#1
ok so my idea is to get a big list of popular tube amps (maybe 50-100) and get their schematics. if i made a digital circuit that only acted as a component selector and the signal didnt even pass through the digital parts then that crcuit could effectively route the signal to certain parts to mimic the electrical pathway of the original which if the same components were used then should sound as close to the real thing as possible.

the amount of tubes would be a littl extreme. i would most likely need 4 of each common type of power tube used alog with 8 of each preamp tube and just have the digital circutry activete all the caps/resistors/tubes used for that specif amps signal path. i dont think anyone has done this with tubes before, does anyone have any opinons?
#2
....holy crap....are u like.... a scientist or sumthing????
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#3
that's some crazy **** man. props if u can pull it off.
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#6
Wow. As an electronics technician, I can tell you that you're up against a VERY daunting task. The circuit variations from one manufacturer, and even one tube amp to the next, are so overwhelming that you'd never be able to pack the circuits of 50 to 100 amps in one box that could be carried with your two arms. It would take a forklift to carry it. It'd be a much easier task if everyone followed the same circuit design, but just varied a capacitor or resistor here and there, but that's not the case. The switching circuitry alone would be so complex, that it'd be a nightmare to work on. With all of the switching going on, I think it could have an effect on the tone. If you decide to try it, be sure to send me pics of the final board layout. Also, I want a before and after picture of the hair on your head.
#7
Thats Nucking Futs!
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#8
So do you have a CDL? You may need one to transport it because its gonna weigh over 5 ton.
#9
Quote by me_llamo_juan
Isn't the Peavey Penta like that?

Edit: nvm not the same thing.


ya its not, but to the others, im a computer programer so the digital parts would be easy for me. ive been looking at caps between oranges, marshalls, fenders, and mesa boogies. most use almost identical caps so im imagining it with 2 pcb boards with 256 caps the other with 256 resistors in sets of 8 being ordered by resistance and uF. the tubes will supply some heat issues so most likely i will end up giving each set its own heatsink to keep temps between tubes even. also im looking at 32 knobs with each one having its own lcd screen which would tell the user what its purpose was.
#10
Try doing it with two, maybe three amps first. Like a Marshall and a Fender.
#11
ok so when (if) you pull this off you have 2 requirements

1. Pics

2. Sounds clips and lots of em
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#12
Quote by KG6_Steven
Wow. As an electronics technician, I can tell you that you're up against a VERY daunting task. The circuit variations from one manufacturer, and even one tube amp to the next, are so overwhelming that you'd never be able to pack the circuits of 50 to 100 amps in one box that could be carried with your two arms. It would take a forklift to carry it. It'd be a much easier task if everyone followed the same circuit design, but just varied a capacitor or resistor here and there, but that's not the case. The switching circuitry alone would be so complex, that it'd be a nightmare to work on. With all of the switching going on, I think it could have an effect on the tone. If you decide to try it, be sure to send me pics of the final board layout. Also, I want a before and after picture of the hair on your head.
\

all the switching would be handeld digitally. im thinking of using some sort of computer bus to configure the selctions of components. there would be little wiring as all paths would be choosen on the pcb by the digital processor. complication arise in the transformers. im thinking of using switchin psu's for versatility making most weight in the tubes.
#13
Not only that, but each manufacturer uses different tubes. By different tubes, I mean tubes that bias at different points. Fender uses tubes that bias at one voltage, while Mesa uses tubes that bias at yet another and so on and so forth. Even if you got the components right and the switching working, just having 4 power tubes would mean that you're likely not getting the right bias point and therefore, not the correct sound of the particular amp ypu're trying to mimic. Then, add in the variations in supply voltages, combines with the variations in output transformers. I think you've got a great idea there, but it's probably best that it be left as just a great idea.

Here's a picture of what your amp could look like:

Last edited by KG6_Steven at Jan 22, 2009,
#14
Quote by CrysisFX
ya its not, but to the others, im a computer programer so the digital parts would be easy for me. ive been looking at caps between oranges, marshalls, fenders, and mesa boogies. most use almost identical caps so im imagining it with 2 pcb boards with 256 caps the other with 256 resistors in sets of 8 being ordered by resistance and uF. the tubes will supply some heat issues so most likely i will end up giving each set its own heatsink to keep temps between tubes even. also im looking at 32 knobs with each one having its own lcd screen which would tell the user what its purpose was.


