Les’ Sustain for Days

Gibson Les Paul TraditionalA couple months ago, I had an unexpected revelation.  An eye-opening, earth-shaking, revolutionary enlightenment.   Ok, maybe I’m exaggerating and obsessing, but it was an honest-to-goodness WTF!

I was at a local music shop (ok, I admit it was Best Buy), and out of curiosity, I picked up an absurdly expensive Gibson Les Paul Traditional from the wall-o-guitars, plugged it into a Vox Night Train, and gave it a spin.  I’ve never really given the Les Paul guitars much attention.  Despite their iconic status and near ubiquity, I’ve always thought the Les Paul was just too heavy to consider. But…

I was shocked! This guitar had so much sustain, it felt like there must be an active sustainer circuit in there.  But no- just passive ‘57 Classic humbuckers, a Nashville Tune-o-matic, and a whole bunch of mahogany and maple.  I was stunned. I always thought my G&L ASAT III with its Saddle-Lock bridge and my Vox SSC-55 with its MaxConnect bridge both had reasonably good sustain, but this was in a whole ‘nother league.   It actually felt like a different breed of instrument, one that may even require a different playing style to accommodate and leverage such an impressive sustain.  And those 57 Classics sounded fantastic!

So, ok, I walked out of there telling Chunling “Wow- that was mind-blowing.  But $2400, forget about it!!”  I convinced myself to let it go, and stopped thinking about it. Until…

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What’s In The Cabinet?

What’s in an amp cabinet?   As it turns out, quite a lot.  In this video I do an experiment with the same two AC15 amps as in my last video– the AC15C1 Custom, and the AC15HW1 hand-wired.

G12M-GREENBACK-8Both amps use the same Celestion Greenback G12M speaker, and these two here have each been played about the same amount, so they should be “broken in” evenly.  Now, by disconnecting the wires from the two speakers, and routing them through an AB box to the external speaker output of one the amps, I can isolate a single amplifier circuit, and hear it through both cabinets in turn.   In this way, we can first listen to the AC15C1 amp circuit through its own cabinet, and then listen to that same AC15C1 amp circuit through the AC15HW1 cabinet.   Switching back and forth really highlights the different sound character provided by the two cabinets.

2011-02-08-VOX-AC15-high-frequency-diffuser-004Why so different?  The AC15HW1 cabinet is obviously larger, which provides a bigger resonant cavity.  It’s also built with birch plywood which is lighter weight and perhaps more resonant than the denser MDF used in the Custom.   Another important difference is the high frequency diffuser used in the AC15HW1 which really softens the high-end.  In the video, I also experiment taping a makeshift little diffuser over the AC15C1 cabinet to see what happens.

Vox AC15 Comparison

In this video, I review and compare these two excellent Vox AC15 amps, the AC15C1 Custom, and the AC15HW1 hand-wired.

These amps are similar in many respects:

Celestion Greenback G12MVox AC15HW1 Tubes

  • same Celestion Greenback G12M speaker
  • same preamp and power amp tube complement (3 12AX7’s and 2 EL84’s)
  • same two channels: Normal and Top Boost.
  • same tone cut and interactive EQ controls
  • same weight – 48 pounds. Handwired is larger but birch plywood is lighter than MDF
  • same AC15 legacy and tradition
  • However, there are some obvious differences:

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    What the Bleedin’ Treble!

    In part one of this, video I explain what treble bleed is, and how to evaluate and select the right cap.  I demonstrate my G&L ASAT III which has a treble bleed cap on the master volume, and I compare that with my Epiphone Riviera P93 which has no treble bleed caps (yet).

    IMG_3475

    The caps I tried are (as shown left to right): Silver Mica 100pf, 390pf and 1000pf, a tiny 1000pf ceramic cap, and Sprague Orange Drop (polypropylene) 1000pf, 3300pf, and 6800pf.

    The tolerances on the caps are a bit all over the place.  I measured the 1000pf caps on my DMM and all were closer to 1250.  The 100pf silver mica was over 250!  This is assuming I can trust my Mastech DMM.

     

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