#1
So heres the story.
Got some cracking news today, for my A2 course, i can build what ever the hell i want.
My initial thought was a guitar, but as i'm already working on my Kaoss Tele at home, i thought i'd go for an amp.
This will be a head and cab build. The cab will be a standard 4x12"

But i wanted to hear some thoughts on the head.
My idea is to have a number of preamps, minimum of two, all switchable between via footswitch and amp. I may be put 3 in. And maybe also, more than one power amp? again all switchable.

The idea behind this, is that i want to be able to quite possibly build the most versitile amp ever, but obviously it won't be one single amp, it will just be a number of them in one enclosure. Almost like a racksetup in an enclosure.

My questions with this are:
- Is it possible to have more than one power amp? or is there any point, as i've seen amps with more than one pre-amp, but never more than one power amp.
- Can anyone reccomend some pre-amps/power amps that i could copy? i may modify them slightly.

Sort of sounds i'm after are like JCM800, Mesa etc, so i will be looking into those schematics.

Just to let you know, i do have soldering experience, and there will always be an electrician in the room, but he is limited to what he can help me with as this is supposed to be a project done entirely by the student, which is why i'm asking for this help here, also, he's not a guitarist so amps are not his area of expertise in what sounds like what, what modifications to do etc, so i'm sure i will be asking those questions later on


At the moment, i'm designing the exterior, as I'm required to have some evidence of me doing something, so i'm doing this bit first.
Plan is a standard looking cab, with a head ( as large as it will be, i know it'll be chunky ) which will be sort of pyramid shaped, the front will be of clear plexiglass, with mirrors on the interior wall, i will then leave the electrics exposed inside with some sort of lighting.


Yes, i know this is an ambitious task, but we have got a while to do this, and i'm not an expert on the technical terms, but i (kind of) know what i'm talking about aha.

So would be great if you could answer any questions i've asked, or express your opinions

This will be done along side my guitar build, so don't worry, thats not stopping
#2
Hey, i cant really help with the questions but it sounds like a hell of a good idea
I hope it goes well for you
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#3
Well i hope so, The general idea is that, due to the fact that i play a lot of styles and my tone is VERY important too me, i want to be able to have all the sounds i want in one box,
1. it will save money on buying 2-3 amps to get my acheived tone and
2. its a space saver and will be much simpler to set up at gigs etc

If i have time, i will also build a 2X12" for smaller gigs, Or if i happen to hit the big time baha
#4
I wouldn't go with more than 1 power amp. If you did then you would have to power those tubes and the current drawn by more than 1 poweramp would be huge and requier a very big power transformer. It would also require more than 1 output transformer, extra filtering and a beefed up rectofier. So basically, all the expensive parts of the amp would need to be doubled so why not just build 2 amps. A better option would be to use 6L6 output tubes (like early marshall and most American amps) and then add a pentode tetrode switch. In tetrode mode (sometimes wrongly called triode mode) your amp will sound more midrangy and british. In pentode mode it'll sound more like an American amp. Then you won't need 2 poweramps.

The preamps is where you can really mix and match. I've got a tweed style preamp on half of my bassman and a blackface style amp on the other side. The 2 chanels don't mix untill right before the phase inverter so they are pretty much independent and sound like 2 compleatly different amps.

schematics heaven is a great place to start looking at schematics. They have dual recto preamp schematics and JCM 800 schematics on there. I'd probably go with a JCM if you are still new at this because it's a much more basic amp.
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#5
Thanks again Courdroy
Just from doing slight more reading and from what you've said i will stick to one poweramp and have more than one pre-amp,

Think i will be deffinatly go for a JCM. its just deciding on what else i can put along side it to get a wider range of tone
#6
Right then, been going over **** loads of schematics. I'm going to go for 3 pre-amps, maybe 4 if i have time, but it may be getting a bit extreme there, but we shall see. And one power amp.

Pre-amps from:
- JCM 800
- Mesa Mk IV
- 5150
- As for a 4th if i do it, i'm want a very nice clean tone, so still after suggestions on that.

As for the power amp, i have no idea what to go for. I want something that will give me the most out of the power amps as i can, something which will handle nice cleans and heavy, powerful distortion. so suggestions there?
I'm thinking mesa, maybe the 5150 poweramp?

Thanks
Last edited by TomR at Jun 11, 2008,
#7
a fender Blackface preamp would be good for a fourth. Dude I don't know if you know but building an amp is no walk in the park especially a four channel tube beast that you are speaking of. Even for a fairly seasoned electrical engineer it is very hard to make a tube amp. Its not matter of just putting it together exactly the way it is on the schematic with all the parts there are a lot more things too take into account. Lots of things can go wrong if you don't have a tube amp specialist with you helping along the way, parts could blow when you first turn it on and in case you don't know parts for tube amps are very expensive especially transformers which can cost up to $250 a piece.
#9
Have fun with this build. I would seriously recommend against this build, the sheer complexity would keep you from getting it done. In my opinion, getting a simplistic working amplifier is a much better ending than having a bunch of components and no clue of what to do with them.

