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Post subject: '74 Silverface Twin Reverb - Recent Craigslist Snag
Posted: Tue Apr 04, 2017 1:37 pm
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Snag. Amp was never gigged. Played only in a home studio. I purchased it from the 2nd owner who'd had it more than 20 years. There are no alterations, it's 100% original.

By referencing the chassis s/n: The amp dates to 1975. (Image below, did I do that derivation right?)

My intent is to service basic functional issues and leave it unaltered. And play it. LOTS.

Channel 1 has dynamic hum / swish -- a cycling noise -- which I may leave unaltered because...

I'd primarily use the reverb channel anyway and it's near perfect. Near perfect because there is a very slight (nearly inaudible) ticking that changes with vibe "Speed."

And I've discovered that the "Pull" on the master get's me a much more... lead, "crunchy" tone.

Image
Image

Image

Here's what I'm comparing it with (an amp I dearly love.)

Image

So, being that I'm ultra happy with the reverb channel -- and kind of enjoying the push/pull master -- what other alterations would folks suggest? I've read about taking the circuits back to 1968, bla, bla, blah ... but seriously? Wouldn't it be best to keep this close to 100% factory?


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Post subject: Re: '74 Silverface Twin Reverb - Recent Craigslist Snag
Posted: Fri Apr 07, 2017 1:07 am
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Bartimaeus wrote:
Snag. Amp was never gigged. Played only in a home studio. I purchased it from the 2nd owner who'd had it more than 20 years. There are no alterations, it's 100% original.

By referencing the chassis s/n: The amp dates to 1975. (Image below, did I do that derivation right?)

My intent is to service basic functional issues and leave it unaltered. And play it. LOTS.

Channel 1 has dynamic hum / swish -- a cycling noise -- which I may leave unaltered because...

I'd primarily use the reverb channel anyway and it's near perfect. Near perfect because there is a very slight (nearly inaudible) ticking that changes with vibe "Speed."

And I've discovered that the "Pull" on the master get's me a much more... lead, "crunchy" tone.



So, being that I'm ultra happy with the reverb channel -- and kind of enjoying the push/pull master -- what other alterations would folks suggest? I've read about taking the circuits back to 1968, bla, bla, blah ... but seriously? Wouldn't it be best to keep this close to 100% factory?


I see you receive no answer, here mine; You find a very nice looking amp, like new

Channel 1 has dynamic hum / swish -- a cycling noise -- which I may leave unaltered because...

With guitar plug or not ?
No guitar ; clean input jack shorting contact, some mess in the wiring may need some lead dress. Try new tube in V1
With guitar; try new tube in V1

My intent is to service basic functional issues
Look into the "dog house" where are the power supply filter caps if you see something wrong like bubble at one end, post pictures about these cap and from inside the chassis; this will tell lots about amps.
Look inside chassis for burn resistors, 6L6's tubes may need some new resistors ; post pictures

Near perfect because there is a very slight (nearly inaudible) ticking that changes with vibe "Speed."
All Fender tubes amps do this ticking, a easy mod can fix it ; adding a capacitor


-- what other alterations would folks suggest? I've read about taking the circuits back to 1968, bla, bla, blah ... but seriously? Wouldn't it be best to keep this close to 100% factory?

Keep it original if you have to pay for mods in Blackface or '68.
On the collector market this is not a very sought after amps with Master Volume but if you like the sound , enjoy it.


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Post subject: Re: '74 Silverface Twin Reverb - Recent Craigslist Snag
Posted: Fri Apr 07, 2017 1:53 am
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By serial number ---- looks to be a 1975 amp. Tranny and speaker dating stamps can verify whether amp has OEM parts. Sure looks to be in great condition. :)


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Post subject: Re: '74 Silverface Twin Reverb - Recent Craigslist Snag
Posted: Fri Apr 07, 2017 2:10 am
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A remarkably pristine specimen, right down to the OEM Utah speakers.

Fix channel one then play it well into the next century.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: '74 Silverface Twin Reverb - Recent Craigslist Snag
Posted: Fri Apr 07, 2017 2:14 am
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Nobody go to see ; View unanswered post ?

