Daisy Cutter hi-gain amp in Doug's new Stout chassis

[Ken Moon]

I started this thread to post my progress on this amp, and to discuss the amp and/or cab design with anybody who's interested.

Here's a pic of the new chassis with 18watt iron (the choke is a Mojo 6V6 amp choke, it looks just like the Weber W02299. The Heyboer HY02299 (open coil, 9H/120mA/125R) will also fit the mounting holes.


I'm going to start with a 6V6 version of the DaisyCutter by Randy Fay (Phaez Amps), with the obvious changes to use 6V6s:


I'll be putting it in a heads-up combo similar to this old prototype cab:


with cosmetics that look something like this (different front panel of course)


With Thanksgiving and Xmas shopping, I haven't worked on this amp since I posted this, but I'd love to hear any initial suggestions 

[MakerDP]

I really like that cabinet design! Is that your own or did you swipe it from somewhere? What do you think about a rubber pad between the chassis and the "floor" of the amp section to give some isolation and extra protection to the tubes?

What changes did you make to the DaisyCutter to convert to 6V6 output? Obviously bias resistor for the power tubes. Anything else? Any changes needed for the P.I.? I've seen other schematics for traditional LTPI 18-watt 6v6 designs but not one with the concertina splitter.

I am re-purposing a Peavey Classic 30 chassis and cabinet and a 6V6 DaisyCutter is actually what I was thinking of putting in there! Maybe add a clean channel and reverb as well since I have lots of room.

[Ken Moon]

I've been making tubes-up combos for over 20 years. I made about 20 of these brown combos (and 3 or 4 black tolex versions), with a variety of guts, but mostly modified 5E3 deluxe or 18watt circuits:


I thought maybe I was the first to do it, but since the internet came around I've found a few from the past, like the Harry Joyce Custom 30:
, and the more recent Suhr Badger combo:


Both of those look like a Marshall head glued to a 1x12 cab, so I wanted to add a twist, which is to make the bottom of the front panel cutout "wrap around". To do this, you have to raise the chassis 3/4" higher, by adding a little platform right under the amp (I didn't do this yet on the prototype pic I posted):


To change an 18watt to 6V6s, I usually lower the power tube grid leaks from 470K to 220K, change the screen resistors to 470R for each 6V6, change the PI output coupling caps form .047uF to .022, and I usually use a 270R power tube cathode resistor with a 100uF bypass cap, but I like to try 300R unbypassed also. The changes to an LPTI are a 470R to 820R cathode resistor and a 27k tail. Since this amp has the Concertina PI, I'll try it with the schematic values first and tweak if needed.

[MakerDP]

Thanks. I'll be keeping an eye on this to see how it turns out.

And your black and grey "wrap around" design is definitely the best of those you pictured! Very classy! Are you going to make that front panel "wrap around" removable so you can get to the tubes easily with them being on the front of this chassis?

[MakerDP]

Do you mind sharing the dimensions of your cabinet?

The more I look at it and think about it, I'm thinking this might be an ideal setup for the band I just joined.

[Ken Moon]

Sure, I'll share all the dimensions of every piece as soon as I figure them out. I need to make a a few adjustments for this chassis.

The unfinished cab in the pic is 17-1/2"wide by 9-1/4"deep by 19"high. The top area is 6" high.

The braces/baffle cleats are all 3/4" x 1-1/2", which you can buy separately in 4-foot length, or you can cut them off the end of a 1x10 (you can only do this for the pieces that are 9-1/4" long or less)

The 9-1/4"depth allows the entire cab to be made from 1x10 lumber (which is really 3/4"x 9-1/4") - I use "select pine" from Lowe's, or poplar if I can get a good price. I've tried the baltic birch plywood, and I always get blow-outs on the corners when doing the roundovers.

I've got 5 different 12" speakers I'll be trying - one of them is the neo Lil' Texas from Eminence. I hope it sounds the best, because it's much lighter. My design goal is <37 lbs.

btw, putting the cap can on top and the choke inside looks like a go (thanks, Silvergun!!):

Cheers!

[eleventeen]

I kind of like your (older) brown styled one, but most likely the other style would be more salable. The brown one is kind of more soft-spoken, if you know what I mean. Reminds me of an old AMPEX amp/speaker combo. They're both very handsome.

[Ken Moon]

Thanks, eleventeen!

I agree about the brown look - I used Fender tolex, grille cloth, handle, slides and corners, and the faceplates from BNP matched perfectly.

The funny thing is nobody under about 50 years old seemed to like that look - oh well..

[eleventeen]

Very reminiscent of an AMPEX 601/602 preamps, but most especially an AMPEX 620 powered speaker.


http://commons.wikimedia.org/wiki/File:Ampex_620_speaker-amplifier.jpg

[Ken Moon]

That is so cool!

It reminds me of my Dad's Samsonite suitcase that he bought in the '50s.

It looked just like this one - Now you've got me wanting to make a vintage suitcase amp

[Ken Moon]

Here's my shot at a layout of the DaisyCutter on a 3"x"6-3/4" board, using the amazing KenCad software (#2 pencil) 

I'll be putting all the tone stack components on the pots, and all of the grid stoppers will be soldered directly to the tube pins.

For the preamp B+ filters, I'll be adding another F&T 50/50 in the open area down by the preamp tubes.

[Ken Moon]

...and here's the turret/eyelet board pattern (8 dots per inch):

[Ken Moon]

pdf version:

https://drive.google.com/file/d/0B2yySkbEPz1mN0Q0ZnRURnFkcGs/view?usp=sharing

[Ken Moon]

Mouser BOM for board components:

https://drive.google.com/file/d/0B2yySkbEPz1mbklaaUkwdHVTMTA/view?usp=sharing

[Ken Moon]

Preamp wiring:
https://drive.google.com/file/d/0B2yySkbEPz1mS19EWEMtdDFyNjQ/view?usp=sharing

[MakerDP]

 

Waiting anxiously for some sound clips!

