THD Yellow Jackets EL34

I'm running a Marshall JCM2000 TSL122 Combo. Currently I have a THD Yellow Jackets (triode version), w/ the EL84's that came with them,in the middle two tube sockets, and two stock EL34 tubes in the outer two tube sockets.

Playing through a PRS Custom 24 Ten-Top. Mainly playing classic rock / hard rock. Here's what I found...

First I tried going w/ only the two Yellow Jackets/EL84 in the middle tube sockets. This did dramatically decrease the amp's power (documentations says down to 20%). Suffice to say, I was unimpressed. This made the amp waaay too trebly... Shrill and unpleasant, even w/ the treble knob backed way off. It made the clean channel very thin to my ears and probably more suited for some country style chicken pickin', but really not dynamic enough even for that. I don't even wanna talk about the crunch and lead channels... Just painful.

But...

When I threw the EL34's back into the two outer tube sockets the amp really came alive. The combination of the two EL34's and the two EL84's is just amazing! It really changed the dynamics of the amp and gave it an amazing depth and texture that I hadn't even realized was missing. The bottom end seems fuller, highs are less brittle and shrill (richer somehow), and the mids are impossible to describe, just very pleasing.

I'm not really sure exactly how to describe it now. The crunch channel nails AC/DC rhythm tones, and the lead channel so far seems rather like if Brian May's Vox and Slash's JCM had a love child. It's really a cool sound.

Bottom line is that for sound quality, used in a split power section, these things really sound great.

Here's where I have to deffer judgement. I've only had them for a week or two, and have played maybe 6 hours w/ the Yellow Jackets... I guess I'll have to wait and see.

THD responded to my email questions the same day every time I emailed. I'll post another review when I've had them for a while.

I've been playing for about 9 or 10 years now. I have played Fender's PRS', Dean Guitars. I have played Marshall solid state and tube amps, as well as epiphone and Randall amps. If my amp were stolen I'd definately get another Marshall, probably a Vintage Modern. And I probably would continue to use Yellow Jackets.

If you're reading this, you must know what it is! It substitutes el84 tubes to el34, reducing the power of the amp and affecting its tone too. I'm using these with my Orange Rocker 30 1x12 combo.

It actually sounds really good. My Rocker has always been a bit toot loud for my uses. We always mike the amps on stage and sound men shout at me to turn down, making the amp sound average. The el84's in the Yellowjackets break up much earlier than the stock el34's. I can now get a great sound at the ideal volume. They change the tone quite a bit too. I can now hear (I think!) a little Vox in there and a lot of 18 watt Marshall too. Pretty cool! I use the Yellowjackets with an American Deluxe Telecaster, a Music Man Silhouette Special (beautiful GREAT Strat-style guitar) and a Les Paul. The amp is as much and maybe even more dynamic than it was.

II can't see how it could break!

Thd has a very good customer support. I've sent them a few e-mails because I had some questions before buying the product. Ed always replied the same day. Thanks Ed!

I'm very satisfied until now. It really gives a second personnality to my Orange. I can't wait to ty it with other amps.

My pair of yellow jackes are the "cathode bias" version, to replace my class A EL34s with EL84, with the purpose of reducing volume while maintaining good tone. The cathode yellow jackets aren't as easy to install, there is an additional wire on each yellow jacket that needs to be screwed to the chassis ground. That's not easy with shock mount tubes, the wire tends to not stay under the screw since the rubber mount flexes. The power was in the right ballpark for smaller clubs, the tone lacked a bit (see below).

I installed these in a HotCat 30R combo amp. The 30R needs to be cranked a little to get it's best sound, which is too loud for a small club. I wanted the yellow jackets to use in the smaller venues so I could get the tone at a lower volume. In reality, though, the EL84s have a tone all their own, which is not terrible, just different. I'd describe them as "thin" compared to the EL34s, until you crank them hard, whereupon they become "fat" and "crunchy" with the characteristic EL84 distortion you'd expect. It's an interesting sound, but unlike the EL34s they don't retain the "chimey" sound once they start distorting.

So far no problem, except that the ground wires pop out from the shock mount screw. At some point I'll have to take the whole chassis out and permanently install snap on ground wires with a reliable connection. Until then, the switchover from EL34s to EL84 is too much trouble to do it frequently.

I emailed THD with some questions soon after I received the yellowjackets. They replied promptly, politely, and with good information. I was pleased with their customer support if not entirely pleased with the product.

I've been playing for more than 30 years. If I had a class AB tube amp, I'd buy the yellow jackets in a heartbeat to get class A sound from the amp. But since I have a HotCat 30R (class A), they're a step down in sound quality from the EL34s. Even so, I might use them for smaller clubs, they sound better than a HotPlate. The ground wires are a pain to attach so I won't be using them much until I "remanufacture" them to be easy on / easy off. I guess the only good solution is to buy a second HotCat, maybe the 15 watt CubIIR for smaller venues, but I'm still looking for the extra $2 grand in my wallet.

I am writing this review to let people know that the THD Yellow Jackets take up a certain amount of space in an amplifier. In my case, the ENGL Screamer 50 amp head does NOT have enough space to use the Yellow Jackets without removing the built-in Accutronics reverb tank on the floor of the case. So be sure you have enough space before you buy the Yellow Jackets. I will have to sell mine without having the chance to use them.

You know the features, changes an EL34 amp into a cathode biased EL84 amp. only difference is that mine have jj tesla EL84's in them.

