Home built amps...

[guitar_ed]

Howdy,

Has anybody built an amp from a kit. I was looking at Torres, but they are wicked expensive. Then my luthier turned me on to Rodgers Amps. They have a 4 watt tweed kit for $375. I am leaning towards the Rodgers.

Any thoughts on these two options? And are there other options? When I look in google, all I get is hifi gear.

Thanks much.

Guitar Ed

[ansil]

hmmm well is tween exactly what you want i and what is all in the kit my friend as i can do you a kit cheaper than that. and i have a nice marshall clone. that i do for around 200 depending on wattage etc

[lovekraft]

Doberman Amps - Chris Hurley is a very helpful guy and sponsors the AX84 Homebrew Amp site.

Mission Amps - Bruce Collins offers a great 5E3 kit and parts galore.

GDS Amplification - Graydon Stuckey offers 18 watt "Marshall" kits and parts.

Before you get involved in building a tube amp, you may want to spend some time doing a little research at the AX84 site - it's a bit more complex than wiring up a fuzzbox, and the voltages involved can kill you dead, so get the info before starting and be careful.

Ansil, tell us a little more about that Marshall clone - I'm gonna need a new project as soon as i get done tweaking my Pignose.

[guitar_ed]

Hi Ansil,

What I would like is something around 5 watts, combo. Blues/jazz orientation is what I like, not heavy metal oriented. Something that I can pickup and carry away.

Talk to you later.

Guitar Ed

[ansil]

well basically its like this after i was looking at the ax84 pages after i got into the firefly from doughammond i started tweaking and modding it till really i got more than i ever bargained for.

what i am doing now is providing all the parts for a plexi clone.

it has a coulpe of versions on it so i will give you the basic one

12ax7 preamp and 12au7 output stage.

i use small transformers and use multilples of them to do what i want it to do.

you have the option of having half voltage on the preamp and full on the poweramp and output transformer to give you more ouput but less headroom

full voltage on preamp and half on the output and transformer to you have a cleaner preamp and a more compressed dirtyier output section

full voltage on both stages and half voltage on both stages.

all at the flick of a couple switches

there are a couple of mods available.

one is to redo the front end and add the fender eq into it. so to get the magic six thing going on. and basicaly rebiasing the second half of the 12ax7 for less gain somethign around the twin reverb type schematic. and i use two 6dx8's as the phase splitters and the power amp section. i was planning on using the reverb tranny from a fender similar in theory to the nanohead.

the other mod is to have the same original amp but now use the 6dx8 as pahse splitter and output section too. and swap the 12au7 for a 12ax7 and add an eq so we have a little more gain out of it.

the last mod of coruse is my favorite and one i play with the most.. put in a ldr and led combo on the cathode of each gain stage.. so you can adjust the led brightness

to affect the gain.. without scracthy pot noise.

and of course as with all of thes kits you can adjust the gain for yourself what i do is provide a couple selections with everyone of them. you get the basic one with all the parts but i add a few extra tone caps in there for you, and i also add in a few extra hiwattage resistors here and there so you can limit or increase the headroom of each stage.

[rob]

how much would you charge for these ansil? They sounds very interesting

[ansil]

right now i am still drawing up plans and wel its different for what you want.. around the 200-275 range.. for all the parts except chassis and speaker and such.. basically i supply you with the schematics of your choices

transformers

input and output

capacitors

diodes for rectifier

tubes, out of my own supply unless you wanted a specific type that i dont' have whcih i will discount for you getting your own tubes.

all pots leds ldr's resistors. tube sockets.

if anyone is interested email me from the frorum here and i will give a 10 percent discount to the forum members.

also it will let me build you a custom quote once i know exactly what you want.

[lovekraft]

Excellent! I'm very interested - could you give us a list of options so we know what we have to choose from? Are you offering board kits or bare boards, or just complete kits? Quite an ambitious project, I hope you do well.

