[ceylon]

ive got a fet valve cf rb. i have a question, and for whatever reason frank wont answer, and neither will wayner.

can this pre run 6414 in its gain section in stead of 12AT7 without any kind of malfunction or doing any harm to the preamp?


heres the data/spec sheet
https://frank.pocnet.net/sheets/138/6/6414.pdf


at least one rebrand seller, national,  mislabeled 6414 as "12AT7." 6414 is in the 12AT7 family, but it is not 12AT7, hence my question.

ceylon

[Hydro]

This is what Brent Jesse says

6414:
An industrial, computer rated dual triode,virtually the same specs as the E180CC or 7062 listed above. Unlike the E180CC, this tube was made in the USA. It is a more rugged build, with the Raytheon blackplate type sporting triple mica and military ratings. This tube is also like a 12AV7 and will work wonders in any 12AT7 spot, and may be just the ticket if you want to boost the gain of a 12AU7 circuit. The 6414 is getting very hard to find, but with a 10,000 hour heater rating you may never need a replacement. Discussion groups rate this type very highly for use in headphone amps. Stands about 1/2 inch taller than the standard 12AT7.

[avahifi]

I have not tried or tested this tube type.  We are using JJ 12AT7 types and 12AU7 types in this preamplifier.

I have not answered due an issue keeping me out of the office for a few days.

Frank

[aln]

Plug it in and let us know!

[Mary]

We don't have any experience with the CK6414 tube, so it's impossible for us to predict its behavior in the FetValve circuit without doing a full engineering analysis. However, a quick review of the datasheet you link to suggests the CK6414 consumes appreciably higher heater current than the 12AT7. This alone makes rolling it in a circuit designed for a 12AT7 questionable at best. It also has a significantly lower maximum plate voltage than the 12AT7. Finally, it has about two-thirds the mu, and the distribution of interelectrode capacitances appears to be different. Given these, our prediction is that the CK6414 is not a good choice for replacing the 12AT7 in the FetValve circuit. We would consider any damage caused by attempting this to be outside a warranty claim.

It's also important to note that the CK6414 was designed for computer applications, not audio. This means that design and manufacturing standards that matter for audio (e.g., low microphonics) may not have been applied to the CK6414.

As Frank stated, we have been very happy with JJ 12AT7 in FetValve preamplifiers for their performance and consistency.

[ceylon]

This is what Brent Jesse says

yep, but brent cant tell me if its suitable for franks circuit.

[ceylon]

Plug it in and let us know!

no way, not unless i find out from AVA that the fet valve cf rb  is compatible with the 6414 and such a substitution carries poses no risk to the preamp or warranty.

[ceylon]

.