Hotrock Posted January 12, 2004 Report Share Posted January 12, 2004 Alright guys. I'm just doing a bit more research on amp building. I've looked at the past thread (on page 5 of the electronics section). Just wondering if anyone else has had any look and could tell me where to buy stuff from. I've got a few links if anyone is interested. I preferably would like to build a valve amp thats not too powerfull (I'm really not good enough for other people to hear), think about 5 watts should be fine. Everything I find is very very expensive. Anyone got any ideas? Quote Link to comment Share on other sites More sharing options...
jbkim Posted January 12, 2004 Report Share Posted January 12, 2004 Yeah, it's the general consensus that it is pretty expensive to do it yourself. There's also an even older thread here where feylya and his(her?) dad could probably do it cheaper than buying one. Perhaps ask here or PM feylya about it? Quote Link to comment Share on other sites More sharing options...
fidgec94 Posted January 12, 2004 Report Share Posted January 12, 2004 I dont know how much of this relevant, take from it what you will: Ive considered building an amp (a small 5-10w one like yourself), i even have a stripped Marshall 15w amp that i was gonna use for a cab. Nearly a year on, its still gathering dust Is it the transformers that you find expensive? I noticed that many self-builders use hammond transformers that have really specific uses. I became discourage quite quickly at the thought of importing loadsa stuff from the US. Although there were a couple on ebay evey now and again. I noticed that ppl were selling old valve amps on ebay, they would be good for parts and not to expensive as most being sold on there were broken or needed an over-haul. You might get lucky with a suitable tranformer there. I guess the really big caps are expensive Caps, resistors, pots and switches can all be obtained from maplin, i think they're quite reasonably priced. My top tip is the local tv repair shop, the bloke in my home town has all manner of crap lying around! Wiring will be cheaper if PCB's arent used, i dont really know all the different types of boards, but a popular method was litterally wires only. I guess an expensive part would be to buy a pre-made metal enclosure for the actual guts of the beast. I had a good tutorial for making one outta an old computer case (i'll have a look for it if you want), thats quite cost effective. All you gotta do then is fashion a cab out of some MDF and whack some vinyl over the top, cloth material for the grille (from ebay) and roberts you mother's brother Make your own cab or try and find one on ebay, or even an old crappy amp that you can gut yourself. The cab i have is a Marshall MG15DFX, just the cab and speaker. Example of stuff on ebay This isn't a bad site Another good 'un Quote Link to comment Share on other sites More sharing options...
Hotrock Posted January 12, 2004 Author Report Share Posted January 12, 2004 Yeah, it's looking expensive. Veeeerrrrrrry expensive . Might build something solid state instead. Luckily I used to live with a few Electrical Engineers so I might get them to nick as many parts as possible from work (they owe me a favour or two). Gotta build my pickups first, but wanted to build an amp to match the new guitar (and guitar case). Quote Link to comment Share on other sites More sharing options...
Hotrock Posted January 12, 2004 Author Report Share Posted January 12, 2004 Yeah, I'd make my own cab and the metal chassis won't be a problem (another mate that owes me a favour). I wanted to build my own mainly for the funky design of cab that I've got bouncing around my head. I really want to build everything I can: guitar, case amp and a few effects pedels just for that warm fuzzy feeling when I'm playing it. Quote Link to comment Share on other sites More sharing options...
fidgec94 Posted January 12, 2004 Report Share Posted January 12, 2004 Solid state would be sooooooooooooooooooo much easier, no need for expensive and heavy transformers and there are millions of schematics out there for them. I will complete my project one day! Quote Link to comment Share on other sites More sharing options...
fidgec94 Posted January 12, 2004 Report Share Posted January 12, 2004 Main problems i found is when it comes to combining modules. I'd find a good preamp by itself but not know how to tie it with a power amp from a different source (i can do basic electronics but i wouldnt know how to make sure the modules match properly with regards to resistance, current etc) Quote Link to comment Share on other sites More sharing options...