[ansil]

hmmm well basically i am doing mostly these..

there is the stock amp.. which is a marshall type building block but it is flexable.

there is the plexi clone.

the boogie clone. suped up plexi with more botttom and an extra gainstage and more eq

the fender mod which basically is the first amp with most of the gain taken out, and added the classic input stage straight into the eq like the twin reverbs of that time..and then into a recovery/gainstage.

basically the first one is more of a begining bluesy type amp that can cross straight into rock, and with a pedal like the SHO from zvex or the Cowbox From myself can be a real monster.

the fender one is meant to be cleaner and a little more versatile as it has an eq straight from the word go. and is already beefed up with the 6dx8 output stage.

the boogie clone has an extra tube and adds eq as well as it is shaped to be more Dual rectifier like.

thats really the bare bones of it. as far as mods they go like this.

all amps can have the 4-8 watt output stage added except for the fender as it already has it.

you can add in extra gainstages if you want i can proved custom schematics as is we are doing stripped down basic amps just the nut and bolts of them

all kits include

input output jacks.

pots

voltage transformers output transformers

all capacitors resistors diodes you need for the build plus a few extras for tone expiramentation

your choice of turret board. or a blank board with the basic layout {i do all mine on turret for the prototype and after that i go to pcb i dont' make a board i etch a turret board basically. i got the idea from a friend. so you can solder directly to a pcb board but still do the turret style layout.}

all the sockets and etch

really everything that you need to build the amp

except the cabinets speakers and chasis's

and i can get you the chasis from a friend online that does custom work for around 40 dollars each.

[bigdguitars]

If you go on ebay and search bogen amplifier you can find the nicest amplifiers around for the price.

Think of this, a kit will cost you 300 bucks. I have bought ten bogen amplifiers all different wattage ratings from 10 to 100 watts for less than 30 buck each.

I know building an amp is a great learning experience, if thats what you are looking for.

if you want a cool deal some great tube amps then I would do the ebay thing.

[rob]

I serched for bogen and it just came up with PA and pro audio, can you show us a link?

[lovekraft]

I think those are the amps he's talking about. They can be used for guitar if they have hi-impedance inputs, or they can be modded into more traditional guitar amps without a lot of trouble.

[cr_XD]

i've red the hole thing and understand nothing of what you say when you speak about electronics ansil...

and basicaly rebiasing the second half of the 12ax7 for less gain somethign around the twin reverb type schematic. and i use two 6dx8's as the phase splitters and the power amp section

... i did know i was not very clever, but that really makes me feel like a complete ignorant in the matter.

Anyway i'll try to build the real mc tube.

how much do you think it would cost to send one of those kits all the way over the ocean to europe???

the only kits i see round here cost like 450 $ for a champ.

[lovekraft]

For amp kits in Europe, you may want to check Martin Adams' MadAmps site in Germany. Don't know about VAT, but you should save a bundle on shipping.

[Hotrock]

I've been looking at doing this for a while and I'm interested. If you think it is feasable to ship a kit over to the UK. I'm after something versatile that I can play the blues on, aswell as using some homemade effects pedels.

If anyone in the UK wants to split the cost of shipping and have the kits sent at the same time then I'll look into it.

I'd quite like something all singing and dancing with lights and buttons and switches and sockets and ................etc etc

[cr_XD]

MadAmp is a great page, i had already set my eye on the ax84 page, and now i'll be building one for sure with one of the kits, i'll just wait to see how the real mctube comes out anyway. thanx for the link.

[ansil]

it would cost around 45 bucks extra to ship this to europe and uk and such..

here is the pinout and spec sheet of the 6dx8

http://hereford.ampr.org/cgi-bin/tube?tube=6dx8

6DX8

High-Mu Triode - Sharp-Cutoff pentode

Data Source and Substitute Data

Data Source ................................... RCA RC-29 - 1975

Prefered Substitutes .......................... None

Substitutes ................................... None

Application

Miniature type used in color and black-and-white television receiver applications. The triode is used as a sync-separator, sync-amplifier, keyed-agc or noise-suppressor tube. The pentode is used as a video-output tube. Requires miniature 9-contact socket.

