I another thread I described how playing a TT through a MF phono stage running through a phono to toslink converter into the dialog of a pair of Phantoms caused the sound to alternate between playing fine and distorting. It was suggested the gain may be too high. Are their phono stages that allow gain adjustment 'on the fly' or is there another method of achieving the same end? I am currently using a MM cartridge but am likely to also use an MC in the future.
Reducing the gain from phono to digital.
- Thread starter Rodrat
- Start date
Arkless Electronics
Trade: Amp design and repairs.
Have you tried feeding the analogue output from a CD player into the phono to Toslink converter? Your phrase "alternate between playing fine and distorting" is something that you could expand on to allow better diagnosis BTW...
No I haven't tried that. When first plugged in the sound is fine for a few seconds then it distorts for a few seconds and then fine etc. I am controlling the volume via the Deviatet app on my macbook air. I was surprised how loud it was even on a low volume setting in comparison to a 'normal' TT, phono, amp and speaker set up.
Arkless Electronics
Trade: Amp design and repairs.
Interesting.... It would be most helpful if you could try it with CD and report back.
Arkless Electronics
Trade: Amp design and repairs.
OK. Do you have any other kit with a variable output level? Or an old vintage tuner with a much lower output level? This would confirm the likely overload. It does seem strange though that in this day of 2V output levels from most kit that the converter is not designed to cope with this...
Darth Vader
From the Dark Side
No analogue input! The overload if thats what it actually is is within the phono to Toslink converter.
Phantom connectivity options:-
Dual-band Wi-Fi (a/b/g/n 2.4 GHz & 5 GHz)
Ethernet RJ-45 10/100/1000 Mbps (Gigabit)
PLC Homeplug AV2
Toslink optical input (TV, blu-ray, video games console, ...)
Cheers,
DV
Arkless Electronics
Trade: Amp design and repairs.
My suspicion is that the Toslink converter is based on non ideal topology for the input signal level. Many modern IC's run of only 3 - 5 Volts which gives bugger all overload margin!
Arkless Electronics
Trade: Amp design and repairs.
I guess your only real choice then is to use attenuators on the output of the phono stage. 10dB will knock it down by a factor of three (roughly) so should be about right. If you have a passive pre (volume control in a box) around then this will do the same job and allow you to optimise the level. put it between the phono stage and the Toslink converter.
Darth Vader
From the Dark Side
Can you not use the USB port om the dialogue? If so that widens your choice of ADC. You could test by squirting a FLAC/WAV or similar via a computer and see if it plays. There are low price ADCs like this one http://www.amazon.co.uk/dp/B000BBGCCI/?tag=pinkfishmedia-21 or of flush you could try something like this http://benchmarkmedia.com/products/benchmark-adc1-usb-audio-converter
Cheers,
DV
Cheers,
DV
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Whilst the USB port is physically there it has not yet been implemented in the firmware, the optical input on the Dialog was only implemented a short while ago in a firmware update (the ones in the Phantoms themselves were implemented from day 1).
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