S., All these years I have been using a Chinese Grounded Grid kit with a few upgrades to it. It's actually VERY hard to beat it if you have a good quality set of 12AU7's in it. The sound stage, bloom and clarity of each instrument is uncanny. Now it's time to pick up where I left off.
Mark
Yes you did and I still have it here. I am getting back into this after a grueling eight years of living, breathing and eating Digital Cinema conversions 24/7. I'd like to take your board design and modify it for better coupling caps that are physically much larger. I never felt the small electrolytics were quite up to the task and I wired larger Multicaps with .01 bypasses to the boards. The problem is there are three of them on the output in parallel so more board real estate is needed there. Both at the input and the output.
The other option is building an Aleph X preamp which I have the service manuals for. Those have balanced supplies and shouldn't need output caps.
P.S., All these years I have been using a Chinese Grounded Grid kit with a few upgrades to it. It's actually VERY hard to beat it if you have a good quality set of 12AU7's in it. The sound stage, bloom and clarity of each instrument is uncanny. Now it's time to pick up where I left off.
Mark
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There were two versions of aleph L. the all time active one and the passive/active one. While some of you rave about how good idea it is the passive/active one I think it is actually not. I have built both, while the all time active I mentioned above was quite nice the passive/active is pretty much a simple potentiometer or resistor ladder up to some point which in my case was 90% of listening levels. It simply acts as any passive volume control instead of impedance matching preamp - simply poor. As I mention before about all time active circuit (single ended one) it is quite good and has a lot of gain, but having built Aleph P even though it is simetrical even when used as single ended with one input grounded it is much superioir to Aleph L. In both cases (like in every signal path caps) the signal capacitors are critical. If you want a very good caps for cheap try Siemens MKV or Bosch MP (slight preference to Siemens, The Bosch is similar but a little soft and not that clear in upper register). These are old big motor cans. You will have a very hard time getting anything similar from audiophile capacitors without spending at least $100-$150 for a piece of few uF value. They are so great only the few top of the world best caps are little better.
Ps I have also built B1 preamp, it is nice and clean sounding but somehow life less and flat (only my opinion) in comparision to L or P preamplifiers, though I think any similar circuit to L or P built with J fets should give improvements over original L or P.
PS II I found P 1.7 a little worse than P 1.0 actually being less relaxed and less extended sounding
PS III Any of these benefit from pure battery supply a lot, the power consumption isn't that high so it is easy to adapt battery supply with dedicated charger (charger disconnected when listening for better sonic results)
PS IV I expect any of X1/X2 or some of X0 versions to be even better but have not tried any of it so can't say
Ps I have also built B1 preamp, it is nice and clean sounding but somehow life less and flat (only my opinion) in comparision to L or P preamplifiers, though I think any similar circuit to L or P built with J fets should give improvements over original L or P.
PS II I found P 1.7 a little worse than P 1.0 actually being less relaxed and less extended sounding
PS III Any of these benefit from pure battery supply a lot, the power consumption isn't that high so it is easy to adapt battery supply with dedicated charger (charger disconnected when listening for better sonic results)
PS IV I expect any of X1/X2 or some of X0 versions to be even better but have not tried any of it so can't say
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"all you need is nice Elna Silmic , paralleled with 100n-1uF MKC (polycarbonat) cap"
I have the Aleph P 1.7 up and running. I am using Glassware attenuator on just the input as in a normal preamp. Signal to noise is excellent and I can't hear any hiss even with my ears right on the tweeter. There was considerable glare on vocals with the caps (Non Polarized) that were in it. So I took Zen's advice and ordered some Elna's from Mouser and paralleled them with .1 - 100 volt Vishay film caps that I had on hand. Now this is starting to sound really, really good. Luckily my DAC is also fully balanced from output of CS-4398 and the DAC chip feeds Lindahl output transformer's directly instead of crappy analog stage. So I get to feed real balanced audio source into P1.7. Sound is excellent and very detailed, much more detail and depth of presentation and excellent bottom end than with Aleph L line stage that already has really good film caps in it. Overall this is darn good for a 40 cent audio capacitor! I still think there are better film caps that I may try and remove the electrolytics though...
