jaudio said:2.7ohm resistor and a 33nf cap will it work
I don't think so.
You need to buy the necessary parts.
jaudio said:Carlosfm:
that was my guess too.
Thanks
Change the 4k input resistors for 8.2~10k.
Reduce the gain! preferably by reducing the size of the feedback resistor, not by increasing the input resistor (smaller resistors make less noise!).
Also try adding a single 0.1 uF or so cap directly across the V+ and V- supply pins of each '3886 (not to ground). Make sure that it is rated at an appropriate voltage (100 V will do).
Also try adding a single 0.1 uF or so cap directly across the V+ and V- supply pins of each '3886 (not to ground). Make sure that it is rated at an appropriate voltage (100 V will do).
jaudio said:The 220uf caps are on chip rail pins.
I have 136000uf per rail for each monoblock,housed in a separated power supply
nice... just checking.
macboy said:Reduce the gain! preferably by reducing the size of the feedback resistor, not by increasing the input resistor (smaller resistors make less noise!).
Also try adding a single 0.1 uF or so cap directly across the V+ and V- supply pins of each '3886 (not to ground). Make sure that it is rated at an appropriate voltage (100 V will do).
The feedback resistors are allen-bradley .1%,that I have very few of.
Thanks for the suggestion.
jaudio said:I plan to change the input resistor to 8k but first I would like to get the hiss as low as possible
You have no hum, right?
You did a good job with the grounds.
You have hiss because you have a high gain on the amp.
These chips were made for power amps, the noise specs are naturally much higher than a signal op-amp.
Don't think you can use them with the gain you want without a pre.
You should bring the gain down on the output stage and use a gainstage with a gain of 2~2.5x.
boholm said:On the input of drv134 - what do you have connected there?
And - have you tested with input connected to ground (or maybe to a source)?
Nothing and yes,I dont think it the source
carlosfm said:
You have no hum, right?
You did a good job with the grounds.
You have hiss because you have a high gain on the amp.
These chips were made for power amps, the noise specs are naturally much higher than a signal op-amp.
Don't think you can use them with the gain you want without a pre.
You should bring the gain down on the output stage and use a gainstage with a gain of 2~2.5x.
There is no hum with nothing connected. with a preamp connected there is hum in one channel(when I switch them, the hum changes channel), so I think it a source problem
I have some gain in the preamp
jaudio said:There is no hum with nothing connected. with a preamp connected there is hum in one channel(when I switch them, the hum changes channel), so I think it a source problem
I have some gain in the preamp
Hum is one thing, hiss is another.
So you have a DRV134 on the input, which has a gain of 2x.
So... that amp has a huge gain...
You need to reduce the gain on the output (LM3886 chips).
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
- Home
- Amplifiers
- Chip Amps
- hiss