12az7a tube
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12AZ7 work a lot better in an 18W than 12AT7. I latched onto them from a comment MrDB made years ago, and they are a real "bang for buck" valve.zaphod_phil wrote:12AT7s don't belong in 18W amps IMO, and therefore neither would these 12AZ7s. But it might still be fine to try as an experiment.
Also, sometimes it is useful to put a 12AT7 or a 12AZ7 in the trem channel, or a 5751, just to stabilise the thing. I know that Gabi has done this, and I know that Graydon always fits a 12AX7WA in that channel to avoid instability.
Apart from that, I'm inclined to agree about the 12AT7, but the 12AZ7 represents a useful alternative to me, and a lot of them look like RFT 12AX7 internally.
Things I could live with include
6n2p, 12BZ7, 6AQ4 and a lot of the obvious 12AX7 types with different numbers.
5751, 5755, or 12AZ7 as "growl tamers".
I've got a messy "18W" that has 7058 and PCL86 -there's a certain compatibility in the heater supply voltages that works well with a lighting transformer I got in a yard sale.
So you don't like 12AT7 - neither do I - but what do you actually like, Phil?
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Sure, it stops the oscillator working. You don't get much more stable than that.Also, sometimes it is useful to put a 12AT7 or a 12AZ7 in the trem channel, or a 5751, just to stabilise the thing. I know that Gabi has done this...
Genuine Mullard ECC83s. Nothing comes close. BTW about the 12AT7s I once did some experiments with 12AT7s in place of 12AX7s in multi-stage preamps, and found that they introduced a muddiness into the tone when overdriven. Later I cane across an article which showed that overdriven 12AT7/ECC81s tend to produce a significant amount of high-odd-order harmonics, particularly 9th.So you don't like 12AT7 - neither do I - but what do you actually like, Phil?
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Nature abhors a clean tube amp