Does Changing Tubes/ Valves In A Guitar Amp Really Make A Difference?

In this video, I wanted to see if changing the Valve or Tubes in your guitar amp really makes that much of a difference.
Recently I was shopping online for some tubes for my Matchless Independence 35 as Ive been told that changing the Valves from the standard factory-fitted JJ Tubes to Electro Harmonix made a massive difference. In this video, we find out if this is true or just Guitar amp cork sniffing.
The Studio Rats are core band members Paul Drew on guitar/production/mixing, drummer James Ivey and Dan Hawkins on bass. They collaborate with singers and musicians to produce radio-ready songs.

[@MrMattsac232]

That matchless is bad ass and great playing as usual. To me tubes often fall into the category of things we worry with now but that the great players of old never worried about. for power tubes I would think you’d need to get them cooking to hear the full difference. Paul thanks for using the same track on multiple videos, for me it helps to hear the difference more clearly having familiarity with the track.

[@Dunk0The0Punk]

Cool test Paul ! really enjoy that song a cracker ! lush cords too, I really liked the JJ"s over all they sounded brighter and more alive especially with your tele.

[@user-pb2nd7pm7f]

Sounds great!!! I hate the guitar videos because you can never hear the difference with sound. You did a great job. Love your playing man!

[@backlineguy]

Buying a used tube amp such as a Hot Rod Deluxe, I tend to replace the output tubes and re-set the bias...as well as check/replace the main capacitors if they're leaky...but tubes will make a difference...great video, great playing as well.

[@Adventuresingearland]

Great episode! Was thinking 'Wouldn't it be good if they were back to back?' Then you went and did it! Through the headphones, the Harma sounded fuller. Quite liked the JJ's though tbh.

[@videoJunke1]

I heard some lovely tunes! Thank you.

[@conanmiddleton925]

Thank you for doing the comparison, through my studio monitors they sound the same, also through headphones if there is a difference it is minimal. It helps to know that as you can save your money for something that will effect your tone, such as a couple of effects pedals or change out your cab to a different speaker.

[@blackstratblues]

Power valve differences are indeed subtle (especially if they're not being clipped). Where you'd want to put your money towards is longevity, reliability and consistency. It helps to buy from a seller who knows how to test and match valves. Preamp valve swaps are another ballgame altogether, especially V1 (closest to the input jack).

[@toddsteele72]

Paul, love this piece of music. Please let us know where we can purchase it. I've been playing it on my tele all evening trying to learn it and thoroughly enjoying myself doing so. Great player mate.

[@robpetoletti826]

Very cool, thank you!

[@ernieb3626]

Paul thank you so much for doing that. As small of a difference as it is I have always wanted to do that and you just saved me some money. That being said with all this worldly stuff going on having extra valves is probably a good thing… Or tubes as we say here up in Michigan lol

[@jamesmaddock259]

Great test . Very useful. As I suspected, very little difference between the valves . But thanks for doing this . Saves us all from buying valves !😀

[@frantisca]

Hi Paul, Watford Valves is a great supplier. I bought a cab & loudspeaker from them. Very good stuff. I changed JJ's to EHX on a Brunetti: huge difference in favour of EHX. Much more clarity. My 2¢... In your test, I thiink that the Harma had an edge over the 2 other sets. Very nice Thinline BTW ;-)

[@prd004.2]

If there’s a difference it’s so subtle, I couldn’t really hear until you solo’d the guitar, even then it was minimal. Good to know as there seems to be a world wide tube shortage as we speak 😳 PS that is a wonderful tune! The vibe, the chord progression… really nice. Dig the drum sounds, the overall mix and production!

[@TheStudioRats]

Cheers PRd!

[@Pete_Harris]

I liked the Harma best! Bit fatter but cleaner on the bottom end to my ears. JJ's were a bit more gritty with less headroom. The 6CA7 seemed to have a more mid bias to me which is odd as they are supposed to emulate the 6L6. Great playing as always 👌

[@garyslash7552]

As intensively as I've been searching for my perfect guitar sound - and never seem to be able to find it - your valve comparison has shown some intersting facts. I agree with you: Your Matchless is one of the best amplifiers I have ever heard and there is no need to change the valves unless they go down (which they don't as often and as quickly as some people want to tell us). I could barley hear the difference between the three sets. And most importantly: It's the music that counts and this song is so wonderful and you play it so soulfully - so who cares about the kind of valves! By the way, have you found a Marshall Guv'nor? Your Matchless in combination with the Guv'nor sounded great!

