Bulldog Substitutes?

[Major Tom]

I have a couple old Peavey Bravo amps (all tube, 2xEL-84, 1x12) that I have modded fairly extensively in an attempt to cop a VOX sound. I think that I am very close to my objective; they have lots of sparkly high end, chime, sweet compression and are capable of delivering a blizzard of razorblades tone, but are missing some of that AC 30 midrange "honk". There's not much more I can do at this point except replace the speaker. I have a Mojotone (v30, I think) in one, and a Peavey Scorpion in the other. The most obvious solution is to drop a Celestion Blue or Weber Alnico Blue Dog in there, but I would would like to find something cheaper to put in one of them for now, that is close to the Vox Blue sound.

 

Any Suggestions?

 

How about these that I have seen on Ebay:

 

Old american made gold Bulldogs pulled from Super Beatles and other SS Vox amps ??

 

VOX Ceramic Bulldogs from recent AC-15 amps ?? (was winning the Ebay auction on one of these but the seller withdrew at the last minute !)

[DIAMOND DUST]

I use JENSEN AlNico speakers in my Ampeg and fender. They sound soooooo sweet. I think they are the best speakers for low watt amps. They have a direct replacement for the bulldog. They are kinda pricey, but it would be the last speaker you would ever need.

 

I have seen them on ebay for pretty cheap.

[Blue Strat]

Originally posted by Major Tom:

I have a couple old Peavey Bravo amps (all tube, 2xEL-84, 1x12) that I have modded fairly extensively in an attempt to cop a VOX sound. I think that I am very close to my objective; they have lots of sparkly high end, chime, sweet compression and are capable of delivering a blizzard of razorblades tone, but are missing some of that AC 30 midrange "honk". There's not much more I can do at this point except replace the speaker. I have a Mojotone (v30, I think) in one, and a Peavey Scorpion in the other. The most obvious solution is to drop a Celestion Blue or Weber Alnico Blue Dog in there, but I would would like to find something cheaper to put in one of them for now, that is close to the Vox Blue sound.

Cool project! Have you been to http://www.newsensor.com ? They've got some lower priced EH speakers that are reported to be good speakers for the money. There's a Celestion copy that might have some of the mid-range tone you're looking for.

 

Now, if you don't mind me asking, what did you do to your amp? Did you take the PCB out and start from scratch, or did you change parts on the PCB until you got what you were looking for? I've got a Peavey Delta Blues 1 x 15" amp, and I've been modifying it, but I can't do anything else unless I scrap the PCB.

[Major Tom]

I'm very pleased with it. I had one that I bought new in '92 for a practice/small gig amp - I always like the sound in my living room, but sounded too thin in a band context, so a few months back I decided that since it was only worth $150 or so, I didn't have much to lose. This amp wouldn't lend itself to taking out the PCB, it is a small chassis, has a separate set of tone controls for both channels, and has all 5 tubes inside the chassis (horizontally mounted), with a small fan to cool them. Needless to say, it is a little cramped in there.

The original Eminence speaker sounded awful - thin bottom, harsh treble. I tried a Celestion G12-75 (I think that's the #) in there a few years back, I thought that sounded even thinner and every bit as harsh. Recently a friend gave me a non-functional Peavey Renoun that was loaded with 2 12" Scorpions. I put one of those in, and it was a huge improvement. The amp immediately had more of the Vox tone I wanted. I went ahead and changed out the tubes, which also improved the tone. Scorpions have a see-thru mesh for the dust cap, so I used some acrylic paint on it to fill in the holes of the mesh, resulting in a solid dust cap. thinking that a little more surface area to radiate sound might yield a little more bass. After doing some of the mods listed below, I decided to get another Bravo, modify it and put it into the old Renoun 2 x 12 cab - unlike other Peavey stuff, its made of plywood. I bought the second Bravo off Ebay for $127.50 + $30. or so for shipping. I also bought a used Mojotone speaker for about $35. total - it has a huge bottom end, and good all round tone. It is a lot more efficient than the Scorp, so that one is about twice as loud.

 

Here's what I have done so far on one or both of them:

Changed out a lot of the ceramic caps with same value Mylars that I robbed out of old electronic junk - might go back and put in Spragues, but they are big...

 

Put a 12AT7 in position #2 to lower the gain of the high-gain channel (was way too saturated for me)

 

Changed the reverb footswitching function (useless) to kick in the pull-pot boost relay of the high gain channel (great for solo boost,probably about 9-12 db or so)

 

Changed a bypass resistor on a preamp tube to lower the gain amount of the pull-pot boost.

 

Installed a 3-position mid-boost switch on the clean channel - copied from Boogie's "Fat" switch, except with the original and 2 different cap values.

 

Increased the value of 3 or 4 coupling caps

 

Changed the 22K/500K input resistors to standard 68K/1 meg

 

Cut out a 39pf cap (from input to ground), and jumpered across a .1 uf coupling cap at the input (both of these must be "peaveyisms", I haven't seen them in any other schematics)

 

Added a presence control on the front panel (less NFB = more Vox-like tone)

 

Added a switchable cathode-bias mode (was fixed bias) I just did this last week, and haven't really evaluated it a lot yet, but the cathode bias mode seems to be more compressed, in a good, Voxy way. Ac-30's are cathode biased.

 

Installed a standby switch on the front panel to help extend tube life.

 

I built an attenuator for each one using a 100-watt L pad, mounted on a bracket in the back. Great for getting power tube distortion at reasonable volume levels.

 

The Bravo's tone stacks are not vintage style, the high gain channel is active, and the clean's is a little different than normal. I have tried a couple things which didn't do a whole lot. If I ever get around to puttin' one in the 2x12, it will have room for a small additional chassis - I may put in a switch to toggle between the original tone stack, and a conventional one...

 

Anyway, they have a lot of complexity to the tone, very dynamic and sensitive, and IMHO beat the pants off most amps in their present state. The sound reminds me a lot of some of The Edge's tones.

[Blue Strat]

Sounds like you've done a lot of work! I've done so many mods to my Delta Blues that the traces are comming off of the PCB. My next step is to remove the PCB completely and install new sockets and terminal strips so I can wire it point to point. I've also thought about pulling the 1 x 15" out and selling it, or just pulling the chassis and reverb tank, then selling the cab and speaker. I'd build a new cabinet and use it as a head.

[Major Tom]

Yeah, I had to repair a couple traces myself. Gutting that thing sounds like a huge job, especially without a layout to copy from - I'm sure you know that a bad layout can cause noise problems if certain circuits/components are too close to others...

One of my future projects is to mod this old 1971 Fender Quad Reverb head (100 watt) that I used to use years ago. I took it in exchange for a $100. debt in the early 80's. It is already a PTP, with tube driven reverb, poly caps, etc., and lots of room to work with. I would like to add channel switching, some switchable voicing options, cathode bias switch, switchable gain boost, a switch to chose between the 2 pairs of output tubes - 6L6's in one, Yellow Jackets or maybe 6V6's in the other, etc, etc. I have tried to sell it a couple times, never got any bites - I guess because it says Quad Reverb instead of Dual Showman on the panel, even though its the exact same thing. I figure I've got nothing to lose since it doesn't seem to have any value.