CDs with Pre-Emphasis

[Theadmans]

Having been collecting CD since around 1985 I have some early ones that have Pre Emphasis (Eg. New Order Low-Life Japan for UK FACD 100 1986 first press CD).

I normally listen to my collection using my Squeezebox Touch feeding my Bushmaster MK2 Dac. To cope with pre emphasis I have processed these CDs using the free software Sox. This seems to work well.

However, sometimes I like to listen to the original CD. For this I have an old Pioneer PD-S705 stable platter CD Player again feeding my Bushmaster MK2 DAC via a coax connection.

My question is - does the CD Player transport (Pioneer) handle the Pre Emphasis decoding or is the DAC (Bushmaster) responsible for this. I am sure the Pioneer being 1990s vintage will handle Pre Emphasis. However, do modern DACs like the Bushmaster still have the ability to handle pre emphasis (assuming the DAC has a role to play in this) ?

[StanleyB]

The Bushmaster doesn't support that option. The Caiman II "can", but the function was a bit of a mystery as far as its operation is concerned in the implementation by Wolfson. Their technical people could not tell me if it would switch over by itself when the de-emphasis is needed, and revert back to normal when it is not needed. So I isolated the function with a resistor and set it to "not in operation". But that won't solve your particular problem.

[JADISMAN]

Why is/was preemphasis used on CDs? I think I understand why it is used on vinyl LPs, but why CDs?

[Theadmans]

I found this quote on Hi-Fi Wigwam which goes some towards what the pre emphsis malarkey on early CDs is all about :-

"De-emphasis means that the treble is rolled off on playback, to match the boost on record. It's exactly the same principle as is used in RIAA equalisation where the treble is boosted by 20dB, the bass cut by 20dB on the LP, and the reverse is done by the RIAA equalisation in the phono pre-amp. This gets rid of a lot of hiss which otherwise would make LP playback impossible.

FM radio does the same, it boosts the treble at the transmitter, and your FM tuner reduces it by the same amount, thus reducing hiss, which is a serious problem, especially with stereo.

The point of it is to reduce noise as the hiss is reduced by the same amount as the treble cut on replay, but unnecessary for CD, as the inherent noise with CD is already so low."

So the problem could be that playing early CDs with Pre Emphasis on a CD Player linked to the Bushmaster could have the treble cut but not re-applied by the DAC - resulting in a dull sounding CD.

....anyway Stan thanks for your reply I guess I need to avoid playing the CDs and stick to my Sox processed FLACs played through the SBT instead. Either that or upgrade to Caiman II !

I found another disc with pre emphasis last night the original Linn Virgin 1989 CD of The Blue Nile's "Hats" this strikes me as quite a late in the day disc to have pre emphasis (so members on here should perhaps be careful to check their Discs). There is a lot of info on the excellent Steve Hoffman Forum as always - here is a 27 page thread which lists most of the commonly found discs with PE :-
http://forums.stevehoffman.tv/threads/pre-emphasis-list.121188/

[StanleyB]

Oddly enough I fitted an auto de-emphasis detection and activation circuit on the TC-7510. But that was implemented through a chip that is no longer available.