THD Yellowjackets YJSD

I bought two sets of these last week. I had some spare cash and decided to try 'em in my JCM 800. I had to email THD to make sure I got the correct ones for my amp and asked them the physical height as the is only about 5 and a half inches of room in the JCM's head cab. I received a prompt reply the next day sayin' they will fit no problems as they are only about 5" high.

Giving them 5 in this category coz there's really no features and 5 is a pretty neutral number

Hmmm.. sound "quality" is a subjective thing. I'll start by sayin' straight up, I don't like 'em at all. They sound way too thin, and have a nasty fizziness in the top end. I understand why they are called "yellow jackets" now. Its coz they buzz like a yellow jacket wasp. Not a nice sound.

I dig the tone of EL84's in my Mesa Boogie and various other EL84 amps I've mic'd (was a live sound engineer for about 7 years) but they just don't work in the JCM800.

The only way I can get anywhere near a pleasant, usable sound is to run the preamp gain way down and not turn the master up past about 10 o'clock or they overdrive too much and sound nasty.

Dunno about reliability as I've only owned 'em for a week. They do get very very hot and develop a hot "smell". The "smell" ya get from electronic equipment right before smoke comes out. I don't trust 'em so I've left the back off my amp so I can keep an eye on 'em.

Like I said earlier, I got a prompt reply from Ed at THD both times I emailed them.

The second time I emailed was the morning the YJ's arrived. One pair was soldered perfectly on the pins but the other pair had several "empty" pins that contained no solder. Ed assured me the lack of solder in the pins would not affect them in any way.

Anyway customer service has been fine so far

One other thing that bothered me about the YJ's apart from the lack of solder in the pins was the way they have been assembled. The yellow tube that contains all the electronics is glued into the tube base. All bar one have been glued in crooked. One is so bad it looks like the leaning tower of pisa!
Not that ya can see 'em when they're hidden away in the back of the amp..but surely it would not have been a difficult task to glue 'em in straight. They charge a premium price for these things, so I want a premium product. Fair?

Anyway overall I'm pretty disappointed. I'll keep 'em for a while and see if they grow on me, but I doubt it.

They don't have any other features than having the ability to block the amp's grid bias voltage so you can run a pair of EL-84 with a pair of 6L6s at the same time without any modification to your amp.They will change your amp from A/B class to single Class A operation.They will reduce your amp's power so it will distort earlier at lower volumes.They will give your amp the classic Brittish sound in just a second.Enough features for me.MAKE SURE YOU BUY THE SHORT ONES IF YOU DON'T HAVE PLENTY OF ROOM INSIDE THE POWER TUBES SECTION.EL-84 TUBES ARE INCLUDED IN THE PACKAGE.

I have a JSX head wich is great and full of features.You can use either 6l6s or EL-34 with it.The amp comes with the EL-34s from factory.The Ultra channel is just amazing with a very modern sound and power.The Crunch channel is more like a Vintage/Marshall thing but honestly,alone it will never going to sound like a true Marshall.(Anyway is a Peavey not a Marshall).I was trying to have an amp which deliver the Modern/Mesa sound at one side and the Brittish/Marshall thing at the other.I changed the power tubes to 6l6s looking for the best of both worlds.I ended up having a more 5150/Laney sound.Now the Crunch had more power and less Vintage sound and the Ultra was a true Diezel/Krank thing.I put two Yellow Jackets in the middle position and left the 6l6s at the corners.What I have right now is just an amazing sounding amp wich plenty of power,but with a smoother distortion,tons of clarity and that Vintage Vox/Marshall middy sound at the Crunch channel.The Ultra now is just perfect.More like a Mesa Mark 4 in steroids.Very compressed sound.Cristal Clear cleans and highs and a lot less hum from the amp.Now the amp is so quiet that it's hard to know when it is on.I had to re-adjust all my settings in order to go for my sound.Now I'm using a lot less bass,mids and highs.The amp will distort at very low volumes.It's like having a new amp at home.I'm using it with a Music Man Axis all stock and a Fender Floyd Rose Stratocaster with a Dimarzio Super 3 i the bridge,an YJM in the middle and a Virtual Vintage Solo Proin the neck.I play mostly 80's Metal.

I don't know how much will they last?

