102 as Lowplate Classic

[aflynt]

Hello!

I'm in the process of bringing my #102 clone back to something resembling the amp's Low Plate Classic configuration as originally shipped back in the early '80s. I realize that most likely nobody but HAD really knows for sure how the amp evolved circuit-wise, but I figured I'd put together a layout that has my (and hopefully other forum member's) best guesses as to what would make a good baseline for that particular build with Twin Iron and repro boards/chassis.

I've attached my layout with the deviations from the official High Plate Skyliner 102 layout in red text.

Some Possible Changes to Proposed Layout:
* 330pF Treble Cap - ceramic? higher value?
* 100k OD Trimmer - higher value?
* 100k OD Level and Ratio Pots - higher values?
* 5uF Cathode Bypass caps - higher values?

-Aaron


Clips of amp in originally proposed configuration (see "102 Low Plate Classic - Revision 2.pdf" below):
With Les Paul
http://youtu.be/SlS6J_9g1rc
With Strat
http://youtu.be/xi56ts6Kj0s

Clips of amp in tweaked configuration (see "102 Low Plate Classic - Tweaked.pdf" below):
With Les Paul
http://youtu.be/dc29A0q_nsI
With Strat
http://youtu.be/k_VFLvGMjtY
With Strat (miced through DAW)
http://youtu.be/cLoCJypWziA

[Charlie Wilson]

Hello, you did see Tony's layout for the Low Plate Classic. #124 pre Skyliner. I built it and it sounds great. A bright circuit. Think Stevie with a Strat. Pretty round on a humbucking neck pickup and very early Robben Ford mutted palm tone on a humbucking bridge. 25uf may be a bit much for bypass caps.
Cw

[aflynt]

Hello, you did see Tony's layout for the Low Plate Classic. #124 pre Skyliner. I built it and it sounds great. A bright circuit. Think Stevie with a Strat. Pretty round on a humbucking neck pickup and very early Robben Ford mutted palm tone on a humbucking bridge. 25uf may be a bit much for bypass caps.
Cw

Thanks for the report! I did see the 124 Low Plate Classic layout and used some of the values from that to fill in some unknowns on this one. I'm more or less trying to figure out if this makes sense as a viable 102 Lowplate Classic alternative to that one. I suppose I should probably just build my layout and report back first...

The bypass caps are 5uF, 25volt in the layout. I should probably put 5uF FIRST in the labels though because it is easy to think they are 25uF unless you zoom in.

-Aaron

[Charlie Wilson]

And I should probably put on my reading glasses before I look at layouts.
CW

[bluesfendermanblues]

Sounds extremely good!

[aflynt]

I converted my #102 clone to the layout above last night. I still need to spend more time getting a feel for it, but so far it seems extremely cool, but not quite as different as I expected. This is my first time playing through the Classic stack. I've only put it through my 2 Emi Delta Pro loaded Forte 3D 1x12 cabs using my tele so far.

The biggest difference is the response of the tone controls and switches. The midrange control is VERY active. It almost seems as though it would benefit from a 100k Audio as there's a ton of change in the first 1/3 of the rotation and not as much from 1/2 on. The treble control, on the other hand is more subtle and seems to effect a higher frequency range. The bass is similar to how it used to be with the Skyliner with the exception of being able to dial out more low end at the bottom of the sweep. The deep switch is neat for more of a scooped eq curve.

Once dialed in, the amp still seems very much a muscular, smooth OD kind of creature. The biggest difference being more clarity in the low end. It likes higher trimmer settings (38k right now), and sounds really great with the OD Level set around 2 1/2 for low gain sounds in addition to being very smooth and fat at higher settings too. To my ears, it's still not a "Fendery" kind of beast. There's a heaviness about the sound that seems to prevent it from really copping the blackface kind of clean. Pulling the mids or engaging the deep feels more like removing a piece out of the middle of a dense material, whereas Fenders seem to have more of a lighter airiness that's innate.

I'll report back in a day or two with more experiences and post clips. Now it's on to Christmas...

-Aaron

[Charlie Wilson]

Yeah Aaron, that is a pretty good description of how mine sounds also. After playing through a blackface Pro Reverb for the last 20 years with a Strat and Jazzmaster I do like having an amp that is a bit fatter sounding. Keep in mind that most Blackface have a .001 PI entrance cap and a 250pf treble cap and a 12AT7 PI tube. I like the sound of mine with the voltages on V1 around 190v and V2 right around but not less than 200v. Some guys like to reduce the V2b coupler to .02uf to trim the bass a bit. I like my OD trimmer at about 30k to ground(with amp on in OD mode). Did you end up using 5uf or 10uf for the clean channel bypass caps? Also did you find the amp to be rather bright, especially with a Tele? I am using a EVMS speaker with mine.
CW

[aflynt]