[@TheStudioRats]

Cheers Gary, James and I are getting together soon for another Guvnor update vid:

[@ericskinner7355]

Every one else is making videos about the unavailibility of tubes. Thanks Vlad.

[@ericskinner7355]

Putin must be stopped!

[@brammanck]

Interesting.. I changed the preamp 12AX into a 12AY Silvana and THAT changed a lot in sound. Never thought of changing the 6L6 and seeing this I wont bother :) Thanks

[@DanielGlenTimms]

I think the maker of a great amp like this would choose tubes that made it sound great. In the grand scheme, the cost is not that much more for an expensive amp. Your amp sounds great, as well as, your playing. Thanks for the comparison.

[@MusicSchuc]

What a great tune !

[@gawentaylor6838]

Out of the three the Harma's sounded clearer, nice headroom and didn't break up as early as the EH's, the JJ's while fine just did not sound as classy IMO :) Really helpful video as currently looking for a spare matched pair of EL34's for my JMP50! Thank you!

[@DBroce]

I have a 1970’s Fender Champ that I use too much and I’ve only bought more valves for that amp as I break them. Unnecessary changes of valves can become a problem. Cheers, Paul.

[@esmoroglu]

Hi Paul! Careful with the tubes, 4 in each hand, there are not that many left nowadays!😀

[@DaveyW6985]

There should be a disclaimer on this video. The Matchless amp is a Cathode Bias ( self Biassing amp), but if people see this and start pulling valves out of amps that are not Cathode Bias then the amp needs to be rebiassed, and can easlily damage amp and indeed the valves if this is not done. Additionally the filter caps in a Valve amp hold a significant charge of High Voltage DC, and will give you a really nasty shock, and could kill you if they are not drained. This why sometimes when you turn an appliance off the on/off lamp stays on. Harma valves are only rebadged valves from the usual suspects. Tube Amp Doctor in Germany have some very nice valves usually. Finally you may find you get a better result by changing the rectifier, much more important than the power amp valves. Pre amp valves will also make a difference - Sorry for the long comment but it really isn't just a matter of whipping valves out and putting different ones in - Stay safe guys

[@TheStudioRats]

Hi Dilly. Although you are right about biasing amps being important, this video is not about biasing, its about if there is a difference between tubes (if any). A you said The Matchless is a self biasing amp, but that is why amp manufacturers have manuals for people to read to know how to use their amps, its not for me to tell people how their particular amp should be used.

[@DaveyW6985]

@@TheStudioRats I'm Sorry that you took that the wrong way. It wasn't meant as a criticism. I agree that it's not up to you to tell people how their particular amp should be used. So many amps people own are second hand and didn't come with a manual, and watching your content, the average Joe , could say Oh I'll just whip out a couple of power amp tubes and change them, in the meantime getting the full whack of the filter caps, perhaps killing them. I believe that content creation does come with a certain amount of responsibility. Not a criticism of you or your show, You know I am a fan and support what you guys are doing. it would have just been nice to drop in by the way" Kids, make sure you have a full understanding of the lethal voltages around in your amp even when it is switched off and unplugged from the power also your amp may not like to just have its power amp tubes changed and may need to be rebiased " if you are in any doubt see an amp tech. Anyway most of us are blokes and blokes don't read manuals 🙂

[@ThinkTankxx]

Filter caps are all gonna kill us! Stay away from trying to know or use your amp or change valves. It will kill you! So stupid, get off your high horse. Nobody is gonna die changing there tubes or rebiasing for that matter, and if they manage somehow to get a little shock, chances are they learned something. Try teaching instead of convincing us how smart you are and how dumb we are. We went from listening to a change in valves to getting killed by our filter caps. Get real.

[@joshjenkinson1929]

If you own electrical equipment, it’s obviously got the potential to be dangerous and it’s your responsibility as the owner to familiarise yourself with this for your own safety, nobody else’s.

[@tonystartup3817]

I've used harma valves from Watford valves for about 22 years. Always noticed quite a difference over stock. They do a number of different types and configuration of valve within the harma brand so you can't make any global statement as to how they sound (they do low gain, high gain, warm, bright etc). I've always thought the difference to stock is like a low quality MP3 compared to a CD/LP

[@Goldsilver]

I once met Hartley Peavey at a conference. Some guy came up and asked a geek question about matching tubes. Mr Peavey shot him down by saying ‘ok, you got a turd in this hand, and a turd in this hand exactly the same. What have you got? You still got two turds.” (Admin)

[@TJauernigElectronics]

I worked at Peavey for a couple years. He hated guitar player geek speak. The bust tubes to him were EL84’s because they were cheap.

