Hi all,
I have dabbled in sound and recording for several years but would now like to take the leap into building my own audio equipment - both speakers and an amplifier.
I currently use a Focusrite 2i4 interface plugged into a couple of 5" KRK active monitors. I would like to replace the monitors with some 7" Samba MTs and will obviously need an amplifer to power them.
Given I will use the setup right by my computer which suffers from some GPU coil whine, I would like to try and make an amp that will take the balanced output of my interface. I gather the interface itself outputs up to c.2.5v on the balanced outputs but this can be attenuated with the volume knob as necessary.
Given I don't yet have the guts to put together a class D amp from scratch, I was hoping someone could give me some advice on what sort of boards to look at. I have scoured the internet and found boards that accept balanced inputs to be fairly rare.
The board below accepts stereo XLR in and has an appropriate power rating for my speakers (c.70W). However, I am conscious that it has a fixed gain and therefore I would need to work out what it's input sensitivity is in order to assess whether I will have full use of my interface's volume knob or only part use, etc. I can't imagine there is any way to work this out without a datasheet (which is non-existent it seems) but if anyone has a way that would be great!
Stereo Power Amplifier Module LM3886 2x68W / 4 Ohm - Audiophonics
My assumption has been that if I find a power amp that has an input sensitivity of around 2.5v then my interface will be able to max it out but also provide a full range of control - is that correct?
If I need to resign myself to not finding a balanced input board with the right input sensitivity, are there other balanced input board with e.g. digital volume pots?
I'd really appreciate some help with this as I seem to have read most of Google but can't seem to get any further!!
Thanks
I have dabbled in sound and recording for several years but would now like to take the leap into building my own audio equipment - both speakers and an amplifier.
I currently use a Focusrite 2i4 interface plugged into a couple of 5" KRK active monitors. I would like to replace the monitors with some 7" Samba MTs and will obviously need an amplifer to power them.
Given I will use the setup right by my computer which suffers from some GPU coil whine, I would like to try and make an amp that will take the balanced output of my interface. I gather the interface itself outputs up to c.2.5v on the balanced outputs but this can be attenuated with the volume knob as necessary.
Given I don't yet have the guts to put together a class D amp from scratch, I was hoping someone could give me some advice on what sort of boards to look at. I have scoured the internet and found boards that accept balanced inputs to be fairly rare.
The board below accepts stereo XLR in and has an appropriate power rating for my speakers (c.70W). However, I am conscious that it has a fixed gain and therefore I would need to work out what it's input sensitivity is in order to assess whether I will have full use of my interface's volume knob or only part use, etc. I can't imagine there is any way to work this out without a datasheet (which is non-existent it seems) but if anyone has a way that would be great!
Stereo Power Amplifier Module LM3886 2x68W / 4 Ohm - Audiophonics
My assumption has been that if I find a power amp that has an input sensitivity of around 2.5v then my interface will be able to max it out but also provide a full range of control - is that correct?
If I need to resign myself to not finding a balanced input board with the right input sensitivity, are there other balanced input board with e.g. digital volume pots?
I'd really appreciate some help with this as I seem to have read most of Google but can't seem to get any further!!
Thanks
3eAUDIO TPA3255 can have either single ended or balanced inputs. There is a jumper on the board that allows you to swap between the two. It is a well regarded board that is not very expensive and has very good sound quality.
You just need an dual op-amp and 8 resistors in front of the amp for converting balanced to single ended, so you can use the LM3886 board.
Gain can also be adjusted by changing resistor ratios.
Gain can also be adjusted by changing resistor ratios.
Thanks, both. Appreciate the responses.
ElliJ - that's the board I've been after for a while but I can't seem to find it available at the moment. 3e Audio do also have a TPA3251 board that would presumably be slightly worse but also worth considering if the TPA3255 doesn't come back into stock.
MAAC0 - I think I'd rather not mess around with my own circuitary if I can, as I'm not totally confident in my skills! Also the LM3886 board above does have balanced inputs and presumably does that.
I think I'm primarily a bit nervous of gains etc. I note that the 3e TPA3255 has a fixed gain of around 21.5db. Using my interface's output voltage of c.2.5v, that should mean that the output of the amp is c.30v which would then equate to 225w output per channel.
I'm concerned that my speakers will only be rated to 70w (4ohm) so I'm worried that I wouldn't be able to use much of my volume control on the interface without blowing the speakers / having the volume too loud. I'm aware that volume pots are logarithmic though so perhaps the problem would not be as bad as I suspect.
Do you think I would be fine or would it be worth sticking some e.g. 4ohm resistors in series with the outputs to increase the resistance and decrease the power?
Final question (I promise) - do you have any views on power supplies and whether linear or switching might be better? It appears that switching should be cheaper and perhaps no worse in noise nowadays. Would the following therefore be a good choice?
SMPS240QR 240W / +/-30V Switching Power Supply Module - Audiophonics
Thanks
ElliJ - that's the board I've been after for a while but I can't seem to find it available at the moment. 3e Audio do also have a TPA3251 board that would presumably be slightly worse but also worth considering if the TPA3255 doesn't come back into stock.
MAAC0 - I think I'd rather not mess around with my own circuitary if I can, as I'm not totally confident in my skills! Also the LM3886 board above does have balanced inputs and presumably does that.
I think I'm primarily a bit nervous of gains etc. I note that the 3e TPA3255 has a fixed gain of around 21.5db. Using my interface's output voltage of c.2.5v, that should mean that the output of the amp is c.30v which would then equate to 225w output per channel.
I'm concerned that my speakers will only be rated to 70w (4ohm) so I'm worried that I wouldn't be able to use much of my volume control on the interface without blowing the speakers / having the volume too loud. I'm aware that volume pots are logarithmic though so perhaps the problem would not be as bad as I suspect.
Do you think I would be fine or would it be worth sticking some e.g. 4ohm resistors in series with the outputs to increase the resistance and decrease the power?
Final question (I promise) - do you have any views on power supplies and whether linear or switching might be better? It appears that switching should be cheaper and perhaps no worse in noise nowadays. Would the following therefore be a good choice?
SMPS240QR 240W / +/-30V Switching Power Supply Module - Audiophonics
Thanks