Transformer Shootout- Hammond vs Magnequest vs Dynaco vs HW

for the DIY ST35, the Dynakit and every other PP EL84

Postby EWBrown » Mon Oct 01, 2007 11:19 am

Still haven't yet done anything with the Trafomatics (Shannon has the second set now). FIrst scheme was to mount them on one of Ned Carlsons DIY35 chassis ith the wood base. I sinve decided to stick with the conventional approach for that, and think "outside the box" (more accurately "inside the box" approach) for them:

I am considering an unconventional / unusual design, in which the toroidal trannies wil be mounted (and hidden) completely under the chassis, the only things penetraring the chassis top will be the tubes, and nothing else.

The trannies look like big grey metallic hockey pucks, and the labels don't align properly, so I'd have to "play games" to make them look right...

As far as "best" trannies for the DIY35:

1: Magnequest MQ-565s (if you can find them, rare and long out of production and fairly expensive). Today, these are made of 100% pure unobtainium, and are rumored possibly to shipped in on the once-per-century freight run from Zeta Reticuli Yellow_Light_Colorz_PDT_11 Yellow_Light_Colorz_PDT_08

2A: Original NOS Dynacos - sometimes these show upon e-pay and other sites. They still have the full length leads and haven't suffered the ravages of time, heat, heat, time and more heat (meaning cracked and flaking insulation).

2B: Original used Z565s, with the cloth leads - the plastic covered leads were later Japanese manufacture, -and though they appear to be the same, I've heard commentary indicating otherwise, YMMV, etc

2C / 3A: The new manufacture Z565s from Triode, Dynakitparts, Tube Zone, etc. These are 99.9 % like the original, but they use more modern insulating materials and some have teflon insulated leads.
Probably the most realistic approach to take, and best for most uses.

4: Hammond 1650Fs, not bad for the $$$, they just don't have the "Hafler Magic Winding Techniques".

5: Hammond 1620s. 6600 ohms CT, UL, 20 watts. They work well with the '35, though the primary impedance is a bit on the low side. The up-side is the price, about $42 each, less when they're n sale.

Not in any numerical scoring order:

The OPTs (and power trannies) salvaged from Heathkit AA-151s. Some state that these sound better than the original Dynaco iron! I've seen AA-151s at yard sales and flea marketws for dirt cheap, even those wit hthe tubes stripped out of them are still good iron donors. I have three-and-a-half of these, now, one works perfectly well as-is (it was a Daystrom factory-built unit), two are in bad need of re-capping, and the "half" was a "tubeless wonder".

/ed B in NH
Real Radios Glow in the Dark
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Postby TomMcNally » Mon Oct 01, 2007 11:28 am

Here is how Velleman mounted the toroids in the 95 WPC K-4000
I built about 10 years ago ... it still shakes the house !

Image

Image

Note the high tech grounding apparatus (yellow) connecting
from the preamp to the Technics SL-1200 turntable.
The preamp has since died, I'm using an Adcom GTP-600 now.
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Postby EWBrown » Mon Oct 01, 2007 12:05 pm

I remember seeing those tube amp kits in the Ramsey Electronics catalog, several years ago - I almost bought one back then...

I always wondered if they were any good or not - apparently they are pretty decent.

/ed B in NH
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Postby TomMcNally » Mon Oct 01, 2007 12:24 pm

I may have one of the first ones in the USA. I waited until
they came up with a 115VAC power transformer, all they
had was 220 at first. I couldn't find a dealer, so I called
Jameco who sold small Velleman kits, test equipment, etc
and asked them if they could get it for me. They called
back after checking on it with a VERY low price. I think
the amp kit was $ 995 retail or something at the time.
I said "sure" let's do it ... and got a call back 5 minutes later
and the girl was stammering ... so I chimed in:
"you quoted me cost didn't you" and she sheepishly said
"yes" ... so I said I'll offer you 10% over cost plus shipping,
and they went for it. So I bought the amp, solid state
digitally controlled preamp and the remote.

The amp is good, could use some tweaks with higher quality
caps here and there, but it sounds great. I haven't done any
mods yet, other than replace the cathode resistors after
the Tesla EL-34's (same as JJ firecrackers) popped them
a few times before I went to Svetlanas.
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