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Old January 12th, 2004, 03:04 AM   #1 (permalink)
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Building a BF Dual Showman?

A few years ago, I sold a real 1965 Dual Showman head, and with each passing day, I feel more and more like a gigantic moron.

I was wondering if any of you guys could tell me how feasable it is to build a Dual Showman head using a Hoffman kit and getting the transformers and whatnot? I can easilly build a cabinet for it. What else is involved that somebody who's never built an amp might miss? There's the obvious stuff, but what's not so obvious?

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Old January 12th, 2004, 09:47 AM   #2 (permalink)
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one thing that might not be obvious is the cost. you need to sit down with a spread sheet and come up with a build of materials. figure in everything. figure in your tubes, knobs, pots, board, wire, trannys, chassis, etc. i love to build amps. it's one of the many joys of my life. but i won't build a bf amp any time soon. you can get a sf amp for about the same price or cheaper. you might even be able to find a bf one if you look around. another aspect of building - it's cool to you cause you built it, but if you ever need to sell it, it ain't as cool as a real fender to your average joe. just something to thinking about. if you do build it, just make sure you do your bom first to see how much it will cost you. and know that it will cost you more than that. cause you probably won't factor in screws, soldering iron, shipping from different places, tools, wood, tolex and grill cloth, glue, etc.
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Old January 12th, 2004, 09:53 AM   #3 (permalink)
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Quote:
Originally Posted by JDO
one thing that might not be obvious is the cost. you need to sit down with a spread sheet and come up with a build of materials. figure in everything. figure in your tubes, knobs, pots, board, wire, trannys, chassis, etc. i love to build amps. it's one of the many joys of my life. but i won't build a bf amp any time soon. you can get a sf amp for about the same price or cheaper. you might even be able to find a bf one if you look around. another aspect of building - it's cool to you cause you built it, but if you ever need to sell it, it ain't as cool as a real fender to your average joe. just something to thinking about. if you do build it, just make sure you do your bom first to see how much it will cost you. and know that it will cost you more than that. cause you probably won't factor in screws, soldering iron, shipping from different places, tools, wood, tolex and grill cloth, glue, etc.
That's the thing... My original Dual Showman is the ONLY piece of gear I've ever sold. Unfortunatley, I came on hard times and I had no choice... The 1969 AB165 Bassman that I'm running now (through the same cabinet) just isn't the same. It breaks up earlier, and it's mushier sounding. I LOOOOOOVED the tone on the DS, cuz it was clean to 8.5 and was just so full sounding.

I don't care much about resell value. It's gonna be a keeper. I just miss that HUGE tone that the DS gave me.

Has anybody else here built such an amp?
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Old January 12th, 2004, 11:33 AM   #4 (permalink)
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I've built several amps. If what you want is an amp that sounds like a Dual Showman, and cost matters to you at all, do NOT build an amp from scratch from parts you source yourself. Building from scratch will cost a lot more than it would to buy a used Showman and get a good tech to go through it. Those amps are not the most popular old Fenders and the prices on them aren't too high.

If you want to build an amp like that, you cannot do better than to buy an Allen Tone Savor head kit ($999) which is a Twin Reverb circuit without the vibrato and with only one channel, but with a useful master volume and Allen's "raw" control that gives brownface-type distortion when you want it. First class all the way, much cheaper than finding the parts yourself, great tech support and plans and instructions.

http://www.allenamps.com/tone_savor.html

http://www.allenamps.com/kits.html
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Old January 12th, 2004, 02:50 PM   #5 (permalink)
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What I want to do is exactly (or as close to possible)duplicate the tone of my old amp. It sounds like the Allen amp is a bit different. I'd probably be better off getting a Hoffman AB763 board that's assembled and getting the rest of the parts. If I were to do such a thing, I know the obvious stuff to do to the amp. Are there things that people usually forget when taking on such a project?

I also have another option that I discovered last night. Modifying my 1969 AB165 Bassman to AA864 specs. From what I understand, that sounds very similar to AB763 amps on the Normal channel. I used to use the Vibrato channel on my DS because of the midrange control. How close could I get to that tone if I were to AA864-ize the amp and add a midrange control?
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Old January 13th, 2004, 04:31 AM   #6 (permalink)
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Hello

Check out the thread on the Bassman I built. I hope this helps. If you need links to resources I can send them to you also.

http://www.tdpri.com/viewtopic.php?t=11495
&highlight=thankyou

I do believe that building a Showman maybe more expensive than getting one second hand. But putting a project together is also great fun !

