Fender Vibroverb 63RI

billzabozo

I keep toying with the idea of getting a new amp but can't bring myself to part with my main amp which has been the vibroverb for sometime now. I love the brownface era amps but don't really have the cash to spread on a more dedicated tweed and brownface type amps.

So as a more economical (or not option) I was curious if anyone had some advice on how to squeeze the most tone out of these amps? It currently has a pair of RI Jensens 10" (can't remember which off the top of my head) apart from that it's stock.

I've seen people using a combination of different speakers etc. and a few other mods that can be carried out but don't want to waste time and money if they wont make a huge difference.

The main thing I want is touch sensitivity when I dig in on the strings or roll back on the volume and early ish break up,

Any words of wisdom appreciated.

ICBM

That amp doesn't have a valve rectifier. You need to either:

Fit one (huge job), you need a new PT or a separate 5V filament transformer, plus the valve socket.

Or:

Fit a pair of resistors in the HT lines from the existing PT to simulate one. This sounds like a 'cheap bodge' but is actually quite close soundwise for about 10% of the work.

If you want to keep all the options open you can easily fit a switch to give stock or valve/simulated rectifier.

It should also possible to convert it to run 6V6s if you've done one of those things, since the HT voltage will then be lower, but that may be too big a change.

billzabozo

Thank you @ICBM that's an interesting option for me to look into and the idea simulating the effect rather than the wholesale surgery of putting in a valve rectifier is appealing.

menamestom

I used one if these at a gig once and a mate had one, they are great sounding amps, with a lovely clean sound that is not blackface bright as I remember.  But they don't have much breakup or compression.  Personally I'd use a pedal to add this rather than do too much to the amp, say a Timmy or Sweet Honey, something that could be an always on pedal that is mainly clean unless you hit the strings hard, in which case you get some give.   If your speakers are ceramic, alnico units could change the feel also.

Trude

Sell it to me! I've wanted one of these for ages...

billzabozo

I've written a classified ad a couple of times and decided against posting it. I've been through plenty of other amps whilst owning this one which have come and gone but always keep this. I really like the sound of them just wondered if there is something I'm missing that would give me something extra. Or maybe I just have that all too familiar itch to buy more gear. 

jacksparrow

The only thing i would do to the vibroverb is install a bias pot and weber 10a125 speakers. And maybe some nice valves.

I had one and stupidly sold it. But i now have a Headstrong verbrovibe which is killer.

billzabozo

The Headstrong and the Rift amps both really appeal to me but a distinct lack of money is holding me back somewhat.

I've seen the Weber speakers mentioned somewhere else as a recommendation and they seem well regarded so might try and give them a go.

Pedal wise the amp loves fuzz, not used much in the way of boost or overdrive so might try that.

What is the benefit of adding a bias pot and is it a big job?

RiftAmps

Eminence Ragin' Cajun speakers are a great match for the RI, definitely worth trying.

The GZ34 mod isn't really worth doing on this amp simply down to the cost of it, but adding a bias pot is something I always recommend on these.

ICBM

RiftAmps said:

The GZ34 mod isn't really worth doing on this amp simply down to the cost of it

I agree, but simulating it with a couple of resistors is dead easy, and cheap.

riscado

You might look into the Eminence Alessandro GA10-SC64 speaker, designed to give you tones which are not unlike what you might find from the old Jensen C10NS and Oxford 10" speakers. I cannot talk too much about the amp you have, except to say that it doesn't resemble a brownface in terms of sound... only aesthetically. This is not to say it isn't a decent amp!

I wouldn't dig into big circuit changes on this amp, I think it would be a waste of time and money, except maybe to add a simple way to bias it, has someone has RiftAmp has already pointed out. This would mostly benefict you from a serviceability standpoint.

So maybe a speaker change would be your best bet for a quick win. I'm using the Eminence Alessandro in a Magic amps vibro prince, and I cannot recommend it enough.

John_A

I would be surprised if there wasn't already a 'sag resistor' in the circuit, but in my experience it's only slightly noticeable, and even then only when the amp is running at quite high volumes.  The 63 Vibroverb reissue is a lovely sounding amp stock, and agree with the others here that a speaker change will give you the most noticeable improvements.

If you're not wanting to play overly loud, it sounds to me like a tweed deluxe type of amp might be what you are looking for, they don't come much more touch sensitive than that.

ICBM

John_A said:

I would be surprised if there wasn't already a 'sag resistor' in the circuit, but in my experience it's only slightly noticeable, and even then only when the amp is running at quite high volumes.

There's definitely no sag resistor. It's not a vintage-style rectifier circuit at all in fact, it's a diode bridge with no centre-tapped PT winding. This was one of Fender's first reissues and they weren't as fussy about getting the circuits right back then.

It's not just the sag it introduces, it also reduces all the HT voltages throughout the amp which lowers the headroom as well. Actually, one of the advantages of doing it with resistors is that you can put in more resistance than a normal valve rectifier will give, if you want.

John_A

I installed a few big resistors on a selector switch in to an 18W Marshall style amp I built ages ago, may have been the circuit, but I didn't think it made a great deal of difference

ICBM

It probably does make less of a difference on a hot-running cathode-biased amp like that, yes. The current draw is much less dependent on the output volume than on something like the Vibroverb.

It makes a huge difference on the Mesa Rectifier amps - both the valve/solid-state switch and the 'bold/spongy' which is another voltage reduction (done by dropping the voltage at the PT).