[@Pantalooj]

Interesting ... haven't owned a valve amp for a few years now, but have been mulling over whether to add a low wattage valve amp into the mix again. My take would also be not to bother changing valves, provided there were no problems, but use Harma when actually needing to replace

[@lets_measure_it]

during covid i bought a vox ac30c2x. realising that i had no spare el84s i decided to buy a so called matched quad of electro harmonix valves. i recorded the amp with the original non branded chinese valves and again with new ones and there was absolutely no discernible difference. it maybe that the design of the vox output stage is immune to small production tolerance variations in the valves (which is a good thing). i did hear some subtle variation in your video but not enough to prefer one brand. bear in mind your valves were at different ages and possibly at different stages of warm up. thanks for the interesting video

[@markattaway4429]

Yep!!! Leave the tubes alone. That’s what an eq is for.

[@pastorkev777]

I prefer the 6CA7 it just has the extra something. One thing I will mention is valves may be Power Amp or preamp will react differently in different circuits. For example I had a Egnater tweaker 15 and changing the valves made a huge difference, it was very sensitive. I've had other amps that changing the valves was a waste of time.

[@acmeyakko]

New tubes are interesting. It seems most of the manufacturers have gotten very good at creating very clean tubes (from a frequency response perspective) such that the differences between them are very subtle, and even the headroom is often very close. If you are looking at new tubes, I'd tend to agree with your overall assessment: it's not worth the trouble, but having backups is useful (especially for power amp tubes since they tend to fail more often than preamp tubes, and especially given their changing availability). Older tubes are where things get more interesting. Old tubes were not as consistent, even for a given manufacturer, so the character can vary a lot more. It's clear to me this is actually because, from an objective point of view, they were not as well made, but the resulting tones can be quite nice. I've played with a few and found different preferences for different types of tubes (e.g. north American 5751 JAN tubes for one mic preamp, north American 7025s for V1 in one guitar amp preamp with modern tubes following, soviet mil-spec power amp tubes in a couple of amps, etc.) but given it's a matter of what kind of wrong you prefer, it's all about... well, what you prefer.

[@acmeyakko]

I suppose it is also worth adding, even with everything I said, if you buy an amp and love it, leave it alone. If it ain't broke, don't fix it. I would mostly encourage people to have spares around since tubes are finicky beasts. Sometimes they last 40 years and sometimes they last a few weeks. Best of luck.

[@timmotel5804]

Most enjoyable. To be honest, they all sound the same to me. Which is good. I also think that my 2023 Strat HSS Ultra sounds just as good as a $25,000 old Strat or custom shop. In the "ear" of the beholder I guess. My "65" Reissue Super Reverb with Alnico magnets sounds the same as an old one. Thanks Best Regards & Happy New Year

[@TheStudioRats]

Thanks for sharing!

[@willsutton3767]

Paul, agreed. I thought the JJs had a touch of grit on the top, although I kinda dug it. I’ve always considered JJs the “tastes like chicken” of the valve world - never awesome but always serviceable. I liked them here though. Lovely tune, by the way!

[@TheStudioRats]

Cheers Will.

[@KunchangLeeMusic]

How much pressure is required to replace a preamp tube - I tried wiggling in the new tube while applying gentle but firm pressure but it just doesn’t seem to go in - do I need to press in really hard ? Just doesn’t feel right cuz all the videos I see of people replacing tubes - it seems to be very little effort -

[@everTriumph]

Can some (all) of the difference between the valves be due to different cathode emissivity giving rise to different bias currents?

[@GCKelloch]

You may know that "Harma" is just a rebrand of one of the tubes made by the three tube plants. It might just be the Mullard RI type made in the Russian Reflektor plant. ShuGuang is no more, but Psvane is now making some guitar amp tubes. Out of the three tube types you tried, I like the EHx 6CA7 in that amp and for your style. The bass is fatter and the high-end is sweeter and clearer. Not sure why you thought the bass was weaker. It's definitely stronger, but the high-end is also stronger (less compressed). That influences perception. You really need to compare the same guitar passages when comparing things. Prerecording a loop is a good idea.

