TRubes and JFETS as SPDIF drivers/buffers?

[Dr.H]

Hello all,

Anyone here tried the following unusual idea:
http://www.lampizator.eu/digilampizator ... zator.html

[SY]

Your link doesn't work.

[Dr.H]

CD Transport Digi-Lampizator


Page down to the bottom

[marce]

Square waves are rarely square in the real world these days, as long as monotoicity is maintained, its surprising how bad a 'square wave' can look, yet the data gets through unaltered.

[Dr.H]

More interested in the sound than whether the dac locks. Anyway, simple enough to try so I'll give it a go.

[SoNic_real_one]

Anything you use as buffer will improve the SPDIF output of the crappy SAA7220... That is not something special.

[Dr.H]

The use of a TUBE/VALVE or a JFET as a buffer for SPDIF is unusual/speacil.

Most SPDIF circuits would use something along the lines of direct output or via a 74HCxxx buffer.

Question remains-how does it sound? Will try to answer that soon...

[SY]

Using a tube or FET will work. It will give you great gains in novelty.

Using the circuit you linked to will get rid of many anomalies by bandwidth limiting. Whether that bandwidth limiting is severe enough to impair the sound is not evident from the rather crude and uninformative photo on that page. Additionally, because the source impedance will not be 75R, you'll have the benefit of ringing at the far end of the coax cable. As before, whether it's severe enough to audibly impair the sound is something you'll have to determine experimentally.

With enough effort and expense, you can probably get a tube circuit to almost equal the performance of a five cent logic chip and a resistor.

[Dr.H]

like the 74hc74, lol?

By the way, the site I linked to appears to show that use of the tube "squares up" the spdif. Have a look.

[SY]

Yeah, you got it. Stick a resistor on the output to get you 75R source and you're done. But it gives you nothing exotic to talk about on teh internets.