UR12 wrote:
I'll try and get you another in the mail in the morning. I'll shoot you a PM. I probably should have mentioned this but you have to be very carefull about bending the leads coming out of the tubes. You need to stay about 1/8th of an inch from the base of the tube before you start bending or you may risk breaking the seal between the glass and the wire. I picked this little tidbit up from the tube data sheet the other day.
Important safety tip, campers!!! I must have man-handled the tube getting the leads aligned... dang it!
I installed the spring clip type of sockets, which don't seem to want to hold the tubes very well.... should I remove these sockets and put in the machined type???
Ron
I would probably leave those sockets on the board and solder the tubes onto a machined socket and then insert the tube (in the machined sockets ) into the sockets you have on the board. For what it's worth I broke one of my preamp tubes that I had soldered onto the board by man handeling the chassis in and out of the cab I built while trying to test it for fit. I now put all of mine in machinesd sockets. I have a few hundred 6112 tubes so not to worry. I'll send you a care package in the morning
Almost up and running with mine. Just waiting on a couple of bits to finsih it off. I have a bigger Mosfet for the VVR and a bigger heatsink which I might use instead. The pilot light is TW style and I still need to implement a drain resistor.
Still needs the cutout for the output jack. Still considering putting the jack on the back panel.
Filament voltages were 7.5v courtesy of the Hammond. Put 1ohms in to drop it for now until Mouser rescues me. They are sat at 5.7v now which was good enough to put a scope on it and look at a few signals
That had me wondering if a few testpoints on the pcb might be worthwhile to make it less fiddly measuring voltages / signals
I drilled the chassis which was good for some long forgotten English but time consuming. The punched chassis clearly wins out although I was pleased all the pot holes lined up well.
A couple of pics from early on in the build. I'll post a few more when I'm truly up and running.
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Lookin good! The replacement tube went out yesterday so hopefully it will be there before this weekend. What size resistor did you end up going with on the 3rd gain stage?
Thanks Dana.
I have a 47k in there right now but that might change. The scope suggests there is plenty on tap with that in. once I get to hear it, I will be more inclined to play with the value more.
Ron Worley wrote:So I fired it up..... thanks for the tube, Dana!
It works... but I have a very loud hum (checked all my grounds) and the tone controls don't seem very effective.
Any Ideas out there guys?? It sounds like 60 cycle hum...
Also, what are you biasing it at, I don't remember that value being stated... but we are 18 pages in to this thread....
The bias should be set about -32v. Which trannys are you using mine or the Hammonds? If it's the Hammonds then you will need to install a hum pot balance pot. If it is the Heyboers did you ground the CT of the heater winding. The green and yellow wire. A loud hum can also be because you have the bias set to high and the tubes are redplating.
I'm up and running. New tube showed up today ( thanks Dana)
A few butt joints and I have a place for the little beast to live. I might get round to decorating the cab, maybe not.
A clip or two then recorded on my digital camera. Hopefully I won't mess this up.
The zip has two files. Noodling
More to follow at some point.
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Very kool clips that little amps sounds fantastic so this is what we can expect. I better get my name on the Hallamplication order list so I can get one.
fishy wrote:I'm up and running. New tube showed up today ( thanks Dana)
A few butt joints and I have a place for the little beast to live. I might get round to decorating the cab, maybe not.
A clip or two then recorded on my digital camera. Hopefully I won't mess this up.
The zip has two files. Noodling
More to follow at some point.
Congrats!! That looks great! Love the lil cab . Thanks for the clips too they sound awesome. I am guessing that is with the 47k in the gain stage. Try swapping it out with a 82k or 100k and play the same thing again and I believe you willl be surprised at the amount of sustain you pick up. It will dirty up a little sooner but you should still be able to roll off your guitar vol and get some good cleans.
Very kool clips that little amps sounds fantastic so this is what we can expect. I better get my name on the Hallamplication order list so I can get one.
Mark
No List to get on. I have everything in stock an I am working feverishly trying to finish the build manual. As soon as that is done (Hopefully this weekend but don't hold me to that) I will be ready to turn Beelzebub Jr. loose on the world. I have a new slogan too. "Everybody Needs a Little Head"
Last edited by UR12 on Sat Mar 07, 2009 2:39 pm, edited 1 time in total.
Ron Worley wrote:Well, I have earned the dumb ass award...
SOMEHOW... I managed to mix up the pots and had the Volume and Presence mixed... 5K volume pot and 1M Presence probably didn't help much...
Anyway, I had to tear the amp apart to get that straightened out...
But now I have zero sound... more troubleshooting this weekend....
Damn, what a ding-bat..... More news as it happens....
Ron
Just keep at it and let us know if you need any help. You'll get there You can change out the Power control pot with the one I sent you while you have it apart so maybe some things happen for a reason. The great thing is that you can remove 5 wires from the board, remove all of the nuts and washers on the controls, Mosfet heatsink and the 4 screws holding the board in and it should come right out.
I am guessing that is with the 47k in the gain stage. Try swapping it out with a 82k or 100k and play the same thing again and I believe you willl be surprised at the amount of sustain you pick up. It will dirty up a little sooner but you should still be able to roll off your guitar vol and get some good cleans.
Yep, 47k right now biased around 34v. I plan on trying a few other values but I think it sounds pretty cool straight out the box so to speak. The chance of me playing the same thing twice is highly remote though
Very kool clips that little amps sounds fantastic so this is what we can expect. I better get my name on the Hallamplication order list so I can get one.
Thanks Mark. Its a cool Lil thing. Highly recommended.
I must have done something in the process..... I did swap out the the VVR pot with the 500K you sent... I suppose I now should recalculate the value of the LED resistor based on a 170V B+ versus.. 190.... right?
I just need to get out the meter and schematic and have at it the old fashioned way...
. Thanks for the clips too they sound awesome. 
I am guessing that is with the 47k in the gain stage. Try swapping it out with a 82k or 100k and play the same thing again and I believe you willl be surprised at the amount of sustain you pick up. It will dirty up a little sooner but you should still be able to roll off your guitar vol and get some good cleans.