Tube/Valve Swap

Eventually, the tubes in your amp are going to go bad, or maybe they just don't have the tone you're looking for... well it may be time for a tube change. Note that this should be one of the final steps in changes for the amp, as it really does not affect tone as much as many think. Your tone is only sculpted by these tubes (a la warmer, crisper, clearer, grainy, more gain presence, etc.). So, if you feel you have you're missing something, consider these tubes.

Please be sure to read the Warnings page before changing the tubes in your amp.
"...Pulling the chassis and poking around inside the amp however is dangerous deadly dangerous...."

--The Valveking 112 comes with 2 6L6GC power tubes and 3 12ax7 preamp tubes--

Changing Your tubes

Charlie's guide to changing tubes!

I basically position my amp so I can work on it and see what I am doing. Usually place it in my desk chair with the chassis down. The amp is leaned back at an angle so I can stand and work on it. The preamp tubes have 9 pins. I can line the 5th pin directly facing me with the open space facing directly away. Thus I already have a good chance of the pins going into the sockets when I finally place the tube down into the socket pocket. I gently move the tube around until it feels like it is not turning from side to side. Now gentle pressure and if you hit the right spot it will start in. Once it starts you have to make sure it goes until it bottoms. Once all are in place replace the metal sleeves. The power tubes are much easier because you can see the socket. The key on the tube is facing directly away and you will see a blank pin space to the right and the pin facing you directly next to that blank space. This is all asuming that you have the chassis down and going thru the back. I think this also applies to the VK100 too.

I assumed famously that everyone knew how to pull the tubes. You know what they say about assuming!

To be sure , pulling power tubes can be tricky. You have to remove any guards and you have to depress the spring retainers and work the tubes out gently. I have removed my retainers altogether. I have the large bottle KT66 and cannot use them with the metal tube bases because of grounding issues. You have to put the screws back in to hold the sockets tight to the chassis if you do not have the retainers mounted in the amp. This insures you won't put undue stress on the circuit board underneath and crack something.

Removing the preamp tubes is achieved by twisting the metal shields and lifting them off first. These little buggers (tubes) can be hard to get a hold of. I use a piece of rubberized shelf material to get a better grip on them. Wiggle and pull and don't give up they will eventually let loose. While you are taking them out you will see the direction the pin layout is facing. It is good to familiarize yourself as you are doing this.

Once you have all your tubes back in place set the amp back up and make sure speakers are plugged in. Turn the amp on and let it warm up. If you get no sound feel each preamp tube for heat. If one is cold recheck that the tube was inserted all the way into socket and in correctly. I had an instance where the tube was aligned but not all the way seated and I had no sound a quick check of heat from the preamp tubes found the one that wasn't seated.

I hope this is a reasonable guide for use by anyone novice or pro (credit cap47)

WARNING!!! Pulling the chassis and poking around inside the amp however is dangerous deadly dangerous. There are two capacitors in this amp that have a 1000volts stored charge one with 630volts and a number with 400-550volts. Yes they can kill you.

Preamp Tube Info

A 12AX7 100% gain, a 5751 will have 70% gain, a 12AT7 can be considered to have 60% gain, and a !2AU7 can be considered to have 20% gain. (credit 311ZOSOVHJH)

(credit bartdevil_metal)
>JJ 12AX7s: Add clarity and more bass response. Darker, so takes out some highs. May cause mud if used in multiple positions with high gain.

>TungSol 12AX7s: Add a tiny bit more gain, and again more clarity + treble

(Credit to leadfootdriver)
>Put a 12AT7 in V3. (closest to the power tubes on the 112) You get more clarity and dynamics. There's still plenty of gain left.

(Credit to IbanezPsycho)
I would check and see what tubes came stock in it. JJ's and Tung Sols are you best options. If you have Rubys or EHX you might want to change them.

>JAN Philips 5751: 12ax7 substitute that tames and smooths out the gain a bit. 70% gain of standard 12ax7, more than 12AT7. This is great tube for V2 if your into blues or classic rock.

credit IbanezPsycho - "Generally your V1 is going to be your clean tube, V2 gain and then V3 is the Phase Inverter. But all three do talk to each other in a since so its best to get a good combo going. So don't skimp out on V1's quality just because you are just looking for more gain in other words.

The phase inverter is part of the power amp. The signal is supplied to the phase inverter from the preamp. The power amp in divided into two sections, each section amplifying part of the signal. The two signals are combined back at the output transformer. And being the phase inverters job is to split the preamp signal into two halves, each half a mirror image of the other. If one is out of whack you will notice different frequencies out of proportion with one another. There balanced so that notes are represented equally and they sustain/decay equally. Balanced PI is not necessary in this amp! (cap47)

Also its one of the hardest worked preamp tubes and its recommended you change it out when you replace your power tubes if not every other time. Its also one of the most important tubes in your amp its what takes your preamp information and pass's it along and itshow this tube breaks down that provides your output stage distortion tone, character, and amp feel.

