In praise of bright switches....

[RC99]

It used to be that I didn't use bright switches a lot in blackface amps, and especially in Deluxe Reverbs I'd just take them out. Often felt they added too much hardness on the attack. But recently, I've added a 120pf bright cap on a switch to the normal 'normal', of both a 5E3 and a 5C5...both with the simple Vol/Vol/Tone array, and it's added a lot more usefulness and versatility. The channel that doesn't have the 500pf treble cap between the Vol and Tone is usually pretty round and a bit too muffled for guitar by itself...maybe better suited to harmonica. But with a 120fp + cap on it, it suddenly becomes a very different animal....dare I say an almost 'scooped' sound with a nice chimey top compared to the more middy tweed grind of the 'bright' channel. It also seems to add a good amount of missing treble (maybe even a touch of high mids) that's noticeably missing without. And what's nice is that it ;lessens' as you crank up to doming the volume in a pretty natural way.

So for those who have felt that the 'normal' channel on your 5E3 or other Vol/Vol/Tone tweed-stype amp only really adds girth, but isn't much a of a guitar channel on its own, I'd recommend a bright cap of 100+ pf. A push/pull 1MA pot could work gray, or a bright switch in place of one of the inputs you don't use, or you might like it so much that you just leave it hard-wired on the pot.

[Chuck H]

That makes plenty of good sense. Considering that your implementing the circuit on NON blackface circuits. If you dig the typical tweed sound then I can see where you wouldn't like the bright switch on BF amps. They're WAYYY scooped to begin with. But on a tweed circuit a bright switch could be just the ticket for adding clarity to a mid heavy tone. You've stumbled on a good thing IMHO.

[Leo_Gnardo]

It used to be that I didn't use bright switches a lot in blackface amps, and especially in Deluxe Reverbs I'd just take them out. Often felt they added too much hardness on the attack.

I think the factory beat you to it on Deluxe Reverbs. Never seen one with a bright switch. Wired-in bright cap, yes. Switch, no.

But I know what you mean. Different people need different things here depending on what speaker, what guitar, FX, where things are dialed etc. On an original BF Deluxe Reverb I replaced the #2 input with a 5-way bright switch for one guitarist. He took @ 2 years to decide his fave bright cap value was 62 pF, as compared to the normal 47 pF. I couldn't hear the difference but he could and that's what matters.

[RC99]

I think the factory beat you to it on Deluxe Reverbs. Never seen one with a bright switch. Wired-in bright cap, yes. Switch, no.

But I know what you mean. Different people need different things here depending on what speaker, what guitar, FX, where things are dialed etc. On an original BF Deluxe Reverb I replaced the #2 input with a 5-way bright switch for one guitarist. He took @ 2 years to decide his fave bright cap value was 62 pF, as compared to the normal 47 pF. I couldn't hear the difference but he could and that's what matters.

Yeah, that's what I mean...they were hard-wired to the pot and I took it out on a '67 I had, left it out on a build, and even undid it on the PCB of a reissue. I tried a push-pull volume pot to switch it in out, but never liked them on anything. On these tweed circuits, it's a much different story.

[Chuck H]

see post #2

[Chuck H]

I think the factory beat you to it on Deluxe Reverbs. Never seen one with a bright switch. Wired-in bright cap, yes. Switch, no.

But I know what you mean. Different people need different things here depending on what speaker, what guitar, FX, where things are dialed etc. On an original BF Deluxe Reverb I replaced the #2 input with a 5-way bright switch for one guitarist. He took @ 2 years to decide his fave bright cap value was 62 pF, as compared to the normal 47 pF. I couldn't hear the difference but he could and that's what matters.

Hmmm.. I've been hardwiring the 47pf cap into BFish builds for a long while. It gave SOME of what I wanted, but only enough that you notice when it's gone. I may need to experiment with a 62pf!?!

[RC99]

see post #2

Agreed.

I think in particular that the Deluxe Rev. is so bright already that it really doesn't need that bright cap. I actually would use it sometimes with humbuckers through a Super reverb (I think it's 120pf on those as well). A 47pf on these tweeds didn't really make much difference. But a 120pf really did...made that 'normal' channel basically two different sounds altogether. It was a bit too much on the 'bright' channel that had the 500pf between the vol/tone, though.

Also makes for an interesting combination of both channels...or if you have an a/b pedal a cool switch between chimier rhythm and a raw lead.

[pdf64]

My guess is that the impact of a bright cap on a 'backwards' volume control arrangement, such as a 5E3, is different (probably less boost) than with a regular volume control.
With a 5E3, the volume control is acting to significantly load the preceding stage, so all the bright cap can do is bypass the (sort of) grid stopper/mixer formed by the remainder of the volume control track.
It can't bypass R1 of the potential divider because that's formed by the plate resistance of the 1st stage.
Pete

[RC99]

Interesting. It's a more pleasing high-boost, to me, than the more 'grating' quality you can get in other arrangements. I'm going to be building a fixed-bias 5C5 somewhere down the line, so it'll be interesting as well to see how it reacts in that as opposed to the more 'saggy' cathode-biased feel of these amps.

[Leo_Gnardo]

I may need to experiment with a 62pf!?!

On that 5 way I had none, 47, 62, 82, and 120 pF. Hey, whatever makes your ears happy. On some old Marshall 4-input amps I've seen 5000 (!) as a brightening cap, dog my cats that's bright!

As a youngster (late teens early 20's) I'd formed an opinion that I liked all the Fenders (consider what was available late 60's) except the Deluxe, because it was too shattering bright. Of course then I had no notion that a bright cap could be removed.

