Just finished a 102 build, some questions

[beasleybodyshop]

Sounds like I just need to get off my are and build a Dumbleator already

I have a DOA vox lil night train with a 300V CT power transformer. Thinking about building one into the chassis of that and mounting it inside my cab for my 102 build.

[ayan]

I would have said that is a lot of HF taper for a Skyliner/RF preamp, but looking at your diagram, you apparently have a classic tone stack -- with the bass pot being 250K, the absence of the .001uF cap across the end lugs and the 1K tail resistor, all of which would otherwise thicken the sound... along with the .01uF mid cap on the board. I suppose the classic preamp coupled with 100K plate loads warrants more drastic measures. Are you using a 100K slope resistor?

Gil

I've found the #102 circuit works best with a D'lator in it's stock form, though the clean can be a bit dull for some people once the OD is smoothed out. The bright on clean mod works well for balancing that out.

Assuming you don't have a D'Lator, some easy things you might try are lowering the V1 and V2 plate voltages by increasing the V2 PS dropper and / or lifting the bright cap. Also, raising the bias current will generally lower the preamp voltages and soften things a bit, so that would be even easier to try.

I personally find the master bright cap to be a PITA if you're not going to just leave the master at a fixed setting. The amp becomes a tonal moving target with different playing volumes. I like what it does in conjunction with the D'Lator in the stock circuit, though. I had the same problem with the loop network filter but in reverse... and the HF taper too (changing OD gain would take me out of the sweet spot), but I fixed that with this circuit:

https://tubeamparchive.com/download/file.php?id=39706

So far, the above (in combination with low plates) is my favorite fix for the bright OD / dull clean issue.

-Aaron

[talbany]

Hello everyone, I just finished building a 50W 102 from fender bassman iron. I have stayed true to the layout/schematic component values, used 6PS caps and mostly RN65 metal films throughout. As per the layout document, i adjusted the OD trimmer entrance to roughly 25K with respect to ground, and adjusted the PI trimmer so the that PI output AC voltage is the same on both sides. Preamp plates are 201/200 for V1, 210/217 for V2. PI plates are both right at 300 volts. Bias is adjusted to 30ma @ 460V plates.

My first impression is woah, this amp is bright. Even with my Les Paul. Clean tone is great, very articulate to my ear. OD channel sounds a little harsh to my ear. overdrive has a bit of a ragged edge to it, has anyone experienced this? Any remedies for this? Any any remedies to tame the brightness ? Thanks Everyone. Mark Fowler and Jelle Welagen have been big influences on me building this 102, big thanks goes out to them for inspiration and everyone else on TAG that has been patient with me over the last few years.

I remember reading a write up a while back where someone interviewed Michael Anthony (Bass Player for VH) and asked him what he remembered about doing those sessions for VH1 and in particular Eddies (grail tone).He replied the only thing I really remember about that was his sound was really bright (loud)..Listen to Robben on the live Paris show and hear how bright the amp was that night, especially with his Tele..I've seen Robben and 102 on a number of occasions and think that amp is pretty bright but given the age of the amp (well broken in) it is pretty smooth..
Fresh builds can sound a bit harsh!..If you play the crap out of it for about a year I'll bet your opinion on that subject will change..
If you play out live...In a band setting with the amp a ways back you really don't seem to notice a bit of grit in the tone and in general if you think an amp is a bit bright where your standing by the time it mixes in with the band and through the PA and gets out it sounds great (especially with horns) ..It's where we live

https://www.youtube.com/watch?v=XUOA_7tInfw

Something else to consider while your shunting highs to ground I guess..
If you don't play out or record...Have at it..

Tony

[aflynt]

I would have said that is a lot of HF taper for a Skyliner/RF preamp, but looking at your diagram, you apparently have a classic tone stack -- with the bass pot being 250K, the absence of the .001uF cap across the end lugs and the 1K tail resistor, all of which would otherwise thicken the sound... along with the .01uF mid cap on the board. I suppose the classic preamp coupled with 100K plate loads warrants more drastic measures. Are you using a 100K slope resistor?

Gil

I've got that in two amps right now. A Low plate classic (100k slope) and a low plate Skyliner (low plate 102, integrated loop, no master - 470k/560k fixed divider, no master bright). The latter Sklyliner is actually my favorite sounding amp right now. It's still plenty bright even with a built in loop. I haven't tried the the HF taper with high plates, though. I imagine that would indeed require less taper.

-Aaron

Oh - that second amp also has a 250k bass pot with 5.6k tail. Still a .001uF across the pot though. I did that on both my 102 builds with new parts since they sounded too boomy in the low end for my tastes.

[CHIP]

I saw Robben last May, small venue, #102, no dumblator and sitting back about 5 rows from the stage the amp didn't sound annoyingly bright to me. It sounded pretty good.
Probably see him again this April.

I noticed my 4 year old 100 watt ODS copy has really smoothed out in the last year. It has finally got to where I wanted it to be to begin with.

Lotta tweaks along the way!

[Charlie Wilson]

Chip, do you think your amp has smoothed out by breaking in or because of the tweaks?
CW

[jam-mill]

My amp was really kind of bright sounding; too much for my taste anyway. So, I'd read about the HF Taper and recommended values were 500K and 0.001u for the pot and capacitor. Tried these values and they did not work for me.

Charlie Wilson subsequently posted a picture of the HF Taper in #094 ( https://tubeamparchive.com/viewtopic.ph ... 573#320573) and it showed a 0.02u cap and that encouraged a test with a larger cap.

Well, 0.01u and 500K was way too much treble bleed for me. Substituted a .0022u and that combination has been perfect. The pot is mounted on the front panel to allow easy adjustment to accommodate the performance situation.

I will submit that there seems to be a bit of loading on the OD with the HF Taper engaged.

-jack

[CHIP]

Chip, do you think your amp has smoothed out by breaking in or because of the tweaks?

CW

Charlie,
I'd say a little of both.
My amp started out as a #183 copy.
Now it's kind of a mix of #183 and #102. still has EL 34 power tubes.

changed the OD drive and level pots to 100k CTS.
put in 30% vol and master pots.

I put in a HF taper similar to Aarons, but didn't put in a dual gang pot.

speaker choice made a difference for me. My amp likes a WGS ET 90.
finding the right tubes for the preamp also makes a difference.

I've used some NOS parts in varying places, but good sounding amps have been built without going down that road.

As Tony said breakin time does have an effect. IMO.

All I can say is tweak things until your happy with the sound of your amp.

[beasleybodyshop]

I installed a .001uf in series with a 250K trimmer over the level control. I set it to about 100K and it took just enough edge off! Man this thing sounds really good now. The HF taper was just the ticket! Thanks everyone.

[carpediemgr]

you exaggerate on RN65 use ...
V1 inputs
slope resistor
Bias splitter resistors
negative feedback resistor

would be more musical and warm with carbon film ...

[beasleybodyshop]

Ive been leaving the amp plugged into a dummy load and signal generator running it at about noon on all the controls overnight.

Going to do it a few more times and see if my artificial break in does anything to help!