Treble Caps & Drive Pot

[odourboy]

Opinions sought (ODS-101-HRM build):

1) Some of the schematics I've looked to use a .002/390pF combination for the treble caps in the clean stack, others use .001/500of. I assumed that it wouldn't much matter as long as the series value worked out to be close to 330pF. Is there a preferred combination?

I ask because I was using .001/500pF, but decided to switch to .002/390pF and feel I lost some smoothness and gained some fizz - most noticable when using the OD (PAB engaged). Now I have to admit that I slipped in a Silver Mica cap for the 390 (that's all I had handy) and that may be the culprit.

2) I noticed that most schematics use a 250K Linear pot for the OD Drive. I used a 250K Audio taper in my build. Am I making it difficult to dial in the sweet spot using an Audio taper or is it somewhat arbitrary?

Cheers!

[dogears]

Pot is 250Ka not linear...... So you are good.

Never use mica IMO. .002 and 390pf ceramic is fine. You may prefer the .001 and 500pf though. The midboost is more useable w/PAB on. IMHO again.

Opinions sought (ODS-101-HRM build):

1) Some of the schematics I've looked to use a .002/390pF combination for the treble caps in the clean stack, others use .001/500of. I assumed that it wouldn't much matter as long as the series value worked out to be close to 330pF. Is there a preferred combination?

I ask because I was using .001/500pF, but decided to switch to .002/390pF and feel I lost some smoothness and gained some fizz - most noticable when using the OD (PAB engaged). Now I have to admit that I slipped in a Silver Mica cap for the 390 (that's all I had handy) and that may be the culprit.

2) I noticed that most schematics use a 250K Linear pot for the OD Drive. I used a 250K Audio taper in my build. Am I making it difficult to dial in the sweet spot using an Audio taper or is it somewhat arbitrary?

Cheers!

[odourboy]

Excellent! Consider that mica cap GONE!

[Bob-I]

Excellent! Consider that mica cap GONE!

So is your fizz

As for that audio vs linear debate. I like audio, dogears likes linear. HAD used linear because that's what was available, in fact even today 250kB are more readily available than 250kA. It makes no difference in tone, but I like the knob set up higher, somehow it just feel louder that way

[ayan]

Excellent! Consider that mica cap GONE!

So is your fizz

As for that audio vs linear debate. I like audio, dogears likes linear. HAD used linear because that's what was available, in fact even today 250kB are more readily available than 250kA. It makes no difference in tone, but I like the knob set up higher, somehow it just feel louder that way

Well, let's not mistake circuits here. HAD used 100K linear pots in the LEVEL, RATIO and MID controls because they were readily avialable from Fender, as they used those pots in the reverb section. 250KA pots were available since forever, as Fender amps and guitars used them. Thus HAD used them for TREBLE and BASS controls in the days of old.

For the newer amps, he basically ditched the 100K pots all together and used a couple of other things here and there (i.e., 250KB treble, 500KA bass, etc.) which I believe make sense.

For the LEVEL (drive) control, to me 10% audio feels too slow for single coils. On the other hand, linear pots feel too fast with humbuckers...

Cheers,

Gil

[dogears]

I like linear on the 80s circuit drive and level pots. 100KB

I like audio on 90s HRM drive and OD master. 250ka and 1ma

[dogears]

You can get a custom tapered 250Ka pot from RS Guitarworks. Great for the midpot too. I think they are at least 25% taper.

Excellent! Consider that mica cap GONE!

For the LEVEL (drive) control, to me 10% audio feels too slow for single coils. On the other hand, linear pots feel too fast with humbuckers...

Cheers,

Gil

[llemtt]

Old Fender audio pots are 30% taper so they are similar to a linear one, just a little bit "audio". I think you can get them from webervst.

Only after black/silver-face era they started to use 10% and 15% but they still stuck to the 30% on the treble control.

I suggest for max usability 10% mid and bass, and linear (or 30%) treble.

my .02
Teo