Hotrock Posted January 12, 2004 Author Report Share Posted January 12, 2004 mmmm. good point. I'm not the person to be asking. Quote Link to comment Share on other sites More sharing options...
JohnnyG Posted January 12, 2004 Report Share Posted January 12, 2004 Atm in my room here at school i have 2 old dead bass amps sitting around that i got off one of the music teachers i know well. they both have metal chassis, cabs, transformers, pots, everything. im planning on building an amp outta one of them at some point tho i need to work out which tags on the transformers are which voltage lol. tbh atm what id really like is just a very simple valve amp (single valve pre amp and Class A single valve power amp output). it wouldnt have any overdrive/gain settings, would be designed so that on its own the amp just gave a very nice clean sound and it wouldnt have any EQ setings. the reason for this is 3 fold 1 Distortion would be provided by my Jackhammer overdrive pedal so having overdrive on the amp as well would be a little sillah. 2 EQ settings are gonna be taken care of when i get my Big Fat Homemade MultiFX rack sorted out. its gradually making it down on top paper, plan is to have Sustain, Delay, Reverb (done with a slinky spring reverb tank), a Treble Booster and an EQ 3 Less stuff needed for amp means cheaper. since i already have alot of the stuff it shouldnt be too hard tho i need to work out how to design valve amps properlly lol. solid state amps are cheaper to build tho you actually need a bit more current know how to do them.... basically quite a few valve amps have a power amp section that has only one valve in it (Called a Class A Amplifier). this means that the entire signal goes through the one valve. the drawback of these is that they're not very efficient. about %60 to %80 of the power that goes into it is given off as heat from the valve. solid state amps that use mosfets to amplify the signal have 2 mosfets in them. they work by having one mosfet amplify the positive portion of the signal and the other amplify the negative portion of the signal (these are called AB amplifiers. Some valve amps are like this as well) the pro of having the 2 mosfets is that the amps are much much more efficient, about %80 upwards. the drawback (and this is where you actually need to know about what ur doing) is that you have to bias them to get rid of crossover distortion. this is caused when the signal being fed in isnt actually large enough to get the mosfets to work (they need to have about +- 0.5 of a volt across them to get them to turn on basically when this happens the mosfets turn off each time the signal dips across the positive/negative boundry and so creates nasty distortion. to get around this you have to bias them by making surethey always have a small DC voltage across them to keep them on. getting it right requires knowing what ur doing there's some of my thoughts on it. tbh it would probablly be easier to build a valve amp however it would be more expensive. what it comes down to is how deep ur wallet is and how confident you are about learning some fairlly advanced analogue electronics off the internet. btw sry if some of this seems condescending to people who already know about it or its a bit totechnical for people who dont. please feel free to ask or abuse Quote Link to comment Share on other sites More sharing options...
Hotrock Posted January 13, 2004 Author Report Share Posted January 13, 2004 Not condesending at all mate. I've always found electronics (and electrics for that matter) a bit of a black art. Infact I'm fairly useless at it. Luckily enough though my electrical engineering geezer came round last night and we bored the missus talking about amps. He plays guitar too and is going to look into it. Also trying to convince him to make some effects pedels. I'll keep you posted (if you're interested as to progress), he's in the middle of exams at the minute so it might take a few weeks though. Quote Link to comment Share on other sites More sharing options...
fidgec94 Posted January 13, 2004 Report Share Posted January 13, 2004 I know this seems obvious but just thought i i'd mention this for anyone planning to work on a valve amp for the first time: Trannys in valve amps can produce a B+ in excess of 400v. Another hazard is accidently touching the contacts on a cap, the big ones can easily be storing 400v as well. Receiving a dose that high can be fatal. Hotrock, im certainly interested in any headway you make - let us know Quote Link to comment Share on other sites More sharing options...
