New Doug Self pre-amp design...

[redjr]

Originally Posted by sandyK

Don't forget that these home brew IDC cables can also cause all kinds of funny things to happen with DACs too.

Regards
Alex

Sandy,

Is there a potential problem in using standard ribbon cable for this pre-amp solution? It is being suggested by Elektor or Doug Self. Or, should I attempt to weave 10 individual wires from the pins of the sockets. The former suggestion seems to be the easiest, but maybe not the best in terms of sonics? What issues should I be concerned with when using ribbon cable with a DAC?

[Bonsai]

Quote"It's no good listening after immediately swapping parts because you are not in the right frame of mind""

It's called expectation bias.

[Nico Ras]

Originally Posted by owdeo

Me too, the acoustic ones make a much nicer sound even though the electric ones are probably considered blameless now

Thanks Mooly, I'm 100% with you on all that

Which of the acoustic pianos sound the most like a real piano? If measured against the first piano ever made then all successive pianos are distorted.

[Mooly]

Originally Posted by owdeo

Me too, the acoustic ones make a much nicer sound even though the electric ones are probably considered blameless now

Nice one

Originally Posted by Bonsai

Quote"It's no good listening after immediately swapping parts because you are not in the right frame of mind""

It's called expectation bias.

It is indeed

[owdeo]

Originally Posted by redjr

Is there a potential problem in using standard ribbon cable for this pre-amp solution? It is being suggested by Elektor or Doug Self. Or, should I attempt to weave 10 individual wires from the pins of the sockets. The former suggestion seems to be the easiest, but maybe not the best in terms of sonics? What issues should I be concerned with when using ribbon cable with a DAC?

Ignore that redjr, Alex was having a dig about another unlrelated project I was discussing with him offline

The ribbon cable in the 2012 preamp is only used for control signals to switch the relays so can't affect SQ - you'll know if there's a problem if your input switching starts going haywire.

For the signal connections in your preamp between the boards I would suggest using sheilded audio cable to minimise induced hum/noise from the power transformer and surrounding environment. Don't use ribbon cable!

[Bonsai]

If you are using headphones to do comparative listening tests, try a 47 to 100 Ohm resistor in series with the headphones.

[redjr]

Originally Posted by owdeo

Ignore that redjr, Alex was having a dig about another unlrelated project I was discussing with him offline

The ribbon cable in the 2012 preamp is only used for control signals to switch the relays so can't affect SQ - you'll know if there's a problem if your input switching starts going haywire.

For the signal connections in your preamp between the boards I would suggest using sheilded audio cable to minimise induced hum/noise from the power transformer and surrounding environment. Don't use ribbon cable!

OK. I haven't decided for sure what type of cable I'm going to use for the internal signal interconnects. I'm just trying to sort through the various 2, 3 and 4-pin headers on all the boards and how the puzzle fits together. I think I will draw up a block diagram of this beast since there are so many boards, and how they all connect was not laid out all that well in the article. Also it seems Elector chose to use 4-pin header on several of the boards when 3 pin headers would have sufficed. The center two pins seem to always be tied together as a ground. So the the extra center pin is redundant and is not required. Where is the KISS approach here!

It's late here so I'm going to bed.

[owdeo]

Somehow I don't think the KISS principle is what this design is all about

I know it seems redundant but there may have been a reason for using a 4 pin header when a 3 pin would do: once you start trying to solder or crimp shielded cable braid into those pins for the 0.1" header sockets you'll see that soldering two braids onto one earth pin can easily make it too fat to fit into the connector housing in which the socket pins are housed. I'd rather have the 4 pins, one for each wire.

[Joachim Gerhard]

At what frequency is that ?
Crossover shows more at higher frequencies.

[Joachim Gerhard]

It may run out of class A in certain conditions but the high feedback will erode most of it so measurements will still be clean.
Some time ago i measured how much class A certain Opamps have. You can put a low value resistor, say 50 Ohm, from the output to ground. Then you put say 10 Ohm resistors into the voltage feed to Pin 4 and Pin 7. You then increase the input voltage of a 1kHz signal ( can be 10kHz or higher ) until the current goes up that flows into the Opamp from the PSU. The 10 Ohm resistors function as sensors by measuring the voltage over them. I would say that the LME49710 has around 2mA class A. When you drive a 600 Ohm load it will leave class A at 1,2V.