BYOC Tweed Royal Amp Kit Build

[duhvoodooman***]

Starting a new thread to document my build of the new amp kit being offered by my friend Keith Vonderhulls over at Buildyourownclone.com. As described in THIS THREAD and also THIS ONE. It's a hybrid of the Fender 5F1 Champ and 5E3 Deluxe circuits, set up so that you can switch between the two different amp configurations. Very cool design!

I received my kit, along with a lacquered tweed head cabinet, earlier this week. As often happens with the first few shipments of a new kit, there were some parts left out, notably some mounting nuts and (unfortunately!) all of the vintage style cloth-covered wire needed to do the turret board connections to the chassis-mounted hardware (pots, switches, jacks, tube sockets, etc.). A minor delay, as BYOC sent them out to me by Priority Mail the next day, and they should arrive this afternoon. Keith and his crew should now have these initial "pick & pack" process issues resolved and I'd expect future kits shipments will be fully complete.

While waiting for the missing parts to arrive, there was still plenty to do. I went ahead and populated the turret board with all the required resistors and capacitors, though many of them are just sitting in place, unsoldered until the hook-up wire arrives and can be added. Last night, I mounted all but the two output transformers into the chassis, did some of the off-board prep work on the hardware, and wired in the power transformer except for the connections to the rectifier tube socket (red and yellow wires). Here's a look at the current state of the project:

[Spudman***]

Very nice looking.

[kidsmoke*]

Holy Crap, DVM, you don't mess around. Looking good!

[duhvoodooman***]

Holy Crap, DVM, you don't mess around. Looking good!

Well, don't be too impressed yet! This is the easy/fast stuff. The really tedious/time-consuming/not-much-fun part is the wiring....and except for a little PT wiring, I have all of that ahead of me. Measure, cut, strip, tin, solder, repeat ad nauseum....

[Ch0jin]

... Measure, cut, strip, tin, solder, repeat ad nauseum....

Didn't you mention cloth covered wiring? That will make the process much easier. I did my JTM45 with it, and being able to cut to length and then just "push back" saves a bunch of wire stripping. (you probably know this already, but I'll mention it in case it helps. Make sure you use SHARP wire cutters, or trim the cloth with a sharp knife as you work, because the downside to cloth wire is that the ends can get furry really fast if you don't cut it clean.)

[duhvoodooman***]

I'll have to see what the wire looks like this time, but the last BYOC amp kit came with cloth covered wire that also had plastic insulation underneath, so still required stripping.

[Ch0jin]

Ah then that makes perfect sense then. The wire I used had an inner sheath of white cotton.

Anyway, really keen to eventually hear what this sounds like. I didn't bother with CC's for the most part in my build because I wanted the lowest possible noise floor, but knowing your stance on "mojo" I'm keen to hear your thoughts on their effect on the overall sound of this amp.

[Jipes***]

Looks great for a start !

[duhvoodooman***]

Wiring phase (shudder) under way. Got the turret board wiring finished last night, top and bottom--see pics below. Tonight I'll start with the tube filament heater wiring, then the output transformers (there are two, one for the push-pull 5E3 mode and one for the single-ended 5F1 mode, plus a rotary switch to select between them), and a few off-board odds & ends. Last thing will be mounting the turret board and doing all the tie-in connections for that (all 29 of 'em).

[duhvoodooman***]

Amp build completed! See photos below. I finished the last of the wiring around noon on Saturday and fired it up for the first time with the usual deep breath & fingers crossed for a new amp build. I don't care how many amps you build, it's always a bit nerve-wracking throwing the power switch the first time, hoping that you didn't screw something up that might blow a transformer or precipitate some similar calamity. But no problem--it fired right up without drama. All was not exactly as it should be, though, as I found that the "bright" channel had no volume control and was permanently "dimed". Turned out to be an error in the wiring diagram that I probably should have noticed before soldering it in that way. In any case, the issue was quickly found & fixed.

The amp itself sounds great. As Keith mentions, if you're looking for clean overhead....keep looking. This amp gets dirty quickly--in a very good way--especially in the single-ended mode. Not surprisingly, given its Tweed heritage, it sounds particularly good with single-coil guitars. My Strats and Tele's sound great through it. To describe the amp's overdriven tone, the word that immediately comes to mind is "juicy". It's a mids-heavy tone with lots of harmonics, well suited for classic rock and (especially!) blues. But I've only had a chance to play through the amp for maybe 20 minutes at this point, so I'm still "tone farming". Because the two channels are connected to an extent through the amp's circuitry, the volume controls are interactive with each other and with the Tone control. Factor in the "Cut" control that Keith added and there are a lot of tonal possibilities to be explored. I expect it will keep me busy for awhile discovering the sounds I like best. BTW, I should mention that I built the amp absolutely "stock", no mods of any sort. We'll see how long that lasts....

The only operational issue I've run into thus far is that the Cut control causes a squeal past 3 o'clock or so. Not sure at this point if it's my build or something basic to the circuit's implementation. As more Tweed Royals are built, I expect this question will be answered. Not a big deal, since I haven't found the need to run the Cut control up that high anyway.

Here are the photos:

[sunvalleylaw]

Wow! Congrats on the swift and I am sure excellent work! Clips hoped for soon!