Here i will state my equipment: 72 Gibson Les Paul Standard with early seymour duncan p-ups, 2000 Harry Joyce Custom 50 (Like a hiwatt dr504,) Hiwatt LS412 4X12 cab (sealed) with 2 fane axiom and 2 weber blue dogs. I play with no fx and use a mxr micro amp as distortion sparingly.

Well, let me start by saying that i didn't expect much. I thought that without my output transformer working at maximum, I would have a loss of gain and a crappy feel. Well much to my suprise! These things sound great! I was thinking that i was going to have to buy a fender deluxe for some good low volume gain.

I normaly play my amp jumpered and cranked, with the master all the way up and both volumes at 2 o'clock, the tone is similar to the sound of the who's live at leads album. This amp is brutaly loud this way, but doesn't sound good unless it is cranked.

Well, I pluged them in and much to my suprise, they sound woody and intricate, with lots of bite and crunch! i was expecting them to sound bright and brittle, but thats not the case. it makes my amp sound more plexi-ish than ever. The amp sounds very british! i highly recommend these to anyone that wants a little volume drop and some awesome tone!

THD stuff is handmade in america

THD is very helpful

You have to put these in your marshall, orange, or older marshall

I replaced my 4 EL's in my Carvin Legacy 100w head with 2 Yellowjacket adapters and the standard EL 84's (Sovtek)they came with..I didn't like the Sovtek's sounded a little harsh and would break up really fast.. I replaced them with some GT Ruby #5 EL84's and it warm it up nice with out any grit...just some very smooth
tube overdrive when turned up..the Carvin still can get loud...but it tamed it from 100 watts of A/B power to 20 watts Class A power ...at low volumes I can nail SRV jazz runs..and at bedroom levels without
getting everyone mad in the neighbor. The problem with Carvin heads is that there is not enough headroom for the Yellowjackets unless you move the spring reverb unit...no problem there..it fits behind the pre-amp tubes on the face plate. That free's up plenty of room to plug them in...the amp has a 50 watt or 100 watt switch..I just kept it swithed to a 100 watt because I pulled the two (2) center EL34's out and put the Yellowjackets on the 2 end slots...it has really improve dthis amp for praticing..and getting some tube vibe...before you could not tun it up past 2 without making everyone in the
band mad...good investment..

I'm using a Les Paul with a Classic 57 in the neck and a
Burstbucker #3 on the bridge...I play blues and and some jazz and some classic rock...the amp makes the hum it should running in class A
The drive channel really has improved and it can sound a little voxy with some pretty creamy overdrive...the ruby tubes really helped compared to the Sovtek's

I will be stocking up on some more EL 84's they make the
Ruby's from #1 to #10's....so I will get a variety...
They light up all the way when the amp is on so they won't last as long...but they don't cost that much.

With Tubes?

I haven't hooked up the Fulldrive 2 to the amp yet but I am sure it will put the amp over the top and make it useful for all my needs.
I'm glad I bought them and plan to keep that Legacy beast chaine dup with the Yellowjackets for some time ...it's really like getting a whole new amp......

replace your power tubes with these things, plug some el-84s into them and suddenly your amp is running in class A. I replaced the el34s in my 80 watt orange amp.

I use buckers and singles. I guess my take on amps is this, no amp will do everything. No amp will give you "the exact sound I heard on (insert album here). All you can hope for is ballpark. I have an orange amp for the brittish ballpark (good substitute for marshall or hiwatt) and a fender musicmaster bass amp for that american sound (not as big as twins or bassman amps, but the voicing is still clean and very 3-d). The only neighborhood I'm missing that I give a damn about (sorry soldano and your super hot-rod cronies) is the vox/matchless class A sound. Again, yellow jackets aren't a dead ringer for these amps, but for about $100 I can get in the ballpark without having to pedal my ass on the street to afford a vox or a matchless. Yellow jackets gave my orange amp that highly detailed, glassy, sparkly, almost transparent shimmer that I associate with vox amps in particular. It's definitely a thinner sound than the stock orange amp, but most amps sound thinner than the orange anyway. The low end is not as huge as it was with the el34s, but is tight and very vox-like. The touch sensitivity is great. I can hear it go from mellow gritty when I bear down on the strings, and it sounds different than the orange pre-amp gain. The el84s have a grittier more ripping kind of distortion that I can hear kicking in when I strum hard, and it is very different than the orange pre-amp distortion that sounds oceanic and packed with nice harmonics. I won't say they made the amp better, just more voxlike. the best part is that it takes all of 2 minutes to switch my old power tubes back (no biasing necessary!!!) and restore that glorious orange sound. If you have a tube amp that doesn't have outrageous plate voltages and you want a vox-like sound for about 1/15 of the price, this is your best bet.

I've only had them for a few days, but there's no moving parts, and I don't anticipate anything going wrong.

These guys are great. I emailed with a question about compatability with my amp (it's plate voltage is kinda up there) and they replied in just over an hour! What's even better than that is that they answered my question honestly and didn't blow a bunch of sunshine up my cornhole. They told me that yes the yellowjackets would work in my amp, but because my plate voltage is pretty high that the el84s might not last as long as in other amps. I appreciate that kind of honesty in a company.

I've been playing for seven years. If stolen or lost I would definitely get another set. I love that these things allow me to get a good class A feel and sound without having to shell out tons of dough for a vox or a matchless. I also love the fact that they are so easy to install and remove. They advertise that it's like having a whole new amp, and they are right. I really dig the fact that there are ways to get a variety of quality sounds from an amplifier without getting some multi-channel hunk of poop that's got more knobs and buttons than most graphing calculators.