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PostPosted: Wed Mar 16, 2011 9:58 pm 
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zaphod wrote:
On which tube? Pins 1 and 6 aren't connected inside a 6V6 or 6L6.


That would be the 12ax7. (I mentioned that in an earlier post. :wink: )

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Yes, the speaker has to be inside a cab.


Yes of course, I wasn't questioning that. I was referring to the voltages being OK.

I had a raw speaker on the bench as a load for testing purposes. From that I could tell that the tone controls were functioning, but of course the sound was far from optimum.


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PostPosted: Tue Mar 22, 2011 9:35 am 
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So things seem to be working well. :D I do have a few tweaks to work out, but she's functioning nicely so I'm starting to look toward the finish line!

I ordered a Russian Tung-Sol EL34 which arrived this week - trying to build an amp around this tube really precipitated this bout of madness, so I tested bias voltages to see if I needed to make any changes. It seems right in line with the stock values of the amp (right? See EL34 thread...). I'm going to add a switched resistor to get the KT66's bias right, but I have to drill another hole for that so I didn't do it tonight.

Lemme tell ya - with an EL34 as a power tube, this little bitch was like buttah! Great distortion with my test Strat - had a lightly compressed softness to the tone. Pure sex, even with an unmounted 10" speaker! The KT66, by contrast, is a more American sound I guess - the breakup is a little less fuzzy, and has a bit more edge to it. Both clean up nicely, BTW.

So anyway, a digression from soldering...it's time to start with the woodworking end of things. I had not yet removed the back of the speaker cab I was converting...and when I did, I saw it was going to be a bit more of a challenge than I first thought.

The rear cover was screwed on all the way around. I took all those out...and the back doesn't come off. :? On closer inspection, I see that all four corners of the board are actually under the edge of the ball corner hardware. :roll:

Sigh...OK, so I took off two of them and managed to get it out. (Note to self: sand the fscking corner points off the back panels!) So now I see that there is a whole other layer behind this, like a big TV front:

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and THAT is going to be in the way of the amp chassis. (It also definitely removed any fantasies about Tolexing this thing - stain it is.) In order to have this thing flush with the rear panel, I have to remove some of that wood. OK, not too impossible...but then I notice that Mr. Woodworker has the board actually embedded in routed slots all around the outer shell. :x

Time for surgery...so I decided to takeoff the top part of the "TV front", leaving the part in the corner to screw the cover on later.

I marked my targets and got out the old-school hand saw to cut as close as I could to the top:
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After I made the cuts there is still a little part I can't cut - so I start scoring an edge with a mallet & chisel:
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Around the 3rd pass, the rest of it starts to pop loose (and I see he hid a few staples in there as well):
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Finally, I cleaned out the bits in the slot. I think this will do the trick!
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Moving on to cutting the the rear panel: I trimmed off about 5 1/2 " to get rid of the cutout for the speaker jacks, which is no longer needed. That left me with an 11" board; I cut again to 6 1/2" for the top panel to cover the electronics & part of the tubes, and the rest goes to the bottom (the "bucket" :D )
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And that was a night's work for me. Tomorrow I hope to get a coat of stain on the thing, and get that switched resistor in place.

Side note (as if I haven't posted enough pix in this post already): I have another project I'll be starting as soon as the amp is done: re-housing an old rotating speaker I pulled from a Hammond organ many moons ago. While I was screwing around in the shop I installed a new 8" BBQ alnico speaker for it. The plan is to yank the chassis of my Champion 600 and build it into a cabinet surrounding this thing.

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Should be interesting. :bugeye:


Last edited by willowhaus on Wed Apr 06, 2011 12:44 am, edited 1 time in total.

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PostPosted: Wed Mar 23, 2011 7:28 am 
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Just a short update (because I'm sure you're all on the edge of your seats here... :D ). Tonight's fun included removing the cabinet hardware, cutting the notch in the top of the box for the amp controls, and my first foray with a router on the edges of said cutout. Only one minor screw-up there: I did it freehand, which was fine except that I forgot about the notch in the wood where I'd removed part of the "TV front" panel...so the guide tip on the rounding bit suddenly had nothing under it, causing me to dig out a bit more than I meant to. :oops: Luckily, it wasn't too bad, so I built it back up with some wood filler after cutting a couple of inserts for that slot (wish I'd thought of that first... :evil: ). I think it will work out OK.

On the amp side: I decided not to mess with drilling another hole for a third switch, so I wired the resistor I needed to the unused side of the output transformer switch which works fine. So, I'm committed to using a KT66 and not a 6L6, but I can still switch between an EL34 and a 6v6 for different character so - screw it. :P

Also made some P-Touch labels for the back panel, so I can remember which switch positions are for what tube. All that remains now is to replace the 1M linear switched pot with the broken shaft - had to mail-order it, nobody around here had one - and it's DONE (the amp, anyway...).

