100-200w Valve Junior

[WintersHarvest]

Hey guys, as far as explanation goes, I'm going to paste my introduction from another thread below.

"Hey guys, what's up? New to the board. I'm a 21 yo from Oklahoma. I play in a stoner metal band and I'm into big rigs and lots of fuzz. Currently running a Verellen Loucks 100w head and an Emperor 6x12 cab. Really into the boutique amp scene right now and wanted to get my foot in the door build wise. I usually run my Verellen flat and control my tone with my fuzz pedals and guitar. Sometimes I run out of headroom onstage so I've been looking at other options. I recently bought a Valve Jr. for my mini home rig and LOVED the way it took my fuzz pedals. This got me thinking about builds and I really want to build a 200w(ish. Doesn't necessarily need to be 200w. Just more headroom than 100w EL34) single volume amp head. Disclaimer: I have lots of experience with soldering and guitar electronics and took a digital electronics course in high school, but have very limited knowledge when it comes to amp building. I decided to put this here instead of starting an amp build thread and totally floundering. I figured this build is a bit out of my reach right now, but maybe if I get involved with the community or start a suggested smaller build then I'll be able to tackle it eventually. Is there a similar kit out there now? I like the sound of KT88's. I searched, but found nothing. Is this as simple as taking a Valve Jr. Circuit and using bigger components? Or maybe taking something like a Thunderverb 200 or an SVT and stripping all of the tone circuits? Like I said, total newbie. Just looking for a place to start digging in. Thank you!"

Like I said, I'm an infant when it comes to the build side of the amp community. I'll try my best to research and understand. I appreciate all the warm welcomes and I'm very excited to get involved! I've posted a standard Valve Jr. Schematic with this. The amp doesn't necessarily have to be a valve Jr. either. Just something incredibly simple (1 Vol, maaaaaybe 1 tone).

[kagliostro]

Doug has what you need

look to  Hoffman 5E1-5F1 Tweed Champ or Hoffman 5F2A Princeton

http://el34world.com/schematics.htm

Franco

[SILVERGUN]

...Currently running a Verellen Loucks 100w head and an Emperor 6x12 cab...
..Sometimes I run out of headroom onstage
 
 
My 2 cents...
Build a Marshall Major.
There is one super creepy guy here who obsesses about how great his amp sounds and how none of us mere mortals will ever know how it feels to push a quad of KT88s 
Sure, you can strip the tone controls out if you have to (with some adjustments)...or just modify them to fit your needs.
 
You won't know until you know.
 
Something like this...
http://el34world.com/charts/Schematics/files/marshall/Marshall_major_1967u_lead_200w.pdf

[HotBluePlates]

... look to  Hoffman 5E1-5F1 Tweed Champ or Hoffman 5F2A Princeton

And this is a good first project, but won't give you much different than what you have now with the Valve Jr.

... Currently running a ... 100w head and an Emperor 6x12 cab. ... Sometimes I run out of headroom onstage ... I really want to build a 200w(ish. Doesn't necessarily need to be 200w. Just more headroom than 100w EL34) single volume amp head. ... Is this as simple as taking a Valve Jr. Circuit and using bigger components? Or maybe taking something like a Thunderverb 200 or an SVT and stripping all of the tone circuits? ...

Push-pull will be mandatory, unless you like working around 1.5-2 kilovolts (and likely using large, obscure transmitting tubes).

The fastest path would be to simply buy a Fender Super Twin or similar, then tinker the preamp to sound like you want.  It might also be cheaper than building a ~200w tube amp from scratch.

Or a solid state power amp (probably marketed for bass/PA use) with a standalone tube preamp between pedals & power amp.

[WintersHarvest]

What about this guy?

https://www.tedweber.com/6s100-c-kt

Based on your experience, would this be too much for me to figure out? It's only $350ish if I don't order a cab or tubes. I have the tubes and can build a cab. This would satisfy my tasted for KT88's and maybe give me enough experience to build something of my own?

[SILVERGUN]

That looks like a decent build...not too-too difficult
It just won't get you much(if any, maybe less) more headroom than your 4- EL34 head.
 