(credit Cap47)
I would strongly recommend these preamp tubes. I have tried many and this is my 1st choice V1 Tungsol RI 12ax7, V2 Penta Labs 9th Gen 12ax7, V3 Sovtec 12ax7 LPS.
In the preamp tube section I have added in V1 the TAD 7025 HighGrade. This is a smooth creamy sounding tube. I think an excellant choice.
My favourites are NOS or ANOS RCA, Mullards! Harder to find but worth it!

Power Amp Tube Info

>JJ 6L6GC: most popular among VK users. Clear, tight bass response, open, late breakup.

(credit Cap47)
I have had the ability to A/B 6L6WXT+ against the TAD 6L6WGC-STR in the power section. The TADS have noticable clarity and overall sound definition. The WXT+ is good sounding but lacks the clarity versus the TAD

Power Tubes are usually Ruby 6L6GC MSTR in the stock unit and are fixed biased. However, they are non-adjustable fixed so you can swap without rebiasing the amp (see Amp Mods-Electronics) if you match exactly to factory setting and order 'matched' tubes. JJ 6L6s are popular with VKr's as well as other amps. See above for links to US tube distributors. These are 8 pin tubes with Pins 1 and 6 being blank so there is a total of 6 actual pins. They match up with the numbering scheme printed on tube socket as well as tube itself.

credit MrCarrot - "Well the schematic tells me it's a non-adjustable fixed bias. So it's just change tubes and play. Just as if it were cathode bias. Cathode bias means at an incredibly basic level non-adjustable bias designed for one tube type, ergo you just plug the new ones in with no worries at all, no rebiasing. Essentially the valveking is set up to be the same. No bias pot that I can see."

It other words, you would have to have it modded to add a bias pot in so that a biasing tool could be used. My Ruby's btw were matched at 44 mAmps. At least that is what is written on the
It is not necessary to unscrew the tube clamps, depress them to loosen grip. Screws should definitely be tight when inserting so board does not flex and crack! cap47
There are 2 screws for each power tube. One in front and one in back. The one in back is the trickiest because you can't really see it. I recommend 6" magnetic phillips with a rubberized handle. You kind of pull the tube out slowly while unscrewing. Otherwise, just unscrew all the way. Then you can giggle/pull tube right out. *There is a trick to putting new power tube back in but you'll have to search and ask* Basically, there is not a lot of support behind these sockets and they get depressed when you try to put new tube in. Don't remove the screws in the 1st place. You have to play with the tube screw brackets, (No you don't) the holes, and the screw to get everthing to catch and screw back in nicely. MAKE SURE your power tube is seated all the way in. If you can see the pins you may not have it down all the way. Clamps will naturally spring open while inserting tube and depressing clamps.

Notes on Combos
--The combo of V1 Tungsol, V2-3 5751 is harsh on the high end and quite bright

Troubleshooting Possible Microphonic Preamp Tubes (credit Cap47)

First thing to do is to re-seat all the tubes. Connections can cause this too! Then check all yor guitar cables and any cabinet cables and EFX cables. How old is the amp? How often is it used? If this amp has had a lot of use it could be power tube getting iffy. I had a bad preamp tube do this too on my VK 112. The thing to do is get a few good preamp tubes to try. Starting at V1 then V2 then V3 trying in each to see if it makes a difference. If none of the preamp tubes makes a difference then get a new matched set of power tubes. Sometimes even cleaning the jacks with contact cleaner helps get the crud out so your cables make better contact. So it isn't so simple but if you work thru the cheaper items first you may find it isn't a tube. I hope this is of help to you.

Tubes can fail anytime. Some have failed out of the box. As far as which ones are right for you I can point you to a tube review has good reviews on power tubes. The ones I like are probably not right for your style music. So do a little research before you buy. I have a 112 and I play country music. I don't require the breakup. They will give you a lot of info on their site. You will have to find a dealer in Europe that you can get tubes from or somewhere local to you. For preamp I would suggest V1 either a 12at7 or a Tungsol RI 12ax7. For V2 I like the Penta Labs 9th Gen 12ax7. V3 I suggest a Sovtek 12ax7 LPS. Works for a wide range.