Yeah Aaron, that is a pretty good description of how mine sounds also. After playing through a blackface Pro Reverb for the last 20 years with a Strat and Jazzmaster I do like having an amp that is a bit fatter sounding. Keep in mind that most Blackface have a .001 PI entrance cap and a 250pf treble cap and a 12AT7 PI tube. I like the sound of mine with the voltages on V1 around 190v and V2 right around but not less than 200v. Some guys like to reduce the V2b coupler to .02uf to trim the bass a bit. I like my OD trimmer at about 30k to ground(with amp on in OD mode). Did you end up using 5uf or 10uf for the clean channel bypass caps? Also did you find the amp to be rather bright, especially with a Tele? I am using a EVMS speaker with mine.
CW

Hey Charlie!

I used 5uF on all the cathodes. The amp is actually fairly dark, though this guitar isn't quite as bright as other teles. The amp is using old '70s twin OT and choke and Piher resistors in a bunch of places. Not sure how much that has to do with it, though. The Delta Pros are quite a bit darker than EVs.

-Aaron

[gz34]

hi Aaron, thanks so much for this. was thinking about a low plate classic stack, 102 or 124, you've solved my problem. great layout, and so much information, real good of you to share. look forward to the sound clips. have a good Christmas.


terry.

[norburybrook]

Interesting thread as I'm about to start my 102 after Christmas.

Did you guys make your boards yourself? I've got a set of Marsh boards and the power supply board has eyelets for the two main caps and 3 smaller ones only. I'm going to have to mount the 4th smaller cap off board which is a bit clunky IMHO.


Anyway Merry Christmas to everyone

Marcus

[aflynt]

Did you guys make your boards yourself?

The layout above is adapted for the agbamps boards and cepedals chassis. I did my own ps board for this amp, but agbamps seems to have a similar "Classic" supply board available too now. I don't really know about the marsh boards. They're designed to fit a Ceriatone Chassis? If you want all the caps on one board you'll probably just have to make one yourself. It's not all that tricky if you've got a drill press.

-Aaron

[aflynt]

Played it some more with other guitars and cabs. A/B'd it with my other 102-in-a-box builds and my '68 Showman too. Overall, there's something about this iteration that I just don't like. On one hand it sounds kind of dull and woofy, but on the other hand it's a bit harsh. It can get bright at higher treble/presence settings, and it definitely has a lot of heavy low mids available. It just seems to be missing that refined clarity that I get from my other builds. There's a kind of papery, nasal, clackiness to the sound overall and the OD gets washed out and buzzy when you have it up beyond a low gain settings.

I'm going to try a higher value trimmer to see if that fills out the OD. Not sure what to do about that dull nasal thing, though. That nasal thing came about somewhere in the Skyline->Classic stack conversion. It still had a decent overal timbre after I converted to Low-Plate (which I did first). All the parts measured pretty close to value, IIRC. The furthest one off I measured was the slope (a 104k 1/2 watt Piher).

-Aaron

[aflynt]

Here's a clip of the amp in Lowplate Classic configuration with a Les Paul. Trimmer set to around 38k to ground w/od on. Starts out with OD level set around noon. Lower gain later and switch to clean. I engage the deep near the end.

http://youtu.be/SlS6J_9g1rc

-Aaron

[bluesfendermanblues]

Aaron,

Is this amp similar in configuraiton to your all-in-a-box 102? if so, does it have built in loop with cable compensation caps (180-200pf) and 68p on the master vol??

On my own 102, which has a classic stack, but high plates, the 68p didn't do much good with the classic stack. And also, IMO, the 102 need much more volume in order to 'open up'.

My Low plate 50w classic and #183 (with classic stack) - and off course tweedle deluxe with classic stack - are much more responsive at lower volume levels.

[ToneMerc]

Played it some more with other guitars and cabs. A/B'd it with my other 102-in-a-box builds and my '68 Showman too. Overall, there's something about this iteration that I just don't like. On one hand it sounds kind of dull and woofy, but on the other hand it's a bit harsh. It can get bright at higher treble/presence settings, and it definitely has a lot of heavy low mids available. It just seems to be missing that refined clarity that I get from my other builds. There's a kind of papery, nasal, clackiness to the sound overall and the OD gets washed out and buzzy when you have it up beyond a low gain settings.

I'm going to try a higher value trimmer to see if that fills out the OD. Not sure what to do about that dull nasal thing, though. That nasal thing came about somewhere in the Skyline->Classic stack conversion.

-Aaron

I've found that none of the circuits are " one stop shop" and there are compromises with each. I love the LPC for strat cleans, but not so much for the OD, unless it's the funky entrance , 12AT7 PI and the early GNFB, but that's a different rawer OD. Also, I like the LPSL with the Dumble PI for OD.

FWIW Aaron you would sound great through a Pignose and $69 Strat.

TM