Go for 4- KT88s and never think about headroom again  ....or not
 

[PRR]

> as simple as taking a Valve Jr. Circuit and using bigger components?

Like I can re-build a MX5 Miata with bigger parts and get a 40-ton gravel truck. Engine, gears, tires-- yup yup yup.

But: pep? economy? handling? All VERY different. Also the scale-up leads to some very awkward parts. Cars and trucks DO have "the same background", a 1920 Ford TT truck is a beefed Ford T car, but took very different paths to today's sport-cars and gravel-trucks.

A "200W Valve Jr" is a 5W Jr and a mike into a 200W PA system. That's how almost everybody does it now. Neil Young uses a 17W DeLuxe into 30,000W stadium PA. The days of The Who lugging 400-Watt guitar amps because stadium PA sucked are (should be) long behind us.

> something incredibly simple

A 200 Watt amp (tube or transistor) is NOT a simple build. A one-tube power section is so inefficient that 200W is really "stupid". Two tubes makes it more efficient, but 200W in two tubes means very high voltage, complex power supply, custom transformers (because nobody does it this way), and much risk of death. 4 to 8 tubes is a more manageable build, but not "simple".

The gain/tone networks can be reduced, of course. That does not get you near the Jr's level of simplicity.

Buy a 5150 or SVT, and figure how to skip the stages you do not need. They throw in all that "extra" because when you have paid for the Power Section, little stages add little cost and more knobs looks spiffier on the showroom floor.

> What about this guy?

Yeah, easy enuff to skip the second stage and tone-stage. Number and purpose of gain-stages is similar to Champ or Jr.

Not to argue with the Weber organization, but they seem to be running the KT-88s at an extreme condition. Peak plate current must be extremely high into the very low 1.9K per pair loading. This may not "sound like" other KT88 amps you have heard. Of course if it sounded like crap they would not have brought it to market. It may be hard on the KT88s. Frankly I would do the same but with four EL34, a known-good loading.

[SILVERGUN]

A little off topic....but
One other option is to run 2 amps all the time.
Keep your 100 watter and build or buy something that sounds somewhat different and run em side by side.
 
Lots of pros do this all the time and when I tried it I was very pleasantly surprised with how my 2 choices really filled each other out and gave me a "wall of tone"
You "could" split the speaker wiring in your 6x12 cab and have both heads going through the same cab, as long as you can make the split impedance match up to your 2 heads speaker outs.
 
I would honestly suggest this to anyone who is looking for more 'headroom' and my few friends who tried my dual head rig were shocked by the fullness. It's very cool to be able to hear the one amp alone and then flick the standby on the other and hear the combined "wall".
 
In your situation and with what you've told us, I'm quite sure that this method would yield positive results.

[Ritchie200]

My 2 cents...
Build a Marshall Major.
There is one super creepy guy here who obsesses about how great his amp sounds and how none of us mere mortals will ever know how it feels to push a quad of KT88s 
Sure, you can strip the tone controls out if you have to (with some adjustments)...or just modify them to fit your needs.
 
You won't know until you know.
 
Something like this...
http://el34world.com/charts/Schematics/files/marshall/Marshall_major_1967u_lead_200w.pdf

Gosh SG, Tubenit's creepy but not super creepy! It hard to get past that tele thing tho....


I thought the Major build would be good for him as well - especially the two tube version as the iron cost would be reasonable and now it's a proven design. I do like the idea of two different rigs. Maybe that and another cab will move enough air to satisfy the headroom requirement.


jim

[HotBluePlates]

... There is one super creepy guy here who obsesses about how great his amp sounds and how none of us mere mortals will ever know how it feels to push a quad of KT88s  ...

Gosh SG, Tubenit's creepy but not super creepy! ...

But Tubenit is right that I'm too cheap to buy 4x KT88's. 

Anyway, it's those "Jim" guys ya gotta watch out for...

[WintersHarvest]

Sorry for the long reply guys, finals week. 