My answer call some expert :lol:


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Post subject: Re: '74 Silverface Twin Reverb - Recent Craigslist Snag
Posted: Fri Apr 07, 2017 3:34 am
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Retroverbial wrote:
A remarkably pristine specimen, right down to the OEM Utah speakers.

Fix channel one then play it well into the next century.

Arjay


Yup. I appreciate that. That's my instinct. Thanks very much for the confirmation!


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Post subject: Re: '74 Silverface Twin Reverb - Recent Craigslist Snag
Posted: Fri Apr 07, 2017 3:47 am
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"Channel 1 has dynamic hum / swish -- a cycling noise -- which I may leave unaltered because...

With guitar plug or not ?
No guitar ; clean input jack shorting contact, some mess in the wiring may need some lead dress. Try new tube in V1
With guitar; try new tube in V1"

The "static" noise - the hum/swish - is there without an instrument jacked in. The noise is absent with Ch 1 volume at minimum and increases proportionate to the volume setting. It's playable, but I wouldn't mic the amp with on Ch 1 like this.

With Ch 1 volume at min. It's silent.


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Post subject: Re: '74 Silverface Twin Reverb - Recent Craigslist Snag
Posted: Fri Apr 07, 2017 4:24 am
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Replace channel 1, V1 12AX7 by V2, the 12AX7 use in channel 2 witch is quiet.

If not quiet, channel 1 may need new plates resistors or and / some lead dress.
Plate resistors may come noisy after so many years

These amps are a real rat nest.


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Post subject: Re: '74 Silverface Twin Reverb - Recent Craigslist Snag
Posted: Fri Apr 07, 2017 8:36 am
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stratele52 wrote:
Replace channel 1, V1 12AX7 by V2, the 12AX7 use in channel 2 witch is quiet.

If not quiet, channel 1 may need new plates resistors or and / some lead dress.
Plate resistors may come noisy after so many years

These amps are a real rat nest.


Cool, I can swap tubes. I have some Mesa 12Ax7's handy...

Thank You!

And so tube replacements (or rotating V1 to V2 and V2 to V1 as you say)

I was reading this page ... and found it helpful.

https://www.kcanostubes.com/content/fen ... mendations


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Post subject: Re: '74 Silverface Twin Reverb - Recent Craigslist Snag
Posted: Fri Apr 07, 2017 9:15 am
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HUGE thanks to everyone... esp stratele52 for the clue on tubes.

I suspected a tube but having never fussed with this particular amp, I'm grateful for the instruction.

So I pulled V1 and replaced it with:

Image

And!!! Silence.

Better yet! The tone from Ch1 is very buttery with astonishing "Shimmer."

I'm amazed!

Couldn't be more grateful to y'all. But for stratele52 ... you've nailed it buddy.


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Post subject: Re: '74 Silverface Twin Reverb - Recent Craigslist Snag
Posted: Fri Apr 07, 2017 9:18 am
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:D

Enjoy your great amp now !


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Post subject: Re: '74 Silverface Twin Reverb - Recent Craigslist Snag
Posted: Sat Apr 08, 2017 10:25 am
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Image

:mrgreen:

Arjay

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Post subject: Re: '74 Silverface Twin Reverb - Recent Craigslist Snag
Posted: Sun Apr 09, 2017 8:05 am
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Played through the Twin Reverb yesterday at a gig in Portland. One fellow player, in particular, was very "taken" with it. After a set, unplugging from ch2 to show him what ch1 sounds like, he practically cried. We both took turns at the instrument so the other could stand back 30'.

Several others were busy with questions. And I pointed them all toward this forum.

If putting a Mesa SP12Ax7 counts as a mod? I don't think so -- they're just production tubes that test better than the rest. Top 5% or something like that. ... What Mesa told me some time back. Here's some independent beta...

http://axepalace.com/guitar-amps/mesa/m ... OpNZVPytuU


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Post subject: Re: '74 Silverface Twin Reverb - Recent Craigslist Snag
Posted: Sun Apr 09, 2017 6:01 pm
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You'll be shocked at the sonic improvement when you hear that amp through a REAL set of speakers.

:wink:

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: '74 Silverface Twin Reverb - Recent Craigslist Snag
Posted: Sun Apr 09, 2017 7:11 pm
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I'll bite.

Gimme the beta, brother...


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