yea I agree with Terry
A suggestion, if redesigning the whole thing looks like an unsurpassable task for the time being then I would suggested a super extended design with 16 or 20 plastics driven at 100-110v giving an easy 400-500w at 8.
Dont know if the driver can take it though....
Jacco Terry Jens & Co interested?
A suggestion, if redesigning the whole thing looks like an unsurpassable task for the time being then I would suggested a super extended design with 16 or 20 plastics driven at 100-110v giving an easy 400-500w at 8.
Dont know if the driver can take it though....
Jacco Terry Jens & Co interested?
terry, it looks like the ksa -50 is too low powered for you right?
The trend nowadays as followed by the big players is to manufacture very high power amps.
My opinion is that once you hear the next beast you realise what you have been missing in the past, and its not a childhood fantasy or anything. The sound does get more close to the real thing.
The trend nowadays as followed by the big players is to manufacture very high power amps.
My opinion is that once you hear the next beast you realise what you have been missing in the past, and its not a childhood fantasy or anything. The sound does get more close to the real thing.
it is very difficult not to draw Jacco's interest in a project😀
OK then how about this, if Jens has the time why dont we have the same board adopted to accomodated more of this fat plastic mamas and be off with it?
Maybe a small exension board can also do the trick giving the flexibility of the user to install as many plastics as he may please. How about it wizards?
OK then how about this, if Jens has the time why dont we have the same board adopted to accomodated more of this fat plastic mamas and be off with it?
Maybe a small exension board can also do the trick giving the flexibility of the user to install as many plastics as he may please. How about it wizards?
Villaw said:
Well there is always the option of adding an output transistor as driver, making the output a 4 DD
\Jens
Villaw said:
There aren't that many high power circuitry designs available.
And even fewer with a proven history, the Double Barrel Leach is the first and probably the best true DIY design.
Building such a multi output device beast is something i've been wanting for a long time.(building a set of JR M7's has been my wish for nearly 2 decades)
Using a plastic output device as driver is the logical choice, with MJL's there is not much difference in speed compared to MJE devices.
I believe there is a lot to be learned from proven pro amps. The QSC 2450 (whose schematic can be downloaded from here http://www.qscstore.com/rmmodaschan22.html) is using 4 pairs of plastics 2sa1943 2sc5200 for 1200w at 2 and a single pair of 15032 as drivers run at 110v.
Forget that it is a more efficient class H, forget about the protection circuits, the fuses etc and the circuit is there.
When you hear the authority that this amp is driving the speakers with, you will never look back. The only thing that it is missing are the clarity of the mids and highs which I beleive can be had with a proper PSU and a fixed design like the leach.
So basically a modified leach will win on all grounds. The only problem which I see is locating proper caps to run at 100 or so volts or obviously using a lot in series with the disadvantages that comes with.
No offence but a live orchestra cannot be listened to properly at 90 or 95 db.
Forget that it is a more efficient class H, forget about the protection circuits, the fuses etc and the circuit is there.
When you hear the authority that this amp is driving the speakers with, you will never look back. The only thing that it is missing are the clarity of the mids and highs which I beleive can be had with a proper PSU and a fixed design like the leach.
So basically a modified leach will win on all grounds. The only problem which I see is locating proper caps to run at 100 or so volts or obviously using a lot in series with the disadvantages that comes with.
No offence but a live orchestra cannot be listened to properly at 90 or 95 db.
This is a very interesting interview which corroborates my case when it comes to the sound quality factor and power is as follows, given by two krell people who seem to know what they are talking about: http://aca.gr/event04-11_krell.htm
One thing though nobody addressed before is the need to have the plastics matched since the loss of quality when using 10 pairs of them per channel will be evident. Any ideas of how we could do that as painlessly as possible?
One thing though nobody addressed before is the need to have the plastics matched since the loss of quality when using 10 pairs of them per channel will be evident. Any ideas of how we could do that as painlessly as possible?
