"Vibratone" Submini Tube Guitar Amplifier

[KazooMan]

An update:  I decided the power supply was the problem so I took a step back and built a new 12V supply.  Using a transformer rated to deliver 450 ma.  Nice, stable filtered 12V output.  The ironic part is I was impatient and wasn't willing to wait for parts, so this is an "ALL Radio Shack" Power supply.  Actually, it came together well in a nice (but plastic) enclosure.  Pretty simple layout with a bridge rectifier, big filter cap, LM317 regulator, a few more caps and out. 

The moment of truth came and I hooked up the main board of my Vibratone build.  Good 12V on the board, and the correct heater voltages!

First problem solved.  I'll get after pulling the pieces together tomorrow evening (morning if my golf game gets rained out).

I should have calculated the power requirements before I set out.  My other power supply apparently wasn't beefy enough.

[stringsthings]

I designed and built this for stereovoid, who was one of my early Murder One customers (he has #3, the first one built in a 1590B). He asked me to build him something similar but with more features, so it's based on Murder One but using a 6112 submini dual triode for the preamp instead of a 6111, a little more gain, which makes up for the losses in the tonestack. There's a bypassable MOSFET boost, based on a varient I developed for Le Craquement Thermionique, but without the Mu amp part. There's also a tremolo section, based on the Vibracaster , but modded slightly for this application. The tonestack is Muffy based. There's a pre amp output taken from after the volume control, and a dummy load on a switched socket, so when there's no speaker plugged in the transformer secondary is bridged by a 18ohm 3 watt resistor (I forgot to add that part to the schematic).

It's really flexible! I wish I still had it to make soundclips, but but's gone to it's new owner. Great as a standalone practice amp, with built in effects - the boost is insane - instant massive compression and feedback at the highest setting! It's even more fun as a preamp into another amp, with a lot of control over the sound using the gain and volume in combination, the boost and trem just add to the fun.

Here's a direct link to a larger version of the schematic: http://dl.dropbox.com/u/967492/Vibratone.JPG

...not my neatest build, but it was a work in progress, took a bit of modding to get it all just right, hence the long wires - gave me a bit of wiggle room when modding different sections.

.... it may not be your neatest build, but it gets the job done, mate  .... i like the way you installed some parts on the other side of the boards .... and the load resistor in the corner looks very nice .... ( in addtion to being fully functional ) .... it's a challenge to make a project mod-able and purdy at the same time .....

[KazooMan]

Another Update:

Success on the first try!  I have been building the Vibratone, using the PCB layout of the Murder One that I modified, and perf board layouts of the boost and tremolo circuits based on the schematic.  I made these on three separate boards with the tone stack built right on the tone pot.  I included the bias switch, boost switch, and pre out.  It took a lot of thought to figure out how to cram it all in a size BB enclosure, but I finally managed.  

So, the moment of truth came and I fired the amp up.  It works!  First try!  boost, bias, tone, tremolo....... it ALL works.  Now I need to finish off the enclosure with decals and tidy up a few things with the wiring.  I think I will also need to mess around with the tremolo a little as I would like a bit more range in the speed and turning up the depth off the zero mark causes a noticeable drop in volume (not a big deal).  

Thanks go to Frequency Central for posting the schematic so we can have a go at this little amp.

Here are two pictures of the progress to date.  I wanted a red enclosure, but they were back-ordered at Small Bear, so I opted for yellow (with the original red knobs I had ordered).  It still looks OK.

[Brymus]

Are you kidding...
Thats an awesome looking job you did !!
Nice work,I too think Rick is a great guy for sharing his designs the way he does.
One of these days I am going to build one of his amps too.
How about some sound clips ?

[frequencycentral]

That looks amazing. It's great to share - I can't tell you what a kick it gives me to see one of my designs built by someone else! Also, I'm kind of jealous because I don't have a Vibratone myself, though I'll eventually do something similar just for me eventually. Good work!

[KazooMan]

Thanks,

I don't know how you can sell your Murder One amps for what you do. The cost of parts aside, there is a lot of labor involved in building one of these things.  But,  that's why I built it; for the fun and challenge of the build.