Yeah...it's not as complicated as it seems. You don't need the exact values of components from amp to amp.

Can the digital stuff control things like a 200 volt p-p swing (floating on top of 100VDC) because that's what you're going to have.

Noise issues are also going to be nuts, you'll need miles of shielded cable and one heck of a grounding scheme to pull it off w/o the hum being louder than the amp itself...

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#15
I would try with just a few amps first, then if you spot any problems you can solve them and once fixed you can scale up the design easily.

Also with the tubes you could have a heatsink for each one and place them so there is a funnel like pattern and have a few silent PC PSU style fans at the back sucking out air and a few at the front sucking cold air in, this will keep the temps down.
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#16
Quote by KG6_Steven
Not only that, but each manufacturer uses different tubes. By different tubes, I mean tubes that bias at different points. Fender uses tubes that bias at one voltage, while Mesa uses tubes that bias at yet another and so on and so forth. Even if you got the components right and the switching working, just having 4 power tubes would mean that you're likely not getting the right bias point and therefore, not the correct sound of the particular amp ypu're trying to mimic. Then, add in the variations in supply voltages, combines with the variations in output transformers. I think you've got a great idea there, but it's probably best that it be left as just a great idea.

Here's a picture of what your amp could look like:



power is definately going to be an issue. a substitution could be to let the digital parts form a variable resistor. this could be used to imitate the tranformers used in the origianl amps as well adjust the bias to what those manufactuers use. it would be a lot of transistors on a board to get the whole effect but in theory it could work.
#17
Okay. So, say you decide to use switchers for your power supplies... You still need the tube voltages, in addition to the logic voltages of 5 and 12 vdc. I haven't seen too many switchers that can produce several hundred volts. I'm not saying they don't exist, just that I've never come across any. You also need a hefty 12 vdc supply for the filaments. I'm not saying this project is impossible, just that it's incredibly not very easy.
#18
Quote by CrysisFX
power is definately going to be an issue. a substitution could be to let the digital parts form a variable resistor. this could be used to imitate the tranformers used in the origianl amps as well adjust the bias to what those manufactuers use. it would be a lot of transistors on a board to get the whole effect but in theory it could work.


I'm getting a design headache just thinking about it. I don't think there's any substitute for the real thing. Again, it's certainly not impossible, but certainly not very easy.
#19
Quote by KG6_Steven
I'm getting a design headache just thinking about it. I don't think there's any substitute for the real thing. Again, it's certainly not impossible, but certainly not very easy.


its simple concept but difficult to program. esentially the digital circutry would apply different voltages to the trasistor similar to apply more grid voltage to a tube. the output (plate) voltage could be then be adjusted easily.

the same can be done with amperage but its a complex equation i dont remember at the moment.
#20
Just a thought hear but, how about this (I know nothing of electornic circuity, before anyone call's me an idiot)


How about having it like this Pre-amp tube > circuit > Tube > effect? > output

Have say a selecton of 3/4 pre-amp tubes which feed into the circuit, the circuit basically just routes the current to the Tube which is selected by the current setting on the circuit board controller, So you can mix any of the pre-amp tubes with any of the Tubes.

You could also have it so it can use 2 pre-amps together and route the signal to 2 diffrent tube types, that way you could have a larger selection of sounds.

Maybe have some kind of power scrubber/ booster in the circuitry which uses a software program, or maybe some kind of component level device to control the volts/ watts for each combination and component.

I'm not sure that'd even work, but just my 2p on the matter.

EDIT: wont the circuit flatten the tone becuase it'd be converted from analogue to digital and back again?

Is there anyway to boost this digital signal when it leaves the circuit, say with a set EQ circuit to boost it a little to get it back to a more analogue state, i.e. more dnyamic?


DOUBLE EDIT: Just thought i'd post this quick diagram to explain what i mean, it may be totally wrong, if it is, well atleast i had a bash at it

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Last edited by Daniel8488 at Jan 22, 2009,
#21
here is an imge of my design. (crudley made in paint)



Red = Signal/Power send
Blue = Signal/Power Return
Green = Power from transformers
Orange = Power send
Black = Modified Power Return

As to the digital vs analog question. it is possible to use a midi or serial or even paraller bus to keep the signal analog. usb/firewire interfaces would create a digital signal. i will most likely use serial buut if complications arise i may chose another.
#22
The development (and production) costs would be epic.