Silvergun & Ritchie200
I like the idea of the Marshall Major! That sounds like something I could get behind. Is there a bill of materials or a walkthrough on this forum? As far as running two amps, I have ABY'd my Verellen rig with an OR50 with a fullstack underneath. But that's so much to lug around I decided I'd live with the breakup.

PRR
Thanks for the dose of realism. In my head I thought it was just going to be a super simple conversion thing. After reading your response I think I would rather get behind the Marshall Major build.

As

[SILVERGUN]

Silvergun & Ritchie200
I like the idea of the Marshall Major! That sounds like something I could get behind. Is there a bill of materials or a walkthrough on this forum?

I don't know of a BOM or build guide for one of these, but you never know.
You'll have to search around and keep asking questions.
I made the suggestion because I truly believe that "IF" you are capable of building a reliable and solid Major, it will solve your dilemma.
**None of us started out building anything close to this much of a beast. You would have to do a lot of reading and commit to building the power supply of this amp as if you were building the space shuttle...because this thing can kill you!
 

PRR
Thanks for the dose of realism. In my head I thought it was just going to be a super simple conversion thing. After reading your response I think I would rather get behind the Marshall Major build.

PRR (and all of these talented, super intelligent, supportive contributors) will support your dream of being an amp builder and at times will try to talk some sense into you, based on decades of experience.
Having watched thousands of budding amp builders come and go and spending countless hours of their time providing invaluable advice, they know, all too well, every detail of how you will or wont succeed.
 
Make it a habit to listen hard to the advice you are given.
The first point to consider in a 4 - KT88 build is "where do I get the transformers and how much are they?"
That alone will give you an idea into the investment necessary to complete this project.
 
If you are lucky enough to be able to use a pre-punched chassis, that alone will save you weeks/months of planning the chassis layout and trying to punch out all of the holes and figure out where everything will go.
 
COPY EVERYTHING YOU CAN....do not try to outsmart the masses who have come before you.
Take a look at any 100 watt Marshall build/guide and you will see the path.
 
Here's a pre-punched chassis that is currently available on Ebay for a Marshall 100 watt amp:
http://www.ebay.com/itm/MODIFIED-100-watt-plexi-style-Tube-Amp-Chassis-/322306278699?hash=item4b0af3852b:g:K7sAAOSwB09YD9be
I'm not sure that the spacing on the power tube sockets, and their relation to the capacitor holes is going to be suitable for running the BIG KT88 bottles. (they need more space than EL34s)
I'm also doubtful that any transformers you find will be able to fit on here either.
 
One nice thing about building this amp almost 50 years after it's inception is that you can get some beefed up filter caps for a decent price. I would make it a point to use larger than stock caps in the power supply as this will provide you with a very stiff and stoner-bass competent amp....there are a ton of other tips you will get along the way.
The best tip I can give you is: Only you know if you can do this
 

[Ritchie200]

SG, I was thinking about the two KT88 mini major that Tubenit came up with in the original Major thread - the one that was suspiciously built on another site and called his own....  Anyway, now it's a proven design. Yeah it's not a champ but still relatively simple.


Jim

[silverfox]

Did a quick search using duckduckgo: "marshall major build schematic"

Of particular interest is the one that indicates a B+ 750V and a paraphrase Base Treble control. This is discussed on the Music Electronics Forum site I found the links below on. In several ways this could be a killer amp. Amp Archives, (one of the links below),  has some images that seem to indicate the actual main board build could be fairly straight forward.

http://music-electronics-forum.com/t17556/

 http://dawkmods.proboards.com/thread/988
 http://s67.photobucket.com/user/supe...RSHALL%20PA200
 http://s67.photobucket.com/user/superchouf/library/PA?
 http://s67.photobucket.com/user/supe...view=slideshow
 http://vintageamps.com/plexiboard/vi...hp?f=1&t=64211
 http://webschem.free.fr/Marshall-Major-PA-PIG.png
 http://webschem.free.fr/xmjwul2t.png
 http://www.amparchives.com/album/Mar...Pig/index.html
 http://www.electricalaudio.com/phpBB...?f=5&p=1814891
 http://www.guitariste.com/forums/amp...67,399858.html
 http://www.guitariste.com/forums/amp...67,399739.html
 http://www.marshallforum.com/lets-ta...-watt-pig.html
 http://www.projetg5.com/phpbb3/viewt...hp?f=25&t=3429
 http://www.rig-talk.com/forum/viewtopic.php?f=3&t=71216
 https://www.facebook.com/media/set/?...9943319&type=3
 https://www.facebook.com/media/set/?...2866916&type=3
 https://www.facebook.com/photo.php?p...d=393694291916
 ! No longer available
 
silverfox.

