Converting Twin Reverb from two 12" to one 15" spe

Blake Wilson · From: Boulder CO, USA

I have a nice Twin Reverb Silverface (converted to Blackface) that I use with my lap and Fender D-8 Pro. I've read that steel players prefer a single speaker on their Twins. I can easily remove the panel with the current two 12" speakers and build a new panel with a single 15". So, my questions:

1. Is it worth it? It won't devalue the amp and effort/cost seems minimal, and somewhat fun.
2. What speaker to buy? The amp is 4 ohm feeding two 8 ohm 12" presently, so I assume I need a single 4 ohm speaker.
3. What can I expect, sonically?

Thanks,

Blake Wilson

Brad Sarno · From: St. Louis, MO USA

Blake.

First of all you can expect a somewhat lighter amp. If you protect the old baffle and make sure the new one uses all the same holes, then you won't devalue the amp. Make sure you position the new 15" baffle hole so that the speaker doesn't run into the amp's transformers. You may want the speaker to sit an inch or two off center to the side away from the power transformer. This will also help balance the amp. I did this to a '69 Twin, and I loved it. Probably the best combo steel amp I ever heard. Go for a JBL D130 or K130 if you can find one. Sonically, it's a different voicing. Definitely steel friendly, but so are the 2-12". A single 15" voices very nicely in that cabinet. Yes, you'll need a 4-ohm speaker. Even a Black Widow 1501-4 will sound real nice in that amp. Maybe keep an eye out for a 4-ohm JBL on this forum. I say go for it. If you don't like it, you can always go back to the old baffle.

Brad

Jerry Hayes · From: Virginia Beach, Va.

Blake, I did that with a Randall Commander II amp about 23 or 24 years ago. The Randall was a solid state 2-12 amp which was basically the same size as a Twin. I made a new baffle board and installed a 15" ElectroVoice speaker I'd bought from another player. It really brought the amp to life so I probably wouldn't hesitate to do it with any other 2-12 amp. Unfortunately the Randall got stolen from a club I was playing so if any one out there ever sees a Randall Commander II with a 15" EV speaker, contact me, it's mine!.....JH in Va.
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Jim Sliff · From: Lawndale California, USA

With the right 4-ohm 15, you'll get more mids and a rounder top end. Bass will be deeper but not as tight.

It WILL devalue the amp if it's a glued-in baffle. But if it's a screw-type, and a very careful job is done, you can always return it to stock.

If I was going that direction, though, I'd get an 8 ohm 15, remove 2 (either the inner or outer pair) of power tubes, and rebias the amp. A 40-50 watt tube combo has more than enough power (biased right and with the right speaker)and will have much richer tone IMO. FYI my 40 watt Vibroverb can overpower a band and sounds much warmer than a Twin.
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional

Larry Robinson · From: Peachtree City, Georgia, USA

I replaced the 2-12" speakers in my '69 SF Twin with a 15" JBL. I had to off-set the JBL to mount it. Removing the baffle board was no problem since it as it was mounted with screws. I cut a new baffle board, painted it, and covered it with a black grill cover. It sounded great with the original cone JBL. I don't recommend removing two of the output tubes and messing with the bias. I have since sold the amp to steel player who uses it on the road.

Bob Hoffnar · From: Austin, Tx

I personally like the sound of 2 12" speakers better than a 15". I know just as many steel players that like 12's as like 15's. If the amp sounds good don't mess with it based on something you read on the forum. Wait until you can hear the difference for yourself to decide. That is unless its fun for you to build stuff and experiment.
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Bob

Chris Lucker · From: Los Angeles, California USA

I had a 1971 Non-Master volume Silver Face Twin Reverb that had the baffle staple mounted in the routed out slot so removal of the baffle was a chore. The amp cabinet was shot, though -- more a trapazoid than a rectangle -- so I went ahead and made the new baffle for the 15 inch speaker. I am guessing 1970 or 1971 is when Fender stopped finger jointing their cabinets and began using overlapping and stapled corners. They needed the strength of the integrated baffle to keep the amp together.
Does anyone know for sure -- are the integrated baffles always particle board and the screwed-in-to runners baffles always plywood?

John Poston · From: Albuquerque, NM, USA

Jerry,

I have a Randall Commander II that I am planning to sell in a couple months once I have the amp I need to replace it. Drop me a line if you're interested - it has the original 2-12" speakers, though.

Drew Howard · From: 48854

Since you're playing non-pedal I'd stick with the 12's.
I have a SF twin with 12's I use for pedal guitar and it sounds fantastic.
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J Fletcher · From: London,Ont,Canada

I think Fender went to particle board speaker baffles in late 1963, when the blackface amps came out. It may have been earlier, but my 1960 Super had a plywood baffle, my 1964 Deluxe Reverb was particle board, as far as I recall...Jerry

Danny Naccarato · From: Burleson, Texas

I have a Dual Showman Reverb in a Twin cabinet. It's the same head/chassis as the Twin, Vibro, Quad. It's got a 15" Kappalite (from Tom Bradshaw). Althought it's 8 ohm, I noticed very little difference. The weight however, has been substantially reduced. The entire amp, with tilt-back legs, is 60 lbs !!!!