[@vespass225]

At least in a HiFi Valve amp situation, 6CA7 has a lot both tighter and punchier bottom end. Also top end is crisper, more present and forward. Generally speaking 6CA7:s sound scooped compared to EL34s in my SE HiFi Valve amp. The 6CA7:s I refer to are JJ's

[@JimiSomeMoore]

Like the JJ's best, seemed more rounded than the others when in isolation. When in the mix could hear only a slight difference. That said 90% of what I play has varying degrees of dirt/more dirt.

[@grinder2401]

Sort answer: Don't bother. It's not just the tubes themselves, but the circuit design. Longer answer: kzbin.info/www/bejne/jJKyaICjnM2ip6M (contains mainly high gain tones, but also Fender clean/slightly overdriven) Check mainly your speakers and mics. Granted these are not "sexy" to discuss and therefore often overlooked.

[@scoobystap3159]

I wish all amps were Cathode Biased. It sure would make things a lot easier. Getting it biased, because I do not have that skill, costs way more than the valves.

[@giulioluzzardi7632]

They all sounded good, those Harma valves are a bit special sounding with a single coil pick-up. As you say they will come in handy anyway so you've covered yourself for output valves for years.

[@skaboosh]

Watford Valves.. good old fashioned style great service

[@hafstrat]

Yep. Subtle differences. Ire valved my amp with harmas from wvs but instantly put the original ehx back in. Harmas sounded thinner with more top and less gain. Ehx sounded warmer. .

[@jeffparryncc1701]

Absolutely! Ruby 6L6 are top end sparkly, and the Tung-Sol 6L6 are more natural/less sparkly top endy, more bottom end. Tung-Sol for metal for sure. Check out the valve forums that discuss changing/mixing various makes to find different tones :) Or are they all wrong? Check them out...

[@grayaj23]

There is pretty solid evidence that people will perceive a sound as being "better" when it's louder , even by a tiny fraction. I'm one of the people who think if you made a single recording, reamped it through both tubes and recorded that, then played them back 180 degrees out of phase, you'd hear silence or close to it. If nothin else, if they were normalized for volume and someone else was randomly switching signals, would you reliably pick out which was the JJ and which was the EHX?

[@danh7739]

You can hear how the tubes sound, but what you can't get is how the the sound of the tubes are reacting to your touch. For me, I can hear a difference between the tubes, but it is subtle. You can change pedal and amps and spend your life chasing the illusive 'perfect tone' or you can get a Marshall and just deal with what you've got. Everyone I know and do sound for, loves the sound of the Matchless, they swear by it, for a while, then they go back to playing Marshalls. There are some 50 watt Marshall heads that sound sweet and they always say that it's from some brand of tube, but other then those all I ever hear is "PLEXI". In the end the great player all say, everyone of them, the sound is in you, in your fingers, your personality. You just have to work your ass of to get there and maintain it.

[@maxpeck4154]

I have a cathode biased amp - a Morgan MVP 23 - pretty much an 18 watt Marshall front end with a Vox power section. I've only ever used JJ el84s but tried a handful of different 12ax7 tubes in V1 and there was a HUGE difference between them, from a JJ (lifeless) a Gold Lion (too bright and brittle, no bottom end) to an NOS RCA (meh) to a couple different current production tubes and the one that sounded the best? The Electro Harmonix tube that came with the amp. Go figure.

[@davidcane7211]

On my lowly Orange Terror Stamp I changed out the stock JJ for a Sovtek. It made the world of difference. For starters there's more clean-zone on the Gain control, and the gain itself is just nicer and more usable. Tested a Tungsol tube too, better than the JJ in the Orange for me but the Sovtek is my favourite.

[@scottpeters4401]

I have “tube rolled”many times….it’s a subtle difference…not something you could pick out blindfolded…or I couldn’t anyway….I care more about reliability than the tiny difference in sonics between different tubes….most are all made by the same manufacturers anyway,just re-branded….

[@AHCHUUU]

Ahhhhh....just clean.

[@thomaswalz3515]

First, I want to thank you for your video style. Most Brits are very verbose, babbling on and on about meaningless minutiae. You sir, get straight to it, your evaluation to the point. You are also a great player, and know how to use the effects you evaluate to get the most out of them. Too many are not capable. They're playing meaningless drivel that no real musician actually would use. Thank you again. I detected no difference in these tubes from headphones... You were there in the room with them, maybe that's whyyou detected variances. Even you said, the differences were subtle. Personally, I'm fed up with so many in the guitar world detecting minute details in sound and claiming, "its better." Often, these differences can be made up for with the twist of an amp's or guitar's knobs on a whim. Let us shut up and play... make a joyful noise.... I feel I'm getting close to my perfect collection of gear. I'm so happy with my sound, and the flexibility to play all of my preferred genres with minimal pedals, and pedal dancing. Keep up the great work.

