Anyone tried JJ E88CC in place of 12AT7 as a 'verb Driver?

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tubeswell
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Anyone tried JJ E88CC in place of 12AT7 as a 'verb Driver?

Post by tubeswell »

I ask because one of these as a parallel triode strikes me as a possibility for getting more drive than what a parallel 12AT7 could give in a BF style circuit.

JJ E88CC spec on this link

http://www.jj-electronic.com/pdf/E88CC.pdf

The job I have in mind for it is driving a standard BF reverb transformer (designed for a parallel triode 12AT7)

Any ideas/comments anyone?
Firestorm
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Re: Anyone tried JJ E88CC in place of 12AT7 as a 'verb Driver?

Post by Firestorm »

It would be neat to try. I don't think you'd get more drive, though; the ECC88/6922 has lower mu and lower plate dissipation. But that might be just what the doctor ordered. Fenders usually have way too much reverb (unless you're Dick Dale) so this might tame and sweeten it a little. It looks like you could just drop it in and see how it sounds.
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Structo
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Re: Anyone tried JJ E88CC in place of 12AT7 as a 'verb Driver?

Post by Structo »

It appears that the E88 has a gain factor of 33.

The 12AT7 has a mu of 60-70 depending on plate voltage.
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Merlinb
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Re: Anyone tried JJ E88CC in place of 12AT7 as a 'verb Driver?

Post by Merlinb »

Structo wrote:It appears that the E88 has a gain factor of 33.

The 12AT7 has a mu of 60-70 depending on plate voltage.
The mu doesn't affect the power output, the plate resistance and max dissipation do. The ECC88 is lower resistance, so can pass more current, but its max dissipation is supposedly lower. However, since both types come in the same bottle and have similar-sized anodes, I'd be willing to bet the ECC88 could take as much as the ECC81/12AT7.

On the other hand, an ECC81 should already be capable of driving a reverb tank to full power, so is there really anything to gain...
mamtiocker
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Re: Anyone tried JJ E88CC in place of 12AT7 as a 'verb Driver?

Post by mamtiocker »

Hello. Could be possible to drive the reverb transformer with just one triode from 12at7, and use the second triode for reverb recovery?

I'd like to add a tube reverb to an amp with just one 12at7. The tranny is 25k primary, 8ohm secondary, typical Fender, and B+ around 350v. I have to find a good cathode resistor value. Thanks
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Re: Anyone tried JJ E88CC in place of 12AT7 as a 'verb Driver?

Post by Stevem »

A 12bh7 for that 9 pin socket may work, but if you open up the chassis for a octal socket then a 6sn7 has the needed plate wattage rating.
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Re: Anyone tried JJ E88CC in place of 12AT7 as a 'verb Driver?

Post by martin manning »

Here is a one-tube reverb design that uses a 12AX7: http://ampgarage.com/forum/viewtopic.ph ... highlight=
labb
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Re: Anyone tried JJ E88CC in place of 12AT7 as a 'verb Driver?

Post by labb »

Give this a look for one tube reverb: http://el34world.com/Forum/index.php?topic=7957.0
mamtiocker
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Re: Anyone tried JJ E88CC in place of 12AT7 as a 'verb Driver?

Post by mamtiocker »

Thank you very much for all responses. I will try it with 12at7 too, maybe for more "swell", stronger drive .
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Re: Anyone tried JJ E88CC in place of 12AT7 as a 'verb Driver?

Post by SoulFetish »

The E88CC/6DJ8 was originally designed to be operated as a cascode, with triode 1 to be operated as the grounded cathode input section and triode 2 as the grounded grid section. Also, it was designed for parallel heater operation at 6.3V. As a cascode, it has high gain and is a very linear. Of course, cascode isn't the only way to operate this tube. You'll find these tubes are used a lot in horizontal amplifiers and in sweep generators on older oscilloscopes.
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