Tube Amps / Music Electronics
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|6/12/1998 12:08 PM|
||Tweed Deluxe DIY-maybe-Opinions please.|
I am considering choosing the Tweed Deluxe as my first DIY project. Unfortunately I've never had the pleasure of hearing one in person, so I'm going on reviews, Neil Young albums, and layout schematics. What I really would like to know is how you all feel about this amp, especially at clean settings, and what you think about a single Tone control.
From what I've read I would probably stick 5881s(maybe not)in it anyway, so please, don't be shy. Joe.
|6/12/1998 4:46 PM|
Depending upon how much amp repair/mod experience you have, the Tweed Champ might be a better choice, since it's a simpler circuit with fewer parts. On the other hand, if you feel confident that you can do a good job implementing a Tweed Deluxe, I think it's an absolutely wonderful sounding amp (I'm talking specifically about the late-50's narrow panel models - 5E3, I think). The single tone control is quite effective, as long as you're plugged into the bright channel. The stock circuit provides tons of bottom end, maybe too much (but this can easily be taken care of by lowering the values of the .1uF caps coming off of the input gain stage (12AY7) plates to .047 or .022). Overall, the tone is big, warm, fat, and singing. By the way, my homebrewed Tweed Deluxe uses a Mojotone alnico speaker and NOS 6V6GTA tubes. Also, I use an NOS 5751 tube instead of a 12AY7 in the first preamp tube socket.
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The Ultimate Tone, Volume III by Kevin O'Connor
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|6/13/1998 6:19 AM|
I have an amp called a Lectrolab, a clone of a Tweed Deluxe. This has been my Frankenstein amp where I have experimented with preamp circuits and phase splitters.
1. Standard tweed deluxe circuit: Very nice tone and feel overall. As far as "clean" settings, the amp was designed with 1950's single coil pickups in mind, even with these, the amp goes into overdrive at around 4 or 5 on the volume knob. I didn't like the single Tone control, all it does is cut highs. I really didn't need two input channels, so...
2. '59 bassman preamp into standard tweed deluxe phase splitter and power amp: Man, I though this would be the most ultimate sound the world has ever known. It sounded like dog poop.
3. Blackface preamp (1 12AX7) into Blackface deluxe power stage with long tail phase splitter: This was better than #2, but something was still not right.
4: Blackface preamp, with 3rd gain stage feeding standard Tweed Deluxe splitter and power amp: This is where I am today, it works great. The 2nd & 3rd preamp stages use unbypassed cathode resistors to keep gain from being too high. Also has variable negative feedback control that is very useful.
We use this amp in 2 ways:
1. acoustic guitar with Dean Markley pickup run thru a hi-fi speaker. Very nice crisp clean acoustic sound with luscious tube sheen.
2. electric guitar run through guitar speaker. Very Nice, same as original circuit in overall gain and touch sensitivity, but with REAL Tone controls! From clean to Crunch City depending on the volume control.
As you can tell, I dig this type of amp and highly recommend it. I'm sure you know these are not the loudest amps in the world. Putting in 5881s won't make it appreciably louder, you would need a different output transformer to get more power. I prefer the 6V6 sound. Remember, 5881s draw twice the heater current of 6V6 any your power transformer may not like that.
|6/13/1998 11:00 PM|
I didn't like the single Tone control, all it does is cut highs. I really didn't need two input channels, so...
The 5E3 Tweed Deluxes use a few tricks with their two inputs. The "mike" input has a 500pF cap which goes to pin #1 of the Tone control so that it will boost trebles as well as cut them. I've also heard that setting the volume control for the unused second input has a subtle effect on the tone as well.
I like the idea of your "FrankenAmp", but just wanted to point out that the stock tweed deluxe circuit has its own charm, especially for a first-time DIY project.
P.S. So the driver/PI you are currently using is similiar to the 6G3 Deluxe (long-tailed driver) not the 5E3 Deluxe (split-load driver)? And does your amp have two inputs/channels, one the basic tweed Deluxe and the other your modded BF?
|6/15/1998 6:25 AM|
I like the sound of my tweed Champ. A Tweed Deluxe (5E3) is what I would like to have. The tweed clone makers are charging too much for these tried and true circuits. I can't shell out the cash right now for a real one.
I only have one problem, I know next to nothing about electronics. However, I am willing to learn. This would be a cool project to tackle over the winter. Building a cabinet would be no problem, and I know where to get a
speaker for it.
I guess the real question for me is it worth trying to do this? I really should be spending my extra time playing my guitar, but I've seen the guts of some of these tweeds and
they don't look overly complex.
Any opinions, let 'em rip.
|6/15/1998 7:30 AM|
To do a nice job, the electronics are only a minor part. I speak from painful experience of the first couple of amps that I built. Even a nice clone of a tweed Champ is harder to trim and make a chassis for, and the other tasks, than it is to build the electronics. And more expensive, unless you have an old amp carcass to work with, you can spend five times as much on trim, cabinet and chassis as the electronics, and twice as long trying to get the grille cloth right
Having said that, if you start with a simple tube amp and a couple of the popular books, you can't go wrong. Some important points
- understand the reason/theory behind everything you do, before doing it to your amp.
- practice first, never practice on your amp 'cause that's where you don't want to make too many mistakes.
- when poking around inside the amp, keep one hand in your pocket at all times. Don't trust the insulation quality on the test leads of $20 multimeters.
- see above, unplug the amp from the wall and put the plug in a drawer before touching anything inside it.
- and also, check the voltage of anything you plan on touching inside the amp.
All of the above points I learnt the hard way
by getting sloppy. It's a matter of good fortune that I'm here to tell the tale.
If you work carefully and practice first,
you can make an amp of equal quality to a
boutique amp, and it is very rewarding.
|6/15/1998 10:53 PM|
For your safety tips I just wanted to add: be sure to discharge the power supply filter caps as they WILL hold a charge after unplugging the amp- and once discharged their voltage can build up again. To discharge the caps build a test cable with two alligator clips and a 10k resistor. I got fancy and used a red boot to go to B+ and a green boot to go to chassis ground. Study the circuit to determine where to clip this test cable; on a BF Pro I clip it to the Standby switch and then turn that switch on after clipping the green clip to the chassis. Leave this test cable in place as charges can build back up on filter caps. Once you are familiar with the amp you are working on you may want to take shortcuts- but you should at least check for any dc voltages on the various B+ points before reaching in. (As for keeping on hand in your pocket, I've heard of that advice more for testing any kind of equipment or appliance out in the field when it is energized- the point is to make sure that your other hand isn't leaning against a grounded chassis to complete a circuit in case your probe slips.)
As for all of the non-electronic aspects of building an amp, I'd assume that most of us already have some amps or cabs around to use for the speaker so at least for the testing stages you can skip most of the woodworking. You can find old stereo or hi-fi chassises at garage sales or flea markets and adapt them for a DIY amp- or buy a Hammond chassis box from Mouser(?) to get fancier. Actually most of my DIY experience has been with solid state circuits so I didn't have to hassle with transformers and tube sockets- just draw up the circuit board with a resist pen, etch it, drill it, stuff it, and wire in the controls, switches and jacks after locating an appropriate metal box. A real breeze compared to building a tube guitar amp! I plan to build a tweed deluxe clone one of these days and will probably use the cabinet and chassis from a junky ss combo amp I have laying around (currently serving time as an extension speaker). Doing that would eliminate most of the non-electronic hassles you mentioned (but it certainly wouldn't look vintage!).
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