Switchable Hi-Z input impedance, how ? - Page 46 - diyAudio
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Old 28th February 2013, 08:00 AM   #451
tinitus is offline tinitus  Europe
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I need +30V and +/-12V for my juma curcuits
a print trafo would give cleaner build
and I found there is in particular one interesting trafo type
originally designed to do a regulated +/-12V and +5V

but connecting 9V in series with 14V and I have a perfect 14-0-14-23V

now, how big ? 6VA, 10VA, 14VA, 18VA ...well, I guess the regs will consume some of it
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Old 28th February 2013, 01:17 PM   #452
shanx is offline shanx  Canada
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Hi Tinitus,
Still following your build..just thought I would say Hi..so how do like the sound of the preamp? Nice smooth overdrive? and do you have enough clean headroom sound? I am still working on my guitar jfet preamp..and I hope yours works out well. Looking good so far.
Have fun!
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Old 1st March 2013, 10:08 PM   #453
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by shanx View Post
... how do like the sound of the preamp? Nice smooth overdrive? and do you have enough clean headroom sound?
Im happy with the way it works now
would say its a quite funny bass preamp
somehow managed to lower the gain
sounds nice and sweet
and kind of charming
volume pot turned out funny
doesnt change SPL a lot
and its the same with the balance pot

both controls change the sound a bit, but not much
almost more like its the tuning or pitch that changes a bit up or down
its a bit weird

but I really need seperate channel attenuators
and output buffers
trying to decide what box to use next
working on the handles...handles are important
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File Type: png bass pre fet front att balance.png (33.3 KB, 39 views)
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Old 2nd March 2013, 07:51 AM   #454
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Quote:
Originally Posted by tinitus View Post
volume pot turned out funny
doesnt change SPL a lot
and its the same with the balance pot
That's because both are designed entirely incorrectly, the balance pot in particular will do absolutely nothing.

Check out Elliot Sound Products website on how to correctly wire pan-pots.
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Old 2nd March 2013, 08:03 AM   #455
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by Nigel Goodwin View Post
...the balance pot in particular will do absolutely nothing.
I should say that one channel is connected to woofer, and other channel to mid/tweeter

the difference is more like choosing between dry in woofer position, and more sustain in mid/tweeter position

dry position for fast and rythmic playing
sustain position for a slower more melodic tune
differences are indeed subtle, but just enough to have a small effect

adjusting attenuator pot also changes this, and the tone

I know there are much better ways
but I just used what I had, more or less

I surely wont do it like this again but still quite fun to use the way it is....and way better sounding than any of the commercial effect units I have
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Old 2nd March 2013, 01:32 PM   #456
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Quote:
Originally Posted by tinitus View Post
I should say that one channel is connected to woofer, and other channel to mid/tweeter

the difference is more like choosing between dry in woofer position, and more sustain in mid/tweeter position

dry position for fast and rythmic playing
sustain position for a slower more melodic tune
differences are indeed subtle, but just enough to have a small effect

adjusting attenuator pot also changes this, and the tone

I know there are much better ways
but I just used what I had, more or less

I surely wont do it like this again but still quite fun to use the way it is....and way better sounding than any of the commercial effect units I have
It's not a question of 'what you had', it's a question of doing it wrongly

You could easily wire the pan/balance pot correctly, using nothing more than a few resistors

The resistors you've marked in red stop the volume control from working properly, and the pan/balance pot does nothing at all - you may as well just connect all three connections together and remove the pot, as any effect you think it has is just your imagination.
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Old 2nd March 2013, 07:36 PM   #457
tinitus is offline tinitus  Europe
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it simply too much fun as is
no, Im not yet tempted to change this one
its just a silly project
but maybe later
right now it just makes me smile every day
and believe it or not, it really does

dang, Im glad to hear my imagination is still working fine, thanks
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Old 4th March 2013, 08:24 AM   #458
tinitus is offline tinitus  Europe
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well, I was missing some of the gain I had lost
and a few days ago I also did some speaker crossover adjustments
in light of that I decided to try look at it again
and this is how it looks now

some was from previous efforts to try and make the balence pot more effective
it has some effect, but remains very subtle, no matter what
so no point in trying

like I previously stated, my next preamp will have two seperate channel attenuators

many thanks to Nigel for the encouragement

btw...I have some doubts about the series 1k and 1M ground resistors on input of last gain stage, after balance/splitter pot
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Old 4th March 2013, 11:38 AM   #459
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Quote:
Originally Posted by tinitus View Post
some was from previous efforts to try and make the balence pot more effective
it has some effect, but remains very subtle, no matter what
so no point in trying
It has no effect at all - it's purely imaginary - and you've done nothing to alter it.

Assuming you don't want to bother doing it properly? (using the link I posted), then change the pot from it's ludicrous 4.7K - make it 2M or more, this will then have a slight effect.
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Old 4th March 2013, 05:49 PM   #460
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by Nigel Goodwin View Post
.... change the pot from it's ludicrous 4.7K ...
thats all I had when I built it
and I had no intention of buying any other for a balance function of which I knew wouldnt work

it was just an experiment to see what would happen
and thats it, and nothing more, really

as I said, the only change will be seperate attenuators for each channel
and thats it

I mainly built this to test Kean's multiplier I plan to use later on
and the 2sk170 I happened have was convenient to use
far from perfect, but seems to work

its really just experimental, and thats all there is to it
it works ok as a very simple 2-channel preamp, and thats all I needed
but its just the beginning, and the work continues....forever and ever
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