Just about 4 years ago, a miracle amp showed up in my shop. Built in Dec. 1963, one of the very first Deluxe Reverbs. In perfect condition. Previously owned by a church, probably bought in early 1964. The grill cloth even looked brand new - no tan or brown as they often show after years of exposure (no cig smoke I'm guessin'.) One of the church members had just bought it and had me go over it. Untouched inside too - only the output tubes had been changed. But the big surprise was tone. Mellow, not spiky bright. Circuit was stock, bright cap in place. Stock Fender Goodmans speaker. Mellow - I didn't expect - but there it was. What made them "go bright?" I tried the amp through other speakers and sounded mellow there too, so it wasn't just the Goodmans 12".

[RC99]

On that 5 way I had none, 47, 62, 82, and 120 pF. Hey, whatever makes your ears happy. On some old Marshall 4-input amps I've seen 5000 (!) as a brightening cap, dog my cats that's bright!

As a youngster (late teens early 20's) I'd formed an opinion that I liked all the Fenders (consider what was available late 60's) except the Deluxe, because it was too shattering bright. Of course then I had no notion that a bright cap could be removed.

Just about 4 years ago, a miracle amp showed up in my shop. Built in Dec. 1963, one of the very first Deluxe Reverbs. In perfect condition. Previously owned by a church, probably bought in early 1964. The grill cloth even looked brand new - no tan or brown as they often show after years of exposure (no cig smoke I'm guessin'.) One of the church members had just bought it and had me go over it. Untouched inside too - only the output tubes had been changed. But the big surprise was tone. Mellow, not spiky bright. Circuit was stock, bright cap in place. Stock Fender Goodmans speaker. Mellow - I didn't expect - but there it was. What made them "go bright?" I tried the amp through other speakers and sounded mellow there too, so it wasn't just the Goodmans 12".

I like the idea of the 5-way as well, to suit different guitars maybe. Or maybe just a three-position toggle with 62 and 120, or 47 and 120.

I've also found that often original old Fenders like a blackface seem to 'settle in' somehow and just sound more organic and warm than even straight-up new clones. True, it might have to do with the speakers as well, but even with the bright switches...and even some Deluxe Reverbs with the cap still in...can just sound marvelous. I don't know if the components somehow all 'jive' after a while or what have you...there's so much interest in aging guitars, but if there was a way to 'age' and amp, it might hold much more concrete sonic benefits.

[pdf64]

'I replaced the #2 input with a 5-way bright switch'
Yes, I've come to the conclusion that to my ears, no single bright cap value suits all guitars, some sort of multi position switch is needed, and the #2 input is a convenient place to mount it.
Also it depends on whether the volume control tends to be set higher or lower; if it lives on '8' then 5000pF may be just nice!

Regards the 63 DR, do you remember what VB+ it was running at?
Pete

[RC99]

'I replaced the #2 input with a 5-way bright switch'
Yes, I've come to the conclusion that to my ears, no single bright cap value suits all guitars, some sort of multi position switch is needed, and the #2 input is a convenient place to mount it.
Also it depends on whether the volume control tends to be set higher or lower; if it lives on '8' then 5000pF may be just nice!

Regards the 63 DR, do you remember what VB+ it was running at?
Pete

That's where I put a simple push-push switch for it on both the 5E3 and 5C5. Actually have two of them on the 5C5, one for each channel. On the next build, I might use 3-position/center-off toggles so they each have two values to choose from.





Probably replace them with sturdier toggles later on.

[Leo_Gnardo]

Regards the 63 DR, do you remember what VB+ it was running at?

Low 400's say 405-415. Fender piled on more B+ later, and that can explain part of the brightness shift.

[soundmasterg]

On that 5 way I had none, 47, 62, 82, and 120 pF. Hey, whatever makes your ears happy. On some old Marshall 4-input amps I've seen 5000 (!) as a brightening cap, dog my cats that's bright!

As a youngster (late teens early 20's) I'd formed an opinion that I liked all the Fenders (consider what was available late 60's) except the Deluxe, because it was too shattering bright. Of course then I had no notion that a bright cap could be removed.

Just about 4 years ago, a miracle amp showed up in my shop. Built in Dec. 1963, one of the very first Deluxe Reverbs. In perfect condition. Previously owned by a church, probably bought in early 1964. The grill cloth even looked brand new - no tan or brown as they often show after years of exposure (no cig smoke I'm guessin'.) One of the church members had just bought it and had me go over it. Untouched inside too - only the output tubes had been changed. But the big surprise was tone. Mellow, not spiky bright. Circuit was stock, bright cap in place. Stock Fender Goodmans speaker. Mellow - I didn't expect - but there it was. What made them "go bright?" I tried the amp through other speakers and sounded mellow there too, so it wasn't just the Goodmans 12".

The first year or so of the Blackface Deluxe Reverbs did have slightly lower voltages and some different cap values in the tone stack too. They are more aggressive and not so bright as most of the others. That said, the bigger amps with the 120pF and higher preamp voltages strike me as way more bright than any vintage Deluxe Reverb....

I'm working on a build for a customer that is loosely blackface based, and I can't figure out why it is doing this. Everything is wired correctly and all the part values check out. It is using the 250pf, .1uf and .047uf caps in the tone stack along with a 100k slope resistor....I've played with raising voltages, adjusting cathode bypass caps and resistors, coupling caps are all same as a Vibrolux Reverb....but the darn amp sounds like the treble is full off and bass is full on all the time. You can move the treble and bass controls and they work like they should....but the amp always sounds dark....I haven't been able to figure it out yet.....anyone have any ideas? Voltages in the preamp are currently around 200v on the first stage and up from there, but I've had it as high as 230v and still have the condition.

Greg