[adamimos]

So I have access to loads of amps/DACs made specifically for single cell electrophysiology. They look something like this: http://www.moleculardevices.com/Products/Instruments/Conventional-Patch-Clamp/Axon-Axoclamp.html
 
Does anyone know if it is possible to use these as an amp for headphones?
 
What exactly do I need to look for for determining if this is possible?
 
Cheers

 

[mcmurray]

You need the DAC specifications for a start.
 
i.e. IO capability, supported sampling rates/bit depths etc.

 

[adamimos]

so it's got both DAC and ADC
 
I can't seem to get the sampling rate for the DAC, but I see that it is 200kHz for the ADC (not sure if that means its the same for DAC). These are the specs specifically for the DAC:
 
 
Analog Output:
Number of channels 4, pseudo-differential
    optically isolated
Type of DAC   double buffered, multiplying
Output connector BNC
Resolution   18-bit converter
16-bit data (1 in 65536)
Output range -10.24 to +10.239 Volts
Conversion speed software selectable, 5µs max
Gain error 0.2% of FSR
Gain linearity <2 dB
Gain drift ±25 ppm of FSR/ °C
Signal-to-noise ratio 116 dB
InstruTECH ITC-18
16-bit Data Acquisition Interface5
Output impedance 200 _ (for output overload pro
tection)
Short circuit to ground indefinite
Output load current 8 mA typical
 
and then the "main features"
 
 

1. All synchronous analog and digital channels are optically isolated
2. Eight simultaneously sampling differential analog input channels
3. Eight 18-bit 200 kHz A/D converters
4. 200 kHz to 12 Hz sampling in 1.25 µS steps (200 kHz max aggregate)
5. Programmable input gain: 1x, 2x, 5x, 10x
6. Analog input range: + 10.24 Volts
7. Four pseudo differential analog output channels
8. Four 18-bit instrumentation grade D/A converters
9. Analog output range: + 10.24 Volts
10. Sixteen synchronous digital input channels
11. Thirty-two synchronous digital output channels, fourteen with current sink
12. Sixteen asynchronous digital output channels
13. Large 1024 kilosample FIFO
14. PCI, and USB 2.0 host interfaces available
15. Easy installation, no IRQ or DMA channel settings
16. Compatible with Windows 2000, XP, Vista (32-bit only), MacOS classic, MacOS X (PPC and intel), LabView for Windows, MatLab and Linux

 
But this is seperate from the actual amplifier, whose specs are here http://www.dagan.com/bvc-700.htm
 
 
I would love if this could work

 

[adamimos]

I'm guessing I'd have to code up something to send the digital output from the mp3 to the serial port (not a problem), since that is how the setup is connected to the computer...

 

[bcg27]

What kind of serial? If it is rs232 you may be limited by transfer rate since rs232 stuff usually tops out at 115.2 kbaud and lossless or uncompressed audio can be in the Mbps data rate. Baud to bps isn't a straight conversion but I doubt it can handle very high bitrate music like that. It might be able to do some lower bitrate mp3s.
 
Taking a look at the amplifier it really doesn't look suitable to this application. First, the lowest gain is 10 which coupled with the +/-10 volt output of the DAC (~7Vrms) will give you WAY too much voltage output. Most headphones only require a couple volts. Second, the output impedance of the amplifier is 500 ohms which is very high and will cause frequency dependent changes to the frequency response of the headphone. It also mentions an offset voltage of +/-200 mV. I'm not exactly sure what that means (is it adjustable or just always there) but a constant 200 mV dc offset is very bad for headphones.
 
All in all I don't think it will work well. But if you want to play with it I would buy a super cheap 5 or 10 dollar pair of headphones to use with it so if (when?) they blow up you won't get upset.

 

[adamimos]

ah yea, the input impedence (among lots of other things concern me). just for completeness of this thread, the voltage offset is completely tuneable.
 
 
much less likely to give it a go now, but if i ever play around with it ill definitely use something cheap

 

[nikongod]

There is a long standing tradition of using several-tens-of thousands of dollars of laboratory equipment to replicate the radio function of a clock-radio. Seeing as how nobody uses radio anymore it seems fitting that the tradition should continue on in the digital realm. 
 
It is a MUCH bigger sin not to use it for audio than to. As long as you dont blow it up you will probably learn a bunch about it. 
 
I wouldn't let the high output impedance of the amp hold you back. At all. 
I would let the fact that it is a measurement preamp, not a power amp, hold you back.

 

[bcg27]

I agree with nikongod nothing wrong with giving things a try as long as you have a cheap pair of headphones to play around with.