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How close are E90CC to 12AU7?

Can I sub E90CC for 12AU7

  • Yes

    Votes: 0 0.0%

  • No

    Votes: 5 100.0%
  • Total voters
    5
mjw21a

mjw21a

Super Member
I've noticed that E90CC's are more reasonably priced and considering there don't appear to be many NOS 12AU7 available if these work then it opens up a few more choices.

I know I've subbed 12AU7's for 6414's in the past with good results despite them being closer to a 12AT7 spec than 12AU7.

Any feedback will be appreciated. Thanks guys.
 
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IIRC 80CC draws more current (may be an issue for your PT)
I think gain is slightly different. A 12BH7 is closer to a AU7 than the 80CC (still more current draw. For many applications it would probably work. They do have different plate curves and might need voltage tweaking for optimum result, Unless you want to run numbers and redesign, you're probably better off using the AU7 anyway. My 2c
Nice old stock 12AU7s come up frequently and if you watch there are good deals to be had.
Its been my personal experience that 12BH7s and E80CCs tend to run higher (pricewise)
 
Hmmmm, are there any socket adapters available that would make this work..... Unfortunately I've bought 4 of these. I should have asked the question first.

EDIT: Ok, I've requested the seller cancel my purchase.Fingers crossed.

So, which tubes are out there which are pin compatible and relatively close to 12AU7. E80CC and 12BH7 are two.... I know my amp will handle more current as I've used 6414's in these stages in the past.
 
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Not sure of your level of expertise but you can always rewire the tube socket(s). I haven't looked at the specs but I assume you would only need to move a few wires.
 
E90CC has only 7 pins, with both cathodes connected to same pin. So it can only sub for 12AU7 (with an adapter) in a LTP circuit, where cathodes are connected together. And I agree, no shortage of 12AU7. Anyway, it's not a very linear tube. 6CG7 is better and has twice the transconductance, requires rewiring three pins for heater.
 
peterh said:
There is no shortage of 12au7, in addition there is new production available.
Click to expand...

+1 I see them all over the place. Many at reasonable prices.

The reissued Genalex are said to be quite good (but a bit pricey) and there are some positive reviews on the reissued Tungsols too.
 
Tom Bavis said:
E90CC has only 7 pins, with both cathodes connected to same pin. So it can only sub for 12AU7 (with an adapter) in a LTP circuit, where cathodes are connected together. And I agree, no shortage of 12AU7. Anyway, it's not a very linear tube. 6CG7 is better and has twice the transconductance, requires rewiring three pins for heater.
Click to expand...

Actually, they're much closer than that, if you compare them in the way most people will use them.

Here's the 6CG7 compared to the 12AU7, both run at 250v plate:

6cg7_vs_12au7.jpg

... and here's the comparison at 90v plate:

6cg7_vs_12au7-90v.jpg

For most purposes, they're functionally interchangeable. I've used both, with no circuit changes, in my modified Dynaco PAS line stage (one stage gain, one stage CF), and they bias up very closely to the same. IMHO, the 6CG7 sounds a little better (more dynamics), but they both will work with the same surrounding circuit components.

In fact, if you used a 12FQ7 (the *FQ7 is identical to the *CG7 of the same heater voltage, with the exception of the FQ7 not having a center shield between the sections- which the 12AU7 doesn't have either), you can drop in a 12FQ7 into my modded Dyna PAS 3 units. It will load the heater circuit more (so keep an eye on transformer temp), but it will work in the circuit, just fine...

Regards,
Gordon.
 
One thought came to mind- I wonder if the OP was mistaking the E99CC/ECC99 for the E90CC.

The E99CC/EC99 is somewhat similar to the 12BH7- which are both pin-compatible to the 12AU7. It draws much more heater current, and has parameters that are much closer to a 6DJ8 (VERY high transconductance).

I wouldn't try dropping in one of these in a 12AU7 circuit, expecting the same operational parameters (bias voltage, plate current and such)- but it will function, in at least a basic sense, when plugged into a 12AU7 socket.

Regards,
Gordon.
 
nj pheonix said:
IIRC 80CC draws more current (may be an issue for your PT)
I think gain is slightly different. A 12BH7 is closer to a AU7 than the 80CC (still more current draw. For many applications it would probably work. They do have different plate curves and might need voltage tweaking for optimum result, Unless you want to run numbers and redesign, you're probably better off using the AU7 anyway. My 2c
Nice old stock 12AU7s come up frequently and if you watch there are good deals to be had.
Its been my personal experience that 12BH7s and E80CCs tend to run higher (pricewise)
Click to expand...

I have used 12BH7s in place of 12AU7s in several applications. Many times, it has worked- and a significant number of times, it has been an improvement.

Mind you, I have also had cases, where the difference in parameters (the 12BH7 has lower plate resistance and higher transconductance than the 12AU7) was enough, to upset the circuit (i.e, put the bias and/or plate current out of its correct range) where it didn't sound as good. It all depends on the way the circuit is configured...

Regars,
Gordon.
 
Hmmmm, does anyone know if there are any pre made socket adapters anywhere? I haven't found any on eBay though I may be searching the wrong words
 
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