Oh not that old chestnut again......

Bias up the old photodiode again eh, we were doing this years ago(and it was old hat then ) andbody think some one had been reading some 3 year posts It might help experimenting with different colours Rob, as different photodiodes repsond *possibly* different to light wave lengths, I'd try a blue one for a sony mech, do give it a seperate psu though, not just tag off a reg some where.

 

Thanks for that Tony.
The Sony has an additional PSU and Tent Labs clock fitted and the leds connect to the supply driving the indicator panel.
It looks brighter in the pic than real life - it's sort of Accuphase blue/green - Aqua in fact according to the led manufacturer.

Can you expand on the biasing idea a little more?

cheers,

 

Simply its about 'high-lighting' the lasers specific wave length (like polishing the torch glass to focus it more), if the Photodiode in the sony is a KSA 151, then I would use a deeper blue LED. Its the same one thats in the Teac's and the Wadias IIRC.
We did a lot of work in this area, it *may* prove benefical by trying a couple of led in the blue zone so to speak.
You could actually attempt to measure this, use of a spectrum analyser in the right place may give you ability to state weather or not this has an effect.
I still would use a dedicated psu for it though, just knock up another clock psu Rob

 

Well, the pen arrived today (very speedy delivery ~ thanks). I have two identical CDs (not CDRs), one now treated and one virgin.

I asked my partner (& she's a million miles from an audiophool) to comment on the discs played. (She couldn't see which disc was being played, or even that a disc had been changed). She reliably (i.e. 100% of the time) could detect a difference.

Much to my amazement, so could I!

It's fairly subtle, but is definitely there. I'm not sure yet whether this is an improvement, or not. But I'm encouraged enough to try a few more CDs.

 

That great !........

I think I did say its not huge but there's a deffinate difference. You now have to decide if it's going in the right dirrection.

On blue leds .....two or three around the area of the disc and shining onto it gave me the best results...and I'll go with the seperate psu. I did no more on this as I started to get more difference from Ic's that I was building at the time. But I'll go back to this when I reach the limit of the current types of cables I'm making maybe.

 

Just thought I would put my pennies worth in ! I purcahsed a Laserway Green Marker via HI-FI News during the 1980's, TBH I couldn't hear any difference, however this I believe was probably to me having a Budget HI-FI at the time.
Having recently read a thread that Zanash posted On Wigwam, I thought I would give it another go, using CD-R.

I was surprised that I could now hear a difference, it wasn't big, and TBH I had to repeatedly swap the disc's over a few times. I found the effect very similar to when I used to use a Audio Tecnica Disc Stabilzer, slightly less dynamics, and the soundstage in terms of width seems narrower. As l've said, at least on my setup, this has a small effect. No doubt, with a better matched source of music, the effect would be more noticeable. Perhaps thats what really needed, CD-R music tracks selected, to show the Green Pen Effect at it's best?