I would like to build an Aleph J.
I did some voltage measurements on my speakers today, and while I managed an absolute maximum of 13.5v with an SPL of ~100 dB, realistic listening levels were closer to 7.5v, maybe as high as 10.5v on rare occasion. All of this into 4 ohms. Ohms law works that out to 14w-25w @ 4 ohm.
Given that these are the maximum values I would expect to hit, and normal listening would be well under that, would it be possible to bump up the bias on an Aleph J enough to accommodate such possibilities?
I did some voltage measurements on my speakers today, and while I managed an absolute maximum of 13.5v with an SPL of ~100 dB, realistic listening levels were closer to 7.5v, maybe as high as 10.5v on rare occasion. All of this into 4 ohms. Ohms law works that out to 14w-25w @ 4 ohm.
Given that these are the maximum values I would expect to hit, and normal listening would be well under that, would it be possible to bump up the bias on an Aleph J enough to accommodate such possibilities?
Last edited:
which speakers you exactly have?
J will produce that power, but results are depending of true impedance module of speakers, not nominal value
J will produce that power, but results are depending of true impedance module of speakers, not nominal value
I have Vandersteen Model 3A. Their impedance graph can be found here: Vandersteen Audio 3A loudspeaker Sidebar 3: Measurements | Stereophile.com
I achieved my maximum voltage readings at 120 Hz and 220 Hz, which I'm estimating to be about 4 ohm each.
nope
"minimum of 2.8 ohms at 35Hz", what is visible in graph
go bigger Aleph, or some other FW amp
F4, if you have capable preamp (full voltage swing, F4 being follower with 0db voltage gain) or BA3
F5 too, but F5 never being my fave, but all Boyz like it
well, M2 is my fave
"minimum of 2.8 ohms at 35Hz", what is visible in graph
go bigger Aleph, or some other FW amp
F4, if you have capable preamp (full voltage swing, F4 being follower with 0db voltage gain) or BA3
F5 too, but F5 never being my fave, but all Boyz like it
well, M2 is my fave
Technical, Philosophical and Humoristic Jewel
besides - sound-wise - producing just music, nothing more and nothing less
Swiss Knife of FW
besides - sound-wise - producing just music, nothing more and nothing less
Swiss Knife of FW
I have used and modified a few Hafler DH-220 and DH-200 amps. They were very good in their day. The Class A designs of Nelson Pass are a good step above the best I was able to achieve with my Haflers. My speakers are the early Model 2C, which are easier to drive.
I don’t think the Aleph J would be a bad choice, but it would need to be a special DIY build. Somewhat higher rail voltage, dual-mono PSU in a larger chassis and high bias current. Will do the job. After that a BA-3 would be one to consider.
I don’t think the Aleph J would be a bad choice, but it would need to be a special DIY build. Somewhat higher rail voltage, dual-mono PSU in a larger chassis and high bias current. Will do the job. After that a BA-3 would be one to consider.
Are the JFETs getable for that?
That would be fun. Any thoughts on the increase in rail voltage or bias current? Or suggestions on how I could identify workable values?
Yes, several varieties of JFETs are available from the diyAudio store. Some are matched by Papa himself.
Much fun to be had with the Aleph J. Dual 300VA transformers with 22V secondary windings. Shoot for 26.5V rails or a little higher. A big 3.5U or 4U by 400mm deep chassis to handle 2.2 Amps bias. There are a couple ways to go with the PSU, but I would probably go with a pair of SLB units, as the big CRCRC boards I used are harder to find now.
Much fun to be had with the Aleph J. Dual 300VA transformers with 22V secondary windings. Shoot for 26.5V rails or a little higher. A big 3.5U or 4U by 400mm deep chassis to handle 2.2 Amps bias. There are a couple ways to go with the PSU, but I would probably go with a pair of SLB units, as the big CRCRC boards I used are harder to find now.
slightly hysteric thread, but certainly informative - About possible Babelfish J interest
it'll give you general idea what is necessary to scale up Aleph amp
but - even with existing Store Aleph J kit ( check, I believe it's available in this moment, JFets included), without increasing rails, but with increase of Iq, you can get amp suitable for your needs
catch with Aleph is that OS can't leave A class envelope and it can give approx twice Iq to load, so Iq must be substantial, comparing to some other FW amps, being able to leave A Class envelope
these being amps having OS in source follower fashion, and also F5 (flippittyflip jobbie, common source amp; ignore term if it is confusing)
anyway - form back of my head without too much calculus - case in range of Modushop 4U/400 or even bigger , will give you enough meat to cope with 100-120W of dissipation per channel, which you need to give enough current to your speaks
but, my advice would be - make another amp, if job is to fill 2R8 sinkhole
edit: Tungsten - I don't think that without really deciding to go wild with hardware, is wise to talk about increase of rails voltage; Aleph watts are costly
just take a look at catalogue of PL Aleph amps ( manuals/schematics) and how they are scaled; imagine each of them with cascoded JFet input and that's it
mucho aluminum, mucho copper, mucho cans ........
it'll give you general idea what is necessary to scale up Aleph amp
but - even with existing Store Aleph J kit ( check, I believe it's available in this moment, JFets included), without increasing rails, but with increase of Iq, you can get amp suitable for your needs
catch with Aleph is that OS can't leave A class envelope and it can give approx twice Iq to load, so Iq must be substantial, comparing to some other FW amps, being able to leave A Class envelope
these being amps having OS in source follower fashion, and also F5 (flippittyflip jobbie, common source amp; ignore term if it is confusing)
anyway - form back of my head without too much calculus - case in range of Modushop 4U/400 or even bigger , will give you enough meat to cope with 100-120W of dissipation per channel, which you need to give enough current to your speaks
but, my advice would be - make another amp, if job is to fill 2R8 sinkhole
edit: Tungsten - I don't think that without really deciding to go wild with hardware, is wise to talk about increase of rails voltage; Aleph watts are costly
just take a look at catalogue of PL Aleph amps ( manuals/schematics) and how they are scaled; imagine each of them with cascoded JFet input and that's it
mucho aluminum, mucho copper, mucho cans ........
Last edited:
Much aluminum for sure. My Aleph J was built to handle up to 2.5A per rail. I never went that far because it sounds so good at 1.8A. Rail voltage is the 26.5V that I mentioned. Chassis is 3.5U x 400mm, with internal aluminum L brackets to augment thermal transfer from the heatsinks to the baseplate. When it’s running in my system, I leave it on 24/7. Runs nice and warm, not hot.
I tweaked the front end slightly to keep the JFETs from running too hot.
I tweaked the front end slightly to keep the JFETs from running too hot.
Last edited:
What is the factory bias amperage per rail?
> My Aleph J was built to handle up to 2.5A per rail.
Is that a matter of heatsink size and power supply voltage?
Also, do you have a build log or other such information about your high-bias Aleph build?
Last edited:
you should not get hung up on an idea and start tweaking a design to fit the bill at all costs. there are already plenty of good choices. Aleph30 can handle the 4ohm load, so can bigger Alephs. but the heat dissipation in alephs gets pretty brutal into lower impedances. Their mid range is warm but bass control is not at its best. BA3 (F4 with a suitable FE which kicks #@@) or M2 are both good choices (the latter regarded as a good allrounder). Also check out Zen Mod's iterations of Papa amps as he often gets more power and sometimes lower distortion too.
You’re right, of course. I was excited about the idea of being able to build a single-ended amplifier with a 2nd harmonic distortion profile. Just because those are the two things people rave amount, and I’d like to try them out.
Are there plans/boards for an Aleph30? I was mostly limiting my options to was sold on the diyA store.