vintageHIWATTconvention.com

The model number and date code should be written on the red label near the speaker terminals. See the bottom of this page (https://hiwatt.org/dates.html) for details. The aluminum dust cap likely means 1980-ish vintage. I'm not sure if it's just the picture, but the other three appears to have diffe...

Any Tolex/Vynide cleaner you'd use on an amp will work fine with a HIWATT.

I'm not sure about the handle, I've never removed one.

The 220k works better with the correct cathode resistor.

Definitely the first thing I would try.

Welcome,

"175" might also indicate voice coil diameter

I don't think buying the speaker you propose would add much of anything; I think the newer HIWATT/Fane speakers may be manufactured in China as well if that matters to you.

Yes, the old Fane speakers were better suited to HIWATT amps then, say, Vintage 30s.

Hello, and welcome. Even stock HIWATTs are pretty bright, so it may be partly an expectation problem. :) The 1000p will lower/widen the treble response, so 220p may seem brighter. This may have been an attempt to change the bright character of the amp. 1uF is large enough that it's probably just upp...

It's close.

If you're more into heavy, the speaker you've got might be OK. Again, try and see.

I wouldn't worry about the grid stoppers until you try it out and see what it sounds like. I am not a fan of the CMod, it was a quick and dirty hack and sounds like it.

I have no advice to offer on glue.

hi Peter,

Thanks for the information.

There were many small changes year-to-year in part values and circuit tweaks as well. I've just captured representative examples on hiwatt.org.

--mark

PS. You need to get a proper Hiwatt cab too.

hi Peter,

I don't recognize the numbering. I could from a be a big band as you suggest, or perhaps a big rental company.

--m

Looks like a voltage doubler for the bias - a common and useful mod for older DR103s, which in stock form don't supply enough bias voltage for modern EL34s. The pot is there to adjust the bias to the correct level. When these amps were made, the original Mullard EL34s Hylight used were very consiste...

The original switches are hard to come by now. If you can find one, great, but any DPDT 250V toggle switch will work (e.g., the NKK S-25AW/B). The threads are fairly standard. If the bat handles look too different, you can always replace both to match.

Try loosening and re-tightening all the ground connections (near the inputs, and near both ends of the 'skinny' board.)