Mechanical Data

Bulb .......................................... T-6 1/2

Outline ....................................... 6-3

EIA Base ...................................... 9HX

Electrical Data

Heater Characteristics

Heater Voltage ................................ 6.3 Volts

Heater Current ................................ 0.72 Amperes

Maximum Ratings (Design Center Values)

Pentode

Plate Voltage ................................. 300 Volts

Grid No. 2 Voltage ............................ 300 Volts

Plate Dissipation ............................. 4 Watts

Grid No. 2 Dissipation ........................ 1.7 Watts

Triode

Plate Voltage ................................. 300 Volts

Plate Dissipation ............................. 1 Watts

Characteristics and Typical Operation

Triode Class A Amplifier

Plate Voltage ................................. 200 Volts

Grid No. 2 Voltage ............................ . Volts

Grid No. 1 Voltage ............................ -1.7 Volts

Amplification Factor .......................... 65

Transconductance .............................. 4000 MicroMhos

Plate Current (Zero Signal) ................... 3 Ma.

Grid No. 2 Current (Zero Signal) .............. . Ma.

Pentode Class A Amplifier

Plate Voltage ................................. 170 Volts

Grid No. 2 Voltage ............................ 170 Volts

Grid No. 1 Voltage ............................ -2.1 Volts

Plate Resistance (approx) ..................... 100K Ohms

Transconductance .............................. 1100 MicroMhos

Plate Current (Zero Signal) ................... 18 Ma.

Grid No. 2 Current (Zero Signal) .............. 3 Ma.

Pentode Class A Amplifier

Plate Voltage ................................. 200 Volts

Grid No. 2 Voltage ............................ 200 Volts

Grid No. 1 Voltage ............................ -2.9 Volts

Plate Resistance (approx) ..................... 130K Ohms

Transconductance .............................. 10400 MicroMhos

Plate Current (Zero Signal) ................... 18 Ma.

Grid No. 2 Current (Zero Signal) .............. 3 Ma.

Pentode Class A Amplifier

Plate Voltage ................................. 220 Volts

Grid No. 2 Voltage ............................ 220 Volts

Grid No. 1 Voltage ............................ -3.4 Volts

Plate Resistance (approx) ..................... 150K Ohms

Transconductance .............................. 10000 MicroMhos

Plate Current (Zero Signal) ................... 18 Ma.

Grid No. 2 Current (Zero Signal) .............. 3 Ma.

cr_XD

sorry it made you feel overwhelmed but its pretty easy.

when you drop the voltage you lower the headroom which is the limit before the input signal will start to clip or distort.

when you rasie this you make it harder for it to distort ie or you need more signal gain for it to hit the ceiling. the headroom is like the ceiling and the floor.

an eight foot ceiling i can touch flat footed without shoes with the palm of my hand.. but a ten foot one i would have to jump to reach..

[HeavnerGuitarWorks]

Ansil,

How much would you charge for one already assembled? Just on the chassis.... no enclosure or speaker? Marshalls rock!

[cr_XD]

when you drop the voltage you lower the headroom which is the limit before the input signal will start to clip or distort.

so if i understand correctly lowering the voltage makes a cleaner sound??

[ansil]

when you drop the voltage you lower the headroom which is the limit before the input signal will start to clip or distort.

so if i understand correctly lowering the voltage makes a cleaner sound??

acutally its the reverse more voltage equals more headroom so the signal doesn't [bump] its head on the ceiling.. kind of a low bridge effect the lower the bridge you could lose your head lol think back to those old scooby doo cartoons where they go under a bridge and u see a headless dog and then he pulls his head out of his shoulders.. anyway.. its kind of like diodes see diodes limit the threshold we have on the signal too.. ie for stompboxes and amps for diode clipping..

more voltage will attribute to a cleaner sound..

