RCA 12AX7A

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leadfootdriver
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RCA 12AX7A

Post by leadfootdriver »

Picked up a handful of some Wurlitzer labeled RCA 12AX7A's. They are solid and clear sounding in the Wreck. I like them better than the Sylvania's. They aren't as bright which is a good thing in this amp.

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Stevem
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Re: RCA 12AX7A

Post by Stevem »

Oh yes, Sylvania's can be that way but they are not thin like some GE's can be!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!😊

Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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Winder
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Re: RCA 12AX7A

Post by Winder »

Sylvanias are pretty "hairy", I think. More so than most 12AX7s I've tried, they seem to be prone to microphonics. You used to be able find them for about $10 bucks a piece rebranded. Hard to find the sweet deals these days. Tube rolling can produce wonderful results. Worth having RCAs, Sylvanias, GE, etc., on hand, IMO. I still haven't found a current production tube that is satisfactory in comparison to NOS options. YMMV.
Stevem
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Re: RCA 12AX7A

Post by Stevem »

I spend a ton of time on my amps picking preamp tubes that sound good overdriven.
Many tubes used in the first gain stage can sound great as they never get overdriven, but further down the signal chain when they start to show there harmonic overtones many can get very nasty and sharp sounding!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!😊

Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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leadfootdriver
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Re: RCA 12AX7A

Post by leadfootdriver »

Winder wrote: Sat Oct 28, 2017 12:00 am Sylvanias are pretty "hairy", I think. More so than most 12AX7s I've tried, they seem to be prone to microphonics. You used to be able find them for about $10 bucks a piece rebranded. Hard to find the sweet deals these days. Tube rolling can produce wonderful results. Worth having RCAs, Sylvanias, GE, etc., on hand, IMO. I still haven't found a current production tube that is satisfactory in comparison to NOS options. YMMV.
Yes, I was wooed by their high gain early on, but they have strong highs and lows which comes off as a bit bloated in this amp now that I've tried the RCA's. They really seem to pull it together while still having a full bandwidth.
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leadfootdriver
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Re: RCA 12AX7A

Post by leadfootdriver »

Stevem wrote: Sat Oct 28, 2017 11:23 am I spend a ton of time on my amps picking preamp tubes that sound good overdriven.
Many tubes used in the first gain stage can sound great as they never get overdriven, but further down the signal chain when they start to show there harmonic overtones many can get very nasty and sharp sounding!

I have all RCA's in there now. Have you tried other mid plate designs like Brimar, Amperex, and Mullard?
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Winder
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Re: RCA 12AX7A

Post by Winder »

Amperex is tasty in V1. Similar to Mullard, but not quite as hard an edge. I have a number of those RCAs; don't recall when I last tried them. Will give them a go in the Express.
lpd
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Re: RCA 12AX7A

Post by lpd »

I have rolled a variety of tubes into amplifiers and may get flamed for saying this...but I have discovered that a variety of tubes can sound good or horrible in a circuit despite the brand or label. It seems that the relationship between the gain stage tubes is as important as the actual tube used. For example I have some 80s Chinese 12AX7s in a Marshall Plexi clone that beat out some of my best brand labelled tubes and believe me I have 100s and hundreds of different 12AX7s to roll. I pay less attention to the brands and now focus on the sound and look for balance bottom to top, less hair and more focus on note clarity :)
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