77 DR505 Crituque Needed!

[Murrrwatt]

Hello everyone! This is my first post and as a recently new Hiwatt owner, I was hoping to get a critique.

I have a 1977 Hiwatt DR505. It's in fairly decent shape with a few bumps and bruises. It was missing the back panel and the heat shield when I bought it. I have made replacements and they look great. There was a cracked indicator lamp which has been replaced with a new one from VHR. It has matching partridge trannys and new production preamp tubes, with some very nice vintage GE 6ca7's in the power section. It's been recapped with JJ's and was told it was professionally done. All in all, a very decent amp! Aside from the cap job and the Canadian gain mod, I can't find another non original solder joint. Is there anything that I can't see that's been modded? Here's something else that is weird...."Harry Joyce Canada" has been blacked out (but has faded to the point you can still see his sig.) and "Bob Dickson" is written beside it. It also has "Quantem Leap" written on the inside of the chassis near the mains switches. This was weird for me when I initially looked at the amp, but all the original solder joints made me pull the trigger. I think it may be the Canadian mod "modder" that has decided to write his name and the name of his band on a then new prodution amp. Just a theory.....Any thoughts?

So onto the cap job.....It looks like they've replaced the originals with JJ 100uf/500v cans. Has it been wired up correctly to achieve the same value and the original 220uf caps? Also, the value of the axial cap is 100uf/100v, is that the correct value for a DR505/504? If not, should it be changed out with say, a 150uf?

Oh! One more thing that's bugging me is whether or not I should get a bias pot installed. The GE's are drawing low and there's no red plating going on, but I don't want to have power tube headaches when they eventually wear out. I guess there's 3 options:

- leave it stock and find low drawing, strong tubes for the rest of my life
- the "quick and dirty" bias trim pot as per Hiwatt.org
- the voltage doubler mod as per Hiwatt.org

I'm leaning towards doing the simple "quick and dirty" bias mod, but advice on this is always welcome. Anyways, thanks for sticking with me here and I appreciate everyone's help!

Cheers

[mhuss]

Nice score.

For bias, I'd just add the bias pot. The 50s don't have a problem with the amount of bias voltage.

I would lose the CA mod as well, but that's just me.

[Murrrwatt]

Yep..definitely losing that Canadian mod. I'm looking forward to getting this baby to my tech. The simple bias pot will hopefully save me from future power tube headaches. Any thoughts on the cap job?

Other than that, I am soooo happy with this amp. I've never heard anything like it..sounds huge!! Now I'm on the hunt for some nos glass...oh, and a vintage Hiwatt 4x12. The Hi-Tone cabs look absolutely stellar too, and those DRF's have me gassing big time. My Hi-tone 100 watter needs it! I'd already have one if it weren't for that damn Canadian dollar.

[mhuss]

The recap job looks decent. The JJ caps are fine and there's no need to fuss with them.

[Murrrwatt]

Great to hear!

I'm curious to know who this Bob Dickson is..I just stumbled onto a random thread where one guy posted that his DR505 Harry Joyce Canada signature had been felted out and "Bob Dickson, Quantum Leap" had been written inside. I guess this could be a previous owner talking about my exact amp, but I have seen stuff like "Haselmere" written inside of Hiwatts. Has anyone else out there seen something like this? Why would Bob want to scribble on a Hiwatt??

[mhuss]

Sounds like Bob has/had an ego problem. No other reason I can think of.