6CA7 in a Marshall DSL100HR. Worth Doing?

Amp Mad Scientist said:
the fake 6CA7....(which is not a pentode)....
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I simply cannot understand why you are referring to beam tetrode 6CA7's as "fake" 6CA7's.
Sylvania, who designed the "original" (meaning very first ever) 6CA7, designed it as a (fat bottle) Beam Tetrode. How on earth then can these beam tetrode type 6CA7 valves be "fake" 6CA7's???

Ascertaining
Robert Herndon said:
If I make the swap, I'm definitely looking for more articulation and tighter low end.
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I've not used new production 6CA7's, but am quite familiar with & have used the original USA fat bottle Beam Tetrode 6CA7's. Compared to an EL34, they are a tad mid scooped with better low end that is definitely tighter than an EL34's. Very nice highs too. Kinda like an EL34 with a bit of 6L6 thing going on. I "believe" that (even though it overdrives earlier, like an EL34) the Electro Harmonix 6CA7eh is similar to the original USA fat bottle 6CA7's in this regard. Cheers
 
ivan H said:
I simply cannot understand why you are referring to beam tetrode 6CA7's as "fake" 6CA7's.
Sylvania, who designed the "original" (meaning very first ever) 6CA7, designed it as a (fat bottle) Beam Tetrode. How on earth then can these beam tetrode type 6CA7 valves be "fake" 6CA7's???

Ascertaining

I've not used new production 6CA7's, but am quite familiar with & have used the original USA fat bottle Beam Tetrode 6CA7's. Compared to an EL34, they are a tad mid scooped with better low end that is definitely tighter than an EL34's. Very nice highs too. Kinda like an EL34 with a bit of 6L6 thing going on. I "believe" that (even though it overdrives earlier, like an EL34) the Electro Harmonix 6CA7eh is similar to the original USA fat bottle 6CA7's in this regard. Cheers
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I might do this at my next power tube service....
 
Don O said:
Santa dropped it off :rolf:. I added the casters.

View attachment 64865View attachment 64866View attachment 64867
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You know, that's cool with the casters and all. I need to put casters on my Motorhead 4x12, but because we load and unload it frequently, I will need to put threaded anchors on the inside of tha cabinet, because it will pull the screws out of the bottom if handled roughly by stage hands.

Where did you get the casters???
 
Robert Herndon said:
You know, that's cool with the casters and all. I need to put casters on my Motorhead 4x12, but because we load and unload it frequently, I will need to put threaded anchors on the inside of tha cabinet, because it will pull the screws out of the bottom if handled roughly by stage hands.

Where did you get the casters???
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I thought about putting steel plates on the inside and using bolts, then realized it's never going to get abused. I got the casters from Amazon. Just bought 6 of these 4" tall, 2" wide casters which can support 700 lbs each. They will be under this granite topped island we had in the loft in our previous home. It will be a "floating" island in the multi-purpose room in the basement. I have a welder over in Cedar Glenn making me the frame.

Caster 700lb.JPG

DSC05373.JPG
 
Don O said:
I thought about putting steel plates on the inside and using bolts, then realized it's never going to get abused. I got the casters from Amazon. Just bought 6 of these 4" tall, 2" wide casters which can support 700 lbs each. They will be under this granite topped island we had in the loft in our previous home. It will be a "floating" island in the multi-purpose room in the basement. I have a welder over in Cedar Glenn making me the frame.

View attachment 64876

View attachment 64877
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Very cool...got a link?
 
Robert Herndon said:
@ivan H - What would be the benefit/detriment in an Origin 50H between KT77 and 6CA7???
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Whether beneficial or not would depend on what you are looking for in installing them (I suspect that in your case they may be). KT77's shouldn't be detrimental to the amp, but we'll get back to that later. How close new production KT77's are to "real" old British KT77's is another thing..
If you want an honest, real-world opinion on how real British KT77's sound/perform in a classic Marshall circuit, ask Mr @67plexi as he uses these very desirable valves in his (also very desirable) '67 100 watt superlead.
Compared to the EL34 (& even the 6CA7), the KT77 is a more robust valve that sonically has greater clean headroom, better low end, is tighter & more articulate all 'round. Audiophools love this valve & will shell out big bucks for the old MOV, GEC, Genalex (all Philips owned) & other NOS variants.