[@bsbrooks455]

Interesting comparison, but as we all know, which sounds better in this case is entirely subjective. However, we must keep in mind that these were all "premium tubes". I have a very inexpensive, but actually good sounding 15 watt tube amp (Monoprice 15W, or on your side of the pond known as the Harley Benton 15W, same identical amp). This amp uses a pair of EL84's for the output tubes. The original tubes were unbranded cheap Chinese tubes (I hear that they now come with JJ's, but the price has also gone up about 35% recently). When I changed to a set of JJ's in this amp, the difference was like night and day. The amp opened way up and the noise level went way down. So yes, changing the valves really did make a huge noticeable difference. I guess the comparison is that you went from a Mercedes to a BMW, both great autos, but is one really better than the other? Maybe slightly different, but not necessarily better. I went from a Kia to a Cadillac, and in that case, even though they will both get you church on Sunday, one really is better than the other.

[@TheStudioRats]

Great comment Bruce.

[@yaniv-nos-tubes]

actually....you went from kia to skoda. all the modern tubes are made in china, russia or slovakia(jj). they all sound really bad compared to nos. harma valves are made in china in the same factory like all chinese tubes.

[@matt926uk1]

Are we going to hear these tiny details over youtube audio?

[@MrVanalen]

I think the lesson here is save your money although the Harma’s did sound nice they would be worth the upgrade . Is the Amp fixed bias?

[@TheStudioRats]

Its a self biasing amp.

[@TheLislemeister]

I may be wrong but understand that Matchless amps are self-biasing and some amps aren't so I would check that before switching too.

[@IvorThomas]

I think the ElectroHarmonix EL 34 tubes had a richer more 3D sound. The other EH tubes were in-between.

[@mikemcglone3184]

Tubes can vary significantly and biasing has a big impact. Not familiar with the Matchless or the valves used.

[@natedanaste]

Very subtle differences between them. Harma may have sounded slightly better but I agree too small to matter.

[@toploadtele]

Good thing you now have the spares... all popular valves/tubes are about to be unattainable at any price. If you can locate what's currently in your amplifiers you should start looking for back-ups right away!

[@jayseb]

I thought the mix was a bit too loud to get a good idea of the differences. Listening on Yamaha 8's. In such a mix the difference isn't that significant. My 2 cents.

[@PK-pk3cq]

Too busy admiring the playing!

[@kennyjohnson336]

Most Harma tubes ARE JJ's??

[@yaniv-nos-tubes]

no one knows these days...maybe chinese?

[@josephbenz4913]

About what I expected. Minimal differences between output tubes when they are not overdriven. Preamp tubes make more of a difference in my experience.

[@bigbasil1908]

The volume of the amps on these videos is too low for me to be able to hear properly or be able to tell any difference. I've got the volume at full on my laptop.

[@benink5690]

The Harma are far less gritty and more accurate to what you'd think a guitar would sound like when you hit the strings. That's my observation

[@joeygentile7829]

Harma valves for the win. They had a wee bit more presence.

[@jquill6]

The only real difference is between old and new valves I find , I really find it hard to hear the difference between brand A and B.

[@fender0942]

I’ve come to believe that if you have to listen this hard to tell the difference between different tubes then it’s probably not worth your time. I have done this in the past so I understand but I realize that the differences are so small that it doesn’t really make a difference. I’ve also heard some of the noted differences just between using different tubes of the same brand. Because they were rated slightly different.

[@tjsogmc]

The valves are all made in the same factory in Russia or China and stamped with the distributor's name on the outside of the glass. The only difference between valves is new vs. old. Check the valves on a Hickok valve tester and you will see that valves that test the same will sound the same. If you want to make a big change to your tone, change your strings.

[@DrKevGuitar]

There is no significant difference, other than small variations in gain/volume. The difference are so small that without the captions I doubt anyone would be able to say the recordings change from one tube to another. And as the most awesome Ian Sheppard points out, without careful LUFS volume matching when making audio comparisons, even +/- 0.5 dB differences in volume are perceived as changes in bass and treble. There is a reason why in 100 years of the industry, no vacuum tube manufacturer has never published frequency response curves for their products; it's because there is no reason to do so.