[SILVERGUN]

SG, I was thinking about the two KT88 mini major that Tubenit came up with in the original Major thread - the one that was suspiciously built on another site and called his own....  Anyway, now it's a proven design. Yeah it's not a champ but still relatively simple.

I get it, Brah...I'm just not sure that a 100watter with 2 KT88s is gonna be a huge headroom improvement over a 100watter with 4 EL34s
 
 
My personal opinion is still 100% that it would be in his best interest to run 2 heads together.
Reasons:
1) If 1 head goes down (and all tube amps eventually will) your still left with an operational head and the show goes on
2) Its much easier to cover the tonal spectrum with 2 amps going together than with 1 amp trying to do it all
3) Building a huge amp is a huge, expensive undertaking and requires more skill than most newbies possess
4) I don't want him to make you happy by building a Major
5) But I kinda agree with you, that if he 'just has to' build his next amp, he can probably get away with the 2 x 88 Major of which you speak, if used in conjunction with his current head. That would make for an incredible wall of sound.
6) 2 heads is better than 1
7) If I was 21 again and knew what I know now, and was into the music that he's into, and needed more headroom, it's exactly what I would do without hesitation. I'd also rewire that 6x12 cab so that it was all the speakers I would need .(maybe even beef up a pair to accent the 2nd head)
 
Here's an example of a power transformer that would be "kinda acceptable" (lower B+ than stock amp) to give you an idea of the price/size/weight: (for the 4 x KT88 build)
http://www.mouser.com/ProductDetail/Hammond-Manufacturing/373HX/?qs=qHByVky%2FdAFYc7WAc7TN%252bg%3D%3D
 
I would be half tempted to search for a 120 pri. x 480V sec. xfmr, and just run a separate filament xfmr.(although...nobody needs 670V B+)
But that's just me being me.

[SILVERGUN]

Just for the record....
I've still got one of these laying around here in an SKB case, like I'm preserving it to fight off the zombies.
2 x 95 watts with 8 total power tubes.
So yes, at one point in my life I thought I was going to have to be louder than a passing freight train.
And, yes, I do remember what it's like to be stoned and think your not loud enough, even thought the sound man has asked you multiple times to turn down and has simply removed you from the house mix.
 
Would sell to any stoner-rocker in need of 'more headroom':

[BetterOffShred]

I started reading this at work, while listening to "The Sword" (Age of winters), and the blonde guy uses a "Big Crunch One-knob" amp, which from what I can tell is basically a 50W bassman with the tone controls stripped out of it and that's all.   http://bigcrunchamprepair.com/custom   and as others have mentioned, the sound guy is going to turn you down in the mix anyway!   I have a bassman and it handles fuzz like a champ through my 4x12, and I'm willing to bet you could get away with way less iron than 100w ..  I have a Triple Rec I bought and played from 2003-2010 when I was doing metal, and let me tell you I much prefer the bassman! The triple weighs about 2 million pounds, and the bassman is deafening anyway turned all the way up, though its not going to pull the shred the Rec does, ever.

I like the suggestion of getting a Super Twin or something and starting to tweak it.  You're going to pound the front end with fuzz anyway.

As a novice amp "builder" myself, I highly recommend starting with tweaking something that is documented and readily available while you learn about how it all works, and then once you've gotten some of that under your belt you can dive into figuring out what may be your Dream Amp, and then go be successful at building it.  I'm still working on my dream amp, but the Bassman is pretty close.   
Good luck 
-Brett