Thanks for the advice on the TPA3116D2 and the TPA3122D2N. I will definitely look into those. If I use it with a trimpot controlling output I should be able to conserve battery life and avoid ugly clipping as well, no? I will probably use the TDA2003 module I have here for just a guitar amp. 4 watts with a good speaker and a good preamp should be enough for guitar alone.

Thanks for the advice. I'll definitely keep searching for ideas. I would just go out and buy a ready made system but I'm not liking the look of most of what's out there. Speakers are always too small (for bass) and usually too few inputs. A mixer section is definitely something I'm thinking of. Possibly adding a reverb for vocals as well. As for power tool batteries, I've got a couple around here but I'm doubtful of their current capacity. They've been sitting unused for some time. Might just go the gel-cell route.

I've been building pedals for years now and built several guitars over the last few decades but I've never built anything amp-wise other than a very dirty sounding little LM386 amp.

My sweetheart and I were trying out and admiring our neighbors' Yorkville portable/rechargeable PA. It's the ultimate thing for busking. Can handle a guitar, bass and microphone all at once. (while disturbing the entire neighborhood for a 3 block radius) Runs for at least 4 hours on a charge. Wonderful thing, but the $700 price tag is just out of our range for something that would only get used for a handful of gigs per year.

I'm sure I've got at least one or two TDA2003 power amp kits around here somewhere. Rated at 10 watts or something. I was going to use a FET based amp-sim kit as a preamp along with an 8"/25-watt guitar speaker. (there are some nice, efficient ones available now) That would take care of my guitar well enough for busking.

I have a 2x/bridged TDA2003 kit here as well. Claims to be 20 watts. If I used that, with preamps on two separate inputs, would that be enough for bass and vocals? I was thinking of using a 10" bass speaker (Eminence has some nice ones) and maybe a smaller speaker with a crossover as well. (I know nothing about crossovers but it would be a good thing to learn) Would I need more power for busking with bass?

Would I be better off using the 2xTDA2003 amp as the guitar amp? Would I be in danger of blowing the 25-watt speaker?

Also concerned about current consumption. There are 12-volt gel-cell options and there are now plenty of lithium-ion options thanks to 10+ years of e-bikes everywhere.

http://www.ebay.ca/itm/1971-ELECTRO-HARMONIX-MIKE-MATTHEWS-FREEDOM-AMP-VINTAGE-ELECTRIC-GUITAR-AMP-FX-/310835229061?pt=Guitar&hash=item485f393185&_uhb=1

Electro Harmonix actually had a portable amp in the early 70s. Looks like it would stomp all over a Pignose.

Nice stuff! That is a very unique and original look you've got going on there. Not an easy thing to achieve, nowadays. I like how it looks almost Cold War Industrial. Your labeling technique is clever. Very cool!

Well, I finally got my hands on one! A Gretsch Gadabout. Canada Customs or somebody in handling had managed to destroy the Jensen C8-R that was in there. Coil had been completely torn from the magnet and the cone was mangled. Had to have happened when the package was opened and "inspected" by some overpaid goon. 

Anyways, tried it out with an Eminence 12" I had around. Sounds great! Flat, but nice, like an old Standel or something. Breaks up nicely when the volume is full. Will post a sound sample when a replacement speaker arrives.

I will also post some gut shots. I've only used it on AC mode so far. The battery leads are cut, and now I'm not sure of the correct polarity. Standard grounded chassis would make sense, but this thing is from the Germanium era, so could it possibly be reverse? I definitely want to get this puppy running on batteries if possible!

For speaker efficiency, have a look at some decent quality ceramic speakers. The "vintage-tone"snobs seem to love alnico, but those speakers are seldom as efficient. If you can find the full specs (including the all-important SPL rating and frequency range) then you can get some idea.

Eminence make really efficient speakers, full specs available. So do Weber. (but they don't publish their full specs) Also, decide on which speaker size works best for you, tone-wise. The larger the speaker, the better chance of it being more efficient. Lots of loud 15-inch, 12-inch and even 10-inch speakers out there. 8-inch or smaller and you're starting to lose out.

Read lots of the reviews online. They may seem subjective, but they've usually steered me right. Anyways, Eminence and Weber both make great sounding, loud speakers.

Well, eventually I will come across one of these at a reasonable price. (the smaller Gadabout model usually goes for $100 - $150 on EvilBay or Craigslist) I really liked the sounds I heard from these amps. Very Vox-like. If there is no schematic paper pasted in the amp, then I will probably be posting gutshots.

