A new 102

[Colossal]

Finished a 102. Thanks to Taylor for the nice chassis and boards, and to Jelle for the Draloric resistor set. Classictone Twin transformers and a Mercury Showman choke. JJ 6L6s running at 480V. It's been burning in and is opening up nicely. Very bouncy and plump cleans.

102 Guts.png

102 Cab.png

[telentubes]

Very nice indeed!

[xtian]

Immaculate lead dress, Dave. I’m making notes.

[Chris Brown]

Very nice!! I love my 102... that amp will serve you well for many years to come.

[andresound]

Nice work

[erwin_ve]

Look great and clean inside!
What about the footswitch leds: that is looking cool!

[martin manning]

Super clean, Dave!

[amplifiednation]

lead dress is outstanding! Wow man. I love the twisted bus bar and twisted output transformer secondaries. Makes it look even nicer!

How on earth did you get the powdercoat off in perfect circles?

[ericlc]

Looks great. Congratulations.

[Colossal]

lead dress is outstanding! Wow man. I love the twisted bus bar and twisted output transformer secondaries. Makes it look even nicer!

How on earth did you get the powdercoat off in perfect circles?

Thanks for all the nice words guys. This amp is for someone else.

Taylor, I did not modify the chassis. I used #4 washers under the nylock nuts so they wouldn't bite into the powdercoat. The grainy photo is probably giving the illusion that the powder is modified. Sorry about that.

Erwin, the footswitches are available with an LED ring in the bezel. Pretty cool! You just hook them up as usual with your 5VDC source and use the 1k dropping resistor on the 5VDC supply board.

Some general notes...I tried to stay very close to Tony's 102 layout but it's still a bit of a mashup with colors here and there. I had a 2.2uF film cap on hand and used that for the Presence cap. So far I like it and the knob has a very useable sweep. I may get a tantalum to test. Overall, I'm quite happy with sound. The amp is very quiet, aside from the usual hiss; no hum or buzz at idle. Each of the switched functions adds a nice flavor. Bright adds quite bit of gain. The ceramic cap is from Jelle and is very smooth. The whole amp is very smooth, in fact. I have not added any bright cap on the Master (yet). I am finding it quite nice, as is. It's not overly bright or strident, but just very full, well balanced, and clear. Playing it, I have the Preamp set at 6 and Rock mode and that gets it breathing. Using a 57 Goldtop reissue with low output pickups, the low end is very plump but never losing articulation. Single notes are really musical and piano like. Bouncy and bubbly comes to mind with a very well-mannered and focused midrange. There is a lot of range in the TMB controls and small changes do change the sound. I have been running TMB all at 5 for now. For the Bass pot, I strapped I think 470k across 1M to get a 300k pot. There is plenty of bass on tap and the range of the pot turned out very good. I bought some 300k pots, but their precision was poor and I ended up with 250k pots . So I made the 300k pot and that worked well. I really like what the LNFB loop does. 10M Dralorics and a met polyester cap there. I did have a bad coaxial lead on the OD channel initially; a dead short from the shield to the conductor. Not sure how I managed that, but got it sorted.

For tuning, I set the inverting side of the PI to about 6-7V higher than the non-inverting side. The OD entrance trimmer is set around 20-30k to ground. I opened it up to where 3 1/2 on Drive and 3 1/2 on OD Vol sounds like the Preamp, but with a volume boost and you get some OD when you dig in a little. It's pretty closely balanced. With the OD set this way you hear the midrange kick in and you get more glow and hair on the note without losing clarity. I may need to get in there and fiddle around a bit more though.

For tubes, I rolled a bunch of POS 12AX7 (current production ) but settled on three Mullard 12AX7 reissues. JJ gold pins or TungSols or a mix of each, had their own sound but it moved away from the Dumble sound. The Mullard long plates seem to capture the essence of that very recognizable 102 RF tone... the plump lows and the sweet, bell-like top end. Power tubes are a matched quad of JJ 6L6GCs. They are running at 480V on the plates, 477V screens, 32-33mA apiece and -52V bias.

[norburybrook]

beautiful work Dave

I noticed the footswitch LED rings too Erwin

#102 is a great amp, I'm debating putting the LNFB on my current build as I too like what it does to the clean. It's easy to have it on a switch too.


when I start a build it always looks like this in my mind.......it never ends up there ....Great build . Inspiring.


M

[Colossal]

beautiful work Dave

I noticed the footswitch LED rings too Erwin

#102 is a great amp, I'm debating putting the LNFB on my current build as I too like what it does to the clean. It's easy to have it on a switch too.


when I start a build it always looks like this in my mind.......it never ends up there ....Great build . Inspiring.


M

Thanks a lot, Marcus. Much appreciated. It did take me a while to wire this one. It is pretty painstaking, as you well know. I'm happy with it though and it's sounding quite good. I may play with the OD and PI balance a bit more but it's sounding pretty thick and airy and will start to bloom at low settings on the Master. Very touch sensitive and easy under the fingers. The PT is the dual voltage Classictone Twin. I opted for the higher voltage tap and liking it so far. Preamp voltages are quite close. My mains voltages run a bit toasty too so I might knock it back with a variac and reassess.

I have another chassis, board set, set of Dralorics, and 416s. I thought if this one turned out well, I may build a keeper for myself. I will go the extra mile on that one and try to get a few more HAD-accurate parts to complement what I have. The devil is in the details.

Dave

[pompeiisneaks]

Indeed that is an incredible build, looks like a work of art! Well done!

~Phil

[M Fowler]

Dave,

I can't even tell that you have been in there tuning this sweet beast, so clean.

Mark

[Colossal]

Thanks Phil and Mark! Alcohol was my friend during cleanup; the cleaning kind, not the drinking kind.