Just start small and model maybe and Fender and Marshall circuit, with a hot-rod version of each.

Parts of it seem like a good idea, but as a whole, I don't think anyone would buy that when they can buy a few different, very good amps that take up less space, can be used on stage, cost less, generate less heat, consume less tubes, cost less, use less power and are easier to adjust.

One thing I want to know is if you switch between amp types, say Fender to Marshall, do you have to wait for the EL34 set to warm up or is every set of tubes running heated? Either way it'll be a pain in the ass or a massive power drain.
#24
That would be the coolest thing ever made.
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#25
To the TS...

Have you built a tube amp before? I recommend you try and build yourself a 5150 clone, and see how hard it is to keep quiet. Every signal cable needs to be shielded and as short as possible, so that's 500something shielded cables, and miles of them...

The problem you'd have is that when you switched to different combinations, you'd be doing things like picking up radios stations, the CB of the trucker down the road who's talking about the hot night he had in Vegas, etc.

In a high gain amp, you amplify your signal sometimes upwards of a ten million times. Now, say your guitar signal comes in at 1V and your external noise is 1uV. Well, you're going to be able to get your guitar to clip for sure, but that will max out at a 200V signal. Your noise also gets amplified 10,000,000 times, so now you have a 10V noise signal. Some amps, that's all you'd need to drive the power amp to full power!

The other problem with this is that you'd have to make the PCB traces small...which is fine, 'cause we're talking mA of current'. However, we're also talking 350VDC on them, so you'd have to make them far apart so your board doesn't arc out...and now it's huge.

I'm honestly not trying to stomp on your idea here, just saying that it's fraught with challenge. I'd recommend building an amp that has a few components that get changed over by a relay or something and take a look at how hard layouts become when you incorporate switching. From there, go build yourself a 5150 or an SLO and find out how hard it is to keep high gain amps quiet and stable. Then take this idea and go as far as you can with it, just don't expect to be able to get more than a few amps in it.

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#26
Quote by DLrocket89
To the TS...

Have you built a tube amp before? I recommend you try and build yourself a 5150 clone, and see how hard it is to keep quiet. Every signal cable needs to be shielded and as short as possible, so that's 500something shielded cables, and miles of them...

The problem you'd have is that when you switched to different combinations, you'd be doing things like picking up radios stations, the CB of the trucker down the road who's talking about the hot night he had in Vegas, etc.

In a high gain amp, you amplify your signal sometimes upwards of a ten million times. Now, say your guitar signal comes in at 1V and your external noise is 1uV. Well, you're going to be able to get your guitar to clip for sure, but that will max out at a 200V signal. Your noise also gets amplified 10,000,000 times, so now you have a 10V noise signal. Some amps, that's all you'd need to drive the power amp to full power!

The other problem with this is that you'd have to make the PCB traces small...which is fine, 'cause we're talking mA of current'. However, we're also talking 350VDC on them, so you'd have to make them far apart so your board doesn't arc out...and now it's huge.

I'm honestly not trying to stomp on your idea here, just saying that it's fraught with challenge. I'd recommend building an amp that has a few components that get changed over by a relay or something and take a look at how hard layouts become when you incorporate switching. From there, go build yourself a 5150 or an SLO and find out how hard it is to keep high gain amps quiet and stable. Then take this idea and go as far as you can with it, just don't expect to be able to get more than a few amps in it.



yes i have built one. all the classic amps from the ax84 website. with heat sinks the size could be limited and tube costs would not be any worse because all the tubes will not be powered on at the same time. they will only be powered on as they are needed.

i see the possibility of arcing and did not take that into consideration. instead of expanding length wise i could go vertically. i would also imagine being able to shield the tube sets by using some sort of box around them the generated a magnetic field (if thats possible) or using the material they use in airplanes against rf signals.


Quote by ljohn
The development (and production) costs would be epic.

Just start small and model maybe and Fender and Marshall circuit, with a hot-rod version of each.

