I am building a guitar pedal which has a vacuum tube on it. (No Arduino involved here for audio.)
I know that different tubes shape the sound differently so the sound of the guitar will be completely different if I use another tube. I have three different tubes which I can replace manually (removing one and inserting other) so I have three different tones on one pedal.(tubes are identical in electrical values so the pedal works with all three tubes perfectly) But replacing tubes manually is not very practical, so I want to use an Arduino to be able to switch between tubes...
I don't know how this may be possible, but my guess is there should be three footswitches for three tubes and whichever I press, that tube should work...
I am thinking of relays and I will be glad if you could give me some idea how to approach the situation...
I am adding the schematics and some information...
BTW: There is a 3PDT footswitch is used on the pedal which reminded me there are also 3PDT relays out there so maybe they maybe used somehow...
Actually, the notion that electrically identical tubes sound different is a myth. It can easily be debunked with double blind A/B tests.
There are selector footswitches on the market already. You could just have 3 units and select between them. I would recommend this vs. tinkering because by the time you would be done building, you would have spent more money doing it. To say nothing of the labour.
aarg:
Actually, the notion that electrically identical tubes sound different is a myth. It can easily be debunked with double blind A/B tests.
There are selector footswitches on the market already. You could just have 3 units and select between them. I would recommend this vs. tinkering because by the time you would be done building, you would have spent more money doing it. To say nothing of the labour.
They are not identical actually, I tried to say that electrical values are same so it is ok to replace the tubes without modifying the circuit...
And btw, same tube but different brands gives different sound Their electrical values are same but the tone is a lot different 8)
And thanks for your suggestion, I think it is not working for me since I need to use one pedal only with three different tubes...
emre:
And btw, same tube but different brands gives different sound Their electrical values are same but the tone is a lot different 8)
If you weren't mentally biased by already knowing what tubes you are using, you wouldn't be able to tell the difference. It is all in your head. That is what a blind A/B test is for, to remove the mental bias. If you were brave enough to try it, you would quickly discover that you are unable to hear the difference.
Why can you only use one pedal? Are they too expensive?
Seems the tubes in that circuit are running on a 9volt plate voltage.
Common triodes made for ~100-300volt and used in starvation mode will all sound bad.
So I think you're right. There might be a big difference in sound.
Like running a petrol car on whisky or vodka.
Seems you like that. I don't.
Just use a small DPDT relay to use or bypass the tube.
One contact for the grid, and one for the anode.
Leo..
There is enough drive in the preamp transistor to supply three grids. All you need is a three way selector switch from the cathodes to the volume control.
aarg:
There is enough drive in the preamp transistor to supply three grids. All you need is a three way selector switch from the cathodes to the volume control.
AFAIK grid impedance can be pretty low at these voltages.
Leo..
Wawa:
Just use a small DPDT relay to use or bypass the tube.
One contact for the grid, and one for the anode.
Leo..
Thank for your suggestion Leo. I am going to work on this, but before I don't have any anode, (have two cathodes) and have two grids... So what's your opinion? I am also attaching a diagram of the tube...
Wawa:
Seems the tubes in that circuit are running on a 9volt plate voltage.
Common triodes made for ~100-300volt and used in starvation mode will all sound bad.
So I think you're right. There might be a big difference in sound.
Like running a petrol car on whisky or vodka.
Seems you like that. I don't.
This makes a really good overdrive distortion sound for guitarists.
aarg:
There is enough drive in the preamp transistor to supply three grids. All you need is a three way selector switch from the cathodes to the volume control.
Thank you aarg. I will work on this also. Can you you show me where to put the selector on schematics?
When you swap tubes, are you really getting enough variation to make this worthwhile?You might be hearing a difference, but there's a good chance that nobody else will hear the difference... Especially if there's a time delay... If you use one tube on Monday and another tube on Tuesday, probably nobody will notice the difference.
You can probably get bigger differences by varying resistors or capacitors while using the same tube.
In a well designed hi-fi amplifier, any tube that's in-spec will sound identical. But, guitar amps & distortion devices can be designed so that tube variations will result in sound variations.
ICs, transistors, and MOSFETs also have production variations but most audio circuits are designed to work properly within normal tolerances.
And I suppose vinyl has no advantage over MP3
I think you've got that backwards, unless you're an "audiophile" that prefers the "warm crackle" of vinyl.
When you swap tubes, are you really getting enough variation to make this worthwhile?You might be hearing a difference, but there's a good chance that nobody else will hear the difference... Especially if there's a time delay... If you use one tube on Monday and another tube on Tuesday, probably nobody will notice the difference.
I do believe that there will be a lot of difference between the tones which everyone can hear. If the tubes were for hifi, we wouldn't hear the difference, but the tubes are pushed into distortion and every tube's characteristics is a lot different when pushed into distortion...
Please watch this video, there is a comparison between two tubes. I am actually making the very same pedal, what I am trying to solve is to switch between tubes without removing them...
I also know that even between different brands of the same tubes, there is a lot of tone difference. Trust me. For example, if we talk about 12AU7 tube, Mullard brand has a warm, smooth sound while RCA (with clear top) brand has a clearer, detailed sound. Also Philips brand (Philips Holland) has a good bass sound... 12Au7 is a very popular tube among guitarists for a decade and you can find tons of information about this on the net.
Also please check here if you can't decide which 12AU7 to buy if you ever need to buy one day. https://www.tubeworld.com/12au7.htm
And these are all for distortion (overdrive) not for hifi...
You are also right about capacitors, oil in paper types (the most expensive ones also) makes a great difference in sound... I try to use them as much as possible. Lets say they are around $25 dollars when the equivalent normal cap is around $0.5.
And thank you guys all, I am new here and enjoying my time reading other stuff too...
And the last thing, whoever said vinyl has no advantage over mp3, is totally wrong or never had he chance to hear the difference between... 8)
emre:
And the last thing, whoever said vinyl has no advantage over mp3, is totally wrong or never had he chance to hear the difference between... 8)
I am so glad the tube/valve and vinyl age is behind me.
Digital audio is (can be) sooo much better.
Don't bring Mp3 into the equasion.
That's a compressed version of digital audio, only meant for portable use.
Modern highly squashed recordings (loudness-war) give digital audio a bad name.
Leo..
emre:
I do believe that there will be a lot of difference between the tones which everyone can hear.
I know that you believe it. A lot of people do, but they consistently fail controlled listening tests in such matters. There is a big difference between saying you can hear a difference, and proving that you can hear a difference. Belief is not knowledge.
hi, I have made a drawing to explain it easier... How do you think that I can make only one tube active (other two will be deactived while one is working) and I can switch between tubes with relays...
My question is where should I insert the relays...
aarg:
I know that you believe it. A lot of people do, but they consistently fail controlled listening tests in such matters. There is a big difference between saying you can hear a difference, and proving that you can hear a difference. Belief is not knowledge.
You understand that the current topic is a distortion device, that is, an electronic amplifier operating largely in a non-linear region?
For a couple of centuries, most musicians believed that Stradivarius violins "sounded better" than any other, and consequently, a genuine one is worth millions of dollars (there are lots of copies).
That distinction was finally and very clearly disproved in blind tests.
Their electrical values are same but the tone is a lot different 8)
