I have decided to build a new speaker. I'm going to try my hand at the Lowther TP-1 Isis using DX4 drivers. I'm curious what amplifier would NP recommend to power these? I'm looking for a range of ideas I guess. I'd love a gen-u-ine (with a Texas accent) INT-30A, and might be able to pull that off, but perhaps there is a better choice? a more realistic choice?
Manu,
Measuring IRFP240, IRFP9240, FQA12P20 & FQA19N20C at 200mA @ 25 deg C and 1A @ 50 deg C I found a relatively strong consistency in the matching.
Measuring IRFP240, IRFP9240, FQA12P20 & FQA19N20C at 200mA @ 25 deg C and 1A @ 50 deg C I found a relatively strong consistency in the matching.
Hi,
I put here my own experience about matching mosfets.
The method :
On a thermostated table home made, regulated at 35°C +/-0.3°C :
I measure the Vgs when Gate and drain are connected, and Ids injected by a regulated source of current.
The Ids are 100ma and 200ma
Two full batches of Irfp240 and Irfp9240 (2x1000 mosfets).
Here the results for the two batches :
Vgs of the Irfp240 and 9240
Magenta : Batch 1, 200ma / Dark Blue : Batch 1 100 ma
Cyan : Batch 2, 200ma / Yellow : Batch 2, 100ma
You can see that the batches of 240 are better than the 9240 ones.
These batches permit to have a good sextet matching (1mv for 240 and 2mv for 9240).
I put here my own experience about matching mosfets.
The method :
On a thermostated table home made, regulated at 35°C +/-0.3°C :
I measure the Vgs when Gate and drain are connected, and Ids injected by a regulated source of current.
The Ids are 100ma and 200ma
Two full batches of Irfp240 and Irfp9240 (2x1000 mosfets).
Here the results for the two batches :
Vgs of the Irfp240 and 9240
Magenta : Batch 1, 200ma / Dark Blue : Batch 1 100 ma
Cyan : Batch 2, 200ma / Yellow : Batch 2, 100ma
You can see that the batches of 240 are better than the 9240 ones.
These batches permit to have a good sextet matching (1mv for 240 and 2mv for 9240).
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Check out the last newsletter with the article about Burning Amp. It discusses the amps Papa used and a filter to make it work..
Thanks for your feedback ... 😎
philbyx said:
Hi Philippe,
Nice setup and interesting results
Thanks for sharing ...
Manu
Hm, I see the F2J mentioned and a network to integrate it with a Seas driver, but perhaps I missed something? Thanks for that though, it was a great read, even a second time 🙂
Luvdunhill -
I use a F2J clone,
with a lowther PM5A, a 10R-10uf across the terminal sounds good to me. (running OB)
next choice was 10R across the terminals. I left out the 3x47R resistors in F2J.
I wonder what Papa or Jon ver Halen use in OB with PM5 or 6A.
I have not experimented around too much. it sounds really laid back, with a sweet mid and really nice top end.
Sorry, you're right, the info was for the Seas driver. Still, clearly the F-2J is a contender!
Papa has a lot going on at the moment so can't post much, but maybe later..
Any word on the F6? Mostly just curious to how it's different from other Zen or FW amps. I remember something about a special feedback implemetation.
No rush. I'm happy with what I have to work with thus far. 😀
Thanks,
Vince
No rush. I'm happy with what I have to work with thus far. 😀
Thanks,
Vince
I did it myself.
I swam past 1000m and only considerably short of breath !
Past was as close to audio as my slow mind can think.
I swam past 1000m and only considerably short of breath !
Past was as close to audio as my slow mind can think.
Hmm, Amplifier?
Maybe you guys need a technical support from China? Or money support?
Hmmmm.....
Maybe you guys need a technical support from China? Or money support?
Hmmmm.....
I built one, and have gotten good review from one of my alpha testers.
It will be along soon enough.
😎
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Had you reversed the D-S pins, the 10R wouldn't be source resistors anymore 
(Donkey ride : arrow pointing to the JFET gate => gate is P => junction is PN => channel is N => drain is positive => source is negative)
(Donkey ride : arrow pointing to the JFET gate => gate is P => junction is PN => channel is N => drain is positive => source is negative)
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Had you reversed the D-S pins, the 10R wouldn't be source resistors anymore
you're right. the beautiful weather must be getting to my brain
thanks!