[ansil]

Ansil,

How much would you charge for one already assembled? Just on the chassis.... no enclosure or speaker? Marshalls rock!

i have enough parts to do three or four of the marshall basic ones.. i have all the trannsformers and such i need just have to get the chasis's so if someone wanted to get one off of me now, then it would be 225 for the assembled kit plus shipping.

this is only good while i have all the parts on hand when i have to start ordering parts again i will have ot go up on building them .

but for future reference i will be selling my micro amp online via email and my website..[when it is completed ie the website] for around 299.

it is a three gain stage tube amplifier with a fourth pentode there for 4watts class A power. with real high voltage 300V b+ and it has the whole bright dark switches and a presence knob and a gain and master volume knob.

i have had two of them ordered allready and the first one shipped out last week. i am doing them in a choice of colors but so far both amps are brushed aluminum finished per customer request.

not to shabby. to fit all of it in a BB box, i originally went for the 1590B box but thats been done and i can't compete with one of my friends..

[cr_XD]

i understand now, i should read more carefully.

how do the output signal levels vary due to the voltage?

maybe they seem really newbie questions, but that's what i am. i'm glad you answer my questions, but somehow feel like wasting your time, is there any reading you can tell where all this has been explained before... that should save you time

and thanx

[ansil]

they function similar in principle it all depends on what you are after .. if you want a tight punchy clean poweramp and derive all your gain from the preamp then i say starve the pre high voltage on the poweramp

ifyou want a blend between the two i say find a nice middle ground.

ifyou want to really cleanup the preamp and just drive the poweramp section into power tube saturation then you lower the output voltage..

theres a ton of stuff you can check out.

ax84.com

ampage.com

http://www.diystompboxes.com/pedals/ampmods.html

geofex.com

[lovekraft]

it is a three gain stage tube amplifier with a fourth pentode there for 4watts class A power.  with real high  voltage 300V b+  and it has the whole bright dark switches and a presence knob and a gain and master volume knob.

So you're doing a pentode SE Class A amp with a 3 triode preamp? Very cool, very "Daktah Zee"! What kind of tone control are you using? I assume you don't have room for a full tone stack in a 1590BB. Way cool idea!! You might also try a 6BM8 for that triode/pentode combo if somebody wants a little more power (but you'd probably already thought of that). I was considering using two triode/pentode combo tubes for a V*xish p/p power amp - I'll have to take a look at that 6DX8, thanks.

[ansil]

actually in a BB box i do have plenty of room for a full tone stacki prety much i could squeeze it in there. i am doing a a .0022uf cap for the bright switch. the dark switch actually rolls of some of the treble with a .001uf cap. and in normal mode both are bypassed. i actully haven't thought of that tube, thats pretty cool but i would have to find them really cheap though cause i get the 6dx8's dirt cheap off of ebay, and i mean lets just say even when i mark up my costs [as well you have to in a buisiness] i can still sell them for under 5 bucks a tube.. not bad for essentially a 5watt tube.. 1 triode watt/4 pentode watt ratting..

the presence is actually a nifty little thing it balances two other cathode bypass caps i use a 1uf cap normally but i have it set up so you can blend in a .1uf or a 25uf there so it can actually clean up somewhat when you roll the presence back.. or really bright bordering on that vox type lead ear piercing.

i am using a .033 coupling cap on the first stage with i belive its a .068uf on the second stage.

of course this is a small amp but after meeting a bunch of people who just mike there "nano" amps for gigs i thought hmmm four watts dirty thats nearly twice as loud sound pressure wise to our ears so that should be plenty.. shoot i used two of the four watters myself and i love it.. i used to use two 8-10watters one dry one wet. but it got to be where i couldnt' crank it up so i went back to the four watter and it will start sweating when i crank it ..

if you want a couple 6dx8's to play with let me know there LK i could send you some. i bought a bunch off ebay.

i am alos having a friend of mine put up some kits for me that i am discontinuing..

hes putting up real tube amp kits a single ended kit that has a preamp tube and a poweramp tube.. so you get a nice clean one volume and a presence control amplifier.. hmm think a micro champ basically.

but hes putting them up on ebay for me. everythign u need for 55 jdollars plus shipping and handling