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Messages - sugrhigh

#1
Preamps and Effects / Re: preamp for LM3886?
February 20, 2008, 04:48:23 PM
Quote from: teemuk on February 20, 2008, 07:50:20 AM
If I would use the circuits in that kind of parallel arrangement I would likely put some kind of a rotary switch to that setup and I would also try to switch at both output and input sides of the pre circuit just to eliminate noise (few hi-gain circuit in parallel may contribute a lot of hiss). If you do not "drop out" the "unused" circuits with some switching arrangement you need to consider the total impedance of all preamp final stages that are connected in parallel: Most of them have a resistor that ties the output to ground reference, when you parallel few of these the total resistance may end up being substantially low, there's a good chance that some of the circuits cannot handle it and at at least it will effect the coupling/cut off frequency. The thing may need mixing resistors or buffers. I'm quite certain that you can't just parallel the circuits and get away with it without any modifications.

Another issue is how wise this paralleling even is in practice. I mean, do you really need all those preamps or could you just work out an arrangement where you remove all the "unnecessary" parts and devise a couple of ways to make the circuits share the parts that are common to all. For example, quite a many of ROG circuits (and their variants) have almost identical attenuating volume and gain control arrangements, the final low-pass filter stage is similar in most circuits, most of them use FET gain stages where only differences are practically the values of gain and coupling capacitance/cut off frequency. These can easily be made switchable and controllable, which allows voicing one basic circuit with many alternative ways. Many ROG circuits also substitute a proper tonestack circuit with some simplified arrangement.

i tried to point out it was a very basic idea, so you would indeed need a way to mute the "off" preamps that i didn't deem necessary to outline my idea

but i do like your idea of using common parts
#2
Preamps and Effects / Re: preamp for LM3886?
February 19, 2008, 11:11:54 PM
oh i see where youre going now

and i believe that is how combo amps do it

as far as input to the preamp, i would to something like:

----------------->power amp
|     |     |
|     |     |
|     |     |
p    p     p
r     r     r
e    e     e
a    a     a
m   m    m
p    p     p

1    2     3


and use a button of some kind to switch between them
#3
Preamps and Effects / Re: preamp for LM3886?
February 19, 2008, 06:00:55 PM
Quote from: darwindeathcat on February 19, 2008, 05:08:29 PM
Hey, how does one connect multiple preamps to the input of a poweramp? It would be VERY cool to build several of these runoffgroove jfet circuits into a combo amp. that way you could have multiple channels, all with a "clone" sound of the different amps those pedals are made to simulate.
  Would one simply connect the outputs of all the differnt preamps in parallel to the input of the poweramp stage? Or would one have to make sure that only one preamp is connected to the power amp at a time (ie. with a rotaryswitch ).I'm sure each preamp would have to have it's own input jack and control pots.
  I'm planning on making a lm3875 "gainclone" as a poweramp, and really would love to build several of these fairly simple ROG circuits as pramps for it... that would make a killer combo!

i think using multiple preamps would ruin the tone, unless thats the sound your looking for

just my opinion
#4
yeah, the noise doesn't bother me too much because i like the distortion it gives me when i use my little travel amp (the one that fits on a 1"x1" pcb...) with the tiny speaker, great for AC/DC type stuff!

but thanks for checking out the blog, i hope to finance my next amp using some of the adsense profit hehe
#5
I also posted this in the preamp section, hope that's okay...

basically it's a tiny preamp that can be built for less than $10 bucks ($15 if you go to Radioshack) that sounds nice but is extremely compact (my test PCB measured 1" x 1") that can be the backbone of MANY audio projects so check it out..... but read on if you want to know more!

On to the good stuff!
Well I have recently fallen in love with a little chip called the LM386 which costs only $.30...
yes 30 CENTS
so bought 20 of them to experiment with (not just audio stuff).

Chip Jr. (the name of the design, Chip Sr. is coming later) is a SMALL amp.
I did a test board that measure 1" x 1" yet sounds rather nice.
It has only 5 parts to it unless you decide to do some of my travel amp mods (on my site)

as always... check out the blog!
#6
Nothing big, so don't plan on using it in any amp over about 10W....
but I use it a lot to level out my single coil and humbuckers...

i have a bunch of ideas for it up there also so check out the article or my entire blog  :tu: (link for blog is in my sig)
#7
Amplifier Discussion / Re: Noisy Cricket Work Log
January 21, 2008, 10:36:07 PM
Well, the breadboard was successful.
Check the site, it's updated!
#8
Quote from: joecool85 on January 21, 2008, 07:06:22 AM
You will have to be careful on this one though since it has tubes in it, tube amps require high voltages that are sustained within the amp for long periods of time after it has been unplugged- normally about 500v.

an off topic question, but you can use a capacitor discharger and it would be safe then correct? well givven that its unplugged and everything...
#9
Amplifier Discussion / Re: Noisy Cricket Work Log
January 21, 2008, 10:25:37 AM
Quote from: joecool85 on January 21, 2008, 07:02:31 AM
This is cool doing a blog for that.  I went to it and clicked on a few ads.  You can do the same to help me here at SSGuitar :-)  Where do you go to school, and for what?  I am finishing a degree in New Media at UMaine right now.
Thanks a lot man.

Well, I just finished my last semester of high school (graduating early) and will be going to Rice University (Houston, TX) in about 2 weeks! I can't wait!

Going for a major in Biomedical Engineering if anyone wants to know. I just gotta learn some more electronics theory haha waited too long for that! I've always been more of a metal, wood, plastic guiy that got addicted to circuits!

Anyway, thanks to everyone who goes to the site and/or clicks the ads because all the ad revenue will go straight to the preamp circuit I have designed for the amp and THEN when I sell the amp as a whole, the profit will go to charity and cover the cost of the next amp...
#10
Amplifier Discussion / Re: Noisy Cricket Work Log
January 20, 2008, 08:01:29 PM
posted a Mouser compatible bill of materials... hope to get a lot of work done tomorrow since there's no class!!
#11
Amplifier Discussion / Re: Noisy Cricket Work Log
January 20, 2008, 02:56:46 PM
sorry for the double post, but thanks to all the people that went to my site, im now up to $1.03 from adsense! heh... but hopefully more people will go for the work log once it starts
#12
Amplifier Discussion / Noisy Cricket Work Log
January 20, 2008, 12:44:54 PM
I will be building my Noisy Cricket amp here soon. The parts are scheduled to come in tomorrow (No one ships on Sundays  :-\)

Check out my blog here for the work log and audio clips when I finish it.
I am also building a Les Paul so you can check that out as well.


Also, if you want to support my next build, feel free to click the ads on the right hand of the page  ;D
#13
Preamps and Effects / Re: preamp for LM3886?
January 14, 2008, 07:15:53 AM
It sounds great too, but would that circuit work?
Just have get the input levels right for the power amp correct?
#14
I thought so but wanted to make sure. Thanks

Yeah I'm used to following a pcb/perfboard layout, soldering, and using my multimeter and being done. Haven't read up on power supplies but I'll check out the whole wiki.

Thanks for all your help
#15
any help?