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Old 8th April 2005, 08:41 PM   #431
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Its basically the same. Source resistors for A5 are 1R, A30 has .47R. 3 fets for output and 3 for ccs for both. i know the input is a bit different for the A30 which results in a higher impedance for single ended input (i think). i studied the schematics but im a bit new at this

thank you

John
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Old 11th April 2005, 02:57 AM   #432
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no help?
i'll just go for it, change the source resistors to 1R, and raise the rails, using irfp244. Anything else?
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Old 11th April 2005, 03:06 AM   #433
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If you are in Newington, i reccomend you go down to the Berlin TPK and go to Cables and Connectors. Pick up a 10A CALRAD?current meter( they are $17.99 each) to measure bias current. Put one in series with one of the rails coming off the power supply and you can measure bias current. I'm in Farmington, and i did this was my Aleph 2's so i could easily monitor bias current. Boy does it make things easier. You might also want to consider starting w/ pots for ac current gain and bias so that you can set those to your liking. For my aleph 2's those were r21 and r19 respectively.

I doubt this answers your question exactly, but it may help overall.

-Matthew K. Olson
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Old 11th April 2005, 05:18 AM   #434
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hmm, got $150 worth of gift certificates for that place, that place is awesome, they moved next door now its huge!!!
thanks for the advice, my meter has a current clamp so i should be fine. saving up for that lab power supply.


John
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Old 11th April 2005, 10:40 AM   #435
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I'm talking about a chassis mount meter.

But yes, Cables and Connectors is really nice to have around. I get most of my stuff online, but there are a few things i only get at Cables and Connectors. Heatshrink is one, pcb stuff, and calrad meters

-Matthew K. Olson
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Old 12th April 2005, 01:16 AM   #436
sklimek is offline sklimek  United States
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i Pick up a 10A CALRAD?current meter( they are $17.99 each) to measure bias current. Put one in series with one of the rails coming off the power supply and you can measure bias current. I'm in Farmington, and i did this was my Aleph 2's so i could easily monitor bias current. Boy does it make things easier. You might also want to consider starting w/ pots for ac current gain and bias so that you can set those to your liking. For my aleph 2's those were r21 and r19 respectively.

Hi Matthew, that does sound like a nice trick for biasing R19 w/ the chassis amp meter, especially because I "believe" I was reading in a search that it takes awhile for the current to reach its maximum point (maybe thats' why some people say their Alephs sound best after warming up for an hour. I couldn't find it at cables and connectore (web site) but I believe this is it?

http://www.arcade-electronics.com/cg...p_prodid=19393

You could take it out when your done or whatever. This "30" is my first Aleph and I have been reading on the biasing quite a bit, I've got R19 (DC bias) figuered and R21 (AC gain) figuered at least mentally but I was wondering about R16? Can't seem to find to much info in searches and I have noticed that it was one of the key resistors in Brians BOM that indicated an adjustment might be necessary after biasing (?). Any thots?
Best - Stan
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Old 12th April 2005, 02:45 AM   #437
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Thats the one. Leave it in. Put it in the back of the amp. Its not terrible looking, but i didn't find it worthy of the front of the amp. The amp i have does not bias slowly. I turn it on, immediately bias goes right to 4A/rail and stays. I like having a meter built into the amp. Peace of mind kind-of-a-thing

-Matthew K. Olson
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Old 14th April 2005, 12:52 AM   #438
BrianGT is offline BrianGT  United States
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I should receive the boards in a weeks time. The status shows the boards in the final phase

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Brian
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Old 14th April 2005, 12:54 AM   #439
jleaman is offline jleaman  Belgium
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Quote:
Originally posted by BrianGT
I should receive the boards in a weeks time. The status shows the boards in the final phase

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Brian

WICKED!!

Parts are all being ordered on friday. Kits will be put together next week i hope.

Jason
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Old 14th April 2005, 01:06 AM   #440
fcel is offline fcel  United States
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Jason,
Per what Matt said, could you include a pot (for extra fee) that would fit the board as part of the kit so that we're able to adjust the bias to our liking? For A30, I'm not sure which is the bias resistor though. From my recollection, 200K pot is good to start with.

Matt,
Do you happen to have the address of Berlin TPK? Do they do mail order?
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