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Topic: 8 ohm speaker in a BF Vibrolux Reverb |
Tom Wolverton
From: Carpinteria, CA
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Posted 23 Jan 2024 5:56 pm
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I friend of mine wants to change his ‘65 Vibrolux Reverb from two 10’s into a single 12” speaker (different cabinet & baffle). Can he run an 8-ohm speaker? I think the Vibrolux Reverb wants to see 4-ohms ideally. Would 8-ohms hurt it? _________________ To write with a broken pencil is pointless. |
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Brett Lanier
From: Madison, TN
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Posted 23 Jan 2024 6:13 pm
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8 ohms is fine, and if he’s going from 2 Jensens to one 8ohm JBL, Altec, Black Widow (high efficiency speaker) - he probably wouldn’t notice any less output in volume. Also gives him the option of plugging in an additional 8 ohm cab. |
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Dave Mudgett
From: Central Pennsylvania and Gallatin, Tennessee
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Posted 23 Jan 2024 6:56 pm
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In general, blackface/silverface Fenders can run a moderately mismatched load (e.g., 8 or 2 Ohms for a nominal 4 Ohm setup) if not pushed too hard. But given the choice of running a vintage blackface Vibrolux Reverb into 4 Ohms vs 8 Ohms, I'd run it at 4 Ohms. Transformer is not real stout. I have two Vibroluxes, one '66 blackface, one '71 silverface. The '71 transformer is significantly more stout than the '66, and that'd be my biggest issue with running the blackface mismatched. Anyway - with an amp like a Vibrolux for pedal steel with a high-efficiency speaker, I'd probably be inclined to push it pretty hard in a loud situation, and I think that's where I wouldn't be comfortable running a smaller load (higher impedance).
If I wasn't pushing it, I wouldn't think twice about running a mismatched load. I mostly use them for guitar, but sometimes for E9 pedal steel - but I generally just use the stock speakers (2x8-Ohm 10" speakers = 4 Ohms). They sound fine for steel if not pushed hard, but they break up early if pushed. But sometimes I will set it atop a 12 or 15" external cab with a JBL, EVM, or Telonics Neo. That does extend the range significantly.
As Brett says - if you wanna run with an 8 Ohm internal speaker(s) plus 8 Ohm external speaker, that IMO is the ideal situation for pedal steel. Set up that way, Vibroluxes can have a surprisingly large amount of headroom. |
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Tom Wolverton
From: Carpinteria, CA
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Posted 23 Jan 2024 11:03 pm
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Thanks everybody. _________________ To write with a broken pencil is pointless. |
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Dave Grafe
From: Hudson River Valley NY
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Posted 24 Jan 2024 6:47 am
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If it's an original 1965 amp it would be foolish to take the risk. It will work fine at half its design impedance until it doesn't. As the Vibrolux is a relatively low-powered amp for PSG and likely to be pushed hard in a band situation that is bound to happen sooner than later. Also bear in mind that an impedance change on the secondary affects the impedance on the primary, i.e. the tube plates, rendering carefully chosen bias settings totally irrelevant. Better - and far cheaper - to spend a few hundred bucks on a RI amp to mess around with, and leave the vintage gear intact.
Thus says another grumpy old man who's seen a thing or two. |
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Dave Mudgett
From: Central Pennsylvania and Gallatin, Tennessee
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Posted 24 Jan 2024 7:48 am
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You didn't mention the amp's originality/condition, but I meant to mention this. With the median price of an original '65 Vibrolux Reverb in excellent cosmetic shape running in the $4000-5000 range or more for a really clean original example, I think it would not be a good idea to modify the amp in any manner that could not be put back exactly to original condition.
It is not difficult to completely remove the baffle of a blackface Fender with the original speakers and all wiring (including the cable to the amp's RCA jack) completely intact. Then one can replace the whole shebang with an entirely new baffle, speaker, and wiring, allowing the amp to be put back completely stock if desired. And any other approach will be detectable, and will degrade the value of the amp. Done poorly, the amount of value degradation can be large. People paying this kind of money for an old Vibrolux Reverb want 'em clean and original, period.
If the amp has already been modified in any significant way, this is not so much of a consideration.