Villaw said:
-buy devices from the same production run/batch
-match Vbe
-match Hfe
-compose two batches for left and right channel
-swap devices with GB members, sending an envelope with a
couple of output devices across the globe only costs a few
dollars and cents.
(being the geek-turd that i am, i match everything to closest tolerance;T's, C's,R's. A reason for buying 10 K of 5% accurate BC metalfilms for next to nothing lately, that i can match within 0.1%)
no problem here:
http://electronica.snuffelsnel.nl/componenten/overvoorraad_condensatoren_ri/
Jacco
On a more convenient approach as regards matching, isnt it a good idea to add in parallel to the emiter resistor of the power transistor a low resistance pot to adjust the current flowing into each transistor thus in effecting matching them?
On a more convenient approach as regards matching, isnt it a good idea to add in parallel to the emiter resistor of the power transistor a low resistance pot to adjust the current flowing into each transistor thus in effecting matching them?
What power handling capability do you think those trimpots need ?
Secondly,
what will be the added cost ?
Thirdly,
as this trimpot adjusting is done for 1 emitter voltage level, what happens if emitter voltage alters because there is a signal on the base of the devices ?
Secondly,
what will be the added cost ?
Thirdly,
as this trimpot adjusting is done for 1 emitter voltage level, what happens if emitter voltage alters because there is a signal on the base of the devices ?
I wouldnt think beyond ordinary ratings as most of the current would flow though the main emiter resistor.
Is this a good idea at all? I cannot think of any problems with it...
Is this a good idea at all? I cannot think of any problems with it...
about matching
Matching Vbe is no option i think, Vbe is very much influenced by temperature.
Matching Hfe is mostly done on one workingpoint and is a rough way of matching, but better than no matching at all.
I would not think of a potmeter in this part of the amplifier.
When matching Stuarts 0,68 ohm resistors i found them a little sensitive to temperature. Spreading was about 5 %.
I heated a resistor (measured 0,652 ohm) with a current of 2 amps during 15 min. After cooling down for 15 minutes it measured 0,665 ohm. So i don't think you should not be to much worried about the emitterresistance matching.
Loek
Matching Vbe is no option i think, Vbe is very much influenced by temperature.
Matching Hfe is mostly done on one workingpoint and is a rough way of matching, but better than no matching at all.
I would not think of a potmeter in this part of the amplifier.
When matching Stuarts 0,68 ohm resistors i found them a little sensitive to temperature. Spreading was about 5 %.
I heated a resistor (measured 0,652 ohm) with a current of 2 amps during 15 min. After cooling down for 15 minutes it measured 0,665 ohm. So i don't think you should not be to much worried about the emitterresistance matching.
Loek
JensRasmussen said:
Is this close enough to Fall? 😀
Sure like to see you pick this up again. Your Leach VI is a very fine amp. I would really like to see what you can do with the Superamp.
Blessings, Terry
Terry,
In about two-three weeks I start the winter break on the DIY house work, and the I will pick up the DIY audio work again.
Thanks for keeping an interrest in this project.
\Jens
In about two-three weeks I start the winter break on the DIY house work, and the I will pick up the DIY audio work again.
Thanks for keeping an interrest in this project.
\Jens
Just trying to keep this up and running. Hoping you get an itch to revisit this. I'm going to need something to work on shortly.
Blessings, Terry
Blessings, Terry
Hello,
I just made a version of the schematics to generate the new PCB from.
Please review and comment.
Parts options we can talk about later
\Jens
I just made a version of the schematics to generate the new PCB from.
Please review and comment.
Parts options we can talk about later
\Jens
Only three little notices, Jens : Try to think about implementation of antisaturation diodes into VAS. At second : Connect into current limiter blocking capacitors ( CB of T17+19 ), 'cos this circuit have tendence to oscilate, when " go " into the function... At third : give instead R18+59 voltage regulator ( for example TL 431 ) and instead R8+71 some current source.... 😎
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