Silverfacing a Deluxe Reverb

[spiral]

Am I the only person on the internet wanting to "silverface" a DR? I used to have a 71 DR that sounded great but I was dumb and sold it. I recently built a Mojotone DR kit and it sounds good but it miss some of that very clean and bright tone of the Silverface.

What would be the significant changes to go from a stock AB763 to an early Silverface (ie. BF PT)?

On the Fender Guru site I found these to be the changes: 2.2k resistor between the B & C filter caps; 330k PI resistors; 5U4GB rectifier; 1200pF caps on the 6V6 grids.
Are those safe / worth doing to go towards a SF? Thanks.

[Leo_Gnardo]

On the Fender Guru site I found these to be the changes: 2.2k resistor between the B & C filter caps; 330k PI resistors; 5U4GB rectifier.
Are those safe / worth doing? Thanks.

Darn little difference between BF and SF Deluxe Reverbs, and you found 'em. In fact Fender didn't even make those changes until further into the 70's IIRC. When the move to "improve" (hak-kaff-kaff...a-herrrrrrmmmm) was on by Fender's new college-edjmikated EE's after CBS takeover, they started with the big amps Twin Reverb, its head version Dual Showman, Super Reverb and Bassman. They left the little amps alone for many years then didn't change much.

You can swap out those few parts, maybe you'll hear a change you like. I'd start with the 2K2 in the power supply. I found swapping in 1M's for 330K resulted in a brighter tone so you can try doing the opposite of that but I don't think it will bring you much joy. 5U4 instead of 5AR4 gives you a lower hi voltage rail, and that will dim the sound just a tiny bit too, not the direction you want to go but it's easy enough to swap one tube & listen. Who knows, you might like it.

More likely if you could get a speaker like the one you had, that would get you a lot closer with a lot less fuss. If you don't remember what it was, just try all speakers you can and get yourself the one that makes your ears happy. It's impossible to tell from descriptions on websites except in the most general way. You gotta listen with your own ears to really know what's going to work for you. There are a lot of tonal changes you can make by swapping out internal components but the biggest can be found in different speakers. What speaker did Mojo send you with their kit?

[Tom Phillips]

...I used to have a 71 DR that sounded great but I was dumb and sold it. I recently built a Mojotone DR kit and it sounds good but it miss some of that very clean and bright tone of the Silverface...

Interesting comment. I have never thought that the 71 DR sounded cleaner or brighter than a BF DR given that each were in proper working order. You don't say how long ago you had this perception so I think you may need to consider have to be open to the possibility that your hearing has changed. Something to consider.

[spiral]

Thanks so much for the replies!

@Leo
Yes the '71 I had was pretty close to a stock BFDR. The speaker was/is identical: a Jensen P12N. I bought a new P12N in '99 for the SF, and just got a newish one for my Mojo kit.

@Tom
Very true: the DR I bought in the early 90's and just sold it a few years ago. It had a life before me, so who knows what mods or resistor drifting it had done. I knew nothing about amps I just knew it was noisy. I wish I could get it back and make notes about all the components. My memory/reference is 10 years of recordings I made with it vs. what I am getting on recordings now. Certainly gear, ears, humidity, and present stomach contents all play a role. Also, who knows how it was biased—maybe super cold. So you could be very correct.

I guess my issue is more with the current BF Mojotone amp. It has kind of a low-mid blurriness whereas the SFDR didn't have that, and had lots of bite. Thanks for the encouragement. I may try the rectifier and power supply but just leave it at that. Thanks!

[Leo_Gnardo]

@Leo
Yes the '71 I had was pretty close to a stock BFDR. The speaker was/is identical: a Jensen P12N. I bought a new P12N in '99 for the SF, and just got a newish one for my Mojo kit.

@Tom
Very true: the DR I bought in the early 90's and just sold it a few years ago. It had a life before me, so who knows what mods or resistor drifting it had done. I knew nothing about amps I just knew it was noisy. I wish I could get it back and make notes about all the components. My memory/reference is 10 years of recordings I made with it vs. what I am getting on recordings now. Certainly gear, ears, humidity, and present stomach contents all play a role. Also, who knows how it was biased—maybe super cold. So you could be very correct.