I thought I had met my Waterloo when it came to mounting the tremolo board in the box.  The boost is on a small, slim board that I mounted on edge between the pots and the main board.  I tried many potential locations for the tremolo and found that I could mount it upside down over the pots.  It is mounted on a standoff that is epoxied to the box.  I had to use nylon nuts to avoid shorting the board out.  The scary part it that I have to remove everything to put the decals on the box. 

I'll post better pics when it is done.

As far as a sound clip, I don't have any way to do any recording.  Also, I would probably have to hire a guitar player   My "glory days" of playing were way back when I was in high school a long, long time ago.  I had to put the guitar on hold when I went to college and graduate school and my current playing ability is less than desired.  I do still have my Blonde/Oxblood Fender Bandmaster, Fender Reverb unit, and red Fender Mustang all from the early '60's  and all in great shape.

[frequencycentral]

I think I will also need to mess around with the tremolo a little as I would like a bit more range in the speed......

Have a look at the Vibracaster thread, page 12, there are some suggested mods.

......and turning up the depth off the zero mark causes a noticeable drop in volume (not a big deal).  

Hmmm, my build did that before I added the 0.47uF cap to ground from the cathode. Do you have that cap in the right place? Maybe try a higher value?

[thomasha]

Hi guys,

I improved my murder one with this tremolo and made a small combo inspired on early gibson amplifiers and old radios.

Removed the tone and master volume, and used a 220v to 6V transformer as output. After rearranging all the laminations to obtain the air gap, as in the SE transformers.

And it sounds nice! a little brighter than when using the reverb tranformer.

Thanks Rick for another amazing project!

Thomas

[frequencycentral]

Great looking amp Thomasha! Weird that you should post today, as I was just looking at this thread yesterday...my Christmas present to myself is a 6112/6021/2 x 5902 amp built into an old radio. I've finished work on the amp itself and I'm now looking to add tremolo and Belton reverb. It started off similar to the JJS class A/B amp, but I've modded it a little along the way. It's actually stupidly loud compared to Superfly or Murder One.

[thomasha]

Hi!
have you seen Dana's 2w trainwreck amplifier? It uses the same tubes.
I've read somewhere that they are really more powerfull and from pictures they are really bigger!
Nice build! Hoping to see this amp. A reverb and a tremolo is almost a big amp!

[tubegeek]

a small combo inspired on early gibson amplifiers and old radios.

It's so WEE!

[Scruffie]

Great looking amp Thomasha! Weird that you should post today, as I was just looking at this thread yesterday...my Christmas present to myself is a 6112/6021/2 x 5902 amp built into an old radio. I've finished work on the amp itself and I'm now looking to add tremolo and Belton reverb. It started off similar to the JJS class A/B amp, but I've modded it a little along the way. It's actually stupidly loud compared to Superfly or Murder One.

I take it you didn't power all those with an SMPS, or can it cope with 5902s?

[frequencycentral]

Back to back transformers. :-)

[thomasha]

Hi,
I took some time to record some videos with my small amplifiers with my big combo celestion greenback 12" speaker.

This one really improved, with a lot of available volume, compared with the small speaker.

I'm thinking of changing that speaker for a better one, but it's difficult to find these small speakers datasheet... there are some old 3" jensen over at evilbay, what you think?

Cheers,
Thomas

[disorder]

Hi guys,

I improved my murder one with this tremolo and made a small combo inspired on early gibson amplifiers and old radios.

Thomas that thing is awesome looking! Mind if I ask what kind of wood and joints you used to build it? I'm not much of a wood worker :/ .

[thomasha]

Hi,
I used an old wooden box, there was no brand on it, but it was made of a very thin piece of wood, only 5-6 mm thick, but bigger than a cigar box.

I found it in my grandpa's garage, and it was filled with nails and screws, but had one side broken.
I cut it into smaller pieces to make the amp, and painted it after a good sanding.

As it's so thin I made a butt joint with small glue boxes and screws and dowels.

I started with the butt joint with dowels but it wasn't stable enough, than I added the glue boxes in the front side and used 1 mm screws and glue.

[Mgt280y]

Dragging up an old post, but was interested in building this see there has been a few built are has any one done any build docs, got the schematic but not that confident to build purely on that, comments and advise from anyone who has built this would be very much appriciated dan