Turning a Crate V33 2x12 combo into a more powerful little tone machine.
Hello Jeff,
Thanks for all the useful information each
month. I’m hoping you may have some insight
that would help me. I have Crate V33 2x12
combo—a 33-watt, class A amp running EL84
power tubes. It’s not a bad little amp—especially
considering the deal I got on it. But I am looking
to turn it into a more powerful little tone
machine. I have swapped the preamp tubes
from the three stock 12AX7s that came in it to
a 5751 in the V1 position, an EF86 in V2, and
a 12AU7 in V3. I also pulled two of the EL84
power tubes, so it is running at 18 watts. This
allows me to drive the power section harder
and that contributes more to the tone.
Next I plan to change the stock speakers to a couple of Warehouse Guitar Speaker models. The amp is currently looking for an 8 Ω load. Would you suggest I get two 8 Ω models and run them in series in order to run the power section even harder? I’m also wondering if you could give me a few mods to make the tone stack more effective. In particular, there doesn’t seem to be much response coming from the mid control. I am looking to enhance the “British” feel, which this amp already has.
Thanks for the suggestions.
—Bryan
Hi Bryan,
Thanks for your question. I hear
that the V33 is a cool amp that
many players have modified over
the years, but let’s address your
particular changes and questions.
I see you have begun swapping preamp tubes. This is a good place to start to make changes to the gain structure and tonal characteristics of most amps. You mentioned installing a 5751 in the V1 position in place of the stock 12AX7. This is a good way to lower the gain a bit in the front end and would generally allow the amp to clean up better when a guitar with lower output pickups is used—or better yet, when the guitar’s volume control is turned down. You can achieve so much sonically by subtly adjusting a guitar’s volume control, yet so few players take advantage of this.
If you feel the need to lower the gain even more, try a 12AT7. There are also other fun tubes to try, such as the ECC832 and ECC823, which are essentially one half of a 12AX7 with the other half being equivalent to a 12AU7. The 832 and 823 are actually mirror models of each other, so feel free to try each and see if either achieves a result better than the 5751 or 12AT7.
As far as your V2 selection of an EF86, I’m sorry but this tube will simply not function in this amp. The stock tube for this position is a 12AX7, which is a dual triode. An EF86 is a pentode style tube and has a completely different pin out configuration that will simply not work if installed in this socket. Besides that, even if you were to rewire the socket to accept this style tube (which is not an easy task in an amp with circuit board-mounted sockets), you would be losing an entire gain stage, since the triode has two but the pentode only has one. This tube serves as a sort of mixer for the clean and dirty channels, as well as a tone stack driver. While these functions could possibly be accomplished by one gain stage with some modification, I would recommend against it. If you wish to experiment with alternate tubes in this position, a 12AT7, 12AU7, ECC832, or 823 would work.
With respect to the V3 position, you mentioned you installed a 12AU7. That tube will certainly function in this position, but being it is the lowest gain of all styles of tubes that will work here, you will have the most reduced signal level driving the output stage. This would translate into more signal level required from prior gain stages in order to drive the output tubes to the same level. Not a bad thing at all, but just know that it definitely changes the feel and touch sensitivity of the amp. This, of course, is all personal taste, so experiment with a 12AX7, 12AT7, and 12AU7 in this position, but steer clear of the ECC832 and 823 here. The two different triode sections would substantially unbalance the output stage making for an asymmetrical output, which is not very good for quality clean tones.
Moving on to your output stage and speakers, you mention you’ve removed two of the EL84 output tubes so the amp would be running at 18 watts. First, I hope you have removed the correct tubes, which would be one of the tubes from the left pair and one from the right pair. Removing two from only one side would result in no load on one half of the output transformer— a condition I’d advise against.
Also, with a pair of output tubes properly removed from the amp, you have now changed its output impedance. Since you have in essence halved the load on the primary of the output transformer, the secondary of the transformer expects to have half the load on it for everything to be balanced. This means that your output impedance is now theoretically 16 Ω, so I would recommend installing two 8 Ω speakers wired in series for the correct 16 Ω load.
Now let’s finish up with your tone stack question. Looking at the schematic, I see there are a few components at the bottom of the tone stack that are not very typical. These components serve to lift the tone stack from ground, rendering it less useful. I assume the FET and associated .001 μF capacitor and 68.1k resistor are used in a “boost” function, which in the boost state would partially lift the tone stack from ground, thereby increasing gain while making the tone controls less functional. This is not unusual. What is unusual is that the remaining two components— the .047 μF capacitor and 220k resistor—serve to keep the stack lifted from a direct ground connection during normal operation. This may be causing the tone controls to be less active.
I would try replacing the 220k resistor with a jumper wire, or if possible, simply installing a jumper wire across the resistor. This would give the tone stack a proper ground reference, hopefully returning some additional functionality to the controls. As far as enhancing the “British” sound of the amp, the capacitor values in the tone stack are pretty typical British values, so no change needed here. Just FYI, you will lose some gain as a tradeoff. If this proves to be too much of a loss, try going back to a higher-gain tube in the V2 position, if you’ve already installed a lower-gain tube.
Hope your Crate crushes!
Jeff Bober is one of the godfathers of the low-wattage amp revolution, co-founded and was the principal designer for Budda Amplification. Jeff recently launched EAST Amplification, and he can be reached at pgampman@gmail.com.