Problems credit rakoro)

The power would come on, with no tubes lighting up, and i found out it was a problem with a heater circuit in the power amp section, apparently its a pretty common design flaw in Valvekings, so keep that in mind if yours ever does the same. (credit cap47) ^^The common design flaw is probably a fuse connected to the heaters. Since when is a fuse a design flaw? Usually a fuse protects the circuit so to say it is a flaw doesn't make sense. It just takes a little time to get it out of the cabinet and change it. When fuses or resistors are affected usually a bad power tube is the reason. If the same power tubes are still in there you could have more problems shortly.

NOS (new old stock) Tubes

NOS tubes are considered the best tubes, but come with a hefty price.
Cap47 is the only UGer to have experimented with a full-NOS setup.


credit Giordano Boschetti - giobos

After trying many configurations, I found the best solution here:

V1: TungSol Reissue 12ax7

V2: Chinese 12AX7B

V3: SovtekLPS (or JJ 12AX7 as a second choice)

Power tubes: Sovtek WXT +

If you want to improve the distorted at the expense of cleaning, reverse the tungsol with the Chinese, more midrange from v1, more push.
with tungsol in v2 in combination with china on v1, you get a more linear distortion, roar and liquid, but on clean, the Chinese tube, goes first in the breakup.



This wiki has my Valve King 112 rocking out pro style!
Thanks to all for the suggestions in this wiki and here are my additions/comments/mods
- - - -
The dummy jack in input 1 and the effects loop trick are spot on.
I upgraded tubes(very easy tube change on this amp easy access to all tubes) for the preamp tubes just press down and twist of the nice little tube protectors to expose the tube and give em a good yank to get them out. Pay close attention to the orientation of the pins when you remove them, you want your replacement tube pins to line up the same as your stock EH 12AX7's when you put them in.
My modifications:
-V1, V3 Tung Sol reissue 12AX7
-V2 vintage bugle boy 12AX7 ( had also experimented with a vintage Ampex 12AT7 in V2, also good would be excellent for country or clean blues)
The change out of the preamp tubes transformed the amp dramatically, it now has extremely high end pro tone, actually quite amazing. She whispers and breathes just like a blackface Fender!
-A month later 6L6GC JJ's matched duet replaced the Ruby's, very minor difference in tone here, the Ruby's actually were quite good. The tone is transformed by the preamp tubes. Spend your dough on those. Just buy a set of backup power tubes so you're not stranded on stage....the stock Ruby's are fine, at least mine were. If you need to pull your power tubes remove the protection cage carefully so as not to break the tubes. Not difficult just have a good small Phillips head ready to go and take your time. Once the cage is removed a firm steady grip on the tubes after gently spreading the retainers results in an easy pull. Of course you have pulled the power cord out of the back and let the amp cool down right?
I have to say once I flipped this amp upside down and went to work on the tubes I was shocked at the workmanship in this amp. Not a sharp edge to be found, everything where it should be with easy access to the tubes. Nice! This thing is a working musician's dreamboat, cheap, well made, bombproof and now killer tone! I have run all of my guitars through this amp setup and they all sound killer. 69 Gibson Les Paul Deluxe (with a PRS Dragon humbucker in bridge position) 57 Fender Stratocaster, 62 Fender Fullerton Reissue Stratocaster and Mexican 50's Telecaster with Noiseless Fender pups and Clapton boost. All sing like they should and sound excellent in the hot rodded Valve King. The single coil guitars really sparkle and chime.
- - - - - - - - - - - - -
Moral of the story:
Get a sweet vintage tube for V2 and the Tung Sol reissue are excellent in V1, V3. Try vintage high end tubes in V2 easily available and not too expensive. In the gain channel the transformation is mind blowing. The stock EH tubes IMHO are absolute junk, at least in this amp. I threw them away.
My Valve King now has world class pro tone.....and I have been the proud owner of many vintage Fender amps. I was ready to junk it but thanks to this wiki it is truly gig/stage worthy.
Also I have a 1x12 Cabinet (actually a 30 Laney amp with the amp removed = perfect ha ha ) with a vintage Jensen Special Design 8 ohm 12" speaker installed. No problem at all running this out of the external out jack (which of course as you know kills the power to the on board stock speaker. I have tested this at loud volumes and it sounds amazing.
Next project of course is to replace the stock Peavey speaker. Any suggestions which will produce tone close to what I get with the vintage Jensen will be appreciated.

Thanks again Peavey fans!


Back again my mods are done....chose a Eminence Red Coat Governor for speaker change sounds sick! Love it!
The speaker change inspired me to tweak tube arrangement just a bit more and here is where I am at....

V1 Inserted the Amperex Bugle Boy 12AX7 (vintage) much fatter more tweedlike tone in clean channel...with the Governor things are poppin" there!
V2 back to the 12AT7 this time a vintage Phillips (UK) plenty of gain, a bit more articulate I would describe..."crunchy"
V3 Tung Sol 12AX7 reissue