To pick up on what Dave G. is saying - definitely, it is sub-optimal to run a Vibrolux Reverb at anything but 4 Ohms. There is an issue of some loss of power through impedance mismatch. But IMO, the main issue is excess flyback voltage, which can not only change the sound but also damage the output transformer, especially if pushed hard. Without original transformers, a $4000-5000 VR is probably worth around half of that.
Last edited by Dave Mudgett on 24 Jan 2024 11:03 am; edited 1 time in total |
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Tom Wolverton
From: Carpinteria, CA
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Posted 24 Jan 2024 10:17 am
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Dave M. You said “ sub-optimal to run a Vibrolux Reverb at anything but 8 Ohms. ”
Did you mean to say 4 ohms?
Also note: my friend is running guitar, not steel thru this amp. But I think he should leave it 100% original. _________________ To write with a broken pencil is pointless. |
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Dave Mudgett
From: Central Pennsylvania and Gallatin, Tennessee
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Posted 24 Jan 2024 11:16 am
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Absolutely - typing too fast. 4 Ohms, not 8 Ohms. Edited to correct.
For guitar, I can't imagine changing the general speaker configuration of a Vibrolux Reverb in the slightest. IMO, the finest Tele amp on planet Earth, and great for pretty much anything. My '66 came with two original Jensen '65 C10Qs, one blown. I found another '65 C10Q, pulled them both, and put in two excellent Kendrick (Gerald Weber) replacements for daily use to make sure the '65 C12Qs didn't get blown. I've had the amp around 30 years and have used it extensively. I doubt those Jensens would have survived, and they're in a box in case I ever sell it (unlikely). |
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George Biner
From: Los Angeles, CA
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Posted 26 Jan 2024 3:42 pm
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Also, I would think the amp would sound completely different with a 8 ohm load vs. 4. _________________ Guacamole Mafia - acoustic harmony duo
Electrical engineer / amp tech in West Los Angeles -- I fix Peaveys
"Now there is a snappy sounding instrument. That f****r really sings." - Jerry Garcia |
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Colin Boutilier
From: Nova Scotia, Canada
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Posted 26 Jan 2024 4:16 pm
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I bought a Weber Z-Matcher for my mad scientist projects, and it was money well spent. I can run whatever, with whatever and not worry about it. It was really a necessity for me, as I had picked up a '75 Super Reverb head conversion and had to contend with that 2-ohm OT. _________________ Carter Starter, Austin dobro, B/G Bender Telecaster, '75 Twin Reverb, '75 Super Reverb 1x15 |
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Jeffrey Maxwell
From: Amarillo, Texas, USA
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Posted 27 Jan 2024 9:29 am
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How about a 4 ohm 12" Speaker |
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Tony Prior
From: Charlotte NC
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Posted 2 Feb 2024 1:52 am
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The OHMS will have nothing to do with "SOUND" , thats based on speaker voicing. As we all know some speakers are voiced for a higher end brighter tone while others the opposite. If we change from 4 to 8 ohms and don't like the "TONE" it ain't the ohms !
Case in point, when I was gigging with a NV 112, I could not bond with the tone, too much mid range. I pulled the 4 ohm stock speaker and replaced it with a 50 watt rated Fender Eminence 8 ohm 12, the one with the gold/brown label. It was just what the Dr ordered. And yes of course many told me I was gonna blow up the amp due to the ohm miss match. I used that amp on a show, 2x month for over 2 years. Guess what, it didn't blow or get hot, but the MID RANGE HONK was gone ! AND I didn't notice any decrease in output either.
PS- I use those Fender Emmy speakers in all of my amps, it keeps the amps consistent.
When changing speakers, the voicing of the speaker matters. _________________ Emmons L-II , Fender Telecasters, B-Benders , Eastman Mandolin ,
Pro Tools 12 on WIN 7 !
jobless- but not homeless- now retired 9 years
CURRENT MUSIC TRACKS AT > https://tprior2241.wixsite.com/website |
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Tom Wolverton
From: Carpinteria, CA
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Posted 3 Feb 2024 8:01 am
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You all will be happy to hear that my friend decided to leave his BF Vibrolux Reverb alone. Thanks so much for the info. He read it all and scrapped his plans to modify. _________________ To write with a broken pencil is pointless. |
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