2nd Gen Build Started (that didn’t take long…)

[Raoul Duke]

So far I don’t have a preference.

“In” - standard 2nd gen bass pot configuration sounds very black panel Fender to me in clean, but a little boomy/hollow in the bottom in OD. “Out” with the .002 cap bypassed like 3rd gen has a more hi-fi/less scooped clean and the OD sounds more ‘70’s mid focused.

Out with the deep switch engaged downright chugs like Steve Jones 30 years ago.

Funny enough - I found a spot on the OD entrance trimmer that sounded good to me, so I measured the pot and ended up right around the stock value. Liking the 12AT7 so far as well.

Should also mention that I ran the 8ohm EV12L on the 4 ohm out and that sounded great as well. Almost too many good sounds in this thing.

[Raoul Duke]

‘Nuther day of break in and I made a change in V2: started with a Sovtek 12AX7WXT that averaged about 200-202vdc on the plates, sounded ok - kind of harsh - but ok for OD.

Today I swapped it for an ANOS National 12AX7 made in Yugoslavia which lowered the plates by ~ 6-8vdc and really smoothed out the OD. Sounds pretty good! Probably leave it.

Power tube voltage and bias is staying right where I set it a couple of days ago: ~448 on the plates biased at ~42ma. Staying consistent

Loving this amp! Once the 3w 3k3 wire wound shows up - I’ll swap that for the 3w MF that’s in there now and throw it into the cab for the thread-ending final picture

[Raoul Duke]

Here it is.
A huuuge “thank you” to all the folks who offered advice/comments/help! I could not have done it without all the expert guidance I get on this forum and I truly appreciate it! And of course thanks to Martin for the “new” board design, technical help, and patience!
Time to spend more time playing them

IMG_0205.jpeg

[dbharris]

Looks great!

[ijedouglas]

Very nice!

[bepone]

nice , some clips will be?

[Raoul Duke]

Thanks Ian and Dan,
I couldn’t have done it without both your helpful guidance!

Thank you as well bepone, I may try to make some clips to hang up here.

I appreciate the kind words guys

[erwin_ve]

Looks terrific! Good job on the footswitch, looks great.
Cheers!

Erwin

[timrobertson100]

Beautiful result. Congratulations

[Raoul Duke]

Thanks Erwin and Tim; very much appreciated!
I did my best to capture the 2nd gen look and sound

[Raoul Duke]

Wanted to share some speaker testing info specific to this circuit for anyone who might be interested. Certainly not scientific, but used the same guitar/same settings on the amp and some quick-change 1/4” speaker cable adapters to make life easier and aid in comparison. Of course; these “are just, like, my opinion man”. Here’s what I found:

First tried the Altec 417-8C. Sounded hollow and a bit “tinny” overall. The clean was better, OD was a little loose; but neither were that great. Guess the Altec will stay in my ‘76 Boogie MkI where it actually sounds pretty good.

Then plugged in to the 2x12 with early 80s Celestion G12K85 and G12T75 that lives under my Vogel TW Express. It actually sounded great with the 2nd gen circuit. Clear, even response from both clean and OD; and it seemed to balance the channel volumes better. Interesting.

Next was a mid-80s Celestion G12M70. This speaker sounds “Ok” with many amps, but never “good” (or better) with anything. It actually sounded pretty good with this circuit as well. I may experiment further with this one.

Then onto an early 80’s silver label G12-80. More mids, enhanced “crunch” in OD. Clean was kind of flat. Not bad, but not as interesting as the previous two Celestion tests.

Also tried an Avatar A50 Alnico (sounded ok, but sort of “lifeless”) and the WGS ET65 cab under my 102 (sounded ok, but a bit muffled) - neither of which interested me at all.

Conclusion: EV12L is still the speaker; but the first two 80’s Celestion cabs will be tested further for sure.

[Dr d]

Great results, well done. Having just build a 2nd gen amp, it was interesting to follow your experiences. If I could make a comment on voltages, you may find this helpful. I found that the V1 and V2 plate voltages were particularly sensitive to the performance of the amp. With Hammond iron also, I found 2k2 > 27K > 2k2 (Tonys dropping string values) gave me 175-180v V1 and about 185 - 190v on V2. These voltages really opened up the amp and made it sing. Ge 12AX7As and balanced GE 12at7 sound really nice and yes, the EVM 12L is perfect for this amp. I am really impressed with the Hammond iron and the amp improves significantly as it burns in. Lovely amp. I hope this helps. Enjoy.
Ps. I much prefer the 3rd gen setting!

[bepone]

Now we are here, to most underrated point in guitar sound- speaker/spk cab combo!. Like the last filter in you singla chain, you are hearing what your speaker-cabinet allows!

Excellent idea is to play with the spekers.. the best sound D sound with small and simple speaker cabs (1x12") i get with G12-65 .. but also nowadays im testing often Jensens which are giving good results as well..

[Raoul Duke]

Great results, well done. Having just build a 2nd gen amp, it was interesting to follow your experiences. If I could make a comment on voltages, you may find this helpful. I found that the V1 and V2 plate voltages were particularly sensitive to the performance of the amp. With Hammond iron also, I found 2k2 > 27K > 2k2 (Tonys dropping string values) gave me 175-180v V1 and about 185 - 190v on V2. These voltages really opened up the amp and made it sing. Ge 12AX7As and balanced GE 12at7 sound really nice and yes, the EVM 12L is perfect for this amp. I am really impressed with the Hammond iron and the amp improves significantly as it burns in. Lovely amp. I hope this helps. Enjoy.
Ps. I much prefer the 3rd gen setting!

Thanks for the info Doc!

I’m still thinking of increasing the 3k3 I replaced the first dropping resistor with just because the line voltage seems to vary up to 8vAC. My V1 is sometimes 185, sometimes 192; and V2 can vary from 193 to 201. I’m leaning toward that resistor vs the B+5 because the voltage swing on the plates doesn’t really affect the tone - but the “feel” between 445vdc and 455 vdc is noticeable in the amp’s response. Very subtle, but certainly there.

I’m also starting to prefer the “bass knob pulled/3rd gen” sound as well.

[Raoul Duke]

Now we are here, to most underrated point in guitar sound- speaker/spk cab combo!. Like the last filter in you singla chain, you are hearing what your speaker-cabinet allows!

Excellent idea is to play with the spekers.. the best sound D sound with small and simple speaker cabs (1x12") i get with G12-65 .. but also nowadays im testing often Jensens which are giving good results as well..

Yes, definitely underrated!
It can be a rabbit hole - so I try to keep it as simplified as possible; make good notes and trust my ears - then second guess my choice about a month later, lol.

It’s all part of the fun