12AX7 Tube Reviews



I guess it’s really more accurate to call this a tube shootout than a review of tubes.  

I’ve always wanted to do a review of 12AX7 tubes but felt that there were too many variables. I also didn’t trust my ears to be objective for long enough to really test all the different models available on different amps etc. The opportunity finally arrived when we (Andrews Amp Lab) celebrated our 10 anniversary at our current location in Dunwoody (Atlanta), GA.

With a total of around 15 people in attendance for the shootout, we set up a double-blind test with a 1972 Fender Deluxe Reverb for clean tones and a Marshall JCM2000 TSL100 for the overdrive test. On the Fender, we installed the tubes in the V2 position and played through the second channel of the amp. V2 is the first gain stage for that channel. On the Marshall, we also used the V2 socket. That position is the overdrive stage for the crunch and lead channels. We tested on the crunch channel with the gain set to “8”

Two of each tube were used so that one bad example wouldn’t skew the results.  I had an assistant mix the tubes in random order and wrap each in 2 layers of blue masking tape to hide the labels so none of us knew which tube was which.

Two guitar tracks of around 15 to 20 seconds were recorded direct on a Zoom H1 recorder, one clean on a Strat and the other more driven on a Les Paul.  When these were played back, we were able to hear exactly the same guitar tone for every test on each amp.

We tested the following current production tubes:

Tung-Sol  12AX7 (Russia)
Electro-Harmonix  12AX7EH (Russia)
Sovtek 12AX7LPS (Russia)
Sovtek 12AX7WA (Russia)
JJ ECC83S (Slovak Republic)
Ruby 12AX7 (China)
Mullard  12AX7 (Russia)

Each tube was installed in the respective amps, allowed to warm up just long enough so that the listeners could retain the memory of the last tube’s tone as clearly as possible.  After all the tubes were heard, some participants requested to hear various pairs of tubes together for comparison. Most listeners kept notes of their impressions and rated the tone 1 – 5 on provided forms.

At the end of it, they were asked for their ratings and comments. The results were interesting!

  • All agreed that we were “splitting hairs”, that the differences in tone were slight and often difficult to hear.
  • The highest rated and the lowest rated tubes in both amps were the two Mullards with one described as “loud and bright” and the other as “balanced”. They loved one the Mullards and hated the other.
  • Other favorites for the clean tone were both of the Sovtek 12AX7WA and one of the Sovtek 12AX7LPS
  • Other favorites for the overdrive tone were one of the EH tubes and one of the JJs.

Some general comments about each tube.  I’ve combined the comments for both tubes of each label. Because of that, you will see some differences of opinion. This was probably caused more by manufacturing inconsistencies than differences of opinion.

Mullard – Bright, balanced, good bottom end, fizzy, defined

Ruby – midrange boost, honky, warm, punchy, lacking bass

Tung Sol – hiss, dirty, muddy, gritty, lacking mids

Sovtek LPS – gritty, dirty, good highs, muddy mids

EH – Smooth, full bodied, cleaner, grainy, articulate

JJ – great, congested, ballsy, dark, aggressive

Sovtek WA – great mids, slightly dark, flat

Again, keep in mind that these differences were very subtle and often difficult for most participants to hear.

A few other comments and observations to consider…

  • Due to time constraints, we did not have the opportunity to adequately test for microphonics. In my experience, the tubes with the larger plates tend to have to be more microphonic. These would include the Sovtek LPS, and the Mullard.
  • There appears to be a lot of variance in sound from different examples of the same tube. Fort this reason I was unable to prove or disprove my suspicion that the Mullard and Sovtek LPS are essentially the same tube with different labels and that the same goes for the EH and the Tung-Sol.
  • Due to variances, it would be very difficult to choose a particular tube for its tone based on any previous experience, test, shootout, video, review or opinion since it’s unlikely that two tubes with the same label would sound the same. Still some of the general tone descriptions might be useful for those who are willing to spend time and money to make small changes in tone.


Posted in Tube Reviews | Tagged , , | Leave a comment

Andrews Spectraverb 22 and Spectraverb 40 are Now Available as Heads and 2X12 Combos

Spectraverb Head and 2X12

Visit Andrews Amplification for More Information

Posted in Uncategorized | Leave a comment

Winged C factory will not be producing any more glass tubes!