This is what make me buy the Jackets.THD's Customer Service is just amazingly fantastic!! I did e-mail them about 5 times before I placed the order.Asking them all kind of questions.Their answers to my e-mails where very fast.They told me they love to answer questions.They are very good selling their image.

I've playing now for 7 years.I have an all rosewood Music Man Axis,a Fender Floyd Rose Strat with Dimarzios.I have a JSX head witha Custom Made Cab loaded with 2 Celestion Vintage 30s and two Enminence The Governor.I do have a Boss ME-50 and a Boss Noise Gate.
That's it.I'll buy the Jackets again if they were stolen.They are an inexpensive way to upgrade your sound without hurting your amp.If you don't have the money to buy a boutique amp,this is the closet you can get with a lot less.

The one prime purpose of the THD Yellowjackets is to give one the ability to reduce the power output of their tube amplifier. The amount of power reduction will be dependant on the original output of their tube amp. THD cites the reduced output as about 20 watts. That being the case , your 40 watt amp will be rduced by 20 watts. Your 60 watt amp by 40 watts etc. All of this under the assumption that you have a 2-tube output stage, 2 x 6L6, 2 x EL34, etc. If you have for example amplifier using 4 output tubes, commonly with an output of about 100 watts(more or less) than the THD Yellowjackets offer even more opportunities for custom power reduction AND sound shaping. You can use just 1-pair of yellowjackets and have a 20 watter. Use 1-pair of yellowjackets AND 1-pair of the original output tubes, and you have an amp with approximately 70 watts. But, more importantly in my opinion, you now have warmth in your tone from the relatively early breakup of the EL-84's in the yellowjackets, PLUS a solid clean BACKBONE to that warmth in the shimmering cleaness of your 6L6's or EL-34's. Using an amp which switches 2 power tubes out of the circuit for 1/2 power, you can carry your amp to an unknown job with unforseeable power requirements several sets of differing tubed, several pairs of yellowjackets and tailor your sound to the situation, acoustics etc. With a certain amplifier I own with 4-output tubes, I have had cause to use all of the following combinations: 1-pair Yellowjackets, about 20 watts: 2-pair Yellowjackets, 1-set with early breakup EL-84's, the other set with mid breakup EL-84's, about 40-watts;1 -pair Yellowjackets, 1-pair if 6V6's, still only about 40-watts but the 6V6's giving some 'BACKBONE' to the tone. 1-pair Yellowjackets, 1-pair 6L6's (early breakup pair so as not to overwhelm the EL-84's in the Yellowjackets.) This may seem like a long way around to describe as features..but believe me if you are patient, have a fair supply of tubes of varying current draw on hand you can make on the spot quick changes to suit your particular playing situation.

