LOWATT - DR103 Clone

[idsnowdog]

The preamp board for my from-scratch DR103 clone is complete. I scrapped a Hammond S6 so the transformers, boards, tube sockets, resistors, and possibly chassis will be reused. The preamp section will be the same as a DR103 but the power section will be two 6P14P tubes for around 15 watts. I lost a few turrets while salvaging the boards but I was able to drill new holes and glue in replacements.

 

[Securb]

Interesting, a 15-watt DR103 would be very cool for studio work.

 

[idsnowdog]

The power section will need to change because the S6 transformers are for two 6V6 tubes. I have a variety of power tubes and I need to do the math to figure out what will work and then modify the component values. Lower power tubes won't give the same clean headroom that a HIWATT is known for but I'm not after clean tones. I like that raspy, hard, and bright thing they do when distorted. I just want that at a lower volume.

 

[hamerfan]

6v6 are not a good choice for your sound wish. I converted a Champ from 6v6 to 5881, which made it less fat and warm. So i recommend modern 5881, if you can‘t make EL84 or 6P14P.

 

[Mincer]

I'd love to try to build an amp one day. I've done a few pedals, but I need to learn more about how amps work before I dive in.

 

[jeremy]

i like the 5881 suggestion, cool tubes that arent quite a 6l6gt, but a little more robust than a 6v6. i ran tung sol 5881s in a few amps that were designed for 6v6's without issue, just make sure to bias things properly. that said, i do love 6v6 tubes. the jj6v6 doesnt have the classic 6v6 tone to me, a little stiffer and tighter on the bottom which can be a good thing. they also handle higher voltages than many 6v6 tubes, if you want a more traditional 6v6 sound, the tung sol 6v6 are really nice

a 6v6 or el84 power section wont nail the classic hiwatt sound, but that doesnt mean it wont be awesome

 

[idsnowdog]

I found a schematic/layout for the Trinity TRIWATT and the preamp section is pretty close to the circuit I built. The Triwatt uses a switchable KT66/6V6 power section and sounds more like a HIWATT than the HIWATT Custom 20. The MARWATT and LOWATT also use EL84s but I don't think they sound much like a HIWATT either. Since the 6V6 and 6AQ5 are similar except for plate voltage I am exploring the idea of wiring both 8-pin and 7-pin sockets so I can switch between the two. I believe the KT66 and 5881 would be too high wattage for what I want. The TRIWATT schematic also has the option to use the 2nd half of V2 as an OD control which is nice.

 

[jeremy]

i love kt66 tubes but there is serious heater draw there so gotta be cautious of the pt, same pin out as 6v6/5881/6l6 obviously. dont know if ive seen an amp with 8pin and 7pin sockets before... cool idea if you can make it work. while the 5881 is capable of more output than a 6v6, run at similar voltage, it isnt that much louder in my experience. or at least any louder than a jj 6v6, which is a bit louder than the tung sol 6v6 as i mentioned before. i think youre endeavoring on a fun experiment!

 

[idsnowdog]

i love kt66 tubes but there is serious heater draw there so gotta be cautious of the pt, same pin out as 6v6/5881/6l6 obviously. dont know if ive seen an amp with 8pin and 7pin sockets before... cool idea if you can make it work. while the 5881 is capable of more output than a 6v6, run at similar voltage, it isnt that much louder in my experience. or at least any louder than a jj 6v6, which is a bit louder than the tung sol 6v6 as i mentioned before. i think youre endeavoring on a fun experiment!

The AmpMaker N5X is a single-ended amp and it has two sockets for EL84 or 6V6. I'm trying to figure out a way to use that same concept.

 

[idsnowdog]

The chassis has been cut down to size and holes patched. Although slightly smaller than a HIWATT chassis I think there will be plenty of room inside and topside for the filter caps and transformers. 12AX7 and 6AQ5 sockets drilled. Heat shield installed. Heater wires run. The bias circuit has been started. When I get my stepper bit next week I can drill the holes for the 6V6s and filter caps.

 

[treedroppings]

Good luck with the build up.

 

[idsnowdog]

Good luck with the build up.

The chassis looks like Tara Reid's boob job but once inside the cabinet and with a nice faceplate I doubt most would notice.

 

[Artie]

Cool project, and ditto on the "good luck." (And skill.)

 

[idsnowdog]

Behold my crappy soldering and inconsistent lead dress! I spliced in a new section for the TRIWATT OD control and its push/pull pot. I need to install the filter caps, transformers, and input jacks.

 

[jeremy]

its not quite hiwatt spec, but looks good! look forward to you getting it all together!