Back to work tonight...weekend's over. :wave:


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PostPosted: Tue Mar 29, 2011 4:04 am 
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Tonight's activity: Grid resistor fix, replacing the Power Level pot (part of the split shaft broke off, replaced with a solid one) and staining the cabinet. 8) I hope to have her finished before Friday - I have a gig, and if everything comes together she's going to make her public debut then. :thumbsup:


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PostPosted: Fri Apr 01, 2011 2:35 am 
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Well, the finish job ended up taking a bit longer that anticipated. It should be good by now, but I'm not going to get the amp done before my gig. :| Still have to finish:

Speaker grill - got a wooden frame built, but need to mount the cloth on it.
Mount amp in cabinet - holes drilled, just waiting to go in.
Mount speaker in cabinet - this is not so bad, because I managed to score a used Red Fang from a local store today! :thumbsup:
Reattach cabinet hardware - I'm a little worried about the handle. I think I'm going to have to get a shorter screw for it, because otherwise I think the power transformer is in the way. :?

So - one more day's work (and a trip to the other side of town to pick up the speaker...) and it should be ready. 8) Pics of the final product will be posted.


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PostPosted: Tue Apr 05, 2011 8:41 am 
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Lots of mediocre iphone pix ahead! :lol:

Picking up again tonight, I got to see how the cabinet finish came out:

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First order of business: cut & add supports to the grill cloth frame. Afterwards, I went all around it with the belt sander to smooth out the edges:

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While the glue dried I put on the feet, corners, and handle. Had to trim the ends off of the handle screws, otherwise one of them would have been in the way of the power transformer:

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Next, I got the chassis mounted in the cab (sorry for the crappy photo). Notice the artistic splooges of stain inside the bottom of the cab. Also notice me, not giving a damn:

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On to the grill cloth:

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It came out really nice...but then, when I fitted it into the cabinet, I suddenly remembered something I forgot to do :oops: so...
I took all the staples out & got out the paint:

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Time for a break, watched a Star Trek TNG rerun to let crap dry, then back to work. I bought a second-hand Red Fang this past weekend to mount in this thing. The dude who had it last had it sloppily soldered in, so after I cleaned up the terminals I mounted it in the box:

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Reattached the grill cloth to the frame:

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Not too bad, although the tensioning could have been better. Could have also been from shoving it into the amp - it was so tight I had to use a mallet to get it in there! Anyhow, screw it. Works for me:

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I noticed that the screws for the back panel were quite long. They must have been protruding into the box :? so I added a little more wood so there wouldn't be any sharp points sticking out. (In case you didn't know this, quick-grip clamps are absolutely essential! :thumbsup: ):

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And finally, I drilled the new holes for the back panels & put them on. That's the Gold Lion KT66 peeking out of there:

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And that's it! I fired it up & tried it out with my PRS in the shed for awhile. With the KT66 it's in solid Fender territory, very spanky with the single coils, and the Z90 I have in the bridge breaks it up nicely. With the 'Tude control was pretty fuzz-y, might not need all these pedals now... :mrgreen:

With the EL34 in the cleans were nice, a subtle difference in character - but in 'Tude mode it was more like a big-ass Marshall! full-on rawk tones from a combo - very nice!! :kool:

I'll get some clips up when I get a chance. I'm definitely looking forward to playing with this puppy, and damn glad I built it! Thanks to everyone who helped out, and especially Stephen for getting this all together. I'm a very happy man today! :thumbsup:


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PostPosted: Tue Apr 05, 2011 11:25 am 
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willowhaus wrote:
With the EL34 in the cleans were nice, a subtle difference in character - but in 'Tude mode it was more like a big-ass Marshall! full-on rawk tones from a combo - very nice!!


Congrats on your build. I actually have yet to plug in the EL34 but it's in the plan! We do want the 'big-ass Marshall! full-on rawk tone'

We stretch the grill cloth stapleing on the short side side, then using clamps every 4 in. clamp the cloth between two long 1/2" or 3/4" boards, stretching it evenly and staple it. Then repeat on the other side. Works nicely.

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PostPosted: Tue Apr 05, 2011 2:39 pm 
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Nice work!

Per my previous posts, I think the Red Fang & Tramp were made for each other. Of the speakers I've tried it covers so many tonal bases well, some exceptionally well, and a couple leave me slack-jawed & drooling. I didn't get to try it with an EL34, but I bet it truly is a monster. I'll be making that a switchable option when I build another one.

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PostPosted: Tue Apr 05, 2011 3:47 pm 
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willowhaus wrote:
I bought a second-hand Red Fang this past weekend to mount in this thing.

I bet that sounds pretty sweet! :D

willowhaus wrote:
in 'Tude mode it was more like a big-ass Marshall! full-on rawk tones from a combo - very nice!! :kool:

Awesome!! :thumbsup: :D That was in fact one my design objectives. :mrgreen:

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PostPosted: Tue Apr 05, 2011 7:37 pm 
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would that be a 10 or 12 in Red Fang in there?

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PostPosted: Tue Apr 05, 2011 9:49 pm 
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It's a 12". Pushes a lot of bass for a single speaker.


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PostPosted: Tue Apr 05, 2011 10:37 pm 
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Oooh, that's killer. What size is the cab? Same as the Trinity Tramp cab ?

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PostPosted: Wed Apr 06, 2011 12:39 am 
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Probably a bit bigger - it's approx. 22"w by 18"h by 12" deep. It's made out of 1/2" ply, so subtract 1 for the interior dimensions. It was a closed-back cab, but I have a 6" opening across the back.


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