[@yaniv-nos-tubes]

swap v1 to hear the most dramatic difference

[@jamiebriggs8277]

this is like every other guitar tone myth out there... "Oh you have JJ tubes? Gotta use the electro harmonix!" "Oh, you have electro harmonix? Gotta use the JJ!" "Oh, you have modern tubes? Gotta use tubes made in 1954!" "Oh, you have old tubes? Gotta use new ones!" with the tolerances involved you're as likely to hear as much difference between two different tubes of one brand as you are between tubes of two different brands And of course, especially at this point - if you have tubes that work, leave them alone! You might not be able to get replacements for a while...

[@aristocaster]

No. (That you could not change with minimal change in settings of tone pots)

[@ianthomas4568]

Harma sounded best to me!

[@timhopkins3810]

“I’ve got a few pairs just in case these go down at any time”. Not sure if you recorded this before or after EHX officially closed up shop on tubes for at least the next 9 months. The £80 you spent on tubes seems to be more than well spent and has probably gone up exponentially on the second hand market! I would agree that the differences were so tiny that you only really need to justify changing them if one breaks but it was good to hear the subtle differences 😊

[@TheStudioRats]

Cheers Tim, yes I made this before the announcement, although in the UK there still seems to be tubes.

[@timhopkins3810]

@@TheStudioRats good to know 👍 I moved over to Helix and sold my main valve amp last year but was pondering whether to go back to something just for home playing with a two notes thing. I guess if the 12ax7s go completely then I can just buy a cheap joyo bantamp to easily replace one 😂

[@sabba25]

subtle maybe heard it once mentioned but struggle to tell a real difference...only difference is your wallet "feels" it...also nothing a slight tweak of the eq cant fix

[@cosmikrelic4815]

at the beginning you said that the company you bought the valves from tested them and picked the best. what does the best mean? a valve is used as an amplifier and to be best it should not alter the sound applied to it. in other words the more linear it is the less effect it has on the sound, any non-linearities add harmonics. if you are making a hi-fi amp you operate the valves in their linear region, in this mode the valves cannot sound any different unless they are not linear. if you run the tube in it's non-linear region i.e. close to clipping then you are adding harmonics. if the amp is class AB then the biasing can add crossover distortion which is also adding harmonics.

[@chrisdrake447]

Interesting demo, Paul. Differences were marginal through my listening device. However, perhaps the most important thing to be aware of is that you now have two spare sets of viable output valves which, given the context of Russia’s invasion of Ukraine and the sanctions imposed, the supply of valves will be increasingly in short supply unless the JJ factory in Slovenia can boost production. Mike Matthews of Electro Harmonix has issued a statement effectively cancelling back ordered valve products until further notice, and it seems unavoidable that other manufacturers will have to follow suit. I’d be very interested in what Watford Valves’ take on this situation is ...

[@garethc3448]

Answer: No

[@ParaBellum2024]

"Tone is in the valves". Said no one ever.

[@ThinkTankxx]

Not sure what we are supposed to be listening for on our end. Ridiculous, like we are supposed to hear a difference from our tv set on KZbin. If anyone can hear or feel a difference it’s you, not us.

[@srfrodoxd]

I couldn't hear any difference and that is what i fear the most because music world is plagued of so many myths and fairy godmother stories and bullshit and all that at least imo, i sold out my katana thinking a tube amp would handle fuzz better but turns out it's not and i have a decent amp with a very good speaker on it so i don't pay that much attention to what people say about gear anymore, i find this kind of content as pure entretainment at this point

[@JariSchroderus]

I think the only difference is a psychoacoustic difference.

[@Pleusch]

0 difference just in volume.

[@Tonetwisters]

Harmas are more "musical," sweeter than the JJ's.

[@Blobby_Hill]

Sounds the same

[@cliverkay]

Silly qusetion ..did you re-bias....

[@TheStudioRats]

It’s a self biasing anp

[@BlueBarrier782]

Not really. Your money is much better spent on a different speaker if you don't like your amps sound.

[@richardpierce7819]

If you dont use the tubes that the circuit is designed for you dont accomplish anything.

[@TheStudioRats]

They are swappable in that amp.

[@kmichaelp4508]

Nope!!! A waist of money!!!

[@adamdagosto570]

This was a terrible video!! With your playing ability and talent, you could re-tube that thing with tubes of tooth paste and it would still sound amazing!! Ok...I'm kidding really. I'm still stuck on the song you were playing....