There are so many facets to what makes a specific amp sound like a specific amp. The number and type of tubes are just the tip of the iceberg, you would need to have certain voltages in certain points in the circuit, and certain values of components in filters and EQs need to be correct.

The circuitry will end up being incredibly complex just by itself, and that doesn't factor in the added and inevitable difficulty of something going wrong.
#10
^I kind of agree.

I think you are in a bit over your head on this one. There is more to an amp than just shoving everthing in a box and hooking it up in the right order. Little things like having a wire 1" too long can make a great sounding amp turning into a noisy monster that does nothing but squeal.

If you want to mix and match a few different preamps, try amps that are basically the same to begin with. A Marshal plexi and a tweed fender are basically the same except for tube biasing. Tube bias switches are easy to do so mixing those 2 amps could be a good option but I wouldn't start mixing peavy and mesa into things. That'll get way too complicated.

Once you understand a bit more about layout you will be able to tackel harder issues but until then it will be a good idea to only slightly modify the vintage layouts.
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#11
Hmmm think you might be right,
I know its more complicated than sticking a few things in,
Thing is i have got a tech on hand to help me with stuff, but i may make my plans a bit simpler just to give myself a simpler run, i can always do these plans at a later date once i've got a fair bit of 1st hand experience with amps.
The thing thats making me be ambitious is that we've been told in order to get top grades it HAS to be complex, but i might be going a bit further than that with these plans aha.

i'm required to do all the woodworking first, so can tackle this issue in more detail a bit further on.
As for the price that was mentioned, it will all be for educational purposes so everythings dirt cheap, which is why i'm trying to make the most of it.

But i will take what you've all said in, and slim it down, have to have a word with the tech 2morrow, its when all the official planning begins, all this has been off my own back up too now.

I think after reading what you've said and i've had a look at other amp build threads, It will most likely be an amp clone then, if i do have a fair bit of time left, look to adding another channel into the mix. But i shall see once i've spoke to the tech 2morrow, could come up with a whole other option

thanks for the input guys
#13
My honest opinion would be to order "The guitar amp handbook" by dave hunter.
http://www.amazon.com/Guitar-Amp-Handbook-Understanding-Amplifiers/dp/087930863X
I read this book before i built my amp and it taught me soooooo much. It is really a good guide to learning all the little things about tube amps and what each component does. It also goes over schematics of different and popular amps from fender to marshall to traynor and so on. It also has in the book a how to guide to build your own amp including the parts list and the steps. I would say this would be the first step if you really want to get an understanding of what you are up against. I built a jcm800 and the assembly was pretty easy but the trouble shooting is the tough part and if you dont know about certain little quirks you could be lost. Also check out these forums to learn even more: ppwatt.com, 18watt.com, ax84.com. there are a lot of knowledgable people there who can help as well.

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https://www.ultimate-guitar.com/forum/showthread.php?t=876434
Last edited by migs_migeezie at Jun 11, 2008,
#14
Quote by TomR
Hmmm think you might be right,
I know its more complicated than sticking a few things in,
Thing is i have got a tech on hand to help me with stuff, but i may make my plans a bit simpler just to give myself a simpler run, i can always do these plans at a later date once i've got a fair bit of 1st hand experience with amps.
The thing thats making me be ambitious is that we've been told in order to get top grades it HAS to be complex, but i might be going a bit further than that with these plans aha.

i'm required to do all the woodworking first, so can tackle this issue in more detail a bit further on.
As for the price that was mentioned, it will all be for educational purposes so everythings dirt cheap, which is why i'm trying to make the most of it.

But i will take what you've all said in, and slim it down, have to have a word with the tech 2morrow, its when all the official planning begins, all this has been off my own back up too now.

I think after reading what you've said and i've had a look at other amp build threads, It will most likely be an amp clone then, if i do have a fair bit of time left, look to adding another channel into the mix. But i shall see once i've spoke to the tech 2morrow, could come up with a whole other option

thanks for the input guys


The thing with amps is that even amps that look simple are very complex. I'm teaching my kids (9 and 10) how to build amps at the moment. So far we have spent an hr a day 3 days a week for 4 weeks going over a schematic for a champ. We have talked about voltage deviders, input impedance, the parts of the tubes, coupling caps, tube biasing, cathode resistor bypass caps, triode, tetrode, and pentodes, and we still haven't touched on transformers, rectifiers and voltages needed to run everything. We also haven't covered heater filiment or negative feedback. Anybody can slap something together but even a "simple" amp is very complex when you get into understanding why it was made the way it was.

