heisthl wrote:... the solid state taps were good for both bias and relay power.
I'd caution you on using the same taps for bias and relays. Relays are noisy and the bias goes directly into the grids of the power tubes so noise gets transmitted easily.
Varying relay current equals varying bias current, not good. Theres enough surplus transformers out there (Radio Shack, Goldmine Electronics or All Electronics) that would provide relay voltages to avoid asking for this kind of trouble. Of-course that microscopic chassis size will make locating said transformer, lots of fun.
Thanks for the insight - on this amp its a moot point - I ended up getting the bias from the main primary winding and using a separate transformer for relay power. In fact you can see the add on xformer in the last picture.
Keep it up ,Buddy. I have a MM RD-50 that I bought new in 1980-81. I just hate to gut it and start over. I'd rather keep it and build from scratch, but boy are you tempting me.
Then , someone asked about a Fender Bassman Ten conversion. I have one of those sitting next to my RD-50. Same problem. I hate to "mess it up" when I can keep it and start from bottom up. I bought a Traynor BassMate to convert to an 18 Watt Marshall. Need I say it? I like the way it sounds as is. So, I've ordered a kit from Trinity.
I'm kind like the old ladies that have a hundred cats. Oh well!
Thanks for the updates. You might lure me in yet.
Latest Schematics and layout - this amp sounds incredible if anyone has any suggestions to make it sound unbelievable, I'm open to suggestions. Right now I can dial in the OD to get several sweet spots on the guitar neck that sound like an overtone harmonizer without any distortion - I wish it would do that on every note. Of course it will sustain any note at will if you want it more distorted. The clean sound is extremely versitile even with all tones on 5 and just using the mid select or deep for styles. It really likes to sound like you just put new strings on the guitar - steely cleans.
There is a switch for using EL34's and another switch for cathode bias on the schematic(and in the amp) that is not on the layout. I have not tried EL34s yet(the switch is based on -52 for 6L6 and -34 for EL34) but the cathode bias works and makes the amp have less power without changing the tone too much - although some of the clean "sing" is gone.
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Project done - except for general cleanup(de-flux, wire routing etc.). The amp sounds better than anything I've owned or modded before. I have tested it with both 6L6 and EL34 at normal or cathode bias. This really makes it 4 different amps - all with different qualities. I think it sounds best with 6L6 normal bias(-52 to -54) but its a coin toss against the EL34 at normal bias(-34 to -36). Using the EL34's lowers the preamp voltages a little bit. Using the cathode bias lowers the preamp voltages even more and gives about 60% music power. The cathode bias seems to work for both output tube types. I updated the previous schematic with the final changes.
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I can't wait for Santa to come by on his midwest tour and deliver my Xmas present! I will post clips of the amp once I have it reassembled and rockin' at the crib!
It's finally here!! I'm extremely pleased. Close to decided on speaker and amp tweaks. I had an EV-12L in there but, I liked the sound of this Eminence OEM that was in the Music Man. Cannibis Rex was close second, RWB was alittle too mid heavy for me. My 12L is ancient and seemed a little buzzy (and heavy). The RWB seemed to cure some of the rasp. The internal tone switch is switched all the way UP. The decision was between switch up or switch down. I was told up was NO tone shaping into the OD - the schematic should reveal the values of components. The clips were dry into the computer with an Ibanez AS. I added a little verb after the fact (I couldn't resist). The tube buffer-o-lator was not used in the clips - although it works great and will get a thorough workout soon. The clean channel knocks me out. The OD is just a tad raspy - any ideas for tweaks would be appreciated. A little compression in front eliminates that pretty much. If anyone is interested in the settings, I will post them. The amp settings were left static for all the clips except the last one. I leaned over and flipped the mid boost on. I really love the thing. The size and weight are ideal and it sounds even better with my regular gig pedals and effects. Many thanks to my friend Henry.
My builder friend lives in Phoenix and I am in Omaha. Instead of the ideal situation of tweaking the amp with me and my guitars there, he put a switch with 3 tone possibilities for the OD section. He made best guesses with me and my guitars in mind. I'd say he done good. The middle position wasn't for me but, the other two were hard to decide between. He can chime in on what value I chose - I believe it is the .01 position. The straight passthru was a close second.
stelligan wrote:The OD is just a little raspy or brittle - any ideas for tweaks would be appreciated.
Don't overlook the possibility that the right speaker choice just may be the final/ultimate tweek for this. My experience has been that the speaker can emphasize (or not) this problem. Experiment with as many speakers as you can, to see which ones minimize the raspy OD tone. (just my opinion)
Very good advice. I am contemplating trying an Emi Red, White, and Blues. Seems I am reading a lot of chatter about this kind of amp + RWB's being a good match. I have also read that the OD in a non HRM amp, like this one is, will be inherently more edgy than an HRM. There are probably threads here regarding best speakers for HRM and best for non. I'll search. Just wish I had a stack 'o speakers out in the shed.......
New clips on above post. I play heavy with 12 gauge E and a 20 on the G string. I rolled off the guitar and turned down the 1st volume control on the amp. That has seemed to smooth things out. Backed the OD trim down a hair. Still speaker shopping, tho....
stelligan wrote:New clips on above post. I play heavy with 12 gauge E and a 20 on the G string. I rolled off the guitar and turned down the 1st volume control on the amp. That has seemed to smooth things out. Backed the OD trim down a hair. Still speaker shopping, tho....
It was with a Shure 57 as in picture into a Line6 toneport usb interface to laptop. I used none of the Line6 processing - just as a soundcard into a program called Cool Edit and added some verb after. Yeah, I'm really diggin' the amp and getting closer to dialed in. I'm thankful to say the least...
My experience has been that the speaker can emphasize (or not) this problem. Experiment with as many speakers as you can, to see which ones minimize the raspy OD tone. (just my opinion)
Cool harmonics 
