vintageHIWATTconvention.com

..to me at least. My new/old DR103 (#2130) has arrived at home from the UK via FedEx.

Of course, I'm still at work.

*Many* thanks to the Doc and buster for all their help in finding this and getting it to Pennsylvania.

--mark

So it was you? I was watching that one (but not bidding). Nice score - congrats!

we want pics, clips and all the other annoying pesky stuff that internet trolls want!

That is Great! I look forward to your evaulation of it!

mhuss wrote: Of course, I'm still at work.

An-ti-ci-pa-tion, An-ti-ci-pay-yay-shun...

Congrats on the overseas acqusition. So, when is the alien autopsy scheduled ?

Dave

OldSchoolDave wrote:So, when is the alien autopsy scheduled ?

Yes, when can we start logging in to the mhuss.com "Alien Autopsy Webcam"?

Autopsy -- Already done.

A few minor changes from my current 'early 70s preamp' schemo, but pretty close.

Mid 1971 dates codes. Has those small blue metal-film-looking resistors (2%) throughout. TG5479 bifilar wound OT with 100V tap, 'H1' date code = 71 also. "cut down" serial plate. model DR504103 with 504 struck out.

Someone already did the "remove the big resistor and replace the screen resistors with 1Ks" mod, otherwise 100% original, One screen resistor was melted so I replaced it.

All Brimar BVA "Made in England" ECC83s. Came with 4 old XF4 EL34s, but 3 are marginal. Put in a set of SED winged-Cs. The SEDs are running around 38mA/tube with the stock bias circuit.

Sound wise, a clean machine, not a speck of dirt at 5/5/5, but really growls at 10/10/7.

--mark

simply Awesome!

mhuss wrote:Has those small blue metal-film-looking resistors (2%) throughout.

Very, very nice!

Looks like they were running out of all kinds of parts that week... resistors, s/n plates.

I'd be interested to hear more about the minor differences between this and your schematic. Not even a speck of dirt? Seems like my clone does a wee bit of dirt at that setting, if you slam it with a PAF.

Looking up "bifilar" now...

those baby blue resistors were used more than the big fat yellow/tan variety. atleast from 1971-1974.

Several of my amps have them and they sound excellent. Not that anyone has said this, but I would not think of them as inferior to the bigger fat ones.

Very nice Mark!! Now I just need one of my amps to go down so I can come see that thing.

The 'baby blues' look like they might even be metal film (vs. carbon film). I don't remember ever seeing 2% carbon film resistors. It sounds just like a Hiwatt, oddly enough. Perhaps not a coincidence, but the hiss is really low on this one, particularly considering its age.

"Bifilar" means two separate secondary windings, usually wound so as to reduce stray capacitance and leakage inductance on "hi-fi" output transformers, producing a transformer with less parasitics and wider bandwidth. These are often brought out as separate wires. You can see this on many older Hiwatt Partridges, with pairs of wires of the same color twisted together and going to the impedance selector lugs. This is obviously more expensive and more complicated to manufacture, and eventually they figured out you don't need "hi-fi" transformers for guitar amps.

--mark

mhuss wrote:The 'baby blues' look like they might even be metal film (vs. carbon film)

I think I came across some of these NOS on eBay... same appearance, anyway.