Back in the `60s there were a couple of small SS amps made for Gretsch that could run off either mains power or batteries. Not sure who actually built them, as Gretsch didn't actually build their own amps. There was the Gadabout, which was just a small, super basic amp, with only a volume control. There was also the Safari, which was also small, like the Gadabout, but also featured a unique sort of tremolo circuit. I see these pop up on ebay sometimes, but they are always either selling for way too much, or else they are not available to buyers outside the US.
These were reputed to be actually quite nice sounding little amps. Producer Daniel Lanois has used them during recording sessions.
I've tried searching for schematics for them but no luck at all. Lots of stuff on the Gretsch tube amps, (all Valco made ones) but nothing on these. Anybody know if there are any schematics floating around for either the Gadabout or the Safari? If I can't buy one, I'd love to give a shot at cloning one.
Never seen one, but being 60's SS battery powered amps, they can't have been anything but germanium output, transformer driven (and probably transformer output too) ones, same as typical radio audio sections of that era.
Google the earliest Pignose amps, they are about the same.
I remember seeing some similar Kay and Harmony amps (probably made by Valco too) which were exactly that.
One of them even had some crude tremolo, and a distinguishing feature was that they had , say, 3 different voiced inputs: the "normal" was the regular one; the "bright" had a too small coupling cap (= no bass) and the "bass" which had, say, a .047 or .022 cap across the input (= no treble).
Very crude designs which *might* be interesting for a very crude, lo-fi sound.
Now that I keep remembering, the tremolo was a square wave multivibrator driving a diode in parallel with the signal. Very crude.
Edit: I´m sure an LM386, with said "equalized" inputs, driving a Jensen or MOD 6" to 10" speaker in a very small, thin walled, open backed box, driven straight from the guitar, must provide about the same sound.
Typical cap values were .0047uF in series for the "treble" one, .022 in series fo the "normal" one, and a .022 cap added in parallel for the "bass" one (or just turn your guitar tone control way down).
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. ;)
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?
Buy a copy of Jack Darr's "How to repair an electric guitar amplifier", I had the 1968 edition.
Lost long ago.
At the end they had some example schematics, divided in Low, Mid and High power amps.
In the low power section you could find those Kay and Harmony 2W amps.
The .PDF version which can be easily found on the Net does not include the schematics, because everybody claims "they can easily be found online" which is stupid and, as you know, not true.
Search EBay, Craigslist, Amazon often has a couple used ones on sale.
*If* you get it, *please* scan and post those schematics, at least the impossible to find SS ones.
The tubed ones, yes, can be found.
Attached is a circuit of an early Pignose which is likely to be very similar to the one you are seeking.
While this uses 2SA-series PNP germanium transistors I am inclined to think that the main factor in determining the tone would be the two transformers, driver and output. While the transistors, similar ones, or even silicon NPN substitutes, I suspect that obtaining suitable transformers would be the main obstruction to cloning this circuit.
Close, but the Pignose has no preamp, you are plugging straight into the flat power amp, which accounts for its perceived "dull" sound.
Those Kay and Harmony (probably made in the same factory as Valco and others) did have a crude preamp, tone controls and EQ, even ¡f a fixed one, through different voiced inputs.
The type of speaker also has a very marked influence in sound.
They were certainly Alnicos, the lightest and cheapest available, thin paper cones, *very* light paper former voice coils and glued with light Nitro.
Maybe a Jensen P8r is the closest available thing today, or a MOD 6-15 .
Any modern speaker (modern being from 1970 on, go figure) will sound very different.
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.
Quote from: Puguglybonehead on June 11, 2012, 08:41:57 PM
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.
The batteries were almost definitely SLA (sealed lead acid) batteries, not gel type.
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.
Gel cells are just a different form of lead-acid. All batteries must be treated with respect because they store energy, sometimes quite a lot of it, and when something goes wrong (like a short) it can all come back in a rush.
I've seen a musician dancing around ripping his jeans off because the 9 volt stomp battery in his pocket got shorted by some change. :o
But I can tell you that anything with lithium in it is a much scarier battery than any lead-acid. Look at any of the lithium battery vids on Utoob. :(
:duh They deserve that for being morons !!! :grr :lmao:
And yes, Lithiums do not "get hot", they *explode*.
Spare lithium batteries (think cellphones and Notebooks) are strictly regulated and even forbidden on planes.
For good reason.
I think it really comes down to when those things were made. The bigger Gretsch solid-state amps such as Rogues, Nashvilles, Tornadoes, etc. that came in the mid to late 1960's did indeed use germanium transistors but they did not have any sort of transformer coupling in them. The tremolo was also based on the usual sine wave phase lag oscillator.
IMO, it's really not too much worth of making guesses about the circuit architecture unless we see some gutshots. It could be a Pignose clone, then again, many battery-powered amps from the era were not.
It's worthwhile to realize that Pignose
- was introduced later than these Gretsch amps
- was already a way dated design that was hardly copied by anyone (who wanted to introduce a battery-powered amp) as is
Well the particular speed stripping musician I'm thinking of was a drummer (and a very good one), but I think as such he can be forgiven for not recognising the danger of putting a new battery in his pocket after helping a guitarist with a troublesome stomp box.
Yeah, you stomp on a lithium battery and the phrase "incendiary device" comes to mind. :o
Thing is, if the amp in question didn't use transformer coupling and was just a comp or quasi-comp there doesn't seem to be a lot of point trying to clone it when there are so many chip amps available these days.
Probably.
I'm pretty certain the interesting aspects of that amp relate more to things like
- speaker choice
- preamp design / "voicing"
- novelty factor of a compact, vintage and moderately rare battery-powered amp that was reputedly utilised by famous person X
...than to some stunningly unordinary power amp design. I could be wrong but I still have a pretty good hunch that it's like that.
Unfortunately, cloning the said parameters isn't all too easy. ;)
Pretty much all of these battery-powered things usually sound damn fine when you listen to them as is, assuming
- they happen to have any larger speakers than some anemic 1-inch ones. Even a generic LM386 sounds killer through a 4x12" cab.
- you don't put them in comparison against larger, more serious amps.
I mean, amps like the legendary Pignose still sound great in right hands but I'd still pick a modern battery-powered Roland Cube amp over one any time. ...And probably most of the guitarists who made Pignose famous would have done the same if they could have ...in the 1970's.
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.
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!
I'd imagine by examining the PCB you could figure out which wire is positive and which is negative. It might even be silk screened onto the board. If not, you should be able to trace which parts of the AC PSU after rectified to DC go where, then match the wires to that.
I hope that made sense. Good luck and keep us posted :tu:
QuoteHad to have happened when the package was opened and "inspected" by some overpaid goon.
Actually, it is WAY more likely the amp was dropped. When you drop an amp, even a boxed amp, on the ground, the sudden stop causes the magnet assembly to shear offg the speaker frame, and when it does this, it will also cause severe damage to the cone.
As an experiment, take an old dead speaker and try to rip the magnet off it. That woulod take one mighty strong goon. In the repair business we see sheared off magnets often enough.