Parts of it seem like a good idea, but as a whole, I don't think anyone would buy that when they can buy a few different, very good amps that take up less space, can be used on stage, cost less, generate less heat, consume less tubes, cost less, use less power and are easier to adjust.

One thing I want to know is if you switch between amp types, say Fender to Marshall, do you have to wait for the EL34 set to warm up or is every set of tubes running heated? Either way it'll be a pain in the ass or a massive power drain.



i would say let them be heated. the digital parts could hold the signal back until they warm up then let it through. having them all heated would make drastic cooling issuses and it would be a lot of tubes to replace.
Last edited by CrysisFX at Jan 23, 2009,
#28
Quote by CrysisFX


i would say let them be heated. the digital parts could hold the signal back until they warm up then let it through. having them all heated would make drastic cooling issuses and it would be a lot of tubes to replace.


It would be anyway.

So you're saying this is going to be completely useless for a live setting?

That rules out the stage, so now it's a studio amp.

Oh ****, where is all of this noise coming from, arggggggghhhh.

Now that also rules out studio amp.

Leaving crane counterweight.

Hang on, prety sure cement is cheaper.

Boat anchor? No.

You could make it aesthetically pleasing somehow, then call it modern art?

Sorry mate, but I'm struggling to think of a purpose.
#29
How about a modeling section with tubes in the preamp and power sections (seems to work for Line 6 and Peavey).
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#30
You should start by taking an Epi VJ and making a digital circuit switching system to choose between the various mod voicings for them (Fender, Marshall, Vox, BadCat etc.) That would be epic, and be a good starting point for your theory to see if it would work. Theres a table somewhere that even shows all the component values for the different mods
#31
Quote by Sunburst PR
You should start by taking an Epi VJ and making a digital circuit switching system to choose between the various mod voicings for them (Fender, Marshall, Vox, BadCat etc.) That would be epic, and be a good starting point for your theory to see if it would work. Theres a table somewhere that even shows all the component values for the different mods


Concur 100%. ljohn's post, while brutally sarcastic and unkind, is pretty much what'd happen if you do the build you're suggesting.

Could be sweet tho...I have a schemo drawn up somewhere for a microprocessor controlled amp, but just to give you 4 or 5 settings... clean, blues, rock, metal, etc...it can be done. Just...yeah...little too epic I think.
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#32
Quote by DLrocket89
Concur 100%. ljohn's post, while brutally sarcastic and unkind, is pretty much what'd happen if you do the build you're suggesting.

Could be sweet tho...I have a schemo drawn up somewhere for a microprocessor controlled amp, but just to give you 4 or 5 settings... clean, blues, rock, metal, etc...it can be done. Just...yeah...little too epic I think.


Not quite as intended, and I'm sorry for any offence, but it gets the point across.

The Valve Junior switching system is completely doable, and I would be on that if done. It'd save having 15 different switches hanging off the front of the amp.

Even if it was a completely new amp which was a system that could switch voicings without digital effects, you would be my hero.

Or something like the Egnater rebel with the ability to switch between types of power tubes.

For instance, if you made a small, low noise amp with options to switch between, say, 12AY7 and 12AX7 preamp tubes, and 6L6 and EL34 power tubes, it could be a brilliant little tone monster and recording tool.

I think an amp with the ability to switch between a fender-ish clean and a marshall growl would be an amazing little tool.
#33
Quote by ljohn


I think an amp with the ability to switch between a fender-ish clean and a marshall growl would be an amazing little tool.


Not hard. I'm working on a couple of amps right now (in the design phase) that do just that (only using KT77s instead of EL34s for better tone and reliability). It requires out of the box thinking and the ability to peel oneself away from making JCM800 clones, but it can be done.



Right now, starting to figure out the layout of an amp that'll be good for about 20 watts (SE amp, not PP...want to proto it in a less complex form that PP). The idea is to have a 6V6 (5 watts) in parallel with a KT77 (15 watts)...when clean, the KT77 will be really clean and the 6V6 will be the first to overdrive. The 6V6 overdrives in a very creamy fashion, so that'll be a sweet clean/OD sound, with the KT77 adding sparkle. As you start really beating the crap out of the KT77, the 6V6 will be going nuts, so it should be like an EL34 ("marshall") only with more nuts.

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