MY particular guitar,pickup types are secondary, but I usually use single-coil Strats with some custom wiring,. The point of my reveiew was to advise people that they are able to tailor their sound to DIFFERING guitar/pickup choices and musical syles with this product.But,,since asked I play blues,country, classic 50's rock as well as what came in the mid 60's when I started playing. What kind of sounds can it get?? Here's the kicker! I've read many reviews where people were either mildly dissappointed or totally bummed-out(hey that dated me didn't it?!) by the sound they got from their (for example) Fender Hot Rod Deluxe.On the other hand some were delighted. Although of course tone IS SUBJECTIVE and tastes very personal, it seemed to me that MOST of these people were descibing the tone they sought in remarkably similar fashion. THE KEY. Repeat THE KEY, to use of the Yellowjackets with EL-84 tubes is to REMEMBER you're STILL DEALING WITH TUBES! The Yellowjackets merely hold them in place and limit current to about 20-watts a pair. Your 'breakup point',;tube saturation', distortion etc. is still dependent on the tubes you put in the Yellowjackets. I use JJ/Tesla EL-84's, but THAT IS NOT WHAT I'M REFERING TO! Whatever brand you favor/choose you need to buy at least 3-pairs! 1-pair of 'early breakup', 1-pair of 'middle breakup', and 1-pair of 'late breakup' tubes. You then try them one after another in your amplifier for headroom, or early breakup, whatever YOU are seeking.And I found that in MY Hot Rod Deluxe, the mid breakup tubes were best OVERALL choice, for most places. At a Country venue I play the late breakup tubes were entirely too loud before any warmth from tube breakup. The middle ones were perfect for THAT venue. Another place I hurriedly switched to the esrly breakup tubes. There really IS A HUGE DIFFERENCE!I think this is the solution to the disappointment and disallusion I read in some revues. Oh, by the way, In my HRD, I placed an Electro-Harmonix 12AX7 in V1, a JJ/Tesla 12DW7(ecc-832) in V2, and a JJ/Tesla 12AX7(ecc-83s) in V3, the phase inverter position. The 12DW7(ecc-832) is a split performance tube. The (A) side performs at 100% of a regular 12AX7, and runs the reverb. The (B)side which adds gain when the "Gain Channel" is switched in operates at only 20% of regular 12AX& output. This reigns in the frequently wild, uncontrollable and overly gritty gain of the HRD gain channel. With this set up I set the master volume at the same level as clean volume, and run the gain between 2 and 4. This gives just a srep up in gain in the switched position, Hitting the more gain swithch now gives a creamy smooth USABLE distortion. By the way This Preamp tube set-up (mainly the substitution of the 12DW7 for the 23AX& ib the V2 position) REALLY makes a difference when you need to switch back to 6L6's for some serious volume and headroom, as well. In Traynor YCV40. the early breakup tubes work best (for me). In Mesa DC-50, early breakup worked best for me as well..with the following change in preamp tube lineup in order to adopt the second channel to my musical tastes. V1, Electro-Harmonix 12AX7, V2, JJ/ 12DW7(ecc-832}; V3, JJ/ 12DW7(ecc-832); V4,V5, & V6, JJ/ 12AX7(ecc-83s). Brings the two channels into close equality in volume, which makes setup MUCH EASIER. Notes on channel 2, now well defined. Crunchy chords now possible with definition, but a creamy sustain still very easy to ontain. Mid(boinky)sound now can be dialed out. By the way, works with original 6L6 power tubes in place as well. My Fender 'Pro-Series' "Concert Reverb" 50-watter loves the LATE breakup EL-84's in HER Yellowjackets. Marshall JCM 800, favored the mixed blend, of early AND late breakup EL-84's in her Yellowjackets. I got another amp using 4-power tubes but, I'm NOT gonna tell you what it is! 'Cause I want to get another one cheap first. It has become my absolute most convenient, versatile carry anywhere, practice to festival amplifier. Whether running Yellowjackets in all 4-slots or 1-pair of Yellowjackets and a pair of 6V6's (or 6L6's) she's ready now for anu continguency. If you are unhappy with your results with Yellowjackets...try what I've outlined above. If you're STILL unsatisfied..sell 'em to me CHEAP. All my amplifiers are DEMANDING that they have their own personal sets to carry around with them and not have to borrow and swap with the other amps. Amps get VERY JEALOUS, you know!Pick a sound you can get it.

We are talking about the most fundamental/basic of electrical components here. A male tube insert coupled to a female tube-socket with , (what?) a resistor between to control voltage. Unless THD receives a bas batch of defective components they're gonna work!Tubes? Well..Tubes ARE tubes. They're gonna wear out. If bumped too hard they'll break. Running Class A they need replacement more frequently than tubes run A/B..PLUS you're gonna play so much more now that you have a decent sound at bearable volumes, you're gonna burn out tubes that much quicker! Hey! You're really not gonna mind that much!No problems with product yet.

To date I've had no need for repair or contact after purchase. Prior to purchase of my first pair I did E-mail THD to ask question about correct type tp purchase for a particular amp. Went about my business (reading reviews on Harmony Central, of course!) Well' before I had finished (Hey! Some of you guys are as long winded as Me!) I had my answering E-mail from THD. And from the head man himself. I believe that qualifies as helpful AND friendly. You know I've forgotten the warranty period..but I believe that were it expired they probably would/could fix for a trifling fee. Also, I believe if worse came to worse I could do it myself.due to my forgetfulness AND lack of need will give them benefit of doubt.