Mark
I have the Aleph P 1.7 up and running. I am using Glassware attenuator on just the input as in a normal preamp. Signal to noise is excellent and I can't hear any hiss even with my ears right on the tweeter. There was considerable glare on vocals with the caps (Non Polarized) that were in it. So I took Zen's advice and ordered some Elna's from Mouser and paralleled them with .1 - 100 volt Vishay film caps that I had on hand. Now this is starting to sound really, really good. Luckily my DAC is also fully balanced from output of CS-4398 and the DAC chip feeds Lindahl output transformer's directly instead of crappy analog stage. So I get to feed real balanced audio source into P1.7. Sound is excellent and very detailed, much more detail and depth of presentation and excellent bottom end than with Aleph L line stage that already has really good film caps in it. Overall this is darn good for a 40 cent audio capacitor! I still think there are better film caps that I may try and remove the electrolytics though...
Mark
Zen, I have used these caps to bypass many times before and they are one of the best for that use. This is one cap I would recommend to you to try out. Some say the MKT-1822 is the best audio coupling capacitor period and the P1.7 preamp sounds amazing with them in. But without the .1 bypass having just the Elna's the sound was just so-so. Fortunately the MKT-1822's are made up to 15uf.
If you google "best audio capacitor" this is what you get:
"I've been into audio for 11 plus years and I have heard dozens of capacitors. Everything from military specd, to audiophile grade. Ranging in price from just a few pennies to hundreds of dollars.
And the best capacitors that I have ever heard are Vishay. These are made in Germany by Vishay Roederstein to be exact, model number MKT 1822. They were previously know as the ERO capacitors. The MKT1822 is a box style timing capacitor, made out of metalized polyester. They range from 1000pF - 15.0uF and have voltages from 63vdc - 250vdc.
Most audiophiles will disagree because it goes against all audiophile grade logic. They don't have Teflon, copper foil, silver foil, polypropylene/foil design, silver leads, oil, etc. But what they have is what counts, absolutely stunning sound.
It is virtually vale free and grain free. I have never heard any other capacitor come close! They have incredible resolution and sparkle to the high frequency. The term "liquid" should have been invented for these caps. Plus they have to most un-electric midrange I have ever heard. The best part is that they are dirt cheap, a few bucks max for the larger values. And they work as well in speaker crossovers as they do as coupling or bypass capacitors in amplifiers, preamps, dacs, etc. Here's a list of some capacitors which I compared the MKT 1822's to.
AuriCap
Hovland
SCR Solen
Jensen
RelCap Audio Cap Theta
MultiCap RTX
MultiCap PPMFX
Russian Military Teflon High Voltage Types"
My use of capacitors somewhat parallels this guy except I have yet to try Russian Military caps. Typically in rebuilds I use PPMFX bypassed with MKT-1822's. MKT-1822's give incredible detail and top end!
Mark
If you google "best audio capacitor" this is what you get:
"I've been into audio for 11 plus years and I have heard dozens of capacitors. Everything from military specd, to audiophile grade. Ranging in price from just a few pennies to hundreds of dollars.
And the best capacitors that I have ever heard are Vishay. These are made in Germany by Vishay Roederstein to be exact, model number MKT 1822. They were previously know as the ERO capacitors. The MKT1822 is a box style timing capacitor, made out of metalized polyester. They range from 1000pF - 15.0uF and have voltages from 63vdc - 250vdc.
Most audiophiles will disagree because it goes against all audiophile grade logic. They don't have Teflon, copper foil, silver foil, polypropylene/foil design, silver leads, oil, etc. But what they have is what counts, absolutely stunning sound.
It is virtually vale free and grain free. I have never heard any other capacitor come close! They have incredible resolution and sparkle to the high frequency. The term "liquid" should have been invented for these caps. Plus they have to most un-electric midrange I have ever heard. The best part is that they are dirt cheap, a few bucks max for the larger values. And they work as well in speaker crossovers as they do as coupling or bypass capacitors in amplifiers, preamps, dacs, etc. Here's a list of some capacitors which I compared the MKT 1822's to.
AuriCap
Hovland
SCR Solen
Jensen
RelCap Audio Cap Theta
MultiCap RTX
MultiCap PPMFX
Russian Military Teflon High Voltage Types"
My use of capacitors somewhat parallels this guy except I have yet to try Russian Military caps. Typically in rebuilds I use PPMFX bypassed with MKT-1822's. MKT-1822's give incredible detail and top end!
Mark
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