Made some progress over the past few days.
I got my relay supply transformer mounted. I then wired up the XLR jack and the rear switches.
I installed and wired the bias supply and pot. I neglected to order 27k resistors, so I substituted a 22k resistor for now. Come to think about it, I have some 24k resistors as well that are a little closer to the original...maybe I will swap that out.
Does anyone think I will encounter problems not using the 27k resistor? If my thinking is correct, I will have a slightly higher bias voltage range with the lower value resistor, correct?
I was also able to get the power tubes wired up as well. Next step is to start wiring on the preamp side..... I will most likely start with the shielded runs. I am going to use RG316 coax for these. It measures out at about 29pF/foot, so I think that should be decent.
Had first power-up yesterday and....no flames - excellent. I even got sound out of it.
Clean channel is excellent, very sparkly and clear.
Overdrive is a little harsher that I was expecting, not quote the smooth singing tones that I have heard in some clips. Hopefully I can poke around a bit and maybe mess with lead dress a bit to smooth that out.....
Can't wait to get a head cabinet and matching 2x12....
I have 2 G12-65s ready to go.
Looks fantastic! A few suggestions, if you dont mind. Firstly, you might want alter your lead dress a little...especially on the OD tube. The cathode wires want to run parallel for @ 1" at least. Have a look at other builders lead dress (eg. Gill Ayan, Funk and HAD!!!). This might help to smooth out the OD a little. You may know, the original #124 had its OD trigger set at @100ohms from wiper to ground. Adjust the trimmer with care to get the sound you like (in general, the higher the gain setting, the fizzier the sound). Finally, you might want to use cable ties to neaten up the cable run from the speaker jacks to underneath the board. Hope this helps. Great amp to do!!!
Yes, aside from some minor lead dress adjustment, be sure just to play the amp a lot to break it in.
You can check your voltages so you have 190-200 on V1 and around 200v on V2.
Try to keep those voltages in that range for smoothest tone.
On V3 the PI, keep voltages up around 290-300.
When adjusting dropping string, start with the PI node.
Thanks for the suggestions.
Structo, those voltages sound pretty close, except I think my PI is around 280-283....
I will measure tonight and report back. The mid switch cap is a 300pf ceramic, as per the original schematic.
So my cabs arrived today. I went with the classic black/black look. Photos are below.
Amp sounds excellent with the proper speakers, my initial power up tests were with some alnico 10s that weren't really suited to this amp. with the 2 g12-65s in this thing, it sounds great. Needs to smooth out the od a bit, but I am hopefull that will occur with break in.
Super100 here built the cabs and they are top notch. I would definitely recommend his work to anyone in the market.
steve_p wrote:So my cabs arrived today. I went with the classic black/black look. Photos are below.
Amp sounds excellent with the proper speakers, my initial power up tests were with some alnico 10s that weren't really suited to this amp. with the 2 g12-65s in this thing, it sounds great. Needs to smooth out the od a bit, but I am hopefull that will occur with break in.
Super100 here built the cabs and they are top notch. I would definitely recommend his work to anyone in the market.
Definitely wait until you have a good many hours on it before judging the OD. I can't say for sure how many hours I have so far, but the amps about 4 months old and I swear the OD is still getting smoother, sweeter. The most dramatic was within the first 30 or so hours. After initial testing I also started out with new speakers, so I'm sure they're getting better all the time.
Did you ever adjust the wires for V2? Doing what Dr d suggests seems put a little mojo into the drive side.
Hi my name is Rich I am a rookie attempting the 124 build
and was looking at yours.
what did you use for filter caps and does the filter board schematic differ from the layout files found here?
The reason I ask is on the layout found here they have
2 300u/350 volt caps in series and I can not find caps
like this anywhere
echo44 wrote:Hi my name is Rich I am a rookie attempting the 124 build
and was looking at yours.
what did you use for filter caps and does the filter board schematic differ from the layout files found here?
The reason I ask is on the layout found here they have
2 300u/350 volt caps in series and I can not find caps
like this anywhere
Thanks
Rich
Hi,
I used (2) F&T 200uf - 300V axial for the first filtering stage. They are available from antique electronic supply.
The OD can be a bit tricky to dial in.
A lot of the time it is how you arrange the knobs.
Try to keep the pre-gain up around 12:00-1:00
Not sure about your amp but my treble pot rides around 2:00
Mids 12:00
Bass 9:00-10:00
OD
Drive 2:00
Volume 12:00-2:00
Presence I keep pretty low.
I run the amp through a 212 with two EVM12L.
If you don't have a Dumbleator I really recommend that you build one.
It really does help the overall tone of the amp.
It enables you to get your master volume up where it sounds better, then you control the overall volume with the Output pot on the Dumbleator.
I like a like a little reverb and delay on my tone (just a little to warm up the sound) so I have a TC G Sharp riding on the loop.
So with the amp Master around 1:00 I play at bedroom levels with the Output of the D'lator between 9:00 and 10:00 at which point it starts getting pretty loud.
Hi Tom,
Thanks for the feedback on the settings. I am just getting ready to start a dumbleator build. I am just trying to figure out what I want to use for a cabinet and power transformer.
I don't use a rack, so I don't really want a rackmount enclosure. I will probably go with the weber standalone reverb transformer for the power without the voltage doubler circuit.
I bought the cabs from a user here: super100
They are very nicely built and the pricing was excellent. He has ads in the classifieds from time to time, I highly suggest purchasing from him.
612]http://i674.photobucket.com/albums/vv10 ... AG0256.jpg[/img]
Great amp to do!!!
