Kudos to Todd Shock, Wakarusa Amplification

I have this cool eBay gem of an amp I got for dirt cheap a couple years ago. It's an Airline (Valco) Model 9131A. It's a huge sized dual 6L6GC head, probably about 35-40 watts. Two channel, reverb (6V6 driven of all things) and trem. It's in VERY nice condition.

It did however need some serious work on channel two which was so muffled and muddy that it sounded like a cap or more went south while Channel One (the inside most channel, amp can be seen in my album link) sounded preety decent but maybe a bit hi fi.

Todd was very busy with this amp as the job list below will attest:

- Inspect channel 2 (component values, etc.). Sounds

muddy/unfocused compared to Ch2
- Basic upkeep on ch 1
- Replace electrolytics, discretes installed in chassis are OK
- Inspect tremolo (low priority)
- Inspect reverb - sounds weak
Comments:
- All electrolytics replaced. Multi-section cans shorted and safed but
left installed for appearance. Discrete caps installed internally as
substitute.
- Most ceramics (particularly coupling and tone stacks) replaced
with metalized polypropylene film type (approved via e-mail).
- Replaced most pre-amp plate load and channel mix resistors
- Replaced input circuit with hi/lo topology and shorting jacks.
Counting from front left jacks 1 & 3 are 'Hi' input, jacks 2 & 4 are
'Lo' (3dB down). Shorting jacks eliminate RFI/stray noise when
channel not in use.
- Tremolo tested and operating correctly after maintenance.
- Reverb tested and operating correctly after maintenance.
- Correct output impedance is 4 ohms
- Channel 2:
-- removed non-standard 0.1uF shunt cap. Muddiness eliminated,
high noise level revealed
-- replaced 2nd gain stage grid lead with shielded coax to cure
high noise level.
Changed both 1st gain stage cathode bypasses to 0.22uF poly.


Increases bass response in Ch 1, corrects factory mistake in Ch 2.
- Changed 0.0033uF phase inverter output coupling caps to
0.0068uF for improved upper bass/lower mid response.
- Noted both volume pots are wired backwards from the factory. No
harm done, so left as-is.
2 Terminal Strip 6 Lug
2 Vishay/Sprague Atom TVA 40uF 500V
2 Vishay/Sprague Atom TVA 20uF 500V
4 Switchcraft 1/4" Female Phone Shorting Jack (12A)
4 Resistor Carbon Film 1W 82K
2 Resistor Carbon Film 1W 150K
1 Capacitor Orange Drop 715P 0.001uF 600V
1 Capacitor Orange Drop 715P 0.0022uF 600V
4 Capacitor Orange Drop 715P 0.0033uF 600V
2 Capacitor Orange Drop 715P 0.0068uF 600V
6 Capacitor Orange Drop 715P 0.022uF 400V
2 Capacitor Orange Drop 715P 0.047uF 400V
1 Capacitor Mallory 150 0.047uF 630V
3 Capacitor Orange Drop 715P 0.1uF 400V
2 Capacitor Polyester 0.22uF 63V
2 Capacitor Electrolytic 6.8uF 63V
1 Capacitor Electrolytic Hi Temp 10uF 16V 105C
2 Capacitor Electrolytic 50uF 50V
1 Capacitor Electrolytic Hi Temp 220uF 10V 105C
2 Resistor Carbon Film 1W 2K2
1 Resistor Carbon Film 1W 68K


2 Resistor Carbon Film 1W 100K
2 Resistor Carbon Film 1W 270K
4 Resistor Carbon Film 1W 470K

I know we have a slew of fantastic technicians here but I have the chance to give recognition to one of them first hand right now and Todd does fantastic work. We all expect that, I suspect, but the experience was great, the communication was clear and the outcome was awesome. This amp is ready for 30-40 more years now with world class tone.

The voicing work he did is more than I expected. I had a hard time deciding which channel to stay on because each has it's own flavor without a doubt. This amp is just plain sweet sounding.

I played it through a JDesign 2x10 with two Weber 10F150s and a JDesign 2x12 with a Weber 12A125 and 12F125 and the amp has an ext. speaker jack so imagine this beautiful sounding amp through both cabs Everything works as designed and she sounds killer! I'm thrilled because counting Todd's service fees and shipping, I'm in for right around $550 (minus tubes) for this amp. and the amp functions as new.

Todd, great job.

Wakarusa is highly recommended.
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The top of that Brown Super is quite nice! I love vintage amp petroglyphs a lot! But then, that looks more like a DNA readout

 

Thanks for the history lesson Amps like that tell someone's story for sure. I have a few myself . . .

 

YIKES, indeed!

I failed to mention that the tubes I sent with the amp to Todd were a pair of tiring GE's. The amp is cathode biased.

Tonight, I installed a pair of perfectly matched JAN Philips 7581A's I snagged from KCA awhile ago (for good measure and Mike, I'm coming back for more) and I'm almost speechless from how awesome this amp sounds with those power tubes. I have a pair of GE's and RCA BP's too and I'm not even going to install them yet. I don't want to ruin this tone. Even if due to my fickleness.

For preamps I have a Valvo in V1 and a Telefunken ribbed (less hi fi than smooth I think) in V2 right now. This may all change too after the jam this weekend.

Todd,

Channel Two just slays me to tears. That was the totally unusable channel but the harmonics and sustain are unreal now. With a high gain humbucker guitar, you'd think you were in Winterland in the good old days.

Channel One is way better than it was back when I thought it sounded really good.

And the hi/lo inputs are perfect. I almost hear some BF clean in Channel Two through the LO input. Nice and sparkly and it has that awesome decaying tube swirl.

The Suhr through this thing only brought on a multiple Had to wash up

The only problem right now, and call it a honeymoon for now if you must, is this Airline, through the JDesign 2x12 with a Weber 12A125 and 12F125 "feels" like my best sounding combination out of all my amps right now, by far, and I have a couple handfuls of amps.

I wish everyone could hear it live. It's really nice and clips just can't depict what this rig sounds like in person.

Thanks again for the refurb, Todd.