Regards

Paul
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Old January 13th, 2004, 10:56 AM   #7 (permalink)
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Quote:
Originally Posted by GilmourD
What I want to do is exactly (or as close to possible)duplicate the tone of my old amp. It sounds like the Allen amp is a bit different. I'd probably be better off getting a Hoffman AB763 board that's assembled and getting the rest of the parts. If I were to do such a thing, I know the obvious stuff to do to the amp. Are there things that people usually forget when taking on such a project?
first off, i read on your other post that you didn't use the trem, you just liked that channel. if that's the case, the you really need to check out david allen. there ain't none better when it comes to bf tones.

second, i hope you're not getting frustrated by what might seem like a lack of help. just do one thing (which might take you a while) and let us know what you come up with. i want you to hunt on some prices for a showman like you had (or a sf version that is close) and get some prices down. then, get a list of materials together for your amp and get the prices down. and total it. then figure out which one cost less. i'm pretty sure that the fender will actually cost less.

the main thing i'm "worried" about is a lot of people look at building because they think it will be cheaper. that's not always the case. now, if you don't care that you might spend twice, or maybe three, times as much to build than to buy, that's another story. plus, for a first build, a push pull, fixed bias fender is a pretty tall order. what sort of electronics background do you have.

also, are you doing all your own wood working? that's another cost to throw in the mix.

answer three questions

1 - what sort of electronics background do you have - can you read schematics, have you soldered before, can you use a meter, etc?

2 - do you want to build for the experience/learning experience (no matter what the cost of the end result will be) or do you want to build because a bf showman is so much and you're hoping to save some money?

3 - how much does the amp that you want cost vs. how much it will cost you to build your own amp?
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Old January 13th, 2004, 05:39 PM   #8 (permalink)
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Whoa - hold on a minute. Didn't you say you already have the bottom???? Non-reverb BF Dual Showman heads aren't all that expensive - there's some on GBase for ~$600 and I remember seeing one locally last fall in decent shape for $500. Blondes & SF DS-Reverbs are a different story and complete amps are quite a bit higher in part because of the JBL speakers(something to consider if you build). Better to sell the Bassman head if the DS is what you really want than to mod it and end up swapping sometime down the road.

On the other hand, if the Bassman IS an AC568 complete with the funky cathode resistors on the power tubes, it would sound a WHOLE lot better if converted back to a AA864. Plus the cool thing about that circuit is you can hot-rod the Bass channel since it has an extra gain stage. For example you could change the tone stack to a tweed-Bassman style and add a cathode bypass cap on that 3rd stage to increase the gain. That still leaves half a tube unused if you want to go way off the deep end(but expect to trouble-shoot problems with noise, oscillation, etc.).

Most Fenders which don't have a midrange control have it hardwired about half way up by the 6.8K resistor on the bottom of the tone stack. Replace it with a 10K resistor and it's like having the mids on 10, a jumper will set the mids on 1.
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Old January 13th, 2004, 08:26 PM   #9 (permalink)
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Originally Posted by Teleologist
Whoa - hold on a minute. Didn't you say you already have the bottom???? Non-reverb BF Dual Showman heads aren't all that expensive - there's some on GBase for ~$600 and I remember seeing one locally last fall in decent shape for $500. Blondes & SF DS-Reverbs are a different story and complete amps are quite a bit higher in part because of the JBL speakers(something to consider if you build). Better to sell the Bassman head if the DS is what you really want than to mod it and end up swapping sometime down the road.
I know some real early SF DS's were AB763... That would be yummy. :) LOL I only paid $350 for my BF one in the first place.

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On the other hand, if the Bassman IS an AC568 complete with the funky cathode resistors on the power tubes, it would sound a WHOLE lot better if converted back to a AA864. Plus the cool thing about that circuit is you can hot-rod the Bass channel since it has an extra gain stage. For example you could change the tone stack to a tweed-Bassman style and add a cathode bypass cap on that 3rd stage to increase the gain. That still leaves half a tube unused if you want to go way off the deep end(but expect to trouble-shoot problems with noise, oscillation, etc.).
Does anybody have a kit or specific instructions on how to go from AC568 to AA864? I actually want the amp to be cleaner. That's my biggest complaint about it in comparison to the Dual Showman. My DS was loud, clean, and had a tight bottom end. The Bassman can get loud, but distorts easilly, and has a mushy bottom end.

