Tube Amps / Music Electronics
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|1/28/1999 7:29 PM|
||Fender Tweed Deluxe -- 5B3 to 5E3 convert???|
I have an option on a 52/53 Wide Panel Deluxe. Model 5B3. I know some of the differences between it and the more famous 5E3. The 5B3 has a 6SC7 preamp tube and the same for phase invertor. And then the negative feedback loop is going from the 5B3 regardless of other mods.
I have one of Weber's books on order to I can compare schematics, but until it arrives, I'n not sure about some things.
Does the 5B3 use just one tube for preamp and one for phase invertor, or ddoes it use 1 and 1/2 a tube for the preamp and 1/2 tube for phase invertor like the 5E3's 12AY7, 12aX7 combo?
The amp I'm looking at has GT "subtitubes" in to adapt the socket to 12A?7's. But doe the power transforer have a 12 volt tap, if not, how does the GT work? WIth a 12AY7 in one substitube and a 12AX7 in the other, is this close to 5E3 specs or is it just using the one tube for preamp and one for phase inverter (refer to last paragraph)?
My plan is to get the amp, disconnect the negative feedback loop, outfit it with proper tubes and see how I like it. From there, is it worth it to rewire it closer to later models?
Any info at all will be a help. I'm really leaning on getting the amp regardless, I just want to make sure it will be usualable and have that familiar Tweed Deluxe tone (big Neil Young nut).
|1/29/1999 6:54 AM|
I can't answer your questions aboud specific differences in each version you mentioned, as I am without the necessary reference books at the moment.
Regarding the tube socket adapters, the 12A_7 tubes have a center tapped heater, so are able to run on 6.3v, and in fact usually are when employed in audio amps (there's a slight hum reduction if the heater is powered from AC).
The 6SC7 dual triode tubes originally called for in the 5B3 are metal tubes. The older ones (c.1950) worked pretty well, but the most recently mfd ones are in my experience too microphonic for guitar combos. However, the 6SL7 tube is plentiful, and widely available in the glass envelope version 6SL7GT. This is a great sounding tube, has a gain similar to a 12AX7, but has a slightly different pinout than a 6SC7.
May I suggest that before you go wild on various mods, to simply modify the current socket wiring on the 6SC7 sockets to allow you to install a pair of 6SL7GTs. Socket wiring changes are easy, only involving connections to pins 1, 3, & 6.
See how the amp sounds with the 6SL7s. You can still perform more mods later, pretending you're working with 12AX7s. Most circuits can use the same component values for either of these tubes.
|1/29/1999 7:33 AM|
I had one of the Tweed Deluxes with the 6SC7s. Mine had 6SC7GTs, which have glass envelope, but they are hard to find. I didn't like the sound of the amp, although it may have been due to the changed output transformer and coupling caps more than the sound of the 6SC7 tubes.
|1/29/1999 9:41 AM|
And also, I think the older tweed Deluxes used a not so well balanced paraphase inverter to drive the push pull 6V6s and then later switched to an modified self-balancing paraphase inverter.
Then in the newest version of the tweed Deluxe,
the more recognizable cathodyne/split load driver.
I'm sure this has all had an impact on the tone too.
5751 instead of the 12AY7 for cool tone and try running a little negative feedback if you want the amp to stay a little cleaner under power.
It's only a 12-15 watt amp at best and way too easy to overdrive at medium volume levels.
Don't just discard negative feedback as a matter of course! There is some merit there.
You'll still get all the power tube distortion you can stand.
|1/29/1999 5:52 PM|
I'd be a little cautious about modifying an amp this old - there probably aren't that many left and a few should be left stock instead of "chopped and hod-rodded." If you want to restore the amp to stock, and I hope you will, I beleive that I can supply you with a couple of glass 6SC7s - I'm pretty sure that I've got some in stock.
As to the Neil Young sound, I don't know what specific model he uses but the earliet guitar amps really don't "crank" as much as the later ones do and this may not the the specific Tweed Deluxe for that specific sound. But, the sound may be just as good for a a different sound or different musician. So, again I urge you not to alter the sound of a historically significant amp - hell, at this point I really hesitate to make ANY modification to pre-CBS Fender amps other than add a properly grounded cord and individual bias controls for output tubes (discreetly installed at that).
|2/3/1999 9:45 AM|
I got printouts of all of these and the Weber book is coming. My hope is that the minimum amount or modding will have to be done to get the sound I want, but I'm not adverese to rewiring here and there to a later circuit. Any mods I do, I can undo, that's the fun of PTP.
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