There has been a rumor floating around for a few months that the Winged C (SED) tube factory has closed down.  I’ve been staying in touch with the importer since then and they’ve been telling me that the factory was temporarily off line while they find a new glass supplier.  I just got word that the factory has announced that they will not produce any glass tubes in 2014.  I think we can now safely say that production of the highly acclaimed Winged C tubes is over for good.  These tubes can now be considered New Old Stock and remaining stock will be priced accordingly around the world.  This is a big disappointment for me as Winged C have been my favorites for a long time.  We will be replacing the 6L6 with Tung Sol 6L6GT.  EL 34 will be more difficult since we have not had good reliability from any brand of EL34 other than Winged C.  We are currently ordering JJ El34 from a new supplier that has more stringent testing procedures than the previous supplier.  We’re crossing our fingers.   For now, the only way to get Winged C from Andrews Amp Lab is to purchase an Andrews amp.  We will continue to use them in our amp production until our stock runs out.
Posted in News, Technical articles, Tube Reviews | Leave a comment

 Read what Premier Guitar magazine says about our newest model.  Andrews Spectraverb 40 Review 

How to get the best tone from your tube amp.

Do you ever wish your amp sounded better?  Are you looking for ways to improve your tone?  All guitarists want great tone yet many players are not getting the best tone their amp has to offer.  There are a lot of factors affecting the sound you get from your amp.  Some of these include tube selection, speaker selection, bias adjustment, guitar pickups, guitar woods, the condition of your strings, the type of cables, microphone selection and placement and many other variables.  Each is discussed in depth in other publications and in some of my other blog posts so we won’t get into that here.  This discussion will focus on getting the best tone from what you already have and I’m specifically talking about tube amps.  Don’t get me started on solid state modeling amps.  That’s a big ole can of worms!

Let’s’ start with the basics.  It’s important that your amp is in top condition to produce great tone.  That means all the controls, jacks and switches should be functioning properly.  If the amp is more than 20 to 25 years old, have your tech check the electrolytic capacitors (caps).  If they are original parts, it’s probably time to replace them.  If the amp is from the 195os or older, the coupling caps are due for replacement too.  The speakers should be checked to make sure they have not become “tired” sounding or have begun to rattle and loose tone.

For the best tone, tubes will need to be in good shape too.  The smaller preamp tubes generally have a very long lives, 10s of thousands of hours.  They usually don’t need to be replaced until they make noises such as sputtering, crackling, ringing rattling or squealing.  The larger output tubes loose tone and power over time and should be replaced between 500 and 1500 hours of use depending on the type of tube and design of the amp.

Assuming all the above maintenance has been done and the amp is working in top condition, it’s time to look at the control settings.  There is a common misconception that on a good amp the tone controls should sound great when kept close to the 12:00 position but this is not always the case so be sure to explore other settings.  There are many reasons why the noon position might not always be best.  For example, pots with the perfect resistance taper for a specific design might not be available to the amp builder.  Another factor is that the optimal settings will likely  change at different volume and gain settings.  For example, amps with good deep bass response or those with inadequate power supplies can become overwhelmed with bass when played at high volume.  If your amp sounds loose and mushy when the volume is turned up, try turning the bass way down when playing loud.  Bass frequencies need a lot more power to play loud without causing bad sounding distortion.  That’s why bass amps generally have much higher power output then guitar amps.  The midrange control on some amps can have a big effect on gain and sustain.  For a more driving, sustaining sound, try turning the midrange way up high.  Sometimes it might help you cut through the mix in a live setting.  Keep in mind that settings that sound great at home or in the studio might not be that great in a live setting.  You might find that you’ll have two or three different favorite settings depending on how the amp is being used and what the rest of the band is doing.

The overall volume of the amp plays a major role in tone too.  Volume can be thought of in two ways.  First the setting of the volume control.  This affects volume but is really a gain control and affects the way the tubes are driven.  The second way to think about volume is the actual volume or “sound pressure level” of the amp.  For example, a 100 watt amp will produce more volume than a 10 watt amp.  The extra volume produced by a high powered amp will create sound pressure waves that will vibrate the wood and strings of your guitar.  This vibration will usually compliment the tone, sustain and response of the amp and guitar.  When playing a high power amp at high volume, less gain is needed to produce nice sustain which will result in more note definition and clarity.  Of course, we can not often play 100 watt amps at high volume but give it a try sometime and find out what has been lost by playing smaller amps through the PA system.  Be sure to experiment with your position in front of the amp too.  You can increase the effect of the amp vibrating the guitar by standing in just the right place in front of the amp.