Quote:
Most Fenders which don't have a midrange control have it hardwired about half way up by the 6.8K resistor on the bottom of the tone stack. Replace it with a 10K resistor and it's like having the mids on 10, a jumper will set the mids on 1.
Think I'd be dumb for actually wiring in a midrange pot?
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Old January 13th, 2004, 11:21 PM   #10 (permalink)
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Originally Posted by GilmourD
Does anybody have a kit or specific instructions on how to go from AC568 to AA864? I actually want the amp to be cleaner. That's my biggest complaint about it in comparison to the Dual Showman. My DS was loud, clean, and had a tight bottom end. The Bassman can get loud, but distorts easilly, and has a mushy bottom end.

Quote:
Most Fenders which don't have a midrange control have it hardwired about half way up by the 6.8K resistor on the bottom of the tone stack. Replace it with a 10K resistor and it's like having the mids on 10, a jumper will set the mids on 1.
Think I'd be dumb for actually wiring in a midrange pot?
i wouldn't say you would be dumb. it would give you more control. you could possible put the mid pot in the second input. you would just need to disconnect the mid resistor and hook up the pot.

and to know how to do that and other such things...

you ask how to mod your amp - i don't know that anyone really sells a kit to do that. and i'm not sure that your bassman could ever become a dual showman. for one, the bassman has 2 6L6's in the power section and the showman has 4. that makes a difference in the clean volume you would get.

with that said, go to www.ampwares.com/ffg and look at the schematics and layouts of your amp, the dual showman, and the earlier bf bassmans. although it's best to be able to work on an amp by using the schematics, most people need the layouts when they begin. do a search on the net for bassman mods. i can't remember off the top of my head but i think i've read in many places that a lot of people like the preamp from one bf bassman and the power amp from another one.

as if i haven't talked enough, part of the bassmans crunch comes from the amount of gain stages if i'm not mistaken. most fenders go
-gain stage
-tone stack
-volume
-gain stage
-phase inverter

the bassman goes
-gain stage
-tone stack
-volume
-gain stage
-gain stage
-phase inverter

the added stage gives it more crunch. as you look at the schematics you'll see what i mean.

hope that helps some on that.
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Old January 14th, 2004, 02:13 AM   #11 (permalink)
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Originally Posted by JDO
i wouldn't say you would be dumb. it would give you more control. you could possible put the mid pot in the second input. you would just need to disconnect the mid resistor and hook up the pot.

and to know how to do that and other such things...
Well, the mechanical process of desoldering and soldering is cake. :)

Quote:
you ask how to mod your amp - i don't know that anyone really sells a kit to do that. and i'm not sure that your bassman could ever become a dual showman. for one, the bassman has 2 6L6's in the power section and the showman has 4. that makes a difference in the clean volume you would get.
I was actually asking about modding back to a previous Bassman circuit. And the difference in clean headroom goes beyond just apparent volume. My DS broke up at 8 on the volume knob, where as the Bassman breaks up at 5 on the volume knob. I'm looking for a little more cleanliness towards the top of the Bassman's output. I don't necessarilly need 85 watts.

Quote:
with that said, go to www.ampwares.com/ffg and look at the schematics and layouts of your amp, the dual showman, and the earlier bf bassmans. although it's best to be able to work on an amp by using the schematics, most people need the layouts when they begin. do a search on the net for bassman mods. i can't remember off the top of my head but i think i've read in many places that a lot of people like the preamp from one bf bassman and the power amp from another one.
I've been doing that, actually. I have the Aspen Pittman Tube Amp Book right next to me, and I've been studying the differences in the circuits. The AB165 and AC568 aren't really THAT different.

Quote:
as if i haven't talked enough, part of the bassmans crunch comes from the amount of gain stages if i'm not mistaken. most fenders go
-gain stage
-tone stack
-volume
-gain stage
-phase inverter

the bassman goes
-gain stage
-tone stack
-volume
-gain stage
-gain stage
-phase inverter

the added stage gives it more crunch. as you look at the schematics you'll see what i mean.

hope that helps some on that.
Hey, keep talking. It's all edumacational. :)

I see what you mean... So, what you're saying is that I'll never get the bright and clean sound out of the Bassman. Basically, I want to tighten up the low end, and clean the beast up. Is that possible?
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