6CA7 in a Marshall DSL100HR. Worth Doing?

Pissed Plexi said:
Ivan! Too much info is too much!

I knew the difference between them. Still? The field tests between JJ and EH are noticeable. Especially when soloing.

However the diff between 34 and 6CA7 is negligible.
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So, are we saying the JJs sound better in a cranked amp? Is there any difference at volumes not driving the power tubes into saturation?
 
Pissed Plexi said:
I used JJ6CA7'S in my ORI50 and found them quite pleasing. Thump. Smoothed out the highs yet remained articulate while soloing. Fat yet articulate? Pretty good tube. And I'm not limited to low volume playing. Always into the power section. Loud and proud. Only cause it gets me off. Not cause it's cool...
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Drop-in an Origin 50H???
 
Robert Herndon said:
Drop-in an Origin 50H???
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Marshall has only ever (as far as Ive known) tied the EL34's suppressor grid (pin 1) to the cathode (pin 8) & then grounded the two in its "classic" designs.
Now I believe that the Origin 20 may be cathode biased also amp designs like the single EL34 Slash 5 watt model etc, but the Origin 50???
To know for sure, with the amp turned off & AC wall power disconnected, remove one EL34. Now, with your multimeter set to the ohms scale, check for 0 (zero) ohms between pins 1 & 8. They are located either side of the valve's guide pin notch in the valve socket. If there IS zero ohms between pins 1 & 8, next check for zero ohms between these two pins (1 & 8) & chassis ground. If there IS again zero ohms, your all good to go & plug EHX or old production USA fat bottle 6CA7's in.
Hope this helps. Cheers
 
Cadorman said:
The EHX 6CA7 works great. Been running them in my DSL100HR for almost a week now. Easily biased right up.
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In some amps it will work great.
But beware.
But if the suppressor grid is tied to the negative voltage (as in Peavey Windsor / Traynor) , Tetrode will short circuit the power supply. Only a true Pentode will work.
I think that was the point of defining "Pentode" VS "Tetrode" in a 6CA7.
 
Amp Mad Scientist said:
In some amps it will work great.
But beware.
But if the suppressor grid is tied to the negative voltage (as in Peavey Windsor / Traynor) , Tetrode will short circuit the power supply. Only Pentode will work.
I think that was the point of defining "Pentode" VS "Tetrode" in a 6CA7.
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Looking for a schematic.
 
ivan H said:
Marshall has only ever (as far as Ive known) tied the EL34's suppressor grid (pin 1) to the cathode (pin 8) & then grounded the two in its "classic" designs.
Now I believe that the Origin 20 may be cathode biased also amp designs like the single EL34 Slash 5 watt model etc, but the Origin 50???
To know for sure, with the amp turned off & AC wall power disconnected, remove one EL34. Now, with your multimeter set to the ohms scale, check for 0 (zero) ohms between pins 1 & 8. They are located either side of the valve's guide pin notch in the valve socket. If there IS zero ohms between pins 1 & 8, next check for zero ohms between these two pins (1 & 8) & chassis ground. If there IS again zero ohms, your all good to go & plug EHX or old production USA fat bottle 6CA7's in.
Hope this helps. Cheers
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Good points, Sir!
 
Robert Herndon said:
Looking for a schematic.
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There isn't a schematic.
They are keeping it secret because they don't want their product copied by Bugera in China...

Behringer, Bugera, etc. - all copies of USA / UK products. Mostly copied from Peavey schematics.
"designed in Germany" --- complete BS.
These products are just copies of other brands, cloned in China.
And everything that Marshall builds --- will be copied in China.
 
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Pissed Plexi said:
You will need to bias but yes.
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We don't know the schematic to an Origin 50.

We should not assume until we actually know what the circuit is.

Many of these newer "power scale" designs may use the suppressor grid for adjusting the amp wattage.
London Power Scaling is one example of a power adjust that uses the suppressor grid.

In other words,
If the suppressor grid is not grounded at the socket...
and you plug in the fake 6CA7....(which is not a pentode)....
It can short the power supply out.

I would not be "experimenting." I would not be assuming based on guessing.

But the one safe method:
As long as you don't use a EHX 6CA7,,,,,,,you know that you have a real pentode.
And that would be OK to use.
 
Amp Mad Scientist said:
We don't know the schematic to an Origin 50.

We should not assume until we actually know what the circuit is.

Many of these newer "power scale" designs may use the suppressor grid for adjusting the amp wattage.
London Power Scaling is one example of a power adjust that uses the suppressor grid.

In other words,
If the suppressor grid is not grounded at the socket...
and you plug in the fake 6CA7....(which is not a pentode)....
It can short the power supply out.

I would not be "experimenting." I would not be assuming based on guessing.

But the one safe method:
As long as you don't use a EHX 6CA7,,,,,,,you know that you have a real pentode.
And that would be OK to use.
Click to expand...

Appreciated!
 
Robert Herndon said:
Appreciated!
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You can check with your ohm meter.
With the power disconnected and the tubes removed.
If pin 1 of the socket is connected to pin 8, then you can use a tetrode.
You should read 1 ohm or less between pin 1 and pin 8 of the socket.

But if pin one is not connected to pin 8, then you can't use the tetrode.
You will see a lot more than 1 ohm between pins 1 and 8.
In which case you must go with the pentode.

It's rather odd that EHX does not warn people about this....because it could destroy your power transformer.
 
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