[Ken Moon]

bare turret board

(not as neat as I would like - my power tools are out in Denver and I'm in Jacksonville until spring, so I had to use a hand saw to cut the Garolite, a hand drill for the holes and a hammer for the turrets - came out OK, though.)

[TIMBO]

Looks Great.

[EL34]

Looks good Ken

I made combos like that also Ken some time around 1994 or 5
I had slide in rack chassis upstairs


Now that you have that turret layout, I can make those for you easy if you get tired of making those boards

[Ken Moon]

Thanks, guys!

Doug, that's what I plan to do after I get the amp built and tweaked.

Man, doing new layouts is like a 3d chinese puzzle. So many things to consider 

[EL34]

yeah, it takes doing a build or two to get everything dialed how you want it


That's why I do those builds and sell the amps for parts when I am done
I take notes during the build and then makes changes to the diagrams and boards to get them dialed in

BTW, I can get all that Mojo stuff for you cheaper than they sell it to you

[Willabe]

That board looks fine Ken, nothing wrong with it at all that I can see.


                  Brad     

[jojokeo]

Looking good Ken. I love it when a plan comes together.  Nice to see more designs come along to be used with Doug's new chassis' too.

[MakerDP]

That turret board came out better than mine do using proper saws and drill presses!

On a side note, I did start building a tubes-up combo cabinet based on your designs here. Hopefully tomorrow I can start covering it with Tolex and then I need to order some grille-cloth for it.

All I need to do is decide what amp to mount in it! I'm thinking of putting rack-mount ears in it and then doing the same on all of my chassis so I can have one convertible cabinet that fits all of my amp builds to take with me depending on what I feel like using for that gig. Just slide one amp chassis out, replace it with another, and go! All of that mounting hardware would be hidden by a removable front panel - a grill-cloth frame fastened with Velcro is my plan... unless I can find where to buy those little plastic "knobs" like you see on hi-fi speaker grill-cloth frames from time to time that hold the frames on.

[Ken Moon]

Sounds like a great idea.

I'm mounting the components on my board right now 

[Ken Moon]

Components mounted.

The only snag I hit was a lack of two 56k resistors, so I had to put two 110k's in parallel in each spot.

Now I have to add some jumpers, and solder it all up, then I'll be ready to mount the board in the amp.

[jojokeo]

Ken, 1st of all it looks great. 2nd is you don't have to use 56k's if you don't need to. Do you have anything close? Also, the wattage on those is way overkill so check your supply of even 1/2w resistors and you'll be fine. The only negative thing about wrapping the components on the turrets is that if you decide you want to change/modify anything later then it's a beeyotch to do so. The power tube's cathode resistor should be mounted away from the bypass cap since this heats up. Heat & capacitors don't do well together. Same if that PT gets hot next to your cap can. Lastly, if you wanted to get your garolite edge's straight (& you don't have your normal tools handy) - simply take a sheet of sandpaper and lay it down on a flat surface. Then you can run the edges of the circuit board on this and it will straighten your sides (the inexpensive way to accomplish this task) for that "professional" look. 

[Ken Moon]

Thanks for the tips!

I'm thinking of putting the cathode resistor on the back of the board, to let the heat rise up towards the chassis. That will keep the heat away from the board, but I'll have to careful to not run any wires in that same spot.

If there's nothing (like the OT) right over that spot, I could even drill a small hole or two in the chassis to let the heat escape.

I'll watch to see if the PT gets hot, and if necessary, make a little aluminum heat shield and mount it in between the PT and the cap can.

The trick to even up the board edges is a great idea too - thanks again 

[Willabe]

Looking very nice!

The power tube's cathode resistor should be mounted away from the bypass cap since this heats up. Heat & capacitors don't do well together.

Yes.

I'm thinking of putting the cathode resistor on the back of the board, to let the heat rise up towards the chassis. That will keep the heat away from the board, but I'll have to careful to not run any wires in that same spot.

If there's nothing (like the OT) right over that spot, I could even drill a small hole or two in the chassis to let the heat escape.

I don't think that's a good idea. IF that K R ever goes out, how are you going to get at it to change it?

I'd flip the K R from right to left so it's just a little further away from the K bypass cap. Right now it's wrapped so the R is on the right side of the 2 turrets, put it on the left side of the 2 turrets. Leave the bypass cap up in the air as you have for air circulation and lift the K R up just a little off the board for the same reason, say ~1/4"? A few holes in the board there might help a little, can't see how it would hurt, but not a must.


                      Brad     

[Ken Moon]

Thanks, Brad - that's a great solution!

[MakerDP]

How's your build coming?

I'm almost done with my first tubes-up combo cabinet thanks to your inspiration! It's looking really nice in spite of my mistakes.

[Ken Moon]

Slow but sure - I have to sneak in time to work on it while doing a list of touch-ups on the house to get it ready to put on the market in March...

[sluckey]

Lookin' good!

[MakerDP]

ugh... i know what you are going through. I recently finished getting my parents' house prepped for sale -- including getting rid of 40 years of clutter. It's a time-sink for sure!

BUT your build is looking nice! Can't wait to hear it!

[Ken Moon]

Thanks, guys 

Yeah, we've lived in Jacksonville since 1982 and we still have boxes of baby toys from my adult sons' childhoods, and enough knick-knacks to filll the Smithsonian.

But we already have a house waiting for us in Denver, and I hope to be chillin' there full time by summer