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I need to replace some unfortunate, house-brand 12AX7s I purchased 20 years ago or so, as part of rejuvenating my old preamp. I've read the AES 12AX7 comparison about 20 times and am leaning towards the JJ 12AX7S. The Paragon is a bass-happy unit anyway. The original tubes that came with System Es were Amperex Holland (long gone from mine) and at one time I also had British Mullards that sounded too dark to my ear.
The Paragon uses 6 12AX7s, 4 in the phono section, 2 more in the line stage, so I sadly cannot afford to go shopping for NOS anything. I'd appreciate any input regarding the current production crop.
At this point, I honestly like the Shuguang 12AX7s best, especially those that have been tested/graded.
I install 12AX7s constantly in guitar amps, and I've stopped using Russian 12AX7s after having too many come back with noise issues. Some Russian versions cannot be used as cathode followers due to heater-cathode short problems. JJs work well in many situations, but they have their own signature.
Another tech I know with a curve tracer recently tested current-production 12AX7s and found that the Shuguang tube is closest to the original datasheets.
Ten years ago, I would not have given this advice, but my views have changed.
JJ-ECC83MG ( another 12ax7 from JJ ) seems very consistent and small tube-to-tube variation. See if that is available in your region.
Eurotubes seems to have it on stock
I have a sneaking suspicion that North America gets "floor sweepings", when JJ tubes are being sourced. The problem is definitely worse with Octals than it is with Novals.
The Sovtek is a good tube, but I've always found it a bit sterile sounding in the phono of my CAT SL1. I have a predilection for the JJs.
Sondek, do you use JJ regular or gold pin? Some sources cite different behavior between the two.
I use the gold version of the 803s. That was the only version my source had way back when I bought my first ones, and I liked them so much I figured why deviate. So, I've never tried the non-gold ones. I recently purchased some JJ ECC83s that are waiting a turn in the pre. They are supposed to have a bit more gain and might be marginally better suited to phono section. I'll give them a try one of these days soon. If you've not seen it before take a look at this comparison the folks a Tube Depot put on their site. Just hit the drop-down and select 12ax. I've found it a good reference.
Clean, quiet, and highly affordable is the Sovtek 12AX7LPS, which will be OK even with AC heating, given its spiral wound, hum bucking, heater.
I suggest you use another variant in the line section. The "reissue" TungSol will give you a bit of the famous NJ "chime", which seems to be needed.
In any event, discuss your needs with AA sponsor Jim McShane. He deals in honest advice and properly culled merchandise.
Just curious but what is a NJ chime?
NJ the land of fences. But you know what the fences are for don't you - to keep people IN!!!! NJ has so many people leaving that they actually added an "EXIT TAX". Yes it is called an exit tax. If you move out of the state you pay 2.5% of your house sale.
NJ "chime" is a bit of top end energy associated with RCA (Camden/Harrison) and TungSol (Newark/Bloomfield) made tubes.
Guess why I like a mixture of Mullard and RCA tubes. :> D Balance, not overemphasis, is what I crave throughout the entire audio band.
BTW, I am located very near exit 8A of the NJ turnpike.
Don't forget the big bang was discovered in Holmdel NJ by Arno Penzia and Robert Wilson. Or was that the microwave background radiation? Just kidding.
I just moved out of NJ about a year ago. The entire shore area is changing and not for the better.
The new Tungsol 12ax7 has been great as the input tube on my Quicksilver monos ......they are dead quiet and are great top to bottom. I prefer them to several nos 12ax7 i have used. Great for a modern production. Ive used the LPS and they are quiet and seemed to last forver. Didnt like them in my dac, but were very good in amps
Thanks, Eli. The Paragon uses DC filament heating but has always been susceptible to hum, so the spiral filament of the Sovtek can only help. I use the phono section primarily to drive a professional sound card for digitizing LPs; low noise is of particular concern; the less there is, the less to clean up later in production.
The AES 12AX7 survey shows the Sovtek as one of the more noisy (3 out of 4) and having a bit of a bass rise; seems to be at bit at odds with your comments. Maybe just a fluke of the test methodology?
I do think Eli is right about the sound of the new production Tung Sol. Nice tone if you can't invest in something fancier than that (NOS). I wouldn't mess with the phono gain tubes but the other two might be amenable to a meaningful tone roll.
just realized the AES survey "noise" figure reflects microphonics; not really a concern in this application. Hrm.
Yes about being somewhat microphonic prone. LPS = long plate spiral. ;> ) The variant is more of a HIFI than a guitar tube. You can always use silicone or neoprene rubber "O" rings, to tame microphonics.
Make sure that you get phono grade specimens.
Before I even considered answering....scary
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