I'm just a little worried about the pot and cap series connection you show from cathode to ground. As the pot resistance reduces then you shunt the AC signal and reduce the bootstrap effect, thus that pot becomes an input Z control - 500K at min resistance and approx 5M at max resistance - Is that what you wanted to achieve?
Cheers,
Ian
Cheers,
Ian
not my intention, no
I see your point, and also thought it might be too tricky fore me to handle
I was trying to use the tube stage like adjustable distortion control only
and hopefully a mild one
it was inspired by reading the valvewizard triode gain stage article(pdf file)
Valve Wizard - How to design valve guitar amplifiers
just a note(thought)
maybe 'one' point of using 6C19n is that it has very little gain(6db ?)
thus I wont need any attenuation of the tube output level as such
but only control of distortion, and character
dont know if it makes sense(?)
I have found that to me the best bass distortion is not really heard diretly when playing
but only gives a more 'distinct' natural character
funny that my very cheap analoge small combo comes close
but the advanced digital unit I tried wouldn't do this half as good
really strange to be talking about 'natural' distortion
maybe 'one' point of using 6C19n is that it has very little gain(6db ?)
thus I wont need any attenuation of the tube output level as such
but only control of distortion, and character
dont know if it makes sense(?)
I have found that to me the best bass distortion is not really heard diretly when playing
but only gives a more 'distinct' natural character
funny that my very cheap analoge small combo comes close
but the advanced digital unit I tried wouldn't do this half as good
really strange to be talking about 'natural' distortion
hopefully this would be more 'realistic' 
btw, cathode 'adjust' is a small pot with switch off function
in switch off position its fully bypassed with bigger cap
in adjust position, only a small cap
but not sure yet how it really works
not sure about the clean(feedback) function either
btw, cathode 'adjust' is a small pot with switch off function
in switch off position its fully bypassed with bigger cap
in adjust position, only a small cap
but not sure yet how it really works
not sure about the clean(feedback) function either
Attachments
tinitus,
this is the input stage and so you are not really going to get any significant distortion from it. For Guitar amp type distortion you need to push a stage hard with high input signal level - that sort of thing is generally got from the 3rd gain stage althouigh you can get a bit of mild overdrive from the second stage as long as you don't have too much loss between the stages.
For thinking about this:
Think of a Fender Clean Channel Preamp - 1 gain stage , then (lossy) tone stack and volume, then a 2nd gain stage. It is very difficult to get any real distortion from either stage.
Then think about the typical Trainwreck preamp, same as above with an extra gain stage tacked on the end, allowing you to drive the "sound" off the guitar volume control and generate serious brown sounds - it is that 3rd stage which gives the tonal flexibility.
If you want serious (metal) overdrive you need a fourth stage and some of the really high gain amps run 5 stages in the pre.
The "role" of that first stage is to "match" the required instrument and get the most amplification you can manage which will boost the signal up enough to get some overdrive of latter stages.
For you info - I'm doing this during a break at work, tomorrow is last day before 5 weeks leave so I won't be back here till next year. A Cool Yule to all.
Cheers,
Ian
this is the input stage and so you are not really going to get any significant distortion from it. For Guitar amp type distortion you need to push a stage hard with high input signal level - that sort of thing is generally got from the 3rd gain stage althouigh you can get a bit of mild overdrive from the second stage as long as you don't have too much loss between the stages.
For thinking about this:
Think of a Fender Clean Channel Preamp - 1 gain stage , then (lossy) tone stack and volume, then a 2nd gain stage. It is very difficult to get any real distortion from either stage.
Then think about the typical Trainwreck preamp, same as above with an extra gain stage tacked on the end, allowing you to drive the "sound" off the guitar volume control and generate serious brown sounds - it is that 3rd stage which gives the tonal flexibility.
If you want serious (metal) overdrive you need a fourth stage and some of the really high gain amps run 5 stages in the pre.
The "role" of that first stage is to "match" the required instrument and get the most amplification you can manage which will boost the signal up enough to get some overdrive of latter stages.
For you info - I'm doing this during a break at work, tomorrow is last day before 5 weeks leave so I won't be back here till next year. A Cool Yule to all.
Cheers,
Ian
Last edited:
I thank you fore support
take care
btw, I thought driven the tube at too low voltage and/or bias would give me moderate distortion
remember, its specialised fore bass guitar
Im not after screaming guitar distortion
maybe it wont make much sense to build this 'thing'
but I might build the box, just fore fun
anyway, its designed in a way that its easy to change front layout
and I 'found' a cost free alternative to the expencive and problematic 'engraving' of the front
and equally easy to change as well
design the front on your PC, using paint or something more advanced
with just about any color you desire
print it, on your printer
regarding paper quality, I have no idea what is available
but some may be able to do really fancy stuf this way
glue it on to the front
spray with laquer
or maybe finish it with clear vinyl, pvc or something
well, end of story, and on to some simpler stuff, like building that jfet hi-Z buffer
but I might build the box, just fore fun
anyway, its designed in a way that its easy to change front layout
and I 'found' a cost free alternative to the expencive and problematic 'engraving' of the front
and equally easy to change as well
design the front on your PC, using paint or something more advanced
with just about any color you desire
print it, on your printer
regarding paper quality, I have no idea what is available
but some may be able to do really fancy stuf this way
glue it on to the front
spray with laquer
or maybe finish it with clear vinyl, pvc or something
well, end of story, and on to some simpler stuff, like building that jfet hi-Z buffer
Attachments
well, end of story, and on to some simpler stuff, like building that jfet hi-Z buffer
found this small power supply with +/-20V
easy to make it +40/0 instead
or +30/0 with a reg
Attachments
may sound funny, but I have this strange idea that a guitar pickup is quite strong, despite its low SPL
and because of this it needs 'stronger' devices
thus I have my doubts about small signal IC's and jfets
which is why Im looking at driver mosfets
or possibly a tube
but then, what if the input of a SS power amp is jfet design, or similar
then my idea would be a wash
but maybe Im completely nuts thinking like this
any ideas ?
and because of this it needs 'stronger' devices
thus I have my doubts about small signal IC's and jfets
which is why Im looking at driver mosfets
or possibly a tube
but then, what if the input of a SS power amp is jfet design, or similar
then my idea would be a wash
but maybe Im completely nuts thinking like this
any ideas ?
intelligent answer, but was not the question
so you dont think there is any reason why some people like el84 of 6V6 in a preamp stage
Some people are idiots
Some people (yourself included) seem to like the lower qualty sound that valves give you, there's no accounting for taste. An active pickup gives better tone controls, and removes most of the problems with a passive pickup, there seems little reason to go back to one?.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.