The Musician's Room Recording Tools: Gretsch 6150T "Compact Tremolo" Vintage Amp

I don’t know whether or not you know it, but an open secret of the recording business over the years has been the use of small vintage amplifiers to record many, many albums. Tweed Fenders have been favorites for years as well as a handful of small fifties and sixties combo amps. Vintage connoisseurs greedily stalk eBay, Gbase, and local Craigslist ads for these little gems. Any hint that some star used one drives their prices through the roof and the collector's scurrying to snap them up. Meanwhile, some models are gems and some are dogs, and unless you do your homework, you can end up with a lovely vintage rattle box with rotten tone, or worse, an amp with a dangerous design that could shock you.

Gibson Skylark, Supro Super, Gibson GA-20, Alamo Model 3, Univox U-185, Supro Spectator
From the collection of j45

Back in 2007 a member of the Les Paul Forum who has a rather large collection of goodies posted a thread called ES-335 on Six Small Vintage Amps that inspired me to look into small vintage amps. The poster, j45, recorded a backing track and then played the same guitar through six cool little amps, one after another, allowing listeners to compare their sound. I was immediately drawn to the second amp in the series, the Valco-built Supro 1606 Super. This little guy is a small combo about the size of a briefcase that sports a big five watts, an eight-inch speaker, and a volume control. Folks often refer to it as a "tweed Champ killer." If you know your amps, you'll know that the tweed Fender Champ was used on hundreds of classic recordings including Clapton's Layla sessions. It lent its voice to those recordings while we all thought we were hearing big stacks of amps. Of course, that fact drove the price of vintage tweed Champs through the roof. But as it turns out, the Supro Super was also a favorite, though less well-known choice. If you listen to the clip in that thread, you'll see that these little vintage three-tube amps can HOWL, despite being about the size of a briefcase. But by the time this article was written, the Supro’s prices were already shooting up sky high due to their association with Jimmy Page and the early Led Zeppelin albums. A mint condition Super just went for $3100 on eBay and I wasn't ready to throw down that kind of coin.

Then, five years later, the same fellow posted on the Les Paul Forum another thread, Eureka! ...again... in a Gretsch #6150, in which he described tracking down another Valco-built amp that is identical to the Supro Super except for upgraded hardware, tolex, and grille cloth, and it typically sells for a fraction of what its Supro-branded brothers do. That amp is the Gretsch 6150 Compact. That did it. I started searching for one to use for recording. Over a several weeks I followed fleaBay, Gbase, and elsewhere, watching the conditions and prices. After a long search, some missed bids, and seeing a lot of these amps in widely varying conditions, one morning a really clean one popped up on Gbase. This little amp was listed as a '64 Gretsch 6150T Compact Tremolo which has the same basic circuit as the Supro Super, with tremolo added.

1963 Gretsch 6150T Compact Tremolo
Click for larger pictures

I nosed around on the Internet and made a few calls. With a litle friendly wheeling and dealing on the phone, the salesman and I struck a deal that pleased us both and the amp was on its way. After we closed the deal the salesman kind of wistfully said the amp was the cleanest fifty-year-old amp he’d ever seen. It sure looked that way to me from the pictures on the site. Four days later it arived, extremely well-packed and safe. After filling up the speaker cavity in the back with bubble wrap, the dealer had covered the speaker cloth and back opening with cardboard panels and floated the resultant sandwich in a sea of Styrofoam peanuts. I had a fifteen minute battle with the most highly static-charged packing peanuts I've ever encountered as I tried to remove the amp from the box. Folks, clumps of these peanuts literally leaped two feet out of the box to attach themselves to my hands, arms, and clothes. I couldn't shake or wipe them off because they would simply leap back onto me. I looked like a beekeeper covered with a swarm of white bees. Eventually I washed my hands and applied lotion and the packing peanuts relented.

Removing and bagging the peanuts indeed revealed about the cleanest fifty-year-old amp I've ever seen. It looks like it could be a few months from new - like it spent its life in a closet. I think the term, "clean enough to eat dinner off of," works well here. There is evidence that the amp came from the private collection of a serious player or from a recording studio - it was one of several small amps bought by the dealer as a group that all shared two mods: the addition of a very short three-prong cord and a small plate in the back with two jacks that allow the amp to be connected to another cab, or another amp to play through this cab's speaker. Two small screws and little soldering and the mod could be gone, but I'll probably keep it, as you'll see below under "Further Notes." I immediately found a little six foot one tap extension cord that extended the short cord to just the right length. After a little research on the Internet I found that the unit’s serial number actually dates this amp to 1963. I poured a cup of coffee and moved into my home studio to check it out.