This coming December I'll Have been playiing 40-years, minus some times when I gave up and quit entirely, selling all my equiptment!What equiptment do I have? Lots of guitars and TUBE amps! Thats where I'm gonna leave it,cause if I list what I have NOW, I'll start mentally comparing to what I once had and a deep near-suicidal depression may descend! I love what the product does! Wish I'd have had them 35-years ago when I started showing some proficiency on guitar.Hate nothing about them. Compared to the 'Groove Tubes' equivalent, but could not find many outlets selling..so cost became an issue. I frankly don't know..the Groove Tubes' version may be just as good, BUT I did read some reviews citing trouble with them.Is there anything I widh they had? Actually, yes there are 3, things I think would improve them. I have modified mine to reflect 2 of these improvements(which I don't even think would void any warranty) My 3-rd idea WOULD require R.& D. and more expertise than I have! I'm thinking about contacting THD about all 3.....Well I.ve tried to avoid hyperboyle and just tell you folks how I used them, AND more importantly HOW I made them usable for me. I truly believe that some of the folks who were not well pleased with their experience with Yellowjackets, might truly find the sound they were earnestly seeking and hoping for had they just conducted a controlled experiment in tube swapping. In other words don't just call brand X tube crap and buy another brand. Buy 3-sets of one brand ,EACH with different breakup points THEN try the tone-test. Once you find what you want, i.e.headroom/clean versus breakup, if such and such a brand tube is not bright enough or too bright or dull sounding or lacking bass, THEN buy another brand in the breakup range you found closest to your ideal.That could get expensive you say? Well, not as expensive as getting rid of that multiple /hundred or thousands of dollars amp because you wouldn't spend a hundred bucks for 4 or 5 sets of EL-84's! Not to mention what would become the wasted expenditure of the price for the Yellowjackets. A little trial and error, alittle patience, and a relatively small additional exprnditure will reap a rich TONE REWARD! And NO..I don't have stock in any of the tube manufacturers, importers or retailers, nor do I work for amy of them! Chuckle!!

Bought these for my '89 Marshall JCM 800 2210 (100 watt channel switching amp). These amps are brutally loud, and on the bright side (trebley)due to the EL34's. But they have great gain, and come on, it's a Marshall! I use this amp for venues from 50 people to 2,000 people. The Yellow Jackets knocked it down from 100 Watts to what they claim is 20 Watts. But let me tell you, this is one loud 20 Watts! I can use this for the largest of venues and have plenty of volume. I play loud live, and this still has more than enough volume. Just pull out all the EL34 tubes, and put these 2 EL84 Yellow Jackets in Powertube slots 2 and 3. You can add the EL34's to slots 1 and 4, but I have no need to do that, and don't see myself having to.

I use this with a Jackson USA custom, Duncan JKB in bridge and 59 in neck. My style is 80's hair metal (Nuno, Lynch, Vito, etc.). These My complete setup includes rack mounted tuner, G Major, BBE Sonic Maximizer, HUSH, and wireless system. The Yellow Jackets changed my sound and got me EXACTLY what I wanted. More mids and punch, and more crunch! I have searched forever for this tone, and I am just floored at how great they sound. I have tried Mesa Dual Rec, POD, and ADA MP-1, and none of them touch this sound. I can back off the volume to clean it up some, and of course channel switch for clean (well, it is a Marshall, so sort of clean!) I use a MicroAmp pedal for extra gain during the solos, but no more! Don't need it now....this amp screams!

THD is known for awesome products and great customer service, so I expect no problems there. I understand these tubes get quite hot, so I will keep my eye on that...

Great customer support, and they will even walk you through the process of installing (should you need it), but it is a brainless install, so it should be easy. Regardless, you can even contact them to find out if it will work with your amp. Great people, great products.

I have been playing 20 years +, and have tried allot, I mean allot, of gear. This simple addition at such a great price is, in my book, an absolute must for any guitar player. The Marshall is just so loud, this cuts the volume, and adds more crunch. I can pinch harmonic till the cows come home! Great product, cheap price, and huge tone change. I highly recommend this product. It is a must have for any serious player.

Easy, just plug in and play. Plugged them into a Fender super twin reverb. They set down the effekt by 50 to 70 percent and made a class AB amp into a class A. The result is fantastic. I play blues and blues based rock'n'roll and want that 70:s sound, these yackets got it for me! Set a 9 because they do just what their advertised to do.

