quick update
Ok, after playing w/ the amp (6 chip parallel/bridge gainclone) a little, I can't get the hum to go away, its annoying, but definitely much more prominent than what my other gainclones have been as far as hum. Aside from that, what worries me is that I have a big snap/pop when I shut off the amp. I'm using 24kuf per rail + 1200uf caps on the chips, two tranny's in parallel, mur860 diodes (single bridge), and a 3a inrush current limiter. Anyway, as soon as I hit the switch, I get a loud pop (which gets worse the longer I leave the amp on) but the hum goes away and the music continues until voltage drops. Any ideas gents? Thanks!
-Matthew K. Olson
Ok, after playing w/ the amp (6 chip parallel/bridge gainclone) a little, I can't get the hum to go away, its annoying, but definitely much more prominent than what my other gainclones have been as far as hum. Aside from that, what worries me is that I have a big snap/pop when I shut off the amp. I'm using 24kuf per rail + 1200uf caps on the chips, two tranny's in parallel, mur860 diodes (single bridge), and a 3a inrush current limiter. Anyway, as soon as I hit the switch, I get a loud pop (which gets worse the longer I leave the amp on) but the hum goes away and the music continues until voltage drops. Any ideas gents? Thanks!
-Matthew K. Olson
Re: quick update
you have DC on the output -- a serious problem (if you value your speakers) and probably a ground loop problem as well.
for the DC on the output -- you could pull up one of the cookbook designs from Randy Slone's books -- as in the Audiophile Guild -- but basically you want to design a circuit which will charge a non-polarized capacitor when there is DC present -- when the level get's high enough (i.e. 2 volts) it causes a relay to engage, disconnecting the speakers --
in my "turn-on" protection device I use an IRFD110 HexDIP MOSfet which will turn on at about 2.3 volts. the same principal can be employed for DC detection. will post schematic tomorrow.
Mattyo5 said:
you have DC on the output -- a serious problem (if you value your speakers) and probably a ground loop problem as well.
for the DC on the output -- you could pull up one of the cookbook designs from Randy Slone's books -- as in the Audiophile Guild -- but basically you want to design a circuit which will charge a non-polarized capacitor when there is DC present -- when the level get's high enough (i.e. 2 volts) it causes a relay to engage, disconnecting the speakers --
in my "turn-on" protection device I use an IRFD110 HexDIP MOSfet which will turn on at about 2.3 volts. the same principal can be employed for DC detection. will post schematic tomorrow.
Well, when I measure dc on the output, its only 2mV... so only at power down am I getting DC I guess. Which is strange because the music keeps playing (plenty of capacitance) when I flip the power switch. I don't understant why it popps when I interupt ac (power switch) going to the transformers... shouldn't send a surge though the chips...should be even power. Yes, i could use Rod Elliots Loudspeaker protection circuit....if I had enough room in this chassis hehe. Ok, so I have the problem, but using a protection circuit doesn't solve the problem...more like a bandaid.
I suspect that whatever the popp is may have something to do w/ the ground as well...but thats just a hunch.
-Matthew K. Olson
I suspect that whatever the popp is may have something to do w/ the ground as well...but thats just a hunch.
-Matthew K. Olson
Hey Mattyo5-
Is the switch a single pole or double? Both work, but if it is a single, you "MAY" have a voltage spike from the switch contacts separating.
I have had similar issues where spikes kept blowing regulated logic circuits and the fix was a double pole switch.
Just a suggestion, I do not know what type of switch you are using.
Hope you are able to resolve it and please let us know how it sounds on music.
Thanks,
Troy
Is the switch a single pole or double? Both work, but if it is a single, you "MAY" have a voltage spike from the switch contacts separating.
I have had similar issues where spikes kept blowing regulated logic circuits and the fix was a double pole switch.
Just a suggestion, I do not know what type of switch you are using.
Hope you are able to resolve it and please let us know how it sounds on music.
Thanks,
Troy
Hey Mattyo5-
Is it a 60Hz hum from the transformer that is removed when the switch is thrown?
What is the distance between it and the audio circuitry?
Is the signal input cable routed anywhere around the power?
Pictures? Maybe a different pair of "eyes" will notice something.
Thanks again,
Troy
Is it a 60Hz hum from the transformer that is removed when the switch is thrown?
What is the distance between it and the audio circuitry?
Is the signal input cable routed anywhere around the power?
Pictures? Maybe a different pair of "eyes" will notice something.
Thanks again,
Troy
Is it a 60Hz hum from the transformer that is removed when the switch is thrown?
yes
What is the distance between it and the audio circuitry?
its all fairly close, but I tried to keep the tranny's as far away as possible (2 tranny's in parallel)... these are the buyout PE tranny's 200va each supposedly....and yes I did match them
Is the signal input cable routed anywhere around the power?
I tried to not do that...
Pictures? Maybe a different pair of "eyes" will notice something.
pics coming soon, right now there are quite a few clip leads
thanks
-Matthew K. Olson
yes
What is the distance between it and the audio circuitry?
its all fairly close, but I tried to keep the tranny's as far away as possible (2 tranny's in parallel)... these are the buyout PE tranny's 200va each supposedly....and yes I did match them
Is the signal input cable routed anywhere around the power?
I tried to not do that...
Pictures? Maybe a different pair of "eyes" will notice something.
pics coming soon, right now there are quite a few clip leads
thanks
-Matthew K. Olson
There can be two kinds of turn off thumps.
Type 1: Flip the AC switch and you get an immediate thump. Output starts to decay.
Type 2: Flip the AC switch and the output starts to decay. Just as output is almost gone you get a thump.
You described yours as Type 1. I'd suggest a Class X AC rated 0.1uF capacitor to be placed across the switch contacts.
Type 1: Flip the AC switch and you get an immediate thump. Output starts to decay.
Type 2: Flip the AC switch and the output starts to decay. Just as output is almost gone you get a thump.
You described yours as Type 1. I'd suggest a Class X AC rated 0.1uF capacitor to be placed across the switch contacts.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.