Progress report

[Doc B]

I've been taking the Tode home every night to play around with and refine. We had a small issue with oscillation, that was easily remedied with a bit of extra shielding on the input wiring. I also removed a bass control we had initially incorporated, that didn't seem to be functional. In its place is a very functional adjustable brake. Last night I was playing with the input volume control maxed out and the brake turned on hard, such that I could play with max distortion into a pair of headphones at quite gentle listening levels. So one can crank up the volume and turn off the brake and rock out, brake the amp for a distorted sound at quiet practice levels, and also vary the brake to allow a wide range of clean to distorted sound over headphones.

Tode now also has a reinforced cabinet and a carry handle.

 

[dbishopbliss]

What does the term "brake" mean?  Is it a master volume, power scaling or something else?

 

[Doc B]

A brake is simply an L-pad attenuator on the speaker, that allows you to crank the amp to distortion and then cut the signal level going to the speaker, so you can play an overdriven or distorted output stage at low volume levels. This being a very simple two stage direct coupled amp there are only a few ways and places where one can control levels - with a pot at the input, at the cathode of the EL84 (with a variable resistor in series the cathode bypass cap to adjust the gain), or with an adjustable L-pad brake at the output.

I think we're about 90% of the way there. There is a slight issue of what seems to be blocking distortion on the low strings that seems to be related to the very high impedance of the grid leak at the cap input first stage. The issue is a slight case of "farting out", the transition into distortion is not as gradual as it should be it, sort of cuts in and out at times when you are right at the threshold due to the waveform at the grid being pushed down into cutoff and taking some time to recover to the correct bias point. The issue shows itself with higher output humbuckers. Single coils like the sweet Teisco gold foil on my Tele and stock single coils seem to work very well. We're going to analyze this over the next day or two and figure out a way to minimize it - besides "stop using humbuckers" ;^)>.

 

[vanofmonks]

Is the Tode something you are planning to release soon?  How complete of a kit is planned?

Thanks,
Chris

 

[Doc B]

Yes, I want to release it as soon as we work out the last details. It will be as complete as the rest of our amp kits - cabinet, circuit components, tubes, etc. and it will include the speaker.

You'll have to supply your own guitar though...I just bought a Squire Mini Strat on ebay to see if the short scale neck works for my teeny hands. I try to stretch my pinky to the 6th fret on the 335 with my index finger on the 2nd fret and I come up about 1/4" short!

Don't know pricing yet, I need some quotes for panels and speakers before I can determine that.

 

[Dr. Toobz]

Doc, any chance of adding in a headphone jack for private practicing? I'd think the arrangement with series resistors, as in the SEX amp, would be fine, and with the brake you speak of, it sounds like distortion could still be attained without having to crank the headphones up very loudly. Am I correct?

 

[Doc B]

No chance of my adding one - because I already put one in there ;^)> There is also an external speaker jack on the back (drives a 12" Eminence Legend 1218 pretty nicely). Plugging into either jack cuts out the internal 8" Weber driver. With the brake you don't even need the series resistors, it can be set to very safe headphone levels with the existing controls even when distorting. Works very nicely.

 

[Yoder]

You'll have to supply your own guitar though...I just bought a Squire Mini Strat on ebay to see if the short scale neck works for my teeny hands. I try to stretch my pinky to the 6th fret on the 335 with my index finger on the 2nd fret and I come up about 1/4" short!

Another option may be to try a Godin electric nylon hybrid (they do not sound bad at all on a non-accoustic amp.) They also have wider necks, but they are not as wide as a typical classical nylon. Taylor also makes a nice nylon hybrid, but it does not have MIDI capabilities like the Godin or Carvin models. I used to put my Taylor through some effects pedals and play it through a Suprema 55 with no problems (the more fuzz, the better and less quack.) I think that Carvin may even offer some electrics with hybrid necks, and from I have heard they are pretty decent guitars.

I just traded my Gibson Advanced Jumbo and my Taylor NS-32 nylon. The Gibson body was too wide for my jacked-up shoulder and so I did very little flattop playing. In trade I got a brand new Martin 000-28EC (Eric Clapton model.) I gave the guy the two guitars and $200 and walked out of the store with a great axe. Wow! What a beauty and what a sound, and it so easy to play with the v-neck and short scale. For me the v-neck is the greatest guitar improvement I have come upon in years. It just makes playing so much easier and I also have somewhat short fingers.

