Gain resistors.
Are we talking R41 and R43 here? I am still using the stock pots to reduce the hiss, which is quite loud in my system.
Also, has anyone come up with an idea for damping the transformers? Mine have become louder over time.
theAnonymous1 said:
You can also change the resistors on the outputs of the op-amp to suit your gains needs. I think they are 11k or 12k.
Are we talking R41 and R43 here? I am still using the stock pots to reduce the hiss, which is quite loud in my system.
Also, has anyone come up with an idea for damping the transformers? Mine have become louder over time.
Re: Gain resistors.
Yes, the resistors are R41 and R43.
I got rid of the tranny hum on my amps by removing the ground pins on the power cords. This "works", but I think I discovered a bigger issue and perhaps the source of the hum.......
There seems to be a voltage leak on the chassis
I discovered this when I was holding a RCA cable connected to one amp in my hand and I touched the face plate of another amp. I felt a very strange sensation as I moved my fingers across the face plate surface. I went and got my meter and measured from one amps chassis to the others and got 67.4VAC.
I haven't had time to figure out where it is coming from.
PassiveO said:
Yes, the resistors are R41 and R43.
I got rid of the tranny hum on my amps by removing the ground pins on the power cords. This "works", but I think I discovered a bigger issue and perhaps the source of the hum.......
There seems to be a voltage leak on the chassisI discovered this when I was holding a RCA cable connected to one amp in my hand and I touched the face plate of another amp. I felt a very strange sensation as I moved my fingers across the face plate surface. I went and got my meter and measured from one amps chassis to the others and got 67.4VAC.
I haven't had time to figure out where it is coming from.
Re: Re: Gain resistors.
I noticed the same thing while checking the values of R41 and R42 with a meter earlier today. If I rested my hand on the heatsink, I could feel an uncomfortable "tickel." I guess this must not carry much current, or it would have been painful!
Thanks for the confirmation.
theAnonymous1 said:
I noticed the same thing while checking the values of R41 and R42 with a meter earlier today. If I rested my hand on the heatsink, I could feel an uncomfortable "tickel." I guess this must not carry much current, or it would have been painful
!Thanks for the confirmation.
I was just doing some poking around and now I am really confused.
From the IEC socket, the neutral goes directly to the transformer and the live connects to the on/off switch and then also goes directly into the transformer.
When I measure the voltage between the AC ground at the outlet and the amp chassis I get ~12VAC with the amp off and ~67.4VAC when the amp is on.
I don't understand how there can be a voltage differential between the chassis and mains ground if the live and neutral go directly to the transformer primaries.
Is this caused by some sort of leakage inside the transformer?
From the IEC socket, the neutral goes directly to the transformer and the live connects to the on/off switch and then also goes directly into the transformer.
When I measure the voltage between the AC ground at the outlet and the amp chassis I get ~12VAC with the amp off and ~67.4VAC when the amp is on.
I don't understand how there can be a voltage differential between the chassis and mains ground if the live and neutral go directly to the transformer primaries.
Is this caused by some sort of leakage inside the transformer?
I had something goofy like this before and found there was a blown fuse.
It was a dual fused IEC connector of which one fuse was blown. Drove me crazy - I ripped out the transformer thinking it was leaking and put another in and same thing.
I eventually found the bad fuse (on Neutral leg) after 3 hours of scratching my head...
It was a dual fused IEC connector of which one fuse was blown. Drove me crazy - I ripped out the transformer thinking it was leaking and put another in and same thing.
I eventually found the bad fuse (on Neutral leg) after 3 hours of scratching my head...
john65b said:
Hmmmm... definitely not a blown fuse. I get the same "leakage" with all three amps.
It's obviously not much of a problem though. All my equipment works fine connected to the amps so the current flowing isn't enough to do any damage. It's just barely enough to even feel.
I would still like to know whats causing it nonetheless.
I finaly got around to cleaning up the input on this thing
pulled out cerfine on input board and bridged the open ciruit left from that
pulled the resistors that connected to the passthrough board
bypass the pot knobs on the front
pulled the ne5532
pulled the input resistors for the ne5532
and finaly jumpered the input connector to where the output pins of the ne5532 used to be
leaving the rubycon input caps for now till i can get some wima
sound is definately very different
seems less compressed and i hear difference in the upper mids
not sure wich way i prefer it, i may go back to stock but with LM4562 instead
pulled out cerfine on input board and bridged the open ciruit left from that
pulled the resistors that connected to the passthrough board
bypass the pot knobs on the front
pulled the ne5532
pulled the input resistors for the ne5532
and finaly jumpered the input connector to where the output pins of the ne5532 used to be
leaving the rubycon input caps for now till i can get some wima
sound is definately very different
seems less compressed and i hear difference in the upper mids
not sure wich way i prefer it, i may go back to stock but with LM4562 instead
There should be a resistor either before or after the input coupling caps. This sets the gain of the amp and without it the amp will be running wide open with plenty of noise. The stock resistors for this are R41 and R43 on the board. I can't really tell by your description if you bypassed these or not.
Amp 7 Schematic
I have been follow this board for a while, and just ordered 2 of
these amps. I realize that there may be some problems, however,
these look like they would fit my immediate needs.
Does anyone have a schematic for this amp? I looked clear through the forum and notice a couple of people have ask but they got no response. Could someone please let me know if a schematic is available, and where I might obtain one.
Thanks In Advance,
Brent
I have been follow this board for a while, and just ordered 2 of
these amps. I realize that there may be some problems, however,
these look like they would fit my immediate needs.
Does anyone have a schematic for this amp? I looked clear through the forum and notice a couple of people have ask but they got no response. Could someone please let me know if a schematic is available, and where I might obtain one.
Thanks In Advance,
Brent
Well mine developed a new problem..
The Unit itself Humms like no tommorow..
If I leave it on for about an hour, the noise goes away.
I also have to turn one of them on twice. For some reason the audio doesn ot make it through on the first attempt..
I see why AudioSource held these back...
Didn't they make a prototype before going into production? heheh
Jeff
The Unit itself Humms like no tommorow..
If I leave it on for about an hour, the noise goes away.
I also have to turn one of them on twice. For some reason the audio doesn ot make it through on the first attempt..
I see why AudioSource held these back...
Didn't they make a prototype before going into production? heheh
Jeff
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.