Guitar on-board tube driver

[erio fraga]

Hi everybody

Does someone know or have used this “on-board tube-driver”? Any idea if is a JFET, opamp or trannie device ?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=41416&item=3728737977&tc=photo

Thanks

Erio

[petemoore]

Depending on if there's any actives in that small metal box, [probably not/since the board looks to be outside there], I would guess it's a [2?transistor] transistor overdrive, a well chosen, tuned one, probably a nice unit, seems reasonably priced.
 Seeing the top of the board would give more clues I suspect, but I see no opamp configurations from the bottom of the board.
 No sound clips and the link to 'his site didn't work for me.

[R.G.]

It's clear from the pictures. The metal box is the back side of an Alpha push/pull switched pot. The circuitry is a booster, probably transistor.

The pot costs about $4.00 at Mouser, less from Alpha direct. The circuit board, assembled, is about $2.00 manufactured in quantity in Asia.

It's funny - the info I put out a decade ago in the Guitar Effects FAQ as "Effects Economics 101" still hold true. The cost in a commercial effect is almost entirely in the box, jacks, controls, battery clip, switches, etc. The actual effect is almost inconsequential.

What this effect does is do away with the box, jacks, etc. $49.00 is a healty mark up for something that does not get eaten up by retail markup and survives on only free ebay marketing.

[Eric H]

The "box" is the push-pull switch attached to the pot, pete --pretty cool if you haven't used them before.

As far as the circuit it's most likely op-amp based --look at the other links at the bottom of the page and you'll see what I mean. Witth SMD construction, looking at the bottom of a board frequently tells you very little.

edit: gotta type faster when RG's in town

-Eric

[Lonestarjohnny]

If you keep clicking on the picture's it'll give you a shot from the front, it's got a chip like 4558 on it and I see no transistor's, check it out !
JD

[petemoore]

If there'a a dual in there, it is most probably a TS type circuit then...no?
 The written description certainly brought to mind the TS circuit. Pretty tight little board for a TS, though possible I suppose.
 I'm not seeing the top of the board...looks like too few connections on the bottom to be a TS circuit...but I'm not experienced with 'reading' the bottoms of these small boards, maybe they have more connections made in some other way.

[Peter Snowberg]

The adds show four different boards. One has a DIP-8, one an SOIC-8, one looks like a 1 transstor JFET or MOSFET boost, and one has a ton of SMDs on it with a 5 position rotary switch. Pretty cool stuff except... that the caps are all ceramic SMDs. Now I wonder what quality they are?

I'm really thinking that before and during fuzz circuits, I generally like tone of higher ESL caps. It is a cool idea overall.

Oh hey! The one with the DIP-8 is a 2.5W amp.    Let's see... at 9V, 2.5W = 277mA. Hmmm... I wonder how long batteries last in there. Most guitars don't have the luxury of easy change outs for 9V batteries.

:mrgreen: Check out what Duracell has to say about service life when you pull 1W out of an alkaline 9V. http://www.duracell.com/oem/Pdf/MX1604.pdf  :wink:

It might be really cool to plug your guitar into a 4x12 cabinet for the first 4 minutes.  :lol:

Take care,
-Peter

[sir_modulus]

I personally think it's usless. It's probably(99% sure) not TB, so it sucks tone when off, and will remove one of your guitar tone pots, and if installed elsewhere needs quite a bit of routing to put in. As far as what it is, I think the one they're advertizing is just a two Transistor distortion pedal with a variable gain stage. As said earlier, the caps will sound like crap, and the circuit will probably not sound too good either.

[Ben N]

Looks to me like the boards are different for each auction.  The first one, based on the copy, sounds rather like an op-amp Clapton boost.  The compactnessof it is nice, but that doesn't tell us anything about the circuit. I don't necessarily expect it to be TB (althouigh with a DPDT switch it cetainly could be), but I do expect a quality low-noise buffer to be there when the boost is off.
Ben

[Alpha579]

It would be cool to make a 2 Jfet bosster/overdrive similar to that, and those pushpull pots look cool!

[vdm]

ahh Mr. snowberg, you never cease to amuse!

I like the way the ad says something like "a massive 2.5 watts!", it's great.. and looking at that duracell graph, i can see what you mean about the 4 mins... i wonder how low the voltage supply on a 2.5W power amp chip goes before it stops working. maybe 8 volts by memory, from looking at TI chips...

oh well.. the idea of putting effects in the guitar isn't new... though it is quite an interesting idea.. it's just a shame that all these guitars with inbuilt effects haven't teamed up with a company that actually makes decent effects. I know i'd prefer to buy a guitar that had a "real" TS or Dist+ built in, rather than the crappy effects companies usually put out.

anywho... this reminds me that i have to put that 3" speaker into the front of my chinese squier, and hoook it up to my little gem... that'll be the day, walking round the schoolyard playing guitar til the cows come home! oh dear... i've only got... 4 months of school left ever!.... then again uni is just around the corner... I hear the chicks are good  :wink:

trent (stressed about exams)