This is what i've been asking myself many times....only way i see viable is for the forum to organize an amp project and Papa include these treasures in the GB......if he can be persuaded to part with them this way.
...is ZM listening............
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This is what i've been asking myself many times....only way i see viable is for the forum to organize an amp project and Papa include these treasures in the GB......if he can be persuaded to part with them this way.
...is ZM listening............
Hah!!!!! ZM will consider all others
- buuuuuuuuuut I would not blame him if he took care of himself 1st. The purpose being to make sure that circuits and devices work correctly. He would do this out of the kindness of his heart and dedication to his fellow DIYer's. I suspect that it would probably take a year or so - all good amps and vino's take a while to mature. Now then - if you actually believe what I juz said - welllllllllllll - then do I have some deals for you!!!!
If you want to play, I suggest acquiring some NOS parts from the Sony or
Yamaha production of Vfets. Last time I looked they were a lot cheaper.
I haven't made a decision about the availability of my parts, as the quantity
is too precious and the uses are still being explored. More can be purchased,
but the last quotation for a suitable run was over $300K. I have more work
to do before making such a commitment, but if you are prepared to take the
risk for me, you can PM me.
anyone having radar or two , disposed in back yard ?
Russian or American , whatever .....
They made me give it back when I retired.
Greetings,
I'm considering an upgrade to power my midranges and tweeters in my bi-amped system. I *think* I could get an Aleph built and running nicely - at least with a bit of the always generous support from folks here. My first question is: which Aleph?
My midrange drivers are older, modified JBL LE8T-H. Sensitivity is 89db, minimum impedance is ~6-6.2 ohms. I like to drive them hard - they can take it and sound fantastic since I've tweaked the cones and domes. Would the Aelph J be able to manage? ...maybe with 3 MOSFET pairs?
My secondary requirement is that the amp have an input sensitivity in the neighborhood of 2V for max output.
Any opinions from those of you who have personal experience with these designs?
TIA!
Frank
I'm considering an upgrade to power my midranges and tweeters in my bi-amped system. I *think* I could get an Aleph built and running nicely - at least with a bit of the always generous support from folks here. My first question is: which Aleph?
My midrange drivers are older, modified JBL LE8T-H. Sensitivity is 89db, minimum impedance is ~6-6.2 ohms. I like to drive them hard - they can take it and sound fantastic since I've tweaked the cones and domes. Would the Aelph J be able to manage? ...maybe with 3 MOSFET pairs?
My secondary requirement is that the amp have an input sensitivity in the neighborhood of 2V for max output.
Any opinions from those of you who have personal experience with these designs?
TIA!
Frank
...forgot to mention: I roll them off at 150 Hz, so fairly broad freq. spectrum.
plenty of db with standard J's 30+ W
go for it
or make F5 , if you prefer slightly less romantic
I appreciate the perspective. I now realize that there is no chance of building the F5 because the thread here on DIYA is 1060 pages!!!
Regarding the J, I would love to go for it because I think my LE8T-Hs are quite special and have outgrown the (very nice) amp that is driving them! To help with the go/no-go decision, is it OK if I ask a couple of Pass DIY-noob questions on this thread? I'll try... then if I take the plunge I'll move over to the J thread during implementation.
1. As much as possible (without destroying the magic!), gain on a new Class A midrange amp should resemble the differential amp driving the woofers. That is set for 10X voltage gain per side, and full power is achieved at ~2 volts input. In terms of db, the Aleph J is 17db per side, or 7X (if I'm not mistaken). In other words, woofer gain would be 1.4X that of the midranges. Not ideal. Is there some latitude to slightly increase the J's output gain or input sensitivity (or both)? If not, then I would have to lower the gain of the amp driving the woofers but it's not uncommon now for me to play the system at 0db attenuation! I could also slightly increase the output of the DAC I/V stage, but only as a last resort...
2. I take it that heat management is a major limitation in tweaking the performance. I'll definitely use active cooling so I can place the amp in my equipment rack. So... 2a) if the extra heat from a 3rd pair of MOSFETs/channel is not an issue, do they detract from the sound? ...and 2b) With decent cooling, what rail voltage is the 'real sweet spot' for the Aleph J's PS?
Thanks so very much for the benefit of your experience!
Frank
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in this thread everything is OT
1 . Aleph J gain is 10x ( without taking in account why that is so important - it's easy to compensate wherever you wish in chain)
2. there is no need to include third pair of outputs , especially if you plan to use it for bassless reproduction ; I'm using just one pair of IRFP150N in my Babelfish J , with some benefits - less capacitance and no need for matching of outputs
say that sweet spot - regarding PSU voltage - is right there .... and up
;but - taking care of input jfets , say that you don't need more than +/-28V to be on safe side
for more info - look for Babelfish J schm ( my small web site ), compare with Papa's original , think about ...... and build
edit - to prevent possible question - no - I don't have pcbs for Babelfish J
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