The Grammy-nominated, singer-songwriter string bender joins John Bohlinger at the Eastside Bowl where the two cover serious topics (bipolar), new gear (a pair of El Dorado guitars from Epiphone and Banker), and working with monster producers.
The riffmeister details why he works best with musical partners and how that's been successful in both Alice in Chains and his solo career, including new album I Want Blood.
This passionate builder designed a custom Strat/Tele pair, both adorned with hand-painted replicas of The Starry Night.
Okay, I plead guilty to having owned over 150 electric guitars in the past 60 years. So, for kicks, with my experience by way of Fender, Gibson, Ricky, Gretsch, PRS, Guild, Teisco, and others, I decided to attempt to make my own axes from scratch. I found that this endeavor was synergistic—much like envisioning, composing, performing, and recording a song. With my long-time San Diego techie, Val Fabela, doing the assembly, I started carefully designing, engineering, and procuring all of the components.
Our winning guitar builder, Edward Sarkis Balian.
The Vincent van Gogh Stratocaster, aka “Vinnie,” was the initial project. Starting with a Canadian alder body, an artist in Italy (who wishes to remain anonymous) applied the Starry Night painting to the front, sides, and back. The heavily flamed, roasted maple neck has the typical 21 frets with a 25.5" scale, and sports yellow pearl-dot inlays. After careful consideration of my playing styles, I went with a configuration using Fender ’57/’62 Stratocaster pickups. I used an upgraded, noiseless, 5-position Switchcraft assembly for the switching circuit. Fender locking tuners, a custom-fitted bone nut, and a Kluson K2PTG 2-point whammy system and brass bridge complete the low-action setup. Overall gold hardware completes the look. Vinnie’s fighting weight is 7.1 pounds.
This is what stars look like from further in space, at least as far as this special build is concerned.
I was so happy with this Strat that I decided it needed a brother, so I started on a Tele. Logically, I named the Tele “Theo,” after Vincent van Gogh’s younger brother. Again, with a Starry Night body painted by the same artist, I coupled a Canadian alder body with a lightly roasted, flamed-maple Stratocaster neck. (Hey, if it was good enough for Jimi to experiment with a Strat neck on a Tele body, why not try it?) And, as expected, my techie Val did a brilliantjob of joining the neck to the body.
The Van Gogh Tele, aka “Theo,” built to similar specs as the Strat and also featuring a lightly roasted, flamed-maple Strat neck.
For pickups, I went with Fender’s vintage-correct ’64 Tele set. As for a harness, the super-quality Hoagland Custom 4-position switching is unique, in that it gives a 15 percent boost and a very killer tone in position 4! Fender locking tuners, a custom-cut bone nut, and a Gotoh GTC201 brass bridge completes its setup. Gold hardware complements the overall look. Strangely enough (or perhaps hereditary?), the Tele matches his Strat brother’s weight exactly, at 7.1 pounds.
It's not in a museum, the the Theo guitar is certainly a work of art.
But how do they sound? Magnificent!Throw in my trusty Keeley compressor, Fulltone OCD, and Fender or Mesa/Boogie tube amps, and the van Gogh boys both easily equal or surpass my White Penguin, White Falcon, PRS Custom 22, Lucille 345 stereo, 335, SG TV, Les Paul Standard, Esquire, or Joan Jett.
I’m hoping the real van Gogh brothers would have been proud of these two magical, musical namesakes.
Jeff "Skunk" Baxter expands his acclaimed first-ever solo album, Speed of Heat, with a brand new Storytellers Edition, featuring brand-new commentary tracks.
For over five decades, audiences worldwide have marveled at Baxter’s inimitable and instantly recognizable guitar playing and generational songcraft. His output spans classic records as a founding member of Steely Dan and member of the Doobie Brothers in addition to hundreds of recordings with the likes of Donna Summer, Cher, Joni Mitchell, Rod Stewart, Dolly Parton, and many more. During 2022, he initially unveiled Speed of Heat, showcasing yet another side of his creative identity and introducing himself as a solo artist.
On the Storytellers Edition, his fascinating commentary pulls the curtain back on both the process and the message of the music. This version traces the journey to Speed of Heat and its core inspirations as shared directly by Baxter in the form of detailed anecdotes, candid stories, and insightful commentary on every track.
The 12-songalbum, co-produced by Baxter and CJ Vanston, is a riveting and rewarding musical experience that features a host of brilliantly crafted originals co-written by the guitarist and Vanston, as well as inspired versions of some of the great classics. Along the way, Baxter is joined by guest vocalists and songwriters Michael McDonald, Clint Black, Jonny Lang and Rick Livingstone. Baxter notably handled lead vocals on his rendition of Steely Dan’s “My Old School.” Other standouts include "Bad Move" co-written by Baxter, Clint Black, and CJ Vanston, and “My Place In The Sun”, sung by Michael McDonald and co-authored by McDonald, Baxter and Vanston.
As one of the most recorded guitarists of his generation, Baxter’s creative and versatile playing has been heard on some of the most iconic songs in music history, including “9 to 5” by Dolly Parton and “Hot Stuff” by Donna Summer.
The stunningly diverse collection of material on Speed of Heat presents a 360-degree view of the uniquely gifted musician.
STREAM / SHARE / PURCHASE HERE.