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Re: Guytron GT-100 (Radical new design for tube amps?)


 :
12/12/1997 12:30 AM
Steve A.
Re: Guytron GT-100 (Radical new design for tube amps?)
R.G., et al  
 
    Would a "deconed" speaker work effectively as a dummy load? Leave the voice coil in, but cut out the cone with a razor knife?  
 
    For what its worth, GP gave the Guytron head a very positive review although I've never seen one, let alone played one myself. If properly designed into the amp circuit, a dummy load could be used effectively, with later stages com  
pensating for whatever deficiencies the initial output from the dummy load might have.  
 
Steve Ahola
 
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12/27/1997 8:06 PM
Ted

>> Would a "deconed" speaker work  
effectively as a dummy load? Leave  
the voice coil in, but cut out the  
cone with a razor knife?  
>>>  
 
Unfortunately, most of the complex  
signal required to emulate a loudspeaker  
would be the back EMF or flyback  
due to what is called 'motional impedance'  
. With the voice coil just sitting there taking the power and not moving, all you would get woudl be the resistance and inductance of the voice coil. There is a description of this  
motional impedance as well as a couple of methods to emulate a speaker in a dummy load on our 'Let's Talk Speakers Q and A at  
http://www.webervst.com/sptalk.html  
It's down toward the bottom where a guy askes a qustion about emulating for direct injection to the board in a studio.  
 
Ted
 
12/28/1997 3:25 AM
Steve A.

Ted:  
 
    I just visited your site last night and plan to go back when I have a bit more time... Here's another idea: what about a driver pushing a viscous fluid? It obviously wouldn't respond like a speaker cone in air, but it should be clo  
ser than a purely resistive load.  
 
    I was just reading somewhere that one studio in the 70's had a speaker hidden away in a sound-insulated closet with a microphone for those late-night sessions.  
 
    I'll check out the article you mentioned. Thanks a lot!  
 
Steve Ahola
 
12/28/1997 7:08 AM
Ted

>>>>  
Here's  
another idea: what about a driver  
pushing a viscous fluid?  
>>>>  
 
Yes, I think that would work. The fluid would  
have mass, though and would represent inductance, meaning you might not get the high frequency gyrations that the cone goes through  
which generate alot of the texture of the speaker.  
If you could connect springs to the voice coil, that would work also, although I'm not sure how you could maintain the delicate balance required to keep the voice coil from rubbing. That is how spring reverb works, only in a reverb the spring undergoes to  
rsional (twisting) movement  
rather than extension (stretching) movement.  
 
 
I hadn't heard of the speaker in the closet, but it word work just fine. Another studion trick was to stick a microphone in an underground tank,  
vary the level of water in the tank, and voila,  
reverb...  
 
Ted
 
1/4/1998 8:09 AM
Mike T

Hi Ted,  
 
I think I read somewhere where John Lee Hooker used to stick a microphone in a tiolet bowl. Probably sounded shitty (har..har...)  
 
Mike
 
1/4/1998 6:35 PM
Ted

>>>I think I read somewhere where  
John Lee Hooker used to stick a  
microphone in a tiolet bowl.  
Probably sounded shitty  
(har..har...)  
>>>>  
 
Aha... so that's what they mean when  
they say "early 60's brown sound" ??  
 
(((-:  
 
Ted
 
1/5/1998 11:59 AM
Mike T

>>Aha... so that's what they mean when  
they say "early 60's brown sound" ?? <<  
 
 
Touche`! :-)  
 
Mike
 

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