You say it sounds great with single coils. It is kind of a bassman-esque clone, right? OR at least a vintage tweed clone. I understood that emulation of the Bassman circuit was where Marshalls came from, and so it would seem humbucker guitars would sound good on this too. Am I wrong?

[piebaldpython***]

Sweet.......can't wait to hear some clips. Outstanding work as always. GAS attack is here.

[Ch0jin]

@SVL As I understand it, the JTM45 (Marshall) was a revised 5F6A Bassman (Fender). Originally with 6L6's like Fender in '62, but by '64 they had KT66's in them.

The Fender Tweed Deluxe was an even older design ('55-'60 according to wiki) with the last and most popular being the 5E3 version, unique in Fender land for it's cathode bias and lack of power stage feedback (same as the Vox AC30 apparently) which gives it the ability for easily attained power tube distortion.

Most notable though is that the TD is a 15W 6V6 powered amp, whereas the Bassman/JTM is a 45W 6L6/KT66 amp. Different animals, but both very cool!

So back to the amph!

That's an interesting layout with the tubes sticking horizontally out the back like that. Obviously that's a tweed combo layout that happens to fit nicely into a head shell, but it's going to make tube swaps super easy! On the down side, I'd be very careful pulling the power cable out after a gig if that rectumfrier tube gets hot...

One question though.... What's the little blue hat that looks like some kind of crimped wire joiner doing in there?

Also, just for your consideration, but I'd be tempted to try and run those heater wires that currently go over the SE/PP wiring -under-. Closer to the chassis and less likely to work as transmitters. I found some pretty small changes to things like that made some big differences in my last amp build. But hey, if it's hum free now, box it up and rock on!

[sunvalleylaw]

Thanks Ch0jin. Guess I was painting with too broad a brush there. Thanks for the clarification. Definitely looks like a cool rig!

[duhvoodooman***]

One question though.... What's the little blue hat that looks like some kind of crimped wire joiner doing in there?

It's a wire nut, used to splice two wires together--strip & twist the two ends together and then screw the wire nut down over them to secure the mechanical splice. Because of the two-OT layout and the SE/PP switch, one of the leads for the SE tranny isn't quite long enough to reach the connection lug on the rotary switch. Keith included a wire nut in the kit to splice the lead to an added length of wire going to the switch. Not how I would do it personally--I'd do a solder splice and cover it with heatshrink--but I always build Keith's kits exactly to stock, at least for the first go-around. Seems to work just fine.

Also, just for your consideration, but I'd be tempted to try and run those heater wires that currently go over the SE/PP wiring -under-. Closer to the chassis and less likely to work as transmitters. I found some pretty small changes to things like that made some big differences in my last amp build. But hey, if it's hum free now, box it up and rock on!

It's pretty quiet as is, but the point is well taken as a matter of good lead dress practice. I have to open the amp up again in the next couple of days to clear up the Cut control squeal issue. Should be no problem to just push those heater wires over toward the rectifier tube socket at the back of the chassis and away from the rotary switch wires.

[duhvoodooman***]

Got the Cut control squeal issue fixed. Turned out to be an error in the wiring diagram which switched the two cathodyne PI outputs to the two 6V6 grid pins. That turned the negative feedback into positive feedback and caused the oscillation when turned up sufficiently high. Swapped those two wires and it's all good now!

Here's a new photo of the chassis with the squeal fix made. I also extended, rerouted, and did a solder splice on the orange single-ended OT primary and got rid of that wire nut, as well as installing a new set of tubes from what I had on hand. Under the preamp tube shields are a next-to-new EICO by Mullard 12AX7 in V1, a NOS BEL 12AX7 in V2, then a pair of current production Tung-Sol 6V6GT's, and finally a NOS GE 5Y3 recto. The amp sounds fabulous. Clearing up the positive feedback wiring error dropped the amp's gain down to a more reasonable level and it's got significantly more clean headroom than at first, while still having plenty of juicy filth on tap at the higher volume settings.

[kidsmoke*]

Did you have a chance to do an apples to apples comparison of the 5F1 circuit with your Champlifier 5F1?

Interesting that you find the other tubes preferable.

[duhvoodooman***]

The Champlifier and the Tweed Royal run in Champ mode (single-ended, Tone control switched off, Cut control at maximum) sound very, very similar, as you would expect they would. The only significant difference between the two circuits is that on the Tweed Royal, the signal from the second gain stage still has to go through the in-phase side of the cathodyne PI to get to the 6V6 output tube. But that's basically just a unity gain path and shouldn't alter the tonal character significantly.

I changed the tubes because I had told Keith at BYOC that I had all the necessary types and didn't need the 5-tube package with the kit. But when it arrived, they had been included anyway. So I used them for the initial start-up (I always build and test any of Keith's new kits totally stock, the way any BYOC customer would receive them) but pulled them out and am sending them back to him. The stock tubes sounded great--I'd have to do a true A/B test to be able to say which sounded better. I've got several NOS 6V6s that I'd like to try a pair of in the Tweed Royal, but they really need to be tested to determine the best matched pair, since I obtained them all as singles.

[jhamnett]

Great looking build! Any chance you'll be making some clips. I've been intrigued by this kit, thinking of making it my first build.