There are also some advantages to playing lower powered amps.  Most tube amps will sound their best when the output tubes are just beginning to clip.  That means the tubes are just exceeding their maximum clean headroom limits and making just a little bit of distortion.  The clipping adds a bit of sustain and acts to filter out some the harshness caused by your overdrive pedal or overdriving your preamp tubes.  The trick is to select an amp that has just the right amount power to clip slightly at the volume you will be needing.  Playing a 50 watt or 100 watt amp with the volume on “1” or “2” will rarely give great results.  You can attempt to compensate with an overdrive pedal or by adjusting the master volume control but the results will be much better if the amp has the right power level to achieve a bit of clipping in the output tubes at the desired overall volume.  Some very high gain amps might be the exception here since they may be designed to achieve all the overdrive tone in the preamp circuit.

While we’re talking about volume settings, amps with master volume controls almost always sound best when the master volume is turned up high enough to clip the output tubes a little.  I’m always disappointed when customers come into the shop to try out an amp and start off by diming the gain and setting the master volume on “1”.  That’s no way to play an amp!  Most amps that sound good at that setting will be overly compressed and noisy and will have poor clarity when turned up loud.  Start with the master volume set between “5” and “9”.  If that’s too loud, it’s time to look for a lower powered amp (or reduce the power setting if the amp is so equipped).

There is one last thing and it’s a big one.  It’s playing technique!  I’ve seen and heard it a thousand times.  A great player can make a cheap amp sound pretty good and a player with a lack of finesse and feeling can make a great amp sound pretty bad.  Don’t forget to work hard on milking all the tone your amp has by paying attention to the way your amp responds to your touch.  No amount of tweaking and modifying can compete with learning how to play with great tone.

Now get out there, crank up your amp and squeeze out every drop of tone it can muster!   Please feel free to comment and share your experiences.

Posted in Technical articles | Leave a comment

News Update from Andrews Amp Lab

Sorry it’s been so long since the last post.  It’s been a busy year and I just got a little breathing from for a couple of days so here is the chance to catch up on news.

First, the new Spectraverb 20 and 40 watt combos are both now available.  They are great platforms for all styles of music and they love pedals although they really don’t need them for many styles.  They have super nice reverb and my new reverb limiter circuit.  See http://www.andrewsamps.com for all the details.  The new amps have been getting some press lately in the guitar magazines and the Spectraverb 40 will be getting a full review in Premier Guitar soon.  Stay tuned!

We now have the Spectraverb 20, Spectraverb 40, Para-Dyne 20, Para-Dyne 50, A-22 and A-50 in the lineup and most of these are available in both heads and combos.

Turnaround time is now under 2 weeks but our busiest season is right around the corner, beginning January 1 so if you’ve been thinking about getting that old amp back in good shape without a long wait, not is the time!

I’m thinking about a new post on how to get the best tone from your amp.  Look for that in coming weeks.

Lastly, we have several nice used amps on sale in the shop.  Log on to Facebook and join the “Gear Talk Georgia” group so see what we have.  Also, look for our listings on Craigs List.



Posted in Uncategorized | Leave a comment

12AT7 tube shootout for guitar amp phase inverters

Very little attention has been paid to the important role that a certain tube plays in most guitar amps.  I’m talking about the phase inverter or PI tube.  The PI is the tube that creates the push-pull waveform and it’s the last tube  the guitar signal sees before hitting the output tubes.  Most amps use either a 12AX7 or 12AT7 for this purpose.  Fender  in particular has historically chosen the 12AT7 (AKA ECC81) for its unique capabilities and tone as a PI tube.   The signal levels in this stage of the amp are fairly high and when the amp is driven hard, the PI tube can be driven to clipping so that’s how we tested them, with the amp driven to a fairly distorted level and then reduced to clean for confirmation that the tone remained consistent when not clipped.  It’s worth noting that although the 12AT7 can be used as a preamp tube in other positions in the amp, it generally does not produce very good tone for applications other than PIs and reverb drivers.

For this review, we’ll be comparing several NOS (New Old Stock) and current production tubes in a Fender Blackface Deluxe Reverb and Silverface Vibrolux Reverb.  I’ll be listing the tubes in order of bright and harsh to warm and fat with some additional description for each tube.

JJ ECC81 – This tube was a big surprise to me when compared to the other on the list.  I must say that it was the most shrill and thin of the group.  JJ makes a decent 12AX7 (ECC83S) but I will be moving away from JJ ECC81 for PI circuits from now on.

Tung-Sol 12AT7 – This one was just a tiny bit smoother on the top end but lacked definition and fullness.  It carries a higher price too.  Not a good buy in my opinion.

Shuguang 12AT7 – This Chinese tube is marketed under various brand names.  Most commonly, they show no brand and just say (China).  This tube sounds very similar to the Tung-Sol but with slightly better note definition.  The good choice when low price is of high importance.  If I was building low-priced mass produced amps, I would probably choose this tube.

