Replies to This Discussion

Permalink Reply by Tim LaFave on January 5, 2014 at 1:19am

What are you using for a volume pot?. Typically, 250k has the warmest, darkest tone, but on today's builds, much higher pots are being used, which can result in a frequency 'spike" which your little amp/speaker can't handle. Tone caps can add to this, the smaller the cap, usually the brighter the sound.

Permalink Reply by Manny Lopez on January 5, 2014 at 5:01am

I'm not 100% on the volume... in the guitar or on the amp? The amp pot is to spec in the schematic, but all my guitars... beats me.

Permalink Reply by Tim LaFave on January 5, 2014 at 1:03pm

The guitar pots and tone caps may have something to do with how it sounds ... I would try different guitars to see if anything changes.

Permalink Reply by Manny Lopez on January 6, 2014 at 4:09am

Thanks Tim. I found the reason for this in another electronics forum. Turns out it was the LM386N4, it doesn't like the higher voltage so much. I got an LM386N3 and the problem was solved. In the stock circuit, the N4 was fine, but the Bassman mod did not like it no matter what guitar I used. The Bassman mod sounds great though and naturally, works well for bass too ;)

Permalink Reply by Jim Woods on January 6, 2014 at 9:33am

I have built several similar amps - the "Noisy Cricket".  Mine do not like 12v either - do very well at 9v.  Also use a tone pot w/.1uf cap.  Since I usually have the tone down max, you could sub the cap the Bassman has on the volume pot for a .1uf and see it it tames the distortion.  I also notice a better sound ( to my tin ears) by palm muting the bass string and trailing a finger behind the slide.  

Have fun and leterrip!

Permalink Reply by Manny Lopez on January 6, 2014 at 1:17pm

Thanks for all the help thus far. I have soldered it and it is running now. Sounds good, and nice to know connections are good. I am curious about the 220pf cap on the Bassman circuit. Do you add the cap and leave all other connections to the pot in place?

"Bassman -
Replace the .047uF cap from the FET source pin to the volume pot with a 0.1uF. Place a 220pF cap from lug 3 to lug 2 on the volume pot. Remove the Gain pot and place 2k2 fixed resistor between pins 1 and 8. In this configuration, Ruby sounds very much like an old Fender Bassman to our ears. With the Volume control at half rotation and below, you'll notice smooth and sparkly cleans with good depth. With the Volume pot set high, you'll hear nice overdrive that is great for blues playing. The transition from dirty to clean can be controlled with your picking or strumming. This aspect can add an extra dimension to your playing."

Permalink Reply by Scott aka Farmer Ted on January 6, 2014 at 1:28pm

Yes, I believe that is what is intended for that capacitor...connecting between lug 2 & 3 of vol pot. Must alter  the signal before continuing toward the LM386. I have a Ruby I made recently, without the Bassman change. Gives a nice clean when needed, and plenty of crunch too. The variable gain creates many different reactions in the amp.

Permalink Reply by Manny Lopez on January 6, 2014 at 3:50pm

My next step is to figure out if I can wire an extra 1/4" jack as a speaker out that will bypass the inner speaker when I plug a speaker cable in. Playing through a 15" cabinet is too loud in the apartment.

Permalink Reply by Scott aka Farmer Ted on January 6, 2014 at 4:42pm

Easy to do, just intercept signal after C5, the 220uF cap, with a three prong, on/on switch. C5 to middle prong, amp speaker to one of other prongs, and remaining prong to jack out...

Permalink Reply by Scott aka Farmer Ted on January 6, 2014 at 4:43pm

Easy to do, just intercept signal after C5, the 220uF cap, with a three prong, on/on switch. C5 to middle prong, amp speaker to one of other prongs, and remaining prong to jack out...

Permalink Reply by Scott aka Farmer Ted on January 6, 2014 at 4:43pm

Easy to do, just intercept signal after C5, the 220uF cap, with a three prong, on/on switch. C5 to middle prong, amp speaker to one of other prongs, and remaining prong to jack out...