Ah, the smell of warm tubes in the evening! You know, the vintage stuff just smells different. At this point in my life it is a lovely smell that brings back fond memories of sampling old amps at my favorite dealer. This amp is a LOUD little booger when cranked - not quite bedroom material. The combination of a single 6v6 power tube, a 5y3 rectifier, and a 12AX7 preamp tube give it plenty of power as a Class-A amplifier for the recording context and offers medium gain. The 6150T amp adds a second 12AX7 tube to operate the trem. On this example everything is solid and operates well. It doesn't appear to have quite the amount of gain found on the Supro in the clip, but with a booster on the front end can be made to sound very much like that one. You wouldn't expect a lot of bass out of an eight-inch speaker and there is no suprise here. However, the natural midrange emphasis of the amp makes it fit right into the electric guitar "space" in a mix readily. There's enough loudness available to excite a recording or iso room and get some early returns off the walls. The trem featured in this amp is of the “Bias Modulation” design where the bias current to the power tube is rhythmically modulated towards the negative causing the tube to repeatedly drop in output. The result is a very smooth, interesting tremolo that sounds quite different from the opto-isolator-based systems found on larger amps. This particular vintage implimentation is also unique in that it has no intensity control. I suppose we can chalk that up to the fact that this was an entry-level amp, huh? The trem is really pretty sounding but quite deep as well. I know there's a use for it, but I haven't worked that out quite yet.

I quickly picked up one lesson: The "Bright" input indeed gives you a brighter, cleaner sound but perhaps "thinner" is a better description because it offers lower gain than the "Standard" input as well. There's a fuller sound with quite a bit more gain in the "Standard" input. When you lean into the amp’s power, the rectifier sag and power tube distortion provide a lovely, springy compression that makes a guitar sing. When dimed, it also magically makes your pick attack go away, also probably a product of the tube rectifier and the saturation of the 6V6 power tube. I've played several guitars throught the amp and have found that the amp has a kind of a Voxy chime when you play a Strat through it, and a kind of mature, muscular vibe rather than a tinny one when you reach right below halfway on the volume. It's a really nice combination of glassy upper end and girth. When pushed on up it goes right into blues territory. When it is driven with humbuckers I can see why the original poster mic'd the amp from about eight feet away: as with most small class-A amps it has a certain "brattiness" that can most easily be smoothed out by moving the mic out from right up against the speaker cloth. By contrast, you get a feel for the amp’s native close sound when you listen to “Layla,” where the amps were close-mic’d. A Gibson with modern P-90 pickups seems to drive this little amp just right into singing sustain while reducing the brattiness. This is also an amp that changes character in an interesting way as you raise the volume. It starts with a bright, clean sound up through about halfway and then the sound smoothly transforms itself into a more rounded, midrangey honk at the top of its gain. This is perfect for moderating the insect-attracting overtones of the distorted tones. The base level Supro Super and Gretsch 6150 Compact have only a volume control and this little circuit design feature plays well to that. However, besides the tremolo, this 6150T model adds a tone control which is attractive for compulsive knob twiddlers like me. Whatever, this continuous transformation of the amp based upon the setting of the volume control means you have a wide variety of tones available at your fingertips even without touching the tone control. The amp also responds well to backing off the volume control on the guitar, cleaning up nicely when pulled down a couple of clicks. The little eight-inch Jensen Special Design speaker conveys the sound of the amp well and adds its own character to the mix. I should mention that the amp loves to have its front end "cooked." Cooking the front-end consists simply of pushing the front-end with a clean boost until it brightens up and blooms. The result is a very pretty and full sound with the amp run about half-way up. Adding in a good compressor can also add to the effect.

And now another revelation: If you plug this little monster into a bigger speaker cab, it can really come to life. Any shortcomings from the small box and speaker simply disappear. Using the little panel with speaker access jacks added in the back, I've run the amp into the Jensen® C-12K 12" speaker in a Fender Deluxe Reverb and was absolutely amazed with the results. The bottom-end filled out and the high-end became much more defined. The amp could really be pushed without any of those cabinet and hardware resonances that you get in a small combo amp. Another surprise was that everything "bratty" about the amp smoothed out. I was also amazed at how loud and powerful those five little watts were!

So, in the final analysis we have in the Gretsch 6150 and 6150T, great little recording amps that can sound really big in the mix. While the 6150 without trem is a more gainy amp than this one, the unique late ‘50s circuit design of this amp yields a broad palette of sounds from clean to overdrive to distorted, all via the volume control. And all this goodness comes at a fraction of the price of these amps direct brethren, the Supro 1606 and 1606T. It’s a hearty little amp that doesn’t appear to need to be coddled but deserves to be preserved in the magnificent condition in which it was received.


Oh, and for tube circuit freaks, here is the Gretsch 6150T and 6151 Schematic
and the Gretsch 6150 Schematic as well, for good measure.