Here is the first photo of the new Andrews amp prototype and here are the details: 40 watts Two 6L6, GZ34 rectifier, two 12AX7, two 12AT7, spring reverb. It’s based on the AB763 Blackface circuit with a few cool upgrades such as: Bigger, better transformers. Circuit changes to reduce bass “flubbiness” A more subtle brightness switch Lush 3-spring reverb Better pot taper for the reverb control An innovative reverb limiter control – info below Heavy duty epoxy glass turret board.
The prototype name “Spectraverb” may change in the future. The amp has a big clean sound and loves overdrive pedals. It’s clean up to about “4″ on the volume control and gradually builds into a nice fat crunch after that. It incorporates a reverb dwell limiter control. When the control is dimed, it operates like normal blackface-style reverb. When dialed back to a minimum setting, the reverb dwell (drive to the reverb tank) is limited. This means you can set up your reverb for a nice clean tone and when you crank your guitar volume control or hit a boost or overdrive pedal to take a solo the reverb level won’t go through the roof like it normally would on other amps. The settings in between allow for varying degrees of limiting up to no limiting at the full setting.
Come try it out at the Geartalk Expo. I would really like to hear some more feedback from players. The price is for this 1X12 is $1850 direct. Now taking orders. A 20 watt 6V6 version will be next!
Please come to the Geartalk Expo this Saturday May 11, to try out all the Andrews amps including the new model to be introduced there. More info on the new model coming soon! Many other “boutique” amp, pedal and guitar builders will be there too. Come say hello and meet the builders. Support USA small business and see what we have to offer.
All tickets will be entered into drawings for free gear. http://www.geartalkexpo.com/tag/gte2013/
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!
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
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.
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.
There are three basic types of tubes used in guitar amps, rectifier tubes, preamp tubes, and output tubes.
Rectifier tubes are used in the power supply. Their function is to turn AC (alternating current) into DC (direct current). The DC is then used by the remaining tubes to amplify the guitar signal. Rectifier tubes generally have a very long life and rarely “wear out”. They typically work fine until failing at which time the amp will stop working and the fuse will probably blow. I don’t recommend replacing the rectifier tube until it fails which could be many years. No adjustment is usually necessary when it is replaced but it is a good idea to check the bias (see below) just to be sure. If the fuse blows, never replace it with a fuse that has a higher amp rating than specified. Note: Some amps do not use a rectifier tube and have diodes instead. Diodes are not user replaceable parts.
Preamp tubes are the smaller ones. Their function is to add gain or increase the guitar signal in the amp. Most common is the 12AX7, aka ECC83 and 7025. 12AT7 is also fairly common. Others are also used occasianally. Like the rectifier tubes, they have a very long life and rarely wear out. Sometimes they will stop working causing various symptoms. The most common failure is “noise”. You might hear static, hum, loud hiss, crackling, and “frying” sounds when they fail. Again, I don’t recommend replacement as preventative maintenance since new preamp tubes have a fairly high failure rate and new tubes might introduce new problems to your amp. Exceptions are the 12AT7 reverb driver in Fender amps and 12AU7 or 12DW7 driver in Ampeg SVT amps. These applications stress the tubes and I often fine weak drivers in heavily used amps. Replacement of preamp tubes normally requires no adjustment.
Output tubes are the big ones. They provide the power to drive the speakers. Since a lot of current passes through the output tubes, they do tend to wear down with usage. The lifespan depends on the tube and amp design but in general, 6L6, 5881WXT, EL34, 6V6 last about 1000 hours and EL84 last around 500 hours. By the time these limits are reached, the tube will loose the ability to produce maximum current and the amp will begin to loose tone. The bass frequencies will start to loose punch and start sounding a bit loose and flabby. There is also in increased chance of major failure of the tubes as they approach these limits. A major failure means the tube dies or shorts out which will usually blow a fuse. The output tubes should be replaced in matched sets. In most amps, the bias will need to be adjusted after output tube replacement.
Bias adjustment – Bias adjustment is necessary when replacing output tubes on most amps. The adjustment requires taking a measurement of the tubes’ current and making an adjustment (usually inside the amp). If the bias is adjusted too low, the tubes will run cool and the tone will suffer. If adjusted too high, the tubes will run too hot and fail much sooner than properly adjusted tubes. Please note that all Andrews amps have external test points and adjustments for bias. Instructions are included in the owners manual so that in the case of tube replacement, you won’t need to make a trip to the amp shop.
After many months of development, the new amps are here in the shop. Please come by and try them out. For all the latest details, sound clips and videos, check out the new web site at http://www.andrewsamps.com
I’d like to let everyone know about some new favorite speakers from WGS. For those who don’t know about WGS, they are located in Paducah, KY and all the speakers are built at their facility here in the USA. They have a selection of great sounding speakers with both American and British voicing.
On the British side, I love the Reaper which comes in 30 watt and 50 watt versions. The voice is somewhere between a Greenback and a G12H30 but louder and easier on the ears. Some other great WGS speakers in that category are the Veteran 30, similar to a Vintage 30 but less piercing in the treble. For a big, clean British tone, try the British Lead 80.
On the American side, I’m really liking the G12C. It sounds like a reissue Jensen C12N but it’s louder in the midrange and bass and handles 75 watts. I’m looking forward to checking out more models soon.
The prices are great and you can support American jobs when you purchase WGS and Eminence speakers. I plan to keep my favorite models in stock. These and other can be drop shipped direct to you as well.
Crank it up!