Caiman passive output mod revealed

**Alex_UK** · 07-09-2010, 09:16

Thanks Ali - I'll do a bit more digging for specs then, as not in the manual.

**Alex_UK** · 07-09-2010, 09:40

Originally Posted by Ali Tait

Alex,if you can find out the input impedance of your amp,you may be able to try a film cap in there for a reasonable price,which should be better than any electrolytic.

According to this review by Hifi Critic - "The line input impedance, measuring 9.5kohm, loads sources more than average" - being a techno (as well as vinyl!) numpty, that doesn't mean very much to me - does that mean I could try some film caps, and any suggestions where to start if I can?

**Reid Malenfant** · 07-09-2010, 16:40

Originally Posted by Alex_UK

According to this review by Hifi Critic - "The line input impedance, measuring 9.5kohm, loads sources mofe than average" - being a techno (as well as vinyl!) numpty, that doesn't mean very much to me - does that mean I could try some film caps, and any suggestions where to start if I can?

What it means is you'll need to fit a larger value capacitor than a pre amp with say 50K or 100K input impedance to get the same -3Db point in the bass.

As an example you'll need an 8uf capacitor to get a -3Db point at approximately 5Hz with a 9500 ohm input impedance. Normally you'd want to make the -3Db point somewhere near 1Hz so you get the least amount of phase shift in the audio spectrum & also the least distortion.

If you wanted to go to 1Hz -3Db you'll need a 40uf capacitor which is close to what you are using now. A 40uf film cap will be rather big to say the least, you might get away with 10uf though

**Alex_UK** · 07-09-2010, 16:57

Thanks for that Mark, makes sense.

**Stratmangler** · 09-09-2010, 13:23

Caps arrived today Alex - many thanks.
Initial impressions are that they're a little bit brighter than the Elna Silmics that I've had in for a while now.
I'll leave 'em running in for a few days and see how they settle down.

**RoboCopper** · 09-09-2010, 13:38

Originally Posted by Stratmangler

Caps arrived today Alex - many thanks.
Initial impressions are that they're a little bit brighter than the Elna Silmics that I've had in for a while now.
I'll leave 'em running in for a few days and see how they settle down.

Sorry for interruption.
What caps seems to be little brighter than Elna Silmics?
Thanks

**Stratmangler** · 09-09-2010, 13:49

rubycon bp 47uF

**Alex_UK** · 09-09-2010, 14:04

Glad they got there safe Chris. (Albeit Mr Postie should have got them there yesterday as they went 1st class early Tuesday.) Look forward to hearing what you think compared to the others you've tried in due course. I'm very happy with them compared to the Opamp board, but they are the only ones I've tried. I must say this mod is doing the business though - piano especially just sounds so amazingly real. Best £1.08 I've ever spent! Still going to try Stan's new board if it comes out, though, as would be nice to have headphones for the odd time I listen that way.

**Jason P** · 10-09-2010, 09:59

Well, I've just done the passive mod, and whilst I appreciate AOS isn't the 'wam...

F****** HELL!!

What a difference, at least in my system. Soundstage has become so wide and deep I almost thought I'd got something out of phase, but that's not possible. So initial (and I mean initial - less than 2 hours) impressions are increased separation, more 'air' and ambience (thanks to cleaner HF?), leaner bass (but not less - just not as rounded, if that makes sense) and much more detail overall.

A/B ing between the CDs analogue outs and the Caiman is a bit tricky as the levels are different, but there is a very different presentation now, whereas there wasn't before.

Think I'll try the board when it's released!!

Jason

**Ali Tait** · 10-09-2010, 10:55

If you think it's good now,try it with some good film caps.

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