If you want the amp to actually look complex then I'd suggest going with something like a tweed deluxe with switches to change the biase of the preamp tubes and a switch to change the 250pF cap to a 500pF cap. This will give you 20 watt marshal type tones and tweed fender tones all in one amp and the extra parts you need only cost a few quid and are easy to install but the variation in tone you will get will be quite impressive to your teacher. Adding a tetrode pentode switch will also be very simple and not take a lot of extra work. If you have a tech helping you then they will have no problem walking you through the whole thing.
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#15
migs_migeezie: I might order that book actually, give me more of an idea with what i'm dealing with. Thanks for the suggestion

Corduroy: I might consider that build, i'll have a more in depth look into it 2night.
I think, yes changing my mind again :p that i will be doing a classic marshall tone for sure, moving away from the High gain, as i've already got my Laney for that aha. something like the JCM, or maybe like you said, the marshall/fender tone.
The tech himself is not allowed to walk me through it, but can give me a fair bit of help.

I was panicking slightly earlier as we were told final designs of all parts, so therefore including diagrams, but turned out was a teacher error and it was just a rough specification, so its all good

So thanks again for the in depth help corduroy and all others that have suggested things.
#17
Cord; How sure are you that it should be called tetrode mode? All the datasheets for tubes I have EVER read designate it as triode mode, are you confident in that?
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#18
^the "triode" mode isn't realy a triode it's a tetrode. The datasheets lable it wrong.
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#19
i wanna build a tube amp too. But definitely not as complex as yours. i just want a basic one maybe two channel amp head with bass treble and mid knobs. and of course the volume knobs. other than that my distortion and stuff will come from pedals. i dont really have much knowledge in electronics and was wondering where i could get info/blueprints/step by step instructions on how to build it. i already have a cab but my current head isn't tube and it sound horrible. i dont have that much cash either.
#21
so here's da story all bout how, my lyf got flipped, turned upside dwn,
and eye'd lyk 2 take a minute, just sit ryt der, eye'll tell ya how eye bcame da prince of a twn called belair
In west philidelphia, born n raised, on da playground where eye spent most ov ma days,
chillin' out maxin' relaxin' out cool, shootin some ppl outside of da skl
When a couple of guyz hu were up 2 no gud, Started making trouble in ma naybahud,
Eye gt in 1 lil' fite an ma mam got scared n said 'ur moovin' wit yo aunty n uncle in belair'
Eye whistled 4 a cab and wen it came near, the liscence plate sed FRESH nd had a dice in da mirror, if nethin eye should say dat dis cab woz rare, but eye thought, nahhhhh 4get it, go home 2 belair.
Eye pulled up 2 da house bout 7 or 8 and yelled to da cabby yo homes smell ya later, eye looked at MEHHHHH kingdom n was finally der, now sit on ma thrown cus eye'm da prince of belair
#22
Quote by Mary_Huff_Luva1
so here's da story all bout how, my lyf got flipped, turned upside dwn,
and eye'd lyk 2 take a minute, just sit ryt der, eye'll tell ya how eye bcame da prince of a twn called belair
In west philidelphia, born n raised, on da playground where eye spent most ov ma days,
chillin' out maxin' relaxin' out cool, shootin some ppl outside of da skl
When a couple of guyz hu were up 2 no gud, Started making trouble in ma naybahud,
Eye gt in 1 lil' fite an ma mam got scared n said 'ur moovin' wit yo aunty n uncle in belair'
Eye whistled 4 a cab and wen it came near, the liscence plate sed FRESH nd had a dice in da mirror, if nethin eye should say dat dis cab woz rare, but eye thought, nahhhhh 4get it, go home 2 belair.
Eye pulled up 2 da house bout 7 or 8 and yelled to da cabby yo homes smell ya later, eye looked at MEHHHHH kingdom n was finally der, now sit on ma thrown cus eye'm da prince of belair



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#23
If you have never built an amp before I highly reccomend starting at low wattages.

Less complicated schematics and by building it you will gain the foundations of amp building.

What your describing sounds like building the effiel tower when your only qualified to build a dog house.

I'm in a college level electrical/electronics course and for my applied project I took the idea of building a JTM45 to my professor, and they basically outright said no. The high wattage can easily kill you, especially if you have little to non electrical training.

What you described sounds way to intense for a beginer let alone and intermediate amp builder.

Take the smaller wattage and build yourself a nice amp that will sound great!
Don't get too in over your head there.

*Damn, i just saw the post date.

Well, maybe this will help someone haha
Gibson Les Paul Classic w/Stetsbar
Fender MIM Strat w/ EMG DG20 System
Mesa Boogie Express 5:25
EHX Holy Grail
EHX Memory Boy
Maxon OD9
EHX Big Muff
Vox Wah
EHX POG
Last edited by statopaul_mark at Oct 21, 2008,
#24
^I'm not so sure you know what you're talking about. A 5 watt amp is just as capable of killing you as a 100w amp. It's not the wattage, it's the filter caps. The difference between 320v you'd get from a champ and the 350 you'd get from your JTM45 is minimal, and irrelevant. They'll both kill you. Sure, bigger amps have more filter caps, but if you're dumb enough to touch one it doesn't matter how many there are.