 

[Dr. Toobz]

No chance of my adding one - because I already put one in there ;^)> There is also an external speaker jack on the back (drives a 12" Eminence Legend 1218 pretty nicely). Plugging into either jack cuts out the internal 8" Weber driver. With the brake you don't even need the series resistors, it can be set to very safe headphone levels with the existing controls even when distorting. Works very nicely.

Rock on! Woe to my wallet, however - now that I have this AND the Stereomour on my 2012 "to-build" list!

 

[Doc B]

The Mini Strat has a really short scale - 22.7". It ain't never gonna sound like that sweet 335, but it should be a fun project for $39. The demos of Mini Strats on you tube sound like ass, but it sounds like it's probably because of really cheapo p'ups. I'll put something better in if they turn out to be a problem. Sheeyeah, as if I play good enough that it would matter.

 

[Doc B]

This is an initial implementation, admittedly a bit crude, of an idea I had for a pilot light. The speaker baffle will be changing to something more interesting in the next iteration.

 

[fullheadofnothing]

That light is going to look bad-ass behind the new grill, based on the sneak-peek I saw.

 

[Doc B]

Yeah, I think so too. When the amp is sitting in a dark room it looks like the speaker cone is glowing and just about to burst into flame. That and the new grill should really give the little box some personality.  I was bit concerned at first that people won't like the shallow depth of the cabinet because it's non-traditional. After taking it back and forth from home to work every night for the past week or two I have really grown to like fact that it's a lot like carrying a briefcase. We mounted the iron in as low in the box as possible and that makes it pretty resistant to tipping over.

 

[vladimirwolfe]

Very cool Doc. Looks like you could put some fender type legs on either side of the cabinet to tilt it back a bit. As far as guitars go, if you really want to go whole hog, look for an early sixties Fender Duo-Sonic, short scale and killer tone!

 

[Doc B]

I started by looking at vintage Duo Sonics. But they seem to have achieved collectable status, so I figured first I should just get something inexpensive to see if the short scale even works for me. If it does, there might just be a Duo Sonic in the future. One cool thing about this little amp is that it has got me inspired to go downstairs and practice every night for a bit. I had been struggling for motivation for a few months and this project seems to be the solution.

Clark has mentioned some interest in the guitar amp project and we talked about some sort of legs or bottom panel or maybe even a stand, for the amp cabinet. Once we have the amp itself finished and know that it will sell we can start to address a long list of potential upgrades and accessories.

 

[dbishopbliss]

What about moving the controls, transformers, etc to the bottom.  Then you wouldn't have to worry about it being top heavy.  That is the way my Trace Elliot Velocette is configured.

 

[Doc B]

Actually the stuff at the top behind the controls is very light. The transformers are at the bottom. Those and the speaker magnet are the heavy bits. So I think we have their location pretty well optimized, and the cabinet is really pretty stable as is.

 

[Yoder]

It definitely has a retro look to it. Looks like something Buck Rogers would play...pretty cool. Personally, I would be afraid of controls on the bottom--tend to get kicked, plus bending over so low is bad on some of our backs.

Yikes, that mini Strat is a short scale. What is the width of the nut? I got my daughter a 3/4 scale guitar and it is great for her, but my short fat fingers can't  play it.

 

[Grainger49]

Since I don't own an electric guitar I probably won't be on the list of buyers, but... I love the pilot light.  And I worry about getting the tubes out.  I suppose it won't be as hard as it seems to me.

 

[Doc B]

Nut width on the Mini is supposed to be 1.61", about like a Tele. But the fret spacing certainly could end up being too small on the higher frets, we'll see. That's why I was happy to find a used one for a few bucks. If it doesn't work out it just goes back on the bay, or maybe to one of my nieces. After looking at some more you tube demos I'm guessing it might sound kinda lightweight and I'm looking for some better p'ups. Stock ones are something cheapo, like with a single bar magnet. Luckily they are the standard strat size so there are tons of options. If someone has a nice vintage sounding mild wound set of strat pups I'd be willing to do some trading. I think one might even be able to replace the plywood body with a mid-90's MIM Duo Sonic body, or the current CV Duosonic body.

Re the tubes, you have to open up the cab to change them. That's just four screws. The way the tubes are mounted they show a bit and yet they are shielded and well protected. I'm pretty happy with the overall layout and any cabinet changes will probably be focused on the grills and vents.