The sound is amazing. Before modification the Super twin was just as any standard fender amp, very loud and with nice and hard clean but no distortion at all. After modification the sound change to that 70:s sound, varm and brittle with a nice varm distortion if cranced to 10 on the master and all eq knobs (i use this setting to allmost all sound that i desire. Adjust the sound with the volume and tone controlls on the guitar). With my 79 strat i can get that brittle and watery sound that i never reached before, just set the treble and middle to 6 and the bas to 3 and it rings. With my new Ibanez artist ar 300 i reach the nice varm and dirty distortin that i never found before. The best thing about this modification is that it allows you to control the sound with the volume knob on the guitar. Full trottle on the guitar and there is that god distortion, about half trottle and there is that god cleane. The effekt in this amp is 180 watts with all six 6L6:s, now with two yellow yackets its about 30 - 40 watts but that is class A watts and sounds like 60 class AB watts. So, nowadays i'll never say `what` if someone ask me anything the day after a rehearsal. I set a 10 because now its the best sounding amp i`ll ever owned.

So far no problems but its only after a few weeks. I set a 5 because the lack of time used.

I have nothing to say here because i have not been in contact with THD directly. The warranty is one year. I set a 5 because of the one year warranty.

I've been playing since the mid seventies and owned a marshall 100, a vox ac30, an ibanez 50 watts solid state amp, several twin reverbs among all other amps. And now a peavey bandit 65 (bedroom amp) beside the super twin rewrb. If they (it) where stolen i do buy a new pair of yellow yackets and install them into a new twin. I love the sound of vintage amp that i get with these yackets. Even the vox ac30 i owned in the late seventies sounded less vintage! Go buy it, its a better way to vintage sound than a amp at a cost of thousands of dollars.

TUBE CONVERTERS FROM 6L6 TO EL84'S

MY WIFE BOUGHT THESE FOR ME FOR CHRISTMAS TO PUT IN MY BLUES DEVILLE, CUZ I COULDNT AFFORD A VOX AND I AM REALLY FOND OF THE EL84 SOUND. I PLAY A FENDER STRAT. I ACUALLY REALLY LIKED THE SOUND OF THESE, BUT AFTER 1 WEEK ONE OF THEM STARTED OVERHEATING AND HAD TO BE SENT BACK TO THE COMPANY. THE SECOND ONE I GOT EVENTUALLY DID THE SAME THING, SO I HAVE BENN RUNNING ONLY ONE YELLOWJACKET, WHICH SEEMS TO WORK OK.

I WOULD NOT BUY THESE AGAIN, DUE TO ALL THE PROBLEMS OF HAVING TO SEND THEM BACK TO THE COMPANY. THEY DO SOUND AWESOME, EVEN VOX LIKE.
SINCE IT IS A NEW TECHNOLOGY MORE STUDY SHOULD BE DONE TO SEE IF SOME AMPS ARE NOT COMPATIBLE.

CUSTOMER SERVICE WAS GREAT, SENT ME NEW ONES FREE OF CHARGE.

I WOULD NOT BUY THESE AGAIN, NOT UNTIL I COULD BE SURE OF THEM WORKING ALL THE TIME. I ALLWAYS KEEP THE ORIGINAL 6L6'S JUST IN CASE.
I PLAY A WIDE VARIETY OF MUSIC FROM POP PUNK TO WORSHIP AND INDIE ROCK. I ALSO USE A LINE 6 DELAY, TUBE SCREAMER, MXR DISTORTION, SMALL STONE PHASER.

These are the YJSD type that reduce power as well as conver to EL-84.

Convert just about any amp using A/B class power with EL-34, 6L6, 6V6 or 6550 tubes to A class EL-84's

I used them in a vintage Marshall JCM 800 2203 100 watt head

No opinion on the rating because it doesn't really apply

Nice and sweet, warm tube distortion at lower levels, added more midrange, chime and warmth. I used the 2203 with the THD's in it with a Marshall 1960A 4x12. These really altered the characteristics of the amp, still retained the "Marshall" tone but not quit as brittle sounding and very musical. I had to back off the mids a bit on the amps EQ. Nice sounding. Even at 20-25 watts the 2203 was still plenty loud through a 4x12.

N/A brand new

Very good customer service. I had some questions before I purchased them and they were great in answering them.

I play hard rock and metal, used a Jackson USA Strat with a JB in the bridge and a little 59'er in the neck.

These did exactly what I bought them for. Installation was easy and THD includes a set of instructions for installing them and the different options you have for a 100 Watt amp. For example you can replace all 4 power tubes and install Yellow Jackets in all 4 slots. You can remove all 4 tubes and install Yellow Jackets in the middle 2 tube sockets and leave the outer two empty (what I did) or you can use the Yellow Jackets in the middle 2 tube sockets and leave in your existing tubes in the outer 2 tube sockets giving you the best of both worlds (I haven't tried this as of yet)

If you are wanting to give your amp a different sound or tone for little money these Yellow Jackets are the answer. If you don't like the sound of EL-84's they may not be for you. The good thing about this type of Mod is it is reversible and requires no bias adjustments going back and forth.

