The Tube Swapping Thread

Hi All! I'd like to get a discussion going regarding what kind of results you're getting with non-OEM tubes. We all realize that tone preference is subjective, but let's give it a shot anyway! As an aside, the warranty paperwork says that swapping tubes will void the warranty, but the owner's manual mentions swapping tubes in section 7, specifically "All the hard work of biasing gets done automatically, so swapping tubes is an exercise in speed and convenience." I'll email H&K for clarification. Let's go!

Good thread. There are a couple other posts with people's swaps, but having them in the same place will be good.

There's also a post with a link to a video on how to swap tubes without breaking the warranty seals. Check it out and have at it!

As an aside, I haven't swapped yet. While the Chinese tubes are much maligned, they aren't bad sounding tubes. Yes, there are better tubes out there, but that doesn't mean everyone should run out and swap tubes. If you like the tone, cool. If you don't, or if you are having noise issues, swap 'em and let's hear about it!

I'm not so sure that most people have a good enough ear that swapping tubes would make a discernible difference one way or another. Just MHO. Of course there are people out there that can tell the difference, but they are a small minority. But I'm glad that someone started this thread because I indeed am going to change the tubes! LOL!

FYI: I emailed H&K 2 days ago about the tube/warranty issue, no response yet.

My prior amp was TM18 and I replaced the tubes almost right away. Not because I thought they stock tubes sounded bad, it was more out of habit, I almost always replace any stock tubes with JJ's and I do hear an improvement. Yes, it is subtle, but it's there. I know there is a love/hate thing for JJ's but for me there are a known entity and IME they have proven to be reliable.

I've only owned my Grandmeister for a few weeks and I haven't gotten around to swapping the tubes yet but I will. I am confused though about this talk about how to change the tubes without voiding the warranty? To get to the tubes all you have to do is unscrew some chassis screws and you're in. There is no "seal" to break, not that I've ever seen, and I don't think there is more than one way to get to the tubes. What am I missing? I took apart my TM a bunch of times and I've already had my GM apart a couple times just to look around... I have seen no seals or any other special way to take it apart. What gives?

The warranty card plainly states that changing the tubes voids the warranty - the actual tube swap, as you've noted, is itself quite simple.  I was just trying to get confirmation (STILL no reply from H&K) from H&K that the warranty would actually be voided if the tubes were replaced.  It doesn't make sense - if one of more tubes die during the warranty period, they have to be replaced.  And if I do it myself, does that void the warranty? I have a feeling H&K would prefer one take their amp to a certified tech for the tube swap, thus preserving the warranty (if still in effect).

Yeah I'm equally confused about it Pete. Hopefully you get some clarification on that. I think it's ridiculous (and highly usual) that by opening the chassis the warranty gets voided. That's just weird. If I experience a tube failure, I am NOT sending the amp away for weeks - I'm going to change the tube myself. It takes 5 minutes.

BTW I think you're better off messaging them thru FB. They are more responsive that way, compared to email. At least that's been my experience anyway.

Incidentally, I had sent my TM to Yorkville once, under warranty, to check out a possible problem (it turned out to be nothing) and they serviced the amp without question, even though I had installed JJ tubes. They never even brought it up.

Peace,
Dave

Here's a link that describes how to change the tubes that does not violate the warrenty:

Ahhhh now I know what seals you're talking about... when you remove the chassis screws there are black 'stickers' inside the chassis that sort of (half-heartedly) hold the sides on. I had no idea they were "warranty seals". They pretty much look like a couple pieces of black electrical tape. Not very official looking

I don't know guys... I think I'm going to stick to my opinion that it is ridiculous for H&K to say the warranty is voided by opening the amp. That's just nonsense.

i put old stock mullard EL84's in it, along with an OS GE5751 in v1 and RCA 12ax7's in v2 & v3........it works well for me.

Thanks for sharing. Can you describe the tonal differences and/or feel you are getting with the swap?

hi all,

new GM36 owner here !! (my first post in "cab" thread)
I'm used to change my tube in my amps so I did it very quickly in the GM. Very easy to make it , thanks to the vid.
Put some JJ EL84 for power.
For preamp, after many tries with TS gold, JJ 83s, 803S, Ruby, I end up with JJ83s for V1, V2 and JJ 803S for V3 (Phase inverter I guess).
I'll try some 12AT7 and 12U7 too, to tame the gain as I have too much on the tape for my usage (hardrock, heavy blues, up to some heavy rock but not pure metal). Love the Ultra for leads for example but never go up to 9 or 10 o'clock.

We can say the overall ampp takes a slight but clear benefits from that tubes swaping. But the limits is quiet quickly reach as the "electronic part" of the amp appears to be major, even if it sounds great.
The amp is clearly warmer, rounder, less fizz with gain going up (but still too much for my taste - see my post in the Cab thread)

By the way is there a link between the V, V2, V3 and the chanels ? for example I previously had a Diezel Einstein head and the V2 drive the lead channel. Something similar in the GM36, or does the 4 channels are driven by electronic board ?

