Seventh Circle Audio

I'm new forgive my ignorance... I'm posting a link to my post in the J99 forum..... they both completely relate... I've just built a J99 and A12... at first I forgot to test and adjust impedence regs and got a faint signal... but there's more to it.... Now the signal is way too hot... If you have any input that would help, it would be much appreciated....

REad this for the full situation...........

http://www.seventhcirclestudios.com/SCA ... =2635#2635

The gain of the A12 is determined by the ratio of resistors. First, verify that R15 is really 10K. You can get a reasonable measure in-circuit with the power off and the op-amp removed. Make absolutely sure you haven't inadvertently put a 100K in its place. Let us know what you find.

tpryan \$m[1]:The gain of the A12 is determined by the ratio of resistors. First, verify that R15 is really 10K. You can get a reasonable measure in-circuit with the power off and the op-amp removed. Make absolutely sure you haven't inadvertently put a 100K in its place. Let us know what you find.

Tim, Thanx for responding.... you should keep your cape on at all times....lol

Okay.... let me know if this is strange...

R15=9.5k

It took a long time to get there..... not like the other resistors.. which took seconds to read... this one was counting up almost like a stop watch.

That looks reasonable. The "counting up" is due to the charging of C3. It's still not clear to me that you have a real problem. Do you have any idea what the frequency response of your DMM is? Do you have any way of generating a continuous sine wave signal?

tpryan \$m[1]:That looks reasonable. The "counting up" is due to the charging of C3. It's still not clear to me that you have a real problem. Do you have any idea what the frequency response of your DMM is? Do you have any way of generating a continuous sine wave signal?

I'm not sure what you mean what "frequency response" of my DMM, it reads up to 2mega ohms...

I can use the tone generator in Logic.... and if that's good enough.. what do I do with that specifically? I have a friend of mine checking it out with a scope or whatnot.... Let me know what I need to look in the results..

If your friend has a scope and a signal generator, he can measure the actual gain.

Tim was probably thinking about how you could measure the gain without a scope. The scope is better, if your friend knows what he's doing.