Just finished doing some tube rolling - preamp tube comparison

[JGR]

I just got finished rolling some different preamp tubes - standard JJ 12ax7, gold pin JJ 12ax7, Mullard 12ax7, TAD 12ax7, and standard and gold pin JJ 12au7's. Here are my general observations FWIW.

I started out by swapping the 12ax7s in and out of the first position of my guitar amp because I find a lot of the subtleties are magnified in high gain designs. Once I had a basic idea of how they sounded, I tried a few different permutations in my JGR preamp and a pair of DB680's.

Tung Sol Reissue
Update - just tried this tube in the first position of my preamp. I can see why folks recommended this one - great tube. Sounds a lot like the Mullard, but tighter/more focused in the low end, which is a good thing. Really balanced across the spectrum with great mids and rich highs. More hiss than a standard JJ, but pretty much all of them do, and overall noise level is certainly acceptable.

standard JJ 12ax7
I'm quite familiar with this tube since I use it pretty much exclusively in all my guitar amps. High gain, very quiet and great resistance to microphonics. Thick midrange, tight lows, top end is less detailed than some other tubes - this works well with high gain amps where things can get too bright and fizzy. I think they have great midrange complexity, but I'm sure some folks might want more top end detail, especially if you are running really clean.

gold pin JJ 12ax7
It seems they changed more than the pins - even higher gain than the standard JJ with a lot more top end crunch. I didn't like it as much as the standard JJ in the first slot of the high gain amp - a little too bright/fizzy, but still very resistant to microphonics. It has more hiss than the standard JJ due to the additional gain and top end. This tube is hot and bright.

TAD 12ax7
Not sure what the origin is - I know they screen these to find the lowest noise ones. Has a lot of gain though the top end seems a bit fizzier than the gold JJ, whereas the JJ seems to have more of a clear gain to it. Mids are more scooped than both JJ's. Not a bad sounding tube, but not sure I would pick it over the others.

Reissue Mullard
One of the DB680's had these in the two slots and they sounded very nice, which is what prompted me to check them out. This tube was probably my favorite in the first position of the guitar amp - high gain and very balanced across the spectrum. However, it also appears to be the most prone to microphonics - a lot of noise and ringing when you tap on it compared to the other tubes. I probably wouldn't use it in a high gain guitar amp, at least not the first slot assuming they are all somewhat prone to instability.

standard and gold pin JJ 12au7s
I hear the same differences between these as the standard and gold 12ax7s - the gold pin tube has higher gain and and brighter, clearer, crunchier top end.

On to the bass specific observations....

In my JGR preamp, I have been running standard JJ 12ax7's and I am quite pleased with the result. Running three gold pin JJ's proved to be a bit too much of a good thing - starts getting a bit harsh sounding. I then tried a gold pin in the first two slots and the Mullard in the third position which was better, but a bit loose sounding for some reason. I ended up settling on gold pin JJ's in the first two slots and a standard JJ in the third slot. Not a drastic change in this design, but definitely more top end attack.

I recently acquired two DB680's - the first one had two Mullard 12ax7's and three standard JJ 12au7's. Sounded great in that configuration. I figured a bit more top end would be nice since I normally engage the bright switch, so I replaced the Mullard in the first position with a gold pin JJ, and that did the trick. A bit more gain, overall brighter and clearer tone.

I set up the second DB680 the same way (gold JJ and Mullard) expect that I replaced two of the three no name 12au7s with JJ gold pins. Comparing the two preamps, the tone was even brighter and gainier than the one with the standard JJ's. I didn't think it would make a big difference, but it is quite noticeable. So anyone wanting their 680 to be brighter/clearer with a bit more hair should definitely check out the gold pin JJ's in all the slots. If you like the tone as is, but want a bit more gain and richness, the Mullards sound great in both slots of this pre as well.

I didn't run more combinations in these preamps because I had a pretty good idea of what I wanted from them and what would work best based on how I observed the tubes to behave in the guitar amp. I may go back and play a bit more, but I find there is a limit to how long I can do it before fatigue sets in and and I lose objectivity (especially when cranking things), so I'll listen again with fresh ears tomorrow.

Cheers,

JR

[pacojas]

thanks for posting that!

i recently picked up the Demeter HBP-1 with the 12AX7EH. are you aware of a tube better suited for reggae music?

[JGR]

I believe that preamp is pretty bright and clear, so I would think the gold pin JJ's would not be a good match. Of what I just tried, I would think the Mullard would sound very good in there. Maybe a standard JJ if you want to tame the top end and thicken the mids, but that is probably not want you want for reggae.

[pacojas]

thank you!

i want to try a few tubes and will definitely give the Mullard a go! the stock EH sounds great, i just want more bloom in the lows if possible.

btw, i enjoyed your custom preamp thread!

[fretno]

Try a shuguang 12ax7b ( C-9) killer tube and cheap , Marshall , Boogie , everyone uses that tube , it's very consistent in terms of tone and build quality , my fav to date though is the hard to find Mullard cv4004 , I usually put the Mullard in V1 and the C9's in the other sockets .

[pacojas]

@fretno,

thanks for your suggestion!

EDIT: on further review it seems that tube is aimed at the high gain guitar amp crowd.