JohnnyG Posted January 13, 2004 Report Share Posted January 13, 2004 Mains voltage is scary, this is why i havnt built any amps yet lol. if you can get ur EE friend on the case hotrock then please chuck any info from him this way lol. the only reason i understand electronics well is because ive done school courses and i also research guitar electronics and FX designing in my spare time (yes...i honestlly am that sad ) FX circuits are not too hard to get ur head round in general tho alot of it can be very tricky Quote Link to comment Share on other sites More sharing options...
fidgec94 Posted January 13, 2004 Report Share Posted January 13, 2004 the only reason i understand electronics well is because ive done school courses and i also research guitar electronics and FX designing in my spare time (yes...i honestlly am that sad ) FX circuits are not too hard to get ur head round in general tho alot of it can be very tricky Same here dude, i did GCSE electronics (but forgotton alot of it now). I still take an interest and look for stuff like schematics that are of interest. I have loads of sites and info ive gathered, sheesh what a geek! One day i will put it all to use and i WILL 1.Build an amp 2.Build some effects 3.Most importantly, build a splitter so i can use it all!! Quote Link to comment Share on other sites More sharing options...
JohnnyG Posted January 13, 2004 Report Share Posted January 13, 2004 LOLOL mkay this is amusing Im actually currentlly doing AS leccytronics and this term we're doing our project work, building and designing circuits etc etc. my initial idea was just do make a small amplifier to run a pair of speakers off my minidisc player. however after my teacher spoke to the head examiner about all of our projects and he was told that itd be alot better for me to just build a guitar amp lol so thats what im now doing. admitadlly its only gonna be an 18 volt solid state jobby but its still an excuse to play about with it lol. if youguys want i'll put stuff up here as i go. Quote Link to comment Share on other sites More sharing options...
fidgec94 Posted January 13, 2004 Report Share Posted January 13, 2004 if youguys want i'll put stuff up here as i go. if you woudnt mind Quote Link to comment Share on other sites More sharing options...
Hotrock Posted January 13, 2004 Author Report Share Posted January 13, 2004 Yes please dude. Quote Link to comment Share on other sites More sharing options...
JohnnyG Posted January 13, 2004 Report Share Posted January 13, 2004 fair enough guys. as i do bits of my coursework ill post them up here/ bear in mind that not all of it will actually be useful (testing the ting ot see if it fits in with my original spec) and that it wont be an amazing amp since its only gonna be working off 18 volts lol and will have just a pre amp and power amp Quote Link to comment Share on other sites More sharing options...
ansil Posted January 30, 2004 Report Share Posted January 30, 2004 Alright guys. I'm just doing a bit more research on amp building. I've looked at the past thread (on page 5 of the electronics section). Just wondering if anyone else has had any look and could tell me where to buy stuff from. I've got a few links if anyone is interested. I preferably would like to build a valve amp thats not too powerfull (I'm really not good enough for other people to hear), think about 5 watts should be fine. Everything I find is very very expensive. Anyone got any ideas? how much voltage do you need i have high voltage caps and 1/2 watt resistors in nearly every value. i also have a slavaged output transformer from an antique radio that was tube, and it had a 7 watt fender style tube in it. also have some input transformers. i have a 1:1 input transformer that you can step up the voltage too. or you can use two ratshack 120:12.6v transformers take the secondary filiment voltage off of the first transformer and wire in a reverse transformer to the first one.. ie (instead fo the 120:12.6 it would be 12.6:120v side.) and soem 1n4007 diodes. high voltage powersupply caps..??? most of the stuff i have is salvaged so i am cheap. Quote Link to comment Share on other sites More sharing options...
Hotrock Posted January 30, 2004 Author Report Share Posted January 30, 2004 Cheers dude. Only in the initial stages of research but there's a good chance I might need some of what you've got. Cheers for the offer mate, I'll be in touch. I'm in the UK by the way so shipping might be a problem Cheers anyway dude. Quote Link to comment Share on other sites More sharing options...
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