Bruno

AS I 'm conitnuing my test on that great amp, I found it to have too much gaini for my usage, including some heavy hard rock needs.
So I ordered (Banzai Tubes) 2 preamp tubes to tame the huge gain, and help to control the high too:
- JJ 7151 for V1
- JJ 12AT7 for V2 (will check if need to swapp the JJ83s)

for V3 as Phase inverter to hit the power tubes,  I plan to keep the JJEC803s.
Anyway will check that and post the results next week (should receive monday or tuesday).

dears,

just had my GM36 for 3 weeks now.
A great amp I find as versatile as I read on many forums ! Just to remind I have a fender like 40W with JJ6L6GC and a Wem 15W with EL64 and an Axe FX II... And previously had a Diezel Einstein, sold 1 year ago to move to the Axe fx.

Well, to summarize, I swapped out the stock tubes for some better (clearly crappy chineses with no oul & life) tubes.
Ok it's a modern amp, with huge electronics, so it's less impacted by tube swapping, but nevertheless, there are some clear changes in tone.

I swap the power tubes to JJ EL84 / 6BQ5 quad matched: good tube Q and sound immediatly a bit rounder.
AS there is so much gain in the GM, I wanted to have more control on gain/volume and a warmer tone. A first try with JJ and TungSol gold 12AX7 in preamp: gave me a rounder/warmer but still too gainy for my usage (heavy blues to hard rock to heavy rock).

So I put a JJ 5751  (70% gain of a 12AX7) in V1, a JJ 12AT7 (60% gain of a 12AX7)  in V2, a RTC 12AT7 WA NOS in V3 (PI before power tube).

Well the result is very pleasant, with a warmer tone, and of course, as I reduce preamp tube gain, more headroom and more control along the full range of the knobs.
AS a result very pleased, rounder, warmer, less harsh and fizzy (the amp is on the bright side).
I use it paired with a TTCAB 2*12 Eminence Gow+Wizard and a Palmer 1*12 with eminence Cannabis Rex. With Both  the amp is now perfectly under control on the hight, tone and power. Player with drummer with no issues, largely enought power and of course still the dynamic of the awesome GM36.

So Yes U can improve the GM36 with better tubes !

Bruno

Glad to hear the swap worked so well for you. I spend most of my time in the Clean and Crunch areas, with solos in the Lead channel. I don't have a single user preset using the Ultra channel--it's just not my sound. I'm really happy with the cleans and would hate to mess that up. I've got some great old tubes around that I might throw in at some point.

Hi guys!

Just swapped my tubes this evening too!

Power Tubes:
TAD EL84-STR Premium Matched quarted




Preamp Tubes


Preamp V1:
TAD 5751 Highgrade Premium Selected


Preamp V2:
TAD ECC83WA Premium Selected


Preamp V3:
TAD 5751 Premium Selected

So I had a dig through my stash, and ended up with JJ ECC83s in positions 1 & 3 and a Groove Tube 7025 in position 2 which did a very nice job of warming up the tone as did a very old Mullard I tried for a while. I'll be trying some others too to see if I can calm the gain down a touch

Hi everyone!

After hours and hours of swapping preamp tubes, playing guitar, swapping again and playing more guitar I have found MY new setup! For the kind of music I'm playing (Blues/Rock,Hardrock) the grandmeister have way too much gain and too much volume. And you can soften that beast just with swapping preamp tubes!

The most gain comes from V1 but also the V2 tube. Only swapping one of them will decrease the gain, but best results will be if you swap both. I did many many tries with ECC83WA tubes (little less gain then 12ax7), 5751 tubes (70% gain of 12ax7), 12at7 tubes (60% gain), 12ay7 (45%) and 12au7 tubes (20% gain).

V1: The 12au7 did a dramatically decrease in gain but it colors the tone in a way I don't like. The 12at7 is often described as no good tube for the gain stage and I agree to this term. It sounds muddy...but it has other strenghts (read V3). All up from 5751 decreases the gain (and the volume) but still have too much gain in my opinion. So the perfect V1 tube is: The 12ay7! In my setup it's a TAD 12AY7/6072A Premium Selected! Beatifull tone and the half of gain and less volume.

V2: As I mentioned above the V2 also colors the tone and has effects on gain and volume. I tried all tubes in this position. The 12au7 and the 12at7 decreases the gain but colors the tone. I don't like it. The 5751 sounded good and deceased the gain...and it also decreased the volume in comparison to a 12ax7. But surprisingly the ECC83 did the best job! Good sound or positive coloring the tone of the 12ay7 in V1, same gain as the 5751 but more decreasing the volume. And this although the ECC83 is in a league with a 12ax7... So the V2 in my setup is: The TAD ECC83WA Premium Selected!