Now, onto whether or not it may be detrimental to the Origin 50 amp. The KT77 is a kinkless Tetrode, so a beam Tetrode. (As I've no experience with current production KT77's, the following is based on my little experience with old British KT77's). Maximum plate dissipation is 32 watts (though as I don't know the Origin 50's OT spec, bias as for an EL34). The beam forming plates are tied to the cathode/pin 8, pin 1 has no connection, so the socket pins 1 & 8 do not need to be tied together (may not be so for current production variants).
Maybe post the datasheets for the KT77 type you wish to use here so a few of us can go over it.
Hope this helps. Cheers
Edit:
The KT77 is superior to the 6CA7 in audio performance. Cheers
 
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ivan H said:
Whether beneficial or not would depend on what you are looking for in installing them (I suspect that in your case they may be). KT77's shouldn't be detrimental to the amp, but we'll get back to that later. How close new production KT77's are to "real" old British KT77's is another thing..
If you want an honest, real-world opinion on how real British KT77's sound/perform in a classic Marshall circuit, ask Mr @67plexi as he uses these very desirable valves in his (also very desirable) '67 100 watt superlead.
Compared to the EL34, the KT77 is a more robust valve that sonically has greater clean headroom, better low end & is tighter & more articulate all 'round. Audiophools love this valve & will shell out big bucks for the old MOV, GEC, Genalex (all Philips owned) & other NOS variants.

Now, onto whether or not it may be detrimental to the Origin 50 amp. The KT77 is a kinkless Tetrode, so a beam Tetrode. (As I've no experience with current production KT77's, the following is based on my little experience with old British KT77's). Maximum plate dissipation is 32 watts (though as I don't know the Origin 50's OT spec, bias as for an EL34). The beam forming plates are tied to the cathode/pin 8, pin 1 has no connection, so the socket pins 1 & 8 do not need to be tied together (may not be so for current production variants).
Maybe post the datasheets for the KT77 type you wish to use here so a few of us can go over it.
Hope this helps. Cheers
Click to expand...

Always appreciated!!!!!
 
ivan H said:
I simply cannot understand why you are referring to beam tetrode 6CA7's as "fake" 6CA7's.
Sylvania, who designed the "original" (meaning very first ever) 6CA7, designed it as a (fat bottle) Beam Tetrode. How on earth then can these beam tetrode type 6CA7 valves be "fake" 6CA7's???

Ascertaining

I've not used new production 6CA7's, but am quite familiar with & have used the original USA fat bottle Beam Tetrode 6CA7's. Compared to an EL34, they are a tad mid scooped with better low end that is definitely tighter than an EL34's. Very nice highs too. Kinda like an EL34 with a bit of 6L6 thing going on. I "believe" that (even though it overdrives earlier, like an EL34) the Electro Harmonix 6CA7eh is similar to the original USA fat bottle 6CA7's in this regard. Cheers
Click to expand...

Found this on the EuroTubes website:

Marshall Origin 50 Standard Retube

It says the following:

Marshall Origin 50 Standard Retube

This is the Standard Retube Kit for the Marshall Origin 50 Heads and Combo amps. The preamp section uses three ECC83S's with one balanced for the phase inverter in V3. The default power tubes are the JJ Electronic E34L’s but you can configure this kit to use the JJ EL34II's, EL34’s, KT77’s or Big Bottle 6CA7’s by clicking on the "Customize" button.
 
In an Origin 50 gutshot that Robert provided me with, it can be seen very clearly that the V5 pins 1 & 8 are tied directly together & also that both pins are connected to the bias test point.

Great job researching this Robert, & clearing it up for other Origin 50 users that these amps can safely use Beam Tetrode type 6CA7's. Cheers
 
ivan H said:
In an Origin 50 gutshot that Robert provided me with, it can be seen very clearly that the V5 pins 1 & 8 are tied directly together & also that both pins are connected to the bias test point.

Great job researching this Robert, & clearing it up for other Origin 50 users that these amps can safely use Beam Tetrode type 6CA7's. Cheers
Click to expand...

Thank you and your discerning eye!
 
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