This is a simple tweak you can do to almost any tube amp.
Remove existing power tubes and insert the YellowJacket adapters and then insert the new EL84 power tubes into adapters. Power-up and go-for-it.

I have my YellowJackets in a Hot Rod Deville 212. Set Drive to 7 and master volume on 9. With my les Paul the sound is thick and nasaly and really puts a grin on my face. I also tamed the volume with a THD Hot Plate. The EL84's are much smoother than the stock 6L6's. I love the tone when cranked-up loud. These adapters also cut the watts just about in half but the amp is still plenty loud with 30 watts.

So far so good, no problems at all.

No experience yet with customer support.

Fantastic product. Turned an alright amp into a seriously aggressive tone machine that really screams.

see post below

I've now had them for a month.

I have now had the chance to record with them and they sound fantastic. If you want to hear a short soundclip, e-mail me and I will e-mail it to you.

Apparently, not all amps like them, but the Peavey sure does.

I tried putting 2 of the 4 power tubes back in, and actually think it sounds best with just the 2 Yellow Jackets.

I will never go back to the Stock configuration as long as I own this amp.

Not had any problems in a month.

They are fantastic. Will answer all your questions.

Easy to install.

Installed on a Peavy Triple XXX. Made the clean channel sound fuller and bluesy with everything on 10. Chords seem fuller, rounder, warmer, and more pleasant than in stock config.

The crunch channel has lost a little edge in exchange for a smoother distortion tone....but very useable and very good. It did not change the character of the amp substantially. The bottom end is still there...which some have reported was lost. When I say the crunch channel has lost some edge, it sounds very good, just a hair different. I would think with a little e.q., you could get right back to the original sound. Plus, these majorly reduced the overall volume of the amp as advertised, and the slight loss of grit is a fair trade off for being able to run the thing at a higher power amp setting. At full volume with the yellow jackets, I am getting about the same volume I get at 3 in stock config.

I have yet to try these with two of the power tubes put back in (ie. 2 yellow jackets and 2 power tubes) Right now I am just running the two yellow jackets.

The Ultra channel has always sounded muddy to me, and it smoothed out the Ultra channel as well.

Let me put it this way, I don't know that I will ever go back to stock, and I have only had a chance to play with these for about a half hour, that is how satisfied I am. (I just put them in last night)

I can see where these would really make a Fender sound GOOD, because they do change the tone towards a warmer richer sound.

The Peavy is sort of a mix between a Triple Rectifier and a Marshall.
I think it has a better lead tone than most people get out of a Marshall and a way better tone than most get out of a Triple Rec. I will admit that with a really good Marshall, you will get a better lead tone (but you will spend a lot more money getting there) The Peavy can chug chug chug, like a Rectifier, but not exactly. It isn't everyone's cup of tea.

But assuming, you take the stock sound of this amp, and then install these, I think you would be really happy. And at least for 99.00, they are worth the risk of trying.

I have had such good success with these in this amp, I would really like to try them in a Marshall, a 5150, and a Mesa, to see what they would do.

The biggest change seems to be in the clean channel, and I would leave these in just for the change in the clean channel alone.

It doesn't sound like a Vox AC30, and it doesn't sound like a Fender Hot Rod Deville, but comparing the new sound with stock, it is much better.

I realize all of these things are subjective, but I have had this amp for four years, and have never been happier with it.

The flip side is, that if you try it and don't like it, it will take all of about 2 mintues to go back to stock and you haven't spent a fortune to try it.

I would consider these one of the top 5 guitar related purchases I have made in the last 20 years...how's that.

Seem to work fine.

I e-mailed THD asking which version I should get for this Amp and they e-mailed me back in less than an hour.

I don't give them a 10, because nothing is perfect, but they work just as adverstised and it isn't hype. I can really see where they would make some amps sound way better. I could also see where if you have found your "perfect" tone, they might upset your balance...but I was surprised that they didn't really change the amp as much as I expected (from a tone standpoint).

The ability to run the amp at low volume is a huge plus and they have made the clean channel so much better, I will take the slight loss on the crunch channel.