Making my own tube amp - photo essay

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bancika
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Hi,
Besides my guitar I'm also making tube amp (and soon I'll start making tubescreamer 808). I'd like to share few photos and expiriences with you guys.
First, I came across great site ax84.com with NO electronic knowledge nor expirience. Abaut the same time I got dissapointed by my new MG15DFX amp (shitty solid state marshall) so I began researching. Since I play only in my bedroom I need good tone at really low volumes do I decided to go with Firefly 1.5W all tube model from ax84.com.
After 2 months of reading I felt that I'm ready to do it, so I ordered parts from UK, Germany and USA. I found some old dusty chassis that could work in my basement
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and after little modification and painting it was decent amp chassis
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I made custom front and back panel in plexi-glass, first designed it on my computer and then sent it to one local company that does laser engravement and cutting. It costed about 8$.
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I got board material from local shop very cheap and great guy from ampmaker.com sent me wires in different colors sufficient for two amps.
Here's board with turrets installed
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and with components soldered
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I didn't have soldering expirience and solder wire I got was very bad (plus my soldering iron was 1.5$ I got from flea-market) so connections don't look very nice, but they hold ok :)
Here are some photos of chassis with panels, knobs, transformers, tubes and panels installed. At this point I needed to power it up for the first time which was little scarry since I had no previous expiriences, and I was aware that if I messed something up I can destroy some valuable components. But first powerup got preety ok, I measured voltages and they were preety much same as in specifications, nothing exploaded and I wasn't killed by hugh voltage-success :) the only problem-I didn't have my guitar with me (it's in other town where I study) so I coudn't test if it sounds ok...so frustrating :twisted: besides I needed to go back to study for a week.
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After I finally got back my friend came with the guitar to try it. I didn't make speaker cabinet yet, so I left speaker (greenback 25w 8ohm) on the floor connected with two wires to amp. I fired it up and there was it-SOUND, eureka!!! :) Just hum was louder than guitar sound so it was preety unusable. After another week away I got with new solder wire and some instructions from grat ax84.com guys and made some modifications. Again I didn't have guitar so I tested it with my bass. This time hum is gone, and as far as I can tell with bass plugged in it sounds preety cool!
Here are some inside pics:
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Today we worked on head cabinet, here's the result
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I need to get black spray to paint it, I don't have time nor nerves for tolexing
Thank you for you time, I hope I'll have sound files yet. You can see more pics at photobucket.com/albums/c22/bancika/FireFly/
Rock on :)
Bane
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bancika wrote:Hi,

Thank you for you time, I hope I'll have sound files yet. You can see more pics at photobucket.com/albums/c22/bancika/FireFly/
Rock on :)
Bane
Man, that's pretty impressive. I didn't know one could just build an amp so simply. What book did you use for the circuit schematic? The cabinetry for the chassi was also very clean, nice work. How loud is that amp? I just saw 3 preamp tubes, 1.5 W should be about 1/3 as loud as a 15w amp, but tubes always seem much louder than solid state. maybe your future soundclips should compare the marshall and your amp at the same mic/preamp settings.
bancika
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It's loud enough for playing at home without annoying your naightbours. Actually only one tube is preamp, other one is boost and the third one is output tube. Since it's only 1.5w it doesn't need larger output tube like EL34/EL84. First two are 12AX7 and output is 12AU7. Schematics and knowledge is located at ax84.com forum. There are lots of friendly helpfull guys there.
bancika
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Well that 1/3 math is ok, but marshall uses some crappy 8" speaker. Greenback's efficency is 97db. 3db more means twice the volume. Hi-Octane project from AX84.com is 6W and it's enough for gigs and practice, but I think that this one is just perfect for me
Billius
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Man, that's pretty sweet! Nice work with that. Any chance we could get to hear it in action?
bancika
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Sure, as soon as I get a chance to try it with guitar :)
j1mi_h3ndrix
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thats pretty awesome
Jahovasnout
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That's gay
bancika
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Why :?:
Igor
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man.. low wattage tube amps RULE for home practice!!!

and if you think a 1.5W amp aint enough.. well, you're dead wrong. through a 4x12 it can get louder than you imagine. true, the tone aint the same as from a proper 50 or 100 (or 120) W head, but with those you can hardly play at home ;)


nice one.
bancika
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Yeah, it can get preety loud for home practice. Thats why I made little power attenuator in it. Basically it's L-Pad with treble bypass cap, does the job preety good for 10$ :)
My father didn't believe it's gonna be loud enogh cause he's "only 100w, no less" kinda guy. But he was suprised when we turned this little fellow on, even with speaker lying on the floor it's enough. I like it especially cause it's hi-gain amp, you cant get good cranked tone with 100-watter at bedroom volumes, but with this amp you can crank it all way up and just attenuate output a if needed (for night practice). Since I live in appartment with thin walls I don't like disturbing neighbours so I really need those stuff, so I built both master volume control and power attenuator. I also added some tone control (original design doesn't have one). I really like DIY stuff cause you can always tweek gear up to your preference
Igor
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high gain you say?


hmmmmmm


how's it handle 80's metal?
bancika
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you can hear it on this site http://home.cfl.rr.com/dbhammond/ff.htm
note, it's not mine build but from guy who invented it.
unfortunately I didn't have much chance to try it. My whole gear is in town where I spend most of my time (because of my faculty). I go to my home town one day in week and than grab something to work on guitar or amp. So I had chance to test it once with friend's guitar and then I discovered some mistakes I made so hum was preety loud. But below annoying hum I could hear some good tones :) After I fixed mistakes I coudn't find any guitar around so I took my father's basses to try it just to make sure that hum is gone. There's hi-gain tone with bass, but I can't be sure until I try with real guitar :)
Lo Lo
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Bancika?....Maybe you can help me.
I've been to the AX84.com site, very interesting!

I would be very interested in a switchable 50/100 watt single channel head build.


input - Master Volume - Volume - Bass - Mid - Treble - standby - power

^ This is all I would need

Could you point me to the right kit. I am very good with electronics and soldering. For years I installed car alarms and car audio, I am also very good at wood working. This sounds like a very fun project....It's got this guy dreaming!!!

By-the-way, I've seen lots of amp projects and yours is by far the most professional look I've seen. The plexiglass front plate(with grafix) is what really struck me..............Oh man!, I can't wait!
bancika
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Thanks Lo Lo! As I said, panels are made by professionals, just designed by me :) and I got them really cheap (8-9$ for both).
As far as I know there are only low wattage amps at ax84.com (maybe november project is more), so you coudn't make some of their projects but you could lear ALOT by reading their posts. Are you 100% sure you need 100watter? I mean 100/50W switch will not make much difference in volume.
Maybe you could look for kits at
https://weberspeakerscom.secure.powweb. ... /kit_r.htm
but I wouldn't recomment using kits cause you can pay less if you order parts separately.
First pick amp model you want to make, find schematics and layout and then make bill of material. Try http://www.tubesandmore.com for parts, thay have just about everything you need
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