Quote from: joecool85 on June 14, 2012, 04:35:56 PM
The batteries were almost definitely SLA (sealed lead acid) batteries, not gel type.

Well those sound a bit scary to use. I'm sure gel type or Lithium would be a workable replacement.

Thanks for the replies! (both of you) I will get around to purchasing Jack Darr's book soon. The Kay and Harmony amps probably would have been from Danelectro. I don't think they would build for Valco (a competitor at the time) but the approach is probably similar.

The Gretsch Gadabout is listed on one music shop's site as being rated 6 watts. (already sold, unfortunately) Probably the same power output for the Safari. They ran on AC power or on two 6-volt rechargable batteries. (early gel-cells?) They came with an 8-inch alnico Jensen, (a pair of them in the Safari)

I just really liked the sound sample I heard. Sort of like an AC 30 playing in a shoebox. Being able to do small street festivals with that kind of sound would be great. I'll probably end up with the actual amp before I can ever locate a schematic.

Finally got to hear a sound sample of one of these. (on one of the Gretsch forums) Nice, mildly distorted breakup. Not ugly and muffled like a Pignose. More bright sounding, like the early '80s Fender SS amps. Pretty neat. I can see why Lanois uses one in the studio.

Still no luck with finding the schematics and every time these amps turn up on ebay, they're kind of pricey. Anybody out there got a line on one of these, or know somebody who has one with the schematic label intact?

Some of the new model and re-issue amps from Vox have spring reverb. If you want decent reverb without the Fender tone you could try some of the Crate tube amps from the `90s or some of the Peavey tube amps from 1980s to present-day. I had a Crate Club 20 combo that had great reverb and did the Marshall thing perfectly. (but I sold it `cause that sound just really isn't my sound) The Peavey Vintage 30 is another good one. Sort of a cross between a Vox and a Marshall sound-wise.

Just try to find something with EL84 or EL34 power tubes. They usually get you closer to the British tone. Another good one to look for is the Traynor YCV50-Blue. It does the British sounds really well and it comes with a full-size Accutronics reverb tank. I see more of these amps at gigs than any other, lately.

I mention these amps because they were produced in fairly large numbers and they turn up in the used market a fair bit. Just start searching Craigslist and Kijiji.

One thing, most the amps I mention above have probably got transistors driving the reverb. It's generally the approach most companies have taken over the past 30 years or so. Oh, and most of these amps are all PCB. For a point-to-point tube amp, you either have to pay the big bucks or else get very lucky and do lots of research while bargain-hunting.

D'oh! Well, I ordered one of those speakers, so I'll have to see how well it actually works. Bargain-hunting is always a gamble. I'm actually ordering a 4-ohm 8" Jensen for my chip-amp project.

This looks like a cool idea. I'm getting interested in the idea of battery-powered amps myself. I'll be watching this thread to see what you finally end up with as a setup. If you're not totally set on having a 10" or smaller speaker, this 12" might be a better choice. 100 dB SPL, and the price is right.

http://www.ebay.ca/itm/160665836594?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

Thanks for the info on the Kay and Harmony amps. I might have better luck searching for schematics on those. The different voiced inputs definitely sounds like the Valco approach. Not sure if they sounded quite as bad as an LM386 amp.

A bassist I used to jam with in the mid-1970s, played through a late-1960s Standell SS combo. (one that WAS actually used by The Standells! His dad was a well-known jazz trumpetist - had the connections...) That amp definitely did not sound lo-fi. I think there probably were some decent output transistors available at the time. At least in the US and Canada. Clairtone was producing their much-renowned Project G solid state stereo systems in the mid `60s.

Your description of the crude tremolo sounds pretty much like the descriptions I've read of the Gretsch Safari. There were some much more sophisticated SS amps coming out of places like Italy at the time. (being used by bands like The Rokes) Those actually had decent tremolo, real echo built-in and other goodies.

Anyways, thanks for the hint on those Kay and Harmony amps. Your willingness to share your knowledge on all this stuff is much appreciated!  

Edit: Actually, what am I thinking here?! Yes, these amps were battery-operated, so they probably DID sound lo-fi. Germanium transistors, eh? Hmmm.... with all the talk on pedal forums about the "mojo" of germanium transistors in fuzz-faces and whatnot, that could be quite the marketing angle.