Vintage amps with cathode bias + have a reverb circuit

jhawk

Member
Messages
125
Do you guys know of any vintage amps that were cathode biased and had tube-driven reverb?

I say vintage because the schematics are easier to find, but modern would be alright too. I'm looking for a simple-ish circuit to modify and build...simple one knob tonestack would be good. 10-15 watts. 6V6 or EL84 output section.

Let me know if you guys have any hidden-gem circuits you like!
 

zenas

Member
Messages
8,759
Ampeg Reverborocket. But it's not exactly simple.
Not even simple to service ! Holly cow they stuffed a lot of stuff into those little chassis on the 6v6 RRs. There's like no room. What amazes me though is how quit the two 62 RRs I have were after just replacing the electrolytics, adding a grounded cord and replacing the old tin foil sandwich wrap with some aluminum tape. (think they dug that tin foil out the lunch room trash can)
Building a direct clone and getting the lead dress right wouldn't be real easy. You'd want skinny wire not the fat cloth covered stuff. And those clamps like doctor use, hemostats or whatever they call them.
 

Sweetfinger

Silver Supporting Member
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12,521
Kalamazoo Reverb 12, Gretsch Twin Reverb, really, most old lower power Gibsons with reverb, probably all Valcos with reverb. Take most amps with fixed bias and sub a cathode resistor and you're pretty much there.
 

EFK

Member
Messages
1,040
Yes, most of the Valcos with reverb were built in this manner (although there was at least one that used a transformer and was driven via an extra 6973). If I might make a recommendation, I find it a lot easier to work a cap-coupled reverb into these types of circuits as opposed to the more typical (Fender type) transformer driven reverb. And it is very possible to obtain a 'deep' or cavernous reverb with a cap-coupled circuit; as noted above, Ampegs are very well regarded for the quality of their reverb and every old Ampeg I've ever worked on w/ reverb utilized a cap coupled circuit.

The absolute best reverb, to my ear, can be obtained by tapping the signal off the output and injecting it into it's own power amp and dedicated speaker! I recall one or two Guilds built like this, an awful lot of work and cost though. However, it cures the issue of preamp or power amp distortion affecting the reverb signal.

Most of the Valcos kind of suck because they cheaped out on the reverb tank itself, but there were one or two that actually used full size, quality tanks.
 

Blue Strat

Member
Messages
30,183
Not sure that one exists. Use a single channel of a Deluxe Reverb, take out the tonestack and replace with a Tweed Deluxe tone control, remove bias supply and add a higher value (start with 350 ohm) cathode resistor (use Tweed Deluxe Schematic) for the power tubes.
 

Steppin' Wolfe

Silver Supporting Member
Messages
5,059
Imho, this is the best amp ;that fits that description that I have ever owned or heard. Now...where to get the exact schematic?? I don't know....Gibson is a bit crazy that way.

https://images.search.yahoo.com/yhs...s/products/35388/1029060/big.jpg&action=click

This may be it. I have a later Falcon GA-19rvt here that is the next version...and not nearly as good as the rear control GA-19RVT. . This Falcon runs a 6EU7 in V2 whereas we are seeing a 7199 in V2 of this schematic.

 

jhawk

Member
Messages
125
Thanks for the replies guys! Sorry I've been MIA for awhile.

That Gibson Falcon is especially interesting...some cool videos about them on YouTube.
 

teleking36

Silver Supporting Member
Messages
3,949
My '62 Epiphone EA-28RVT is a 1x12 combo, cathode biased 6V6 amp with reverb and tremolo. It echoes the Gibsons mentioned in this thread. It predates the notably tinny and harsh sounding crestline Gibsons and Epiphones from the mid and late 60s, and is a tremendous value for what you get.

It sounds like a leaner tweed amp, but still has good volume and breakup characteristics. The spring reverb on my Epi is particularly great sounding, and different from your typical Fender or Ampeg spring sound.
 

Badside

Member
Messages
1,415
As the reverb is usually part of the preamp, it's usually quite simple to mate a reverbified preamp to a cathode biased power amp. Unless of course you want to specifically build an existing proven circuit.
I like to build amps usually designed for fixed bias and just convert them to cathode bias, it's so simple you can even put it on a switch.

Either way, you can look at this guy's thread: https://www.thegearpage.net/board/i...reverb-5e3-power-stage.1785490/#post-23368539
 

67super

Member
Messages
1,505
Tone King Imperial has cathode bias and tube driven reverb. They sound fantastic and Tone King will gladly give you the schematic for a used one if you provide the serial number.
 




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