V3: The phase inverter! Oh I have read a lot about this tube position. And I agree to the term, that this position has the most influence on volume! Wow! The grandmeister have a great function to decrease volume but still have power amp distortion...the power attenuator. But you will have a big, big smile in your face if you play the grandmeister WITHOUT the attenuator. Hell yeah and with power amp distortion. And on rehearsal room volume level. Great! The tube to get this? The 12at7! I love this tube in this position! In my setup it's a TAD 12AT7/ECC81 Premium Selected!

I had a lot of fun and have learned a lot about preamp tubes and their influences between them. So don't be shy to try some other tubes.

Greetings
Kaipirinha

Thanks for sharing your experiences. I might give this a go, but I'm a bit new to all this...can you clarify which V is which? Is V1 the one with the metal sheath?

Hi limedrop! You are right, the V1 is the nearest one to the input. It's the one with the metal sheath. Then the V2 and finally the V3.

Complete Tonal difference, the amp came alive, especially when you crank it at low voltage. The Pre-amp tube with the cover on it tried to be a pain by not seating, panicked wondering how I broke the whole amp by changing the tubes and then examined the height of the pre-amp tubes and saw that one was sticking up. You can get matched tubes from the tubestore. I got three matched 12Ax7's and 4 EL 84's.
LOVE THIS AMP, I run it through a mini Marshall slant front cab with two GT-75 Celestions. EASY TO CARRY. Everyone swarms the amp, DUDE that sounds so good, running lead with chorus and Delay.
I could have sold 4 last night!

I had a go at following Kaipirinha's suggestion this week and can second the use of a 12AY7 (TAD RT007) in V1 and a 12AT7 (NOS in my case) in V3. After some extensive testing I went with an old Mullard ECC83 in V2 as it sounded more balanced than the TAD ECC83WA. I did still like the JJ ECC83 in V2 and V1 for that matter for its slightly more aggressive mids especially with a Strat, but in the end the Mullard just somehow always brought a smile to my face

I find that V2 has the most influence on actual tone (as opposed to just gain) for some reason; maybe it's my ears and I think that V3 is doing more than just driving the output as swapping that out seemed to affect the send level of the loop. I run a TC Gmajor in there and that's got a visual level indicator.

I quite liked the effect of a NOS 6189W (12AU7 / ECC82) in V1 or V3 but I got a wierd distorted tone in the background in V2. In the end I thought it dropped the gain too much.

Thanks for sharing guys. I followed Kaipirinha and normula's suggestions, but substituting one of the Mullard reissues from eBay. Sourcing the 12AY7 (TAD) in the UK was a bit tricky but managed to get one from Spain.

The Youtube posting on swapping power tubes helped, but it was a bit tricky swapping out v1 (metal sheath). I ended up unscrewing the sheaths base plate to be sure that the valve sat right.

Results were good, although not as game changing as I was hoping for but the gain is much more manageable now. Added to that I just got hold of a Marshall 1960tv and for me that's made a huge improvement.

Hello everybody!

Little update for my tube swapping mission:

I got some beautiful warm "Mullard EL84 Reissue" which break up much earlier!
So I don't have to push the power amp as hard as with the "TAD EL84-STR".
The sweet spot where the EL84 colours the tone is at 12 - 13 o clock master volume.
But the last setup with the 12ay7 in v1 and the 12at7 in v2 had too less gain to drive the Mullard.
So I changed back to my first custom setup with 5751 tubes in v1 and v3, which still have less manageable gain then the stock 12ax7.

I just ordered the next Mullard Reissues quad as fallback!
The next step will be to test some 5751 from another brand or the Mullard ECC83 which normula1 uses.

Great topic! :-)

For your interest: Most power tubes you can buy have values for TC (transconduction). The higher this value, the longer the tubes will be "clean". The TAD EL84 I bought, had a tc above 11000 so they need much more power from the preamp (master volume) to break up as the Mullard EL84 with a tc of 8100.

I ended up with the same types of tubes as Kalpirinha.
V1 Elector-harmonix - 6072A/12AY7
V2 JJ ECC83 S
V3 JJ ECC81 (12AT7)

Electro-harmonix for EL84

The tones are much warmer, in fact I need to add back some brightness. I tried at a practice and a gig. I my master was maxed at 10 for a small club (where I would have been at 6 or 7 before). I can probably adjust my settings so I have more volume on each setting. Most of my presets are at 18 watts although I have a couple cleans at 36. I'm not sure whether this is too much drop in volume or not yet. It's cool that I am driving my output hard (although probably not max since my settings don't typically have master at 10, although a couple do).

I'm not sure whether I should go 36 on more settings and just keep a few maxed out at 18 or maybe go with a higher gain in V3. Although I'm hesitant to mess to much since I do like the sound.