[JGR]

I stuck to current production tubes since they are readily available and affordable. $20 is as much as I want to spend for a preamp tube. I have some NOS GE, JAN, and RCA that I picked up before the prices shot up, but some are a bit noisy and they don't necessarily sound any better. I've no doubt there are some killer NOS out there, but I really don't want to spend the time or big dollars. Just personal preference.

[grendle]

Cool post! Thanks for the info!

[okcrum]

Hey thanks JGR! I agree with you on the NOS GE/RCA. Maybe a bit mellower but not appreciably different from new except for vacuum, QA, and tube life. Even that difference is shrinking gradually.

[R Baer]

My personal favorite 12AX7 at the moment is the Tung-Sol. I really like the sound of these tubes.

[JimmyM]

Honestly, I can't ever tell the difference between tubes, so I buy NOS most of the time because invariably they last longer. I've kind of soured on JJ's because I've never had any last longer than about a year and a half. They sound fine but I'm not especially impressed with their QC. However, one of the most trashed brands on here, Sovtek, have always done well by me. Not as good as what I can get with NOS, but I've had many that have lasted 5 years or longer.

[fretno]

Originally Posted by pacojas

@fretno,

thanks for your suggestion!

EDIT: on further review it seems that tube is aimed at the high gain guitar amp crowd.

the C9 , it's fantastic in a bass pre , it's Fat and detailed with a nice clear high end , it has great gain but stays cleaner than the Mullard RI and some others you mentioned I'd say it's truer to the source than some on your list . Just doo ett I first dicovered them in my old Demeter 201 and have been hooked ever since . The fact that it's the cheapest available is nice too . Shuguang has been at it all these years making tubes , they got it together will just about every type they make . On a side note I think they make the TAD , but not sure if it's a "b" or "a" version .

[Groover]

Thanks for the review, as these are all tubes I've never tried.

Originally Posted by R Baer

My personal favorite 12AX7 at the moment is the Tung-Sol. I really like the sound of these tubes.

+1
This is a really good tube. Recommended by several here on the board, and I'm adding myself to that list.

[JGR]

I'll have to pick up a Tung Sol as well and give it a try; thanks for the recommendation.

Jimmy, I am starting to wonder about the life expectancy of JJs as well. I just pulled a couple that are functioning but have lost a good bit of gain and output. Not really noticeable in a high gain amp, but very apparent in a bass pre. They are probably 7-8 years old with considerable hours on them, but I kind of expect preamp tubes to last decades.

[JimmyM]

Well I don't have the experience with JJ's that you have, but in the past 3 years, I've bought a set of JJ 6L6GC's, a couple JJ 12AX7's, and a couple JJ 12DW7's, and none of them lasted longer than a year and a half. The 6L6's lasted only 4 months, and the 12DW7's are made so flimsy that I'm shocked they even lasted a year and a half! And I'm with you...they SHOULD last decades...but oh well...the price is right

[JGR]

I here ya. It's been a while since I've bought tubes, and it's quite possible the JJ quality has deteriorated. I've always stuck with Winged C for all my power tube needs - El34, 6550, and 6L6, and always had great luck. I was shocked to see how much their prices have risen since I last bought around 5 years ago. Anyone know what is going on with Winged C production?

[rickdog]

Originally Posted by JGR

I stuck to current production tubes since they are readily available and affordable. $20 is as much as I want to spend for a preamp tube.... I've no doubt there are some killer NOS out there, but I really don't want to spend the time or big dollars.

I'm with you there. And I think those of us who appreciate the tone of a nice tube amp will all be happier in the long run if we encourage today's tube makers to make good ones by buying from them.

It would be interesting to buy a handful of one manufacturer's 12AX7 (from different distributors, so they'd probably be from different manufacturing lots) and compare them. I find myself wondering whether the inconsistencies in the tubes from one manufacturer might be as significant as the differences between manufacturers.

[JimmyM]

Originally Posted by rickdog

I'm with you there. And I think those of us who appreciate the tone of a nice tube amp will all be happier in the long run if we encourage today's tube makers to make good ones by buying from them.

It would be interesting to buy a handful of one manufacturer's 12AX7 (from different distributors, so they'd probably be from different manufacturing lots) and compare them. I find myself wondering whether the inconsistencies in the tubes from one manufacturer might be as significant as the differences between manufacturers.

I think that's entirely possible.

[pacojas]

Originally Posted by fretno

the C9 , it's fantastic in a bass pre , it's Fat and detailed with a nice clear high end , it has great gain but stays cleaner than the Mullard RI and some others you mentioned I'd say it's truer to the source than some on your list . Just doo ett I first dicovered them in my old Demeter 201 and have been hooked ever since . The fact that it's the cheapest available is nice too . Shuguang has been at it all these years making tubes , they got it together will just about every type they make . On a side note I think they make the TAD , but not sure if it's a "b" or "a" version .

the C9, huh?!!

okay,... you got me with the Arnold reference!

EDIT: it looks as if the Shuguang C9 has been re-branded as the RUBY 12AX7C5-HG. there is also a 12AX7C5-HG+.

[parsons]

You shoulda told me you didnt have any Tung Sols, I couldve brought some up the other day to try out.