why DIODE CLIPPING in AMP ?

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idnotbe

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i experienced a few amps with the internal diode clipping (jose) and with another tube gain stage (aldrich) .

for me, the diode clipping is hard to be "natural" and hard to be better than a tube gain stage.
and cannot be better than a tube gain stage.

then, why do the amp builders use the diode clipping?
what's the benefit in tone? (not in cost)
 
Depends on the circuit placement. I like diode clipping on some amps.
 
I like the aggressiveness it gives when combined with tube warmth. +1 to what Dave said - it has to be done correctly in terms of location and what exact values of diodes are used.
 
Depends on where and how for the diodes in the circuit. There are good and bad examples of both. If you haven’t found a good example yet... try some others. They exist. Plenty of great sounding diode boosted amps out there.
 
All tube path is a nice concept, but then again, when you use a boost pedal it's not that different from going with diode clipping amp. And some sound outrageously good.
 
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idnotbe":3dyzc4qk said:
i experienced a few amps with the internal diode clipping (jose) and with another tube gain stage (aldrich) .

for me, the diode clipping is hard to be "natural" and hard to be better than a tube gain stage.
and cannot be better than a tube gain stage.

then, why do the amp builders use the diode clipping?
what's the benefit in tone? (not in cost)
Click to expand...
Because you can simply get more clipping without adding stages. Adding stages can ad noise and added heater current requirements can make you have to run the PT beyond it's specs "on paper" Also diode based circuits I've tinkered with clean up real well because the clipping is in relation to the signal levels. I haven't played the aldrich, but I assume that a Jose will tend better with cleaned up and in between tones.

 
Wizard Modern Classic and MTL......they sound terrible!

Seriously, when done well diode clipping can sound killer. But clip too hard and it's too much.

The Helios 80s mode is another great example of diode clipping done well.
 
scottosan":37d8xhur said:
idnotbe":37d8xhur said:
i experienced a few amps with the internal diode clipping (jose) and with another tube gain stage (aldrich) .

for me, the diode clipping is hard to be "natural" and hard to be better than a tube gain stage.
and cannot be better than a tube gain stage.

then, why do the amp builders use the diode clipping?
what's the benefit in tone? (not in cost)
Click to expand...
Because you can simply get more clipping without adding stages. Adding stages can ad noise and added heater current requirements can make you have to run the PT beyond it's specs "on paper" Also diode based circuits I've tinkered with clean up real when because the clipping relation to the signal levels. I haven't played the aldrich, but I assume that a Jose will tend better with cleaned up and in between tones.

Click to expand...
Nice Gary Moore licks!
 
I has the SAT switch installed on my Smallbox combo. Really makes it more aggressive. It does not feel or sound like having a pedal on the front end.
 
idnotbe":zx3n5d27 said:
i experienced a few amps with the internal diode clipping (jose) and with another tube gain stage (aldrich) .

for me, the diode clipping is hard to be "natural" and hard to be better than a tube gain stage.
and cannot be better than a tube gain stage.

then, why do the amp builders use the diode clipping?
what's the benefit in tone? (not in cost)
Click to expand...

Do you use overdrive, boost and distortion pedals?
 
lespaul6":2uoz6c9q said:
technically speaking a tube is a diode....
Click to expand...

You'd be incorrect on this one. Diodes are voltage controlled current devices, tubes are voltage controlled current devices, but not even remotely the same. A tube is closer to a BJT than to a MOSFET, hence why pedals use mainly use BJTs.

edit: To be clear, a tube is closer to an IGBT in terms of power handling and operation.
 
lespaul6":2qjj6uww said:
glpg80":2qjj6uww said:
lespaul6":2qjj6uww said:
technically speaking a tube is a diode....
Click to expand...

You'd be incorrect on this one. Diodes are voltage controlled current devices, tubes are current controlled current devices. Not even remotely the same. A tube is closer to a BJT than to a MOSFET, hence why pedals use mainly use BJTs.
Click to expand...


What are your thoughts on this: https://www.electronics-notes.com/artic ... m-tube.php
Click to expand...

It's a transconductance device used to rectify AC voltage to DC. You'll find later on that solid state diodes could be used to do a similar task, but that does not change the physics which differentiate how each of them operates. If you do some further research, you'll also find a limitation of tube rectifiers: they are susceptible to failure when asked to drive too large of a capacitive output impedance. This is because fundamentally, the capacitive load looks like a short at the output of the tube rectifier. Because solid-state diodes operate fundamentally different based on doping effects of impurities within silicon, there are no design limitations on how they are used as long as the materials can withstand the current or voltage demands.

edit: Replaced diode rectifier with tube rectifier to be more clear.
 
lespaul6":2tzira6y said:
You have failed to prove wrong the fact that the first diodes were tube diodes...and a tube is in fact a form of diode.. here is mike soldano:

http://www.soldano.com/amp-help/tube-vs ... ectifiers/
Click to expand...

Actually, Mike is agreeing with my statement to a T and is saying the same thing but in a different manner. Because the tubes are transconductance, they are voltage controlled current devices. Because they are voltage controlled current devices, they are voltage independent of the load seen at the output which is also what Mike mentioned. They drive an output impedance using current, which produces a voltage both across the tube and the load. They fail because the impedance of the tube is not always the lowest output impedance and as such, the load can have a much smaller output impedance which is not ideal. This is where the tube can get "pulled" to ground, eventually cause a short from anode to cathode since the impedance is in parallel with the impedance of the tube.

This is why those old tube rectifiers in old radios arc from anode to cathode when capacitors go resistive. The resistive load is a lower impedance than the tube itself and essentially shorts the tube to from B+ to ground.

I'm going to mention here that I'm not some internet troll, I do hold an MSEE degree, and analog circuits is my bread and butter for RF design. It's what I do for a living :D
 
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