Tant caps in a Phase 90...?

[Danny G]

I just built a Phase 90 and used tantalum caps instead of electrolytic--that's what i had laying around.  Will that affect the sound/phase at all?  Just curious.

Also, I built a Phase 45 and it sounds much better than the '90.  Deeper, richer phasing.  I thought the 90 would be deeper and richer, but au contraire.  Wondered if the tant caps had anything to do with it, or i needed to match my FETs a little better--used 2N5952's, 3 were identical, one was a little off.  The two for the 45 were identical.

[DDD]

Danny,
tantalum caps work great in higher-frequency circuits, for example in HF DC to DC converters for filtering HF ripple, and in devices that work at low temperatures, down to -60C, e.t.c.
At the same time they need typically more DC bias than usual aluminium caps do, and without sufficient bias they may introduce considerable distortion and/or noise to audio signals.
In any case try to avoid them, except of supply filtering.

[Danny G]

So in other words, I should probably swap them out?  


Like I said, I had some laying around.

[Danny G]

Would BF244A's work better or does it not really matter.  The Small Bear site mentioned them as good for Phase 90's.

[DDD]

Danny,
I do not remember the schematic, but maybe it will be better to swap tant. caps. Maybe not... In any case alu caps are 10 times cheaper.

[Danny G]

Yep, that be the plan.  Like I said, those tants were what I had lying around.  I'll go stock up on some 'lectros this afternoon.

[Mark Hammer]

If you look at the actual MXR boards for many things housed in a 1590B-style case, you'll see that a) they used ceramic caps for just about anything under 1uf, b) they almost always bent caps over to be flush with the board (or close to it), and c) tended to use tantalums for caps big enough in value that a standard electrolytic would have been too big, even bent over.  For some of the pedals where they started to have more room to work with (e.g., those housed in 1590BB-sized or larger boxes or the 6-band EQ, which lacked a switch and so had more "real estate" inside the box), you would see the white box-style Philips plastic caps for the non-polarized units.

That's what THEY did.  How much of the tone of the vintage units depends on those particular cap choices is another matter and certainly open for debate.  What YOU do is thoroughly entitled to be different.

[Fret Wire]

Like Mark said, the older MXR 9v/battery effects used tant's all the time for values of 1uf and over. My old Phase 100 is all tants, ceramic, and box caps. The original Dist.+ uses ceramics and 1uf tants. My Micro Flanger uses tants except for one 100uf electro. They sound fine. I like using tants for anything over 1uf up to 47uf.

[puretube]

matching/biasing the FETs will affect the sound much more, than swapping caps...
the 90 should sound "better/richer" thanthe 45 - regardless whether tant/elco...
IMHO, at least.

[Fret Wire]

matching/biasing the FETs will affect the sound much more, than swapping caps...
the 90 should sound "better/richer" thanthe 45 - regardless whether tant/elco...
IMHO, at least.

Quite true. I guess we all forgot to ask one question: Danny, did you try adjusting the trimpot on the 90? The range of adjustment is small, but you should still be able to dial it in.

After that, you might want to recheck all your resistor and cap values.

[jimbob]

I was looking at a phase 90 board I had lying around and it had tants on it. It was the actual commercial board. I tried to modify it when i first started this habby a while back and ruined the board. I noticed it is diff than the tonepad design. This board has a 16 pin ic and a 8 pin.

[Dai H.]

FWIW, my (early?) Dunlop Phase 90 w/3x TL062 (instead of the 6x 741s in the original) has tants. Space was probably a big consideration, and maybe it has some effect on the sound as well.

[Fret Wire]

What value zener diode did you use?

[Danny G]

The FETS I used were about 296, 296, 296 and 303 or so if memory serves.  That was as close as I could get.  It only really phases when the trimpot is dimed.  I might have to order more FETs to get some better matches, mebbe.  I used 2n5952's, but the Small Bear site mentions that BF244A's are good for Phase 90's...

I don't recall what the exact value zener I used... I got parts for a Phase 45 and 90 at the same time, and each uses a different value zener, so I had two.  The Phase 45 didn't work at first until I put the other zener in, so logically the one that didn't work for the 45 is the correct one for the 90.  But lemme go look at them real quick...

I told the guy at the store what V I needed and this is one they gave me:

Phase 45--1n751A zener
Phase 90--1n750A zener

[Fret Wire]

The 1N750A is a 4.7v, the 1N751A is a 5.1 volt. Try a 5.1v and see how it sounds. Tonepad recommends a 5.1v, but depending on the JFET's, you could end up using anywhere from 3.9v to 5.7v to get good phasing.