Machine Gun Amps
Notes on the blackface Vibroverb

The blackface Vibroverb may be the most sought after Fender amp of all time, right up there with the tweed Bassman. The reason for this no doubt is because Stevie Ray Vaughan is famous for using them. The Vibroverb started as a brownfaced 2x10 combo with reverb in '63. Then in late '63, Fender decided to switch to a 1x15 for whatever reason. They have a circuit that is virtually identical to the later Pro Reverb. Here are some notes on this amp:

1. They came with a few different speakers. I'm not completely sure about this, but I think the first ones came out with Jensen C15N's. Those speakers are really not up to the output of the Vibroverb, so then the amp started coming with a Concert series Jensen (I think the number is the EM1500) and also came with a JBL D130F as an option. SRV used an EV in his, altough there is some speculation that he used JBL's as well (he may have used them, but probably used EV's for a longer period of time).

2. If you have a Vibroverb, take care of it and DON'T MOD IT! They are classic amps, and are very rare as well. They only were available for a time in late '63 to late '64, maybe not even a full year. Get the filter caps changed and new tubes put in it. Then enjoy some of the best Fender tone available (second only to the blackface Super Reverb in my opinion).

3. There has been much talk about building an amp similar to a Vibroverb using a different Fender chassis that has similar features as the Vibroverb. These projects are usually referred to as the "Vibroclone". A Super Reverb, Pro Reverb, or Bandmaster Reverb chassis can be used for this. However, DO NOT USE A BLACKFACE AMP if you are going to build one of these! Blackface amps don't deserve to be modded or hacked up. The main things that are needed to convert a Super Reverb, Pro Reverb, or Bandmaster Reverb to a Vibroverb are the output transformer (for 8 ohm load), tone controls, and the feedback loop. For the output transformer, a good one to use is a multi tap secondary one available from most Fender parts suppliers. These are usually the same size as the Super Reverb, which is the larger one. These usually have a 2, 4, and 8 ohm secondary so they can be used with amps such as the blackface Bassman, Super Reverb, and an 8 ohm amp that never had a transformer this big. The Super Reverb and Bandmaster Reverbs had a middle control on the Vibrato channel, the blackface Vibroverb did not. This control can either be eliminated or installed on the back panel. Or it can be left on the front panel. The feedback loop in the Vibroverb ends with a 47 ohm resistor, while the other amps have a 100 ohm. The 47 ohm resistor does make a noticeable change.

4. Speakers for your project. I like the Weber VST series a lot. I use a P15N right now in my 1x15 Pro (similar to a blackface Bandmaster but in combo format). It is great. I've also heard EV's, JBL's and other Weber VST speakers. There are a lot of speakers out there that are good, you'll probably need to listen to a few to find one you like. For authentic SRV tone, the EV is the best choice, although I'm sure that Weber VST is going to be making something soon that will be right up there in the same league.

5. The price of the blackface Vibroverb seems to be escalating. A good deal on one will be around $1400, and I've seen them advertised for as high as $2500. The high price is probably what is promping so much interest in the "Vibroclone" project.

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