BITMO BLUES J MOD KIT for the AMPEG J-20 GUITAR AMP

This is a great and often over-looked new guitar amp.

·         Hand wired with quality components (2nd picture shows stock circuit)

·         Great bias tremolo

·         Very cool looking - classic

·         Resonant cabinet and light to carry

Specs from Ampeg - RMS Power Output: 20W, Fixed bias, Class AB
Speaker: 1 x 12" alnico
Preamp Tubes: Tubes (3 x 12AX7)
Power Amp Tubes: Tubes (2 x 6V6)
Rectifier: Tube (5AR4)
Controls: Volume, Tone
Effects: Tremolo
Footswitch: Tremolo On/Off
Output: Dual ¼" jacks
Dimensions (W x H x D inches): 20 x 17.5 x 9.75
Weight: 25 Pounds

These amps are going for very reasonable prices (less than $500 if you look around). Where else can you get a hand wired, 20 watt classic looking amp for these few $$$?

The stock amp does have a couple limitations – While the clean is full and beautiful, and the overdrive is classic tube, the in-between range can be a bit ragged. Voicing wise, it is kind of a “one trick pony” (it is a very good trick, however).

With the BitMo Blues J mods, this amp does not sound like other modern amps in my collection. (This is a good thing). It really fills out my tonal options for recording and gigging. I would say it is especially suited to blues (also sounds fabulous with harmonica), classic rock (killer for slide guitar),  rock-a-billy,  or jazz.

If you have any kind of arch-top guitar, you need to check this out!

This kit includes several modifications to the amp’s circuitry.

·         The useless Bright channel is re-voiced  ( the amp is too bright anyway, IMHO).

·         The 2 input channels are ganged in parallel from one input jack

·         The 2^nd input jack is removed and replaced with a version of the famous BitMo 3-way Voicing/Gain switch, (see switch near input jack in the 1st picture) specially configured to enhance the attributes of this amp. My descriptions of the settings are:

o   Thick – great for jazz, emphasizes the “doink” of a Gretsch for rock-a-billy, woman tone at higher gain settings

o   Crispy – a kind of hyper tweed, very much like a tweed Deluxe – fat and crispy as pan-fried chicken!

o   Punch – great for a bluesy crunch or full-on overdrive

·         The 2^nd preamp gain stage bias is changed

·         The bias is changed on the output tubes (I recommend that you have the amp professionally re-biased for your favorite set of output tubes, but I think the bias resister included with the kit is a better default than the stock one – it seems to make the crossover to distortion range much smoother, especially with the tremolo engaged.)

·         Tweakage suggestions for tubes, speakers, etc.

Roll your own J-20!