I guess my issue is more with the current BF Mojotone amp. It has kind of a low-mid blurriness whereas the SFDR didn't have that, and had lots of bite. Thanks for the encouragement. I may try the rectifier and power supply but just leave it at that. Thanks!

Sound "on recordings" is a clue. How it sounds straight from the amp, to your ears, same guitar & cable, wish both amps were there so you could A/B test them but that option's not available. On recording, mic selection and placement can make huge variations in tone. I'd have to say get the amp sounding good to your ears THEN it should translate into the recording, we hope. The cheapest easiest experiment is trying different mic positions relative to the speaker. Mic at the grill cloth, pointed straight down the middle generally gives the brightest result. Using a Shure SM57? Very common for guitar amp recording and often gives an excellent result. For some extra top end, a Sennheiser 421 delivers the goods. Beta 57/58 or EV's Neo series ND757 for instance also deliver extra zip. Like speakers, mic selection can make a big difference. Try whatever you have on hand, borrow a few if you can. Might get what you're looking for without having to change the amp at all.

The speaker is nominally "the same" though the current one is "reissue" Recotone Jensen, not a bad speaker at all but still sounds different from the original item. Possible your old DR had one with an aluminum dust dome? They always project extra high frequencies in a JBL sort of way. Stock C12N have paper dome but amp tweakers even back then, could have pried off the paper and subbed aluminum for some zip-a-dee-doo-dah.

Other possible mods that may have been done to your old departed Deluxe Reverb? Though it's the vibrato channel only, DR's have a 47 pF "bright" cap across the hot to wiper on the volume control. Someone may have swapped in a larger cap and there's more zing for you. You could try it on yours. 100pF to 470pF, somewhere in there you may find the bright level that suits your ears, for very cheap. I'd say start there and if no joy let's try some other "fixes" later.

Would be good to have a photo of the insides. We might be able to spot something out of the ordinary.

[Pedro Vecino]

A huge list of possible differences, but between Blackface and Silverface D.R. versions one of the most obvious is the effect of the capacitor at the input of the driver. 0.001uF in Blackface and 0.01 in Silverface.

[Leo_Gnardo]

A huge list of possible differences, but between Blackface and Silverface D.R. versions one of the most obvious is the effect of the capacitor at the input of the driver. 0.001uF in Blackface and 0.01 in Silverface.

True indeed, that's why I want to see a photo. 0.001 uF aka 1 nF or 1000 pf is about all you need. Many Fenders have 500 pF there. Our OP could experiment with values, especially if there's a way big 0.01 uF = 10 nF there. Some of my customers had me increase the value in their Fenders in a bid to "open up the bass" but it just mushes up the tone. 0.0022 or 2n2 is the practical limit as far as I'm concerned. Quality of the cap matters too. I like to use Mallory 150 film in this position but others are certainly encouraged to try different caps, both construction and value, might find something that pleases their ears. And if it does let us know, thanks in advance.

[JoeM]

On the old Ampage forum there's a thread about curing Fender amps "farting". Bruce Collins posted some great suggestions along similar lines to what Leo states. I may have a copy of the thread on my older laptop. Ive done a few to my DRRI and it sounds great.

[spiral]

@Leo
Yes I wish I had a photo. Like I said: it was dumb and I didn't know much about amp guts when I sold it. The Jensen was purchased in 1999 new so I presume it was a reissue. No aluminum dust cap.

@JoeM
Thanks for the Collins tip. I think I did a similar mod based on some info from TGP: vibrostrat43's DR mods. They essentially change some cap values to cut bass. I still have more bass than I need but it is much better.

re: Silverfacing
I only made 2 mods: the 2.2k resistor between B&C in the PS, and the 330k phase inverter resistors.
I have a few questions:

• The voltage on the preamp plates is much higher: 230v vs. the 180v spec; is that the effect of the smaller value between the filter caps? Are those values crazy?
• I read the higher voltage in the preamps will thin the sound out. Is that right? In my case, that is good.
• My output tubes are measuring 446v on the plate and 70% dissipation is ~21ma which sounds really wooly. It sounds much better at 13ma. Is that at all related to the higher preamp voltages? Is a problem elsewhere if I need to have the bias that low? The amp always sounded "thick" even before I made the SF mods.

Thanks for any insight.