THD Hot Plate with Super Reverb

[Jim]

I recently picked up a 2 ohm "Hot Plate" for use with my Super Reverb
(as refurbed/tweaked by Rich Koerner). I know if Rich reads this, I'll
probably catch hell for using a "tranny toaster." I just don't tolerate
high volumes the way I used to, and I don't gig. So I wasn't playing
this amp like it deserved to get played (at its sweet spot).

Initial impressions are favorable. Tone is reasonably transparent until
-12 dB. Playing with the switches and amp tone controls results in
usable tones, but I'm not thrilled when I dial down below -15 dB. In a
living room situation, -12 dB works great (equates to a speaker output
level of about 3W). Jamming, I'd probably use -4 dB.

There are a couple of "gut shot" pics on the net. Quick run down of
what you get:

- Nice heavy chassis that doubles as a heat sink.

- Rotary -dB switch selects appropriate power resistor loads, which are
cemented into the top of the chassis.

- -16 dB also engages a wire wound high power pot that drops output down
to nil.

- Bulbs parallel to amp output for "noise reduction" at low output (as
bulb filament heats, resistance increases).

- Bright and deep switches alter the built in Fletcher-Munson
compensation (you can see a decent sized inductor and a couple of caps).

- Variable line out, which can be used at all output levels, including
"load."

After consultation, Rich left the higher value silverface coupling cap
in place. I tend to run my bass at around "2," and I still seem to
notice the distortion caused by bottom end. So I think I'll try the
blackface value coupling cap (or another value in between).

I also think I'll put the thing on a variac and find the point where the
heaters are -10% voltage. Then rebias the power tubes and run it at the
lower voltage. That might give me a little more peace of mind that I
won't "toast" the "tranny."

More reviews after I do the above!

[RichL]

"Jim" <inse@ttle> wrote in message
news:9rednXE2cZxuuCfR...@posted.isomediainc...

I've got the 16-ohm version, which I use with my AC30 and JCM 800 2204.

My impressions pretty much coincide with yours except that my "good" limit
seems to be at -8 dB rather than -12. That may be a function of those
particular amps and/or the specific guitars that I've used with it so far.
I don't think I've tried it with buckers yet, but it doesn't seem to react
well to *passive* single-coil guitars at -12 dB attenuation and above; it
seems to exaggerate the high end. However, -8 dB (and sometimes even -4 dB)
is enough attenuation to run those amps in their sweet zones without
rattling the neighbors' cages.

At the moment, mine is "temporarily" with my producer son, who already has
the 4 ohm version and has his own 16 ohm version on order. And I'm missing
it!

[White Spirit]

On 16/10/2010 23:23, Jim wrote:

> I recently picked up a 2 ohm "Hot Plate" for use with my Super Reverb
> (as refurbed/tweaked by Rich Koerner). I know if Rich reads this, I'll
> probably catch hell for using a "tranny toaster." I just don't tolerate
> high volumes the way I used to, and I don't gig. So I wasn't playing
> this amp like it deserved to get played (at its sweet spot).

I'd be too wary of damaging the OT to use something like that. I rely
on the master volume for practising at home. It's not perfect, but I
know the valves and the OT will last longer :)

I have noticed that after playing at volumes high enough to have the
amplifier sounding its best at rehearsal each week, I became less
satisfied with the sound of my amplifiers at bedroom level. It's
something I learned to put up with.

[Mr Soul]

I used the 8-ohm version a lot when gigging and at home. I was pretty
happy with the sound quality (compared to an earlier Weber Mass unit
that I tried) but I always found I wanted a -10 DB becase -8 Db wasn't
enough. -12 Db just didn't work for me. Recently, I got a newer
Weber Mini-Mass and so far I have been pretty happy with it. I really
like the ability to dial in the attentuation which you can do with the
Weber unit. I am sure the regular Weber Mass is even better.

At home I often use the attenuator to simply run a line out into my
computer where I play/practice with my headphones (with the amp
attenuated at 100%). Both the Weber & THD allow you to do this but
the THD has a Line Out volume control which is really nice because the
Weber has a pretty hot line-out signal).

In any event, I'll think I'll be switching over the Weber unit
completely in the near future.

Mr Soul