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I have been reading though some of the posts and I am inspired to try some different tubes in my amp. I currently run new production JJ 12AX7's and JJ EL84's. My rectifier is NOS.

I see lots of recommendations for NOS tubes but I am trying to sort out the options for new production.

Here is what I found so far:

NS TungSol 12AX7's -> Bright (maybe too bright for 18watt?)
JJ 12AX7's -> Nice mids but not very complex
NS Mullards 12AX7-> Warm mids (nice for a new production)

JJ El84-> ??????
NS Mullard EL84-> ??????


Does anyone have any opinion on the new Mullard EL84 vs the JJ EL84?

I like the new TS but really like the new Mullard 12AX7 in the TRIWATT.

For builds we're putting TS in V1 now, instead of JJ in the 18 watt.

The JJ EL84 is a workhorse and does a good job. Havent heard the Mullard yet. The russian EL84M is a nice meaty sounding tube too.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

New Sensor's fake Mullard 12AX7s are sweet sounding tubes, but their mids aren't as warm as real Mullards. JJ 12AX7s also suffer some blurry lack of definition in the mids, although they're warmer then the NS Mullards.

Speaking personally, I wouldn't spend money on modern production tubes for my own amps. Just a talk with Terry Kilgore is all it takes to get some great NOS tubes for not a lot more money than good quality current production ones. After spending all the time, money and effort on building a great amp, to me it makes sense to invest the few extra dollars it takes to really get the best from that amp.

Just my own opinion. YMMV....


Actually, you just did. Yesterday evening. But we didn't really have time to listen to them carefully.

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Great tones come in small glass jars!

Thanks again.

If I do decide to get some NOS tubes. Is there any benefit it putting NOS tubes in only the first pre-stage of each channel? Money is tight.

Yes, you could put a NOS 12AX7 in V1 - and then I'd recommend NOS EL84s. Money-wise, you may be pleasantly surprised at Terry's prices. Or wire the power tube sockets differently so you can use NOS EL83s, like Rory Gallagher used to. They're much cheaper than EL84s. But don't tell anyone else about them.

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Great tones come in small glass jars!

Phil, what would you recommend for a new production tube in a cathode follower position if one couldn't get their hands on NOS? I hear the new Tung Sols aren't holding up well for this application.

Joe G

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Some assembly required,
Brain sold separately...

JJ

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Great tones come in small glass jars!

Thanks Phil... You're a man of few acronyms

Joe G

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Some assembly required,
Brain sold separately...

Thanks again guys.

Terry Kilgore is hooking me up with some NOS 12AX7's for the first tube positions and the PI. and a pair of NOS EL84's. I'll keep a JJ in the cathode follower.

Most NOS tubes will also work fine in the CF position, and I'm sure that Terry can advise on that. It's mainly New Sensor's "Tung-Sol" 12AX7 RIs that have a low heater-cathode insulation breakdown voltage problem.

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Great tones come in small glass jars!

Could you somewhat solve that problem by using a lower value cathode resistor? I imagine it's not that simple though.

Not really, as that affects how the CF works. Sometimes you can get around the problem by applying a +ve DC bias to the heater supply, which BTW also helps reduce noise in the amp.

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Great tones come in small glass jars!

What do you mean by that running them at 12V DC instead of 6V AC? That way the heater/cathode voltage is lower?

No, you run them at 6.3VAC (or even 12.6V AC if you want) but with a large positive DC offset applied to the heater supply, in what is referred to as "heater elevation". Typically the bias voltage is applied to the centre tap of the heater winding, if it has a CT. If not, a pair of resistors (100 to 220 ohms) is placed in series across the heater supply, and the DC voltage applied to the junction of these resistors. However, it also works perfectly well if you apply the bias voltage to either end of the heater winding. Heater elevation can really suppress heater noise, sometimes even more effectively than running DC heaters.

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Great tones come in small glass jars!

Ah I see, I was thinking something similar.

I did that with my Dumble build. Used the node where the two balancing resistor connect at the main filter caps. Provides good elevation when you get the right value resistors.

Received the NOS tubes from Terry Kilgore. What a great guy to deal with. Fair pricing too. Thanks again for the recommendation.