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Re: stupid marshall tricks


 
3/22/2000 6:34 AM
Richie{~}==::: Re: stupid marshall tricks
Another thing is.you could get one of the  
JCM800 combos. Not as bad on the back,  
Their are different models numbers,  
but they will be like a 2203,,,2204  
,,etc.. So you could still unhook the  
speakers in the combo and hookit to a 4x12 when ya need it. (just adjust imp.)  
Richie{~}==:::
 
3/22/2000 6:41 AM
Steve A.
email

Rebel420:  
 
    You left out the 4th choice for a good attentuator: the THD HOTPLATE! < g >  
 
    So how do these differ from the not-such-a-good-choice, the Marshall Power Brake (which uses a multi-section rotary switch, a multi-tap transformer- or choke?- and some power resistors- probably for the lowest setting which has no signal going to the speakers). Does the THD use the same basic design, or something else altogether?  
 
--Thanks!  
 
Steve Ahola
 
3/22/2000 2:19 PM
Rebel420
email

quote:
"So how do these differ from the not-such-a-good-choice, the Marshall Power Brake (which uses a multi-section rotary switch, a multi-tap transformer- or choke?"
 
The hotplate is one that I will NOT reverse engineer, probably becaue it would require a custom choke, and mainly becaue I ahve a LOT of respect for Andy Marshall (heh, with his last name, how could I not *laughs*). it basically IS the same concept as the Marshall Power brake-- Rotary switch using different power resistors, a choke or 2 and some caps. Sound tests between the Power Brake and the hotplate, well the hotplate wins hands down for the 'natural' sound of it. One common feature of the PowerBrake and the HotPlate is the tapping some of the power to drive a fan for cooling purposes. The PowerBrake gives you a few more 'steps' in the switch, ( I think the HotPlate has 6 or 8 if i recall, and the PowerBrake has like 20 or so). Other advantages of the hotplate, the lowest settin, you have a volume pot on there where you cna tweak the volume down evne lower, form barely on etc. There is also a 'load' position which i use all the time for biasing amps and repairs. In the load position, you can youse your head as a massive stompbox, utilizing the compensated line out on the back (adjustable volume on that as well). There are also 2 toggle switches for bass and treble boost on the front. PLUS the hotplate has a light that is part of the 'noise reduction' circuitry, and looks DAMN cool!!  
The hotplate just sounds a bit better to me and many others
 
3/22/2000 2:20 PM
Rebel420
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oh, forgot to add... when I took the cover off of mine (99% of these attenuators is the MASSIVE heatsinking!), on the bottom of the PCB, there is an etching "If you can read this, you have already voided your warranty"... gotta love the sense of humour!!
 
3/22/2000 3:16 PM
Randall Aiken
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Don't forget the other one: "...machined out of a solid piece of alimony" :)  
 
BTW, the Hotplate is a purely resistive attenuator with some LC frequency compensation. The PowerBrake is a reactive load using the Pittman patented circuit he stole from the Radiotron Designer's handbook and other sources, with an autotransformer for attenuation control.  
 
My only gripe with the Hotplate is the attenuation steps are too coarse - it goes in -4dB steps, and invariably, one step was a bit too loud and the next was a bit too quiet. I usually ended up using my PowerBrake on stage because of that, because it goes in -3dB steps and seemed to "fit" better, volume-wise. The Hotplate has a better tone, though, particularly at very low levels. Both sound great at just a couple of clicks.  
 
If I had to choose only one, it would be the Hotplate, which is kind of funny, because "conventional marketing wisdom" (a misnomer if I ever heard one!) says a reactive load is more "natural".  
 
Oh, and Andy is a cool guy, too. He spent lots of time with me on the phone talking about attenuators, amps, etc.  
 
RA
 
3/22/2000 3:26 PM
Rebel420
email

quote:
"My only gripe with the Hotplate is the attenuation steps are too coarse - it goes in -4dB steps, and invariably, one step was a bit too loud and the next was a bit too quiet."
 
That was my only gripe as well!!  
quote:
"If I had to choose only one, it would be the Hotplate, which is kind of funny, because "conventional marketing wisdom" (a misnomer if I ever heard one!) says a reactive load is more "natural"."
 
Watch it! I work in the marketing dept of my company! *laughs* But I do get to do cool stuff, my job is basically to help the marketing folks cut thru the BS that salespeople give them, then test the products before we put them in our catalog... so basically, I get paid to surf the web "looking for new products", then when they come in, I get to play with all the cool toys  
quote:
"Oh, and Andy is a cool guy, too. He spent lots of time with me on the phone talking about attenuators, amps, etc."
 
I spoke with him before I purchased my hotplate--- basically I called the company witha few technical questions, and they put me on the phone with him... Couldnt ask for a better guy!!! (too bad he dont hang out here with us on Ampage). I also got a prompt email response form him on his Reactive Rectifier circuit. I may have to get one of these to see how they work.
 
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