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All my builds seem to HiFi

1/17/2006 2:20 AM
All my builds seem to HiFi
Why is it every time I build or rebuild an amp, they come out sounding too "HiFi". I've used new and old parts, tried different guitars and speakers but the sound always seems to be the same.  
Could it be a layout thing, grounding scheme or something in the air??  
I'm serious about this question. Anyone else come up with this type of issue.
1/17/2006 3:07 AM

What kind of amps are they and what type of Topology are you using ? Fender ? Marshall ? Do you have a schematic ?  
1/17/2006 12:10 PM

Re-Built a Fender Super Reverb with a Hoffman board. Built a Standard Amp from TUT5 and a 18 watt/Matchless Lightening.  
All amps use the same grounding scheme presented in the TUT books called Galactic ground. Where everything is isolated from the chassis to offer a ground lift. I also do the DC lifted heater thing. Other then that, my layouts/builds are like the originals.  
I really can't imagine the grounding scheme to be the issue... What do you think??
1/17/2006 3:07 PM

I think your building them so good that your not getting any thd % + N. The Fender circuit already is a very clean sound and the Matchless is pretty much too. However the Matchless has a little better distortion when pushed harder than the Fender. I'll bet if you take your amp and put it on a spectrum analyzer you would have probably the same as a Hi-Fi DUT would. The Star ground seems fine and the elevated heaters eliminate hum. Maybe tie pins 1 and 8 together and try some EL-34's. Of coarse if you use an open bodied guitar like a Gretch,Gibson or Epiphone it will tend to sound more Hi-Fi than say a Strat or Ibanez. Your building them too good Dan!  
1/17/2006 3:11 PM
Chris/CMW amps

Hi Dan  
Didn't try that way of grounding to be honest. Right know I'm wondering about the powersupply-voltages (preamp and PI nodes) and OTs in your amps...  
Which (preamp)tubes do you use and what type/brand of (e)caps? Is the biasing correct?  
Let us know  
1/17/2006 10:41 PM

Powersupply B+ voltages Matchless is 340, Standard 410, Fender 455. All the PI voltages are what you would expect from the B+ given the circuit we all know.  
OT's are 1965 Fisher OT for the Matchless and the Fender is stock Fender. I also have a Hammond on my Standard Amp.  
Preamp tubes... I've used them all with same results.. 12AX7 RCA Blackplates to Chinese, 5157's AT's and AY's.  
E caps: I tend to use the smaller ones from Weber.. 20mf/450v 105 degrees.  
My biasing is perfect... I'm sort of anal about it.. I like 70%-80% dissipation.  
So what you think???  
1/18/2006 12:22 AM

Warning: bad english  
Can you tell about a popular amp that you played that didn't seem Hifi?  
I have TUT5 and "The Standard" seems(*) to have all the option's we need to make it sound non-hifish..  
Altought it is needed something more than tree gain stages to have a "high-gain" distortion if is that you are looking for.  
Also, if you refer to the general tone of the amp (can that be called "the amp groove"???), start thinking about reduce negative feedback, mismatch OT load, reduce bandwidth by changing coupling and cathode caps, etc.  
(*) - I didn't build that amp, I'm just based on the schematic.
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