JAN Philips 12AT7WC – This is a military grade NOS tube.  Most available today were made in late 70s and early 80s.  It’s a rugged tube and not too expensive for an NOS tube.  However, the tone is not that impressive in Fender PI circuits.  It does have a bit more fatness and a bit less harshness than the above tubes but lacks real warmth and definition. There are better choices.  This tube does make a good reverb driver where tone is less important than ruggedness.

GE 12AT7 – Another NOS tube that is still available –  This one will give you a little more upper mids and clarity while being slightly smoother in the treble frequencies.  It’s a useful tube when you want a little more ability to cut through the mix.  However it has a bit less bottom end roundness than the JAN Philips.

Electro-Harmonix 12AT7 – The other big surprise to me – I’ve never been a big fan of the EH 12AX7 but their 12AT7 is impressive.  It has a nice rich full tone with great definition, punchy bottom and smooth treble.  I suspect the big plate structure contributes to the big sound.  The tubes at the other end of this list tended to have smaller plates.  Small plates can be an advantage in preamp tubes where low noise and microphonics are important but large plates seem to generally work better in PI circuits.  This one is the winner for current production tubes and beats most NOS options!

Posted in Technical articles, Tube Reviews | Leave a comment

New Andrews Artist

Andrews Amps would like welcome Coy Bowles to our family of artists. 

Coy Bowles is a member of the Zac Brown Band. He plays guitar and organ for ZBB as well as writes and arranges music. He also leads his own Atlanta based project, Coy Bowles and The Fellowship, for which he writes all the music and performs lead guitar, piano, organ and lead vocals. He is also a creative writer and founder of a charity foundation called “Coy Cares”.  Find our more about Coy at CoyBowles.com

Check out our expanding artist list and other info about Andrews Amps at AndrewsAmps.com

Posted in Andrews Amps | Leave a comment

JJ 5751 preamp tube review.

5751 Tube Review

I’ve been curious about the new 5751 from JJ since I heard about it a few months ago.   As some of you may know, the 5751 is similar to the very common 12AX7 aka 7025 and ECC83 but with a bit less gain. In this review, I’ve compared the new 5751 with the JJ ECC83S (12AX7) which has been my standard workhorse guitar preamp tube for several years.

A casual visual inspection would give the impression that it’s the same as the JJ ECC83S and some have even suggested that the factory may have re-labeled the ECC83s tubes that measured a little less gain than average.  This is not the case.  A closer inspection reveals that the new tube’s inner construction more closely resembles their ECC81 (12AT7) but some of the materials are obviously different.  It is indeed a totally new tube.

In our test, we used a vintage Fender Vibrolux Reverb and installed the tube in the V2 slot which is the first gain stage for the tremolo/reverb channel of the amp and is critical for good tone and low noise.

Tonally, the tube is smooth and balanced but lacks some of the harmonic complexity of the ECC83S. It also produces just a bit less shimmer and sparkle in the treble ranges. It is however a good sounding tube with no harsh overtones, low noise and low microphonics.  It can be very useful for amps that need a little taming in the treble and gain. Gain wise, it does make a noticeable difference, allowing for at least another number on the volume control to reach similar breakup of a 12AX7.

Does it give you more clean headroom? Well, maybe just a touch if you have hot pickups but headroom in these amps is limited by the output power and speaker efficiency.  It will however give you a wider range of adjustment within the clean zone of your volume control setting. It will break up at about the same actual sound pressure level as any other preamp tube but you might find it easier to adjust your settings when playing at lower volume.

Overall, we like the new 5751 and we expect it to eventually find a place in a lot of different amps. You can plug it into any tube socket that calls for a 12AX7, 12AY7 and most 12AT7 applications.

Posted in Tube Reviews | Leave a comment

More Andrews Amps Reviews

Andrews Amps have been getting a lot of great press lately.  This review of the Para-Dyne 50 c0mbo was just released in the December 2012 issue of Premier Guitar Magazine. http://www.premierguitar.com/Magazine/Issue/2012/Dec/Andrews_Amplification_Para_Dyne_50_Combo_Review.aspx  It’s a great review.  I just wish they had taken more care to do a good job with the sound clips.  Hopefully, I can find time to post more clips soon that more accurately reflect the true sound of the amp.  Stay tuned to http://www.andrewsamps.com

Guitar Player Magazine wrote a nice review on the Para-Dyne 20 combo in the Holiday 2012 issue.  I’ll post a link when it becomes available. 

Scroll down on this page for the review of the A-22 and Para-Dyne 20 in Tonequest Reports Magazine.

Posted in Andrews Amp Reviews, Andrews Amps | Leave a comment