Jim Sliff · From: Lawndale California, USA

Jerry - even some of the particle board ones are screwed in rather than glued - those are the ones you can "mess with" without hurting the amp's value, as you can return them to stock without difficulty. The glued in boards (as I recall mostly post-'71 or '72, but there are some variations) should not be changed - you're better off finding a different amp.
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional

Dan Tyack · From: Olympia, WA USA

I'd replace one of the 12" speakers with a k120 or a d120 and leave the other stock speaker in. It will be easy to convert back, and IMHO will sound 'bigger' than the twin with a single 15". Try it!

Pat Burns · From: Branchville, N.J. USA

....why not just buy a Vibrosonic Reverb, which is a Twin with a 15 inch speaker...

David Doggett · Posted 11 Apr 2007 8:35 pm

Pat, Vibrosonics are pretty rare, and he already has the Twin.

Blake, it's not the single speaker that appeals to pedal steelers, but the 15" speaker voice. It tames the highs a little better, and has lush organ-like lows. But I mainly notice the difference in the mids. A 15 seems to shift some emphasis from the high mids to the low mids. There is a kind of throaty mid-range moan I hear in a 15.

I have a silver-face Pro Reverb that I put a JBL D130 reconed to 4 ohms in. It had the baffle glued in, but the cab was pretty beat up, so I just sawed out the old baffle. It is a master volume silver-face, which doesn't have much appeal for collectors and 6-string players anyway. I put new 1x1 rails in, so my new 1x15 baffle can now easily be removed and replaced with a 2x12 baffle in the future. I guess I ruined the value for purist collectors. But if I ever want to sell it, I'm sure I can find a steeler who wants it, or a 6-stringer Stevie Ray Vaughn fan who wants it as a pseudo Vibroverb. A Pro sounds just like a comparable Twin, only with a little less volume. It has exactly the same cabinet. Like most pedalers I prefer a 15 (or two) for country, western swing and jazz. But I like 12s fine for rock and blues.

For a 15" speaker, I think the Weber 15s can be bought as 4 ohms. But I think a Peavey Black Widow would be a little safer for handling the power of a Twin.

Ernie Pollock · From: Mt Savage, Md USA

I converted an old Pro Reverb back when I first started playing steel, put a 15" altec lansing speaker in it, used it for a long time ago & sold it to a steel player [Nick Valochos] who I have not seen in years, wonder if he still has that Pro Reverb?

Ernie Pollock Laughing

http://www.hereintown.net/~shobud75/stock.htm

Jim Sliff · From: Lawndale California, USA

Mark Ardito · From: Chicago, IL, USA

I'm thinking of converting my Twin (2x12) to the single 15" also. I've been looking at that Weber 15" 4 ohm California. Any of you guys have experience with those Weber speakers?

For my Twin, if I went to the single 15" speaker, would I need it to be 4 ohms? I think so....it would need to draw more power....right? I'm horrible at electronics so go easy on my stupid questions.

Mark

Dave Van Allen · From: Doylestown, PA , US , Earth

MArk, my '68 Twin Reverb came to me with a JBL D130 8ohm in it. I L-O-V-E the sound of it, but feared gigging with it, having read about fragility issues with the JBL's. I have a Weber Cali 4ohm 15" aluminum dome in it now and , initially it sounded a bit
brittle" compared to the JBL's 30 years worth of mellowroonie, but after gigging with it for a while it has become QUITE pleasing to me as a replacement for the JBL. can't really say whether it "burned in" or whether I've adjusted my playing and amp settings to accommodate it...probably both. The 4 ohm match to the output transformer gave me marginally perceptible louder (more headroom)- the mismatch of the JBL to the OT wasn't a quiet amp though ha ha...

the California 15" is Clean and clear (which is what is advertised) throughout the spectrum of my Uni Zum, ...I wouldn't recommend it for a crunchy rock guitarist, but a Surf Stratocaster or Clean Bakersfield style Tele picker, heck yeah.

anyway I've been playing it regular for several years now and I would buy another
and recommend it to others with a Twin conversion.

Mark Ardito · From: Chicago, IL, USA

Dave,

Thanks for the feedback on the Weber Cali. I'm really thinking about that for my speaker choice.

Cheers!
Mark

David Nugent · From: Gum Spring, Va.

Blake, I believe your speakers connect to the amp with a standard quarter inch jack. If you know someone who will loan you a good 15" cab, you can disconnect your speakers and connect the cab to your Twin using any quality speaker cable. This will enable you to determine if it is the sound you are looking for before performing any modifications.

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