[milosz]

I bought Flocchini's  "hybrid" Octal (12AX7's but with 6SN7 cathode follower)-

Looking at the schematic and comparing it to "standard" Cornet2, I see that the 6SN7 cathode follower does not have a constant current load like the 12AU7 does in the "standard" version, so really the circuit differs in more than just the fact that it uses a different output buffer tube.

I wonder what the thinking behind this change is.... can anyone tell me or point me to the answer?  It seems to me that if using a constant current load for the 12AU7 helps it sound good, then it would follow that one ought to be used for the 6SN7, no?

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By the way, after receiving this preamp from Flocchini, it was clear that he added upgrades after a time- he paralleled a lot of caps with  added Russian Teflon caps and so on, and the preamp just kind of "grew" as he added the upgrades, with Flocchini hanging these extra caps where he could squeeze them in to his DIY copper-and-hardwood chassis.  I am rebuilding the chassis, adding a deck of turret strips to mount all those Teflon caps in a secure and "prettied up" way; in addition I am building a new chassis base of Honduras rosewood.  The rosewood will compliment the 1/8" thick copper slabs that Flocchini used for the top plate and a side plate for the relocated input/output jacks.  Flocchini left the copper natural, but I am polishing it to a mirror finish and topping it off with a coating of Incralac gloss copper sealant lacquer.  With the mirror-finish copper and rosewood I think it will end up looking somewhat spectacular; I'll post some pictures.

[tubesurf]

Hi - I am not sure but you may be looking at the schematic of an octal version of the original Cornet - not the Cornet 2 that you have.    I believe the difference between the Cornet and Cornet 2 is includes the addition of the CCS.   I think you do have the constant current source in your hybrid version of the Cornet 2.  The hybrid only involved pin out and resistor changes from the 12au7 to the 6sn7.   I expect the original owner will confirm.

[poty]

...the 6SN7 cathode follower does not have a constant current load like the 12AU7 does in the "standard" version... what the thinking behind this change is.... ? It seems to me that if using a constant current load for the 12AU7 helps it sound good, then it would follow that one ought to be used for the 6SN7, no?

It depends. Here in the forum are several posts concerning the "octal" and "hybrid" version of the Cornet. I can't remember exactly is there any CCS-enabled version of the "octal" last stage? Although it (CCS on octal) is possible and may be preferable to use, but the current have to be increased more than 1.5 times to noval version, so the CCS can be eliminated by purpose. It may be not big problem, but I don't know exactly.

... the preamp just kind of "grew" ... hanging these extra caps...  I am rebuilding the chassis, adding a deck of turret strips to mount all those Teflon caps in a secure and "prettied up" way...

You should be carefull with changing the layout. There are several posts describing the addition of some RFI and hum with inappropriate placed capacitors.

[milosz]

Yes if there is a hum issue I will probably just remove all the Teflon bypass caps not sure they offer any sonic advantage anyway.

[milosz]

Hi - I am not sure but you may be looking at the schematic of an octal version of the original Cornet - not the Cornet 2 that you have.    I believe the difference between the Cornet and Cornet 2 is includes the addition of the CCS.   I think you do have the constant current source in your hybrid version of the Cornet 2.  The hybrid only involved pin out and resistor changes from the 12au7 to the 6sn7.   I expect the original owner will confirm.

Ahh, I see the source of my confusion. Thanks.  I was indeed looking at an Octal Cornet (1)  schematic.  My preamp says "Cornet 2" on the PCB, and in fact there are some CCS installed... and it does seem the 6SN7 has CSS loads as well.  OK, so, I was just looking at the wrong schematic.

Thanks for clearing that up for me.