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Messages - Bob N

Nah, I'm not lookin' for freebies.... I have no problems paying someone for providing a good kit at a fair price...
If we end up doing another run, let me know.... I'd also be interested in the LM3886.... I've got a million uses for these little screamers....
Amplifier Discussion / Re: What is this ic?
November 04, 2006, 10:47:42 AM
Quote from: soren_jepsen on October 31, 2006, 03:43:48 PM
Guess my knowledge in electronics is very simple theory fusioned with trial by ....smoke.

Don't knock it... That's how I learned too... I was fortunate to have my first 10 projects turn out just fine, probably because I'm a stickler for detail, but as my "trial by smoke" has advanced to tubes and transformers, I'm now finding some of my educational limitations. For some reason, I understand Solid State very well, but tubes and transformers are somewhat baffling to me, then you add the much higher voltages and a healthy fear of being zapped makes you think twice about screwing around with it....

What I've found is that the preamp section of whatever amplifier you want feeding into a well documented DIY Amplifier section (Such as LM3886 or LM1875) makes for a very nice setup most of the time, but that doesn't mean you can't DIY a full blown copy of "name your amp". It just means you might run into custom labeled ICs in the schematics, when they are labeled with the IC part number... The reason I like to stick to the Standard DIY amplifier sections such as listed above is for the support factor, in addition to the fact that the parts are usually very easy to come by and are usually very inexpensive as well.... All of which are huge pluses
Quote from: turbolx5oh on October 31, 2006, 08:26:31 AM

How did you wire the power supply up on your preamps?

I've got my schematic back at the house. I'll see if I can dig it up for you, BUT I built my own power supply based off of the Bi-Polar Power Supply project at General Guitar Gadgets... (

I've used this one before in many other projects and it works great. I used this one because of my familiarity with it as well as having a few problems with the one that was provided. My problems with the factory power supply could very easily have been me, so take it with a grain of salt, but I know the one I used very well. All in all, it's quite a punchy little amp in a super small form factor that was extremely easy to build.

My question is are we gonna sell 'em here??? I've got a few more uses for them and just want to know where I will be getting them...
Sorry for the slow response.... Been working a ton at the job and been working out a problem on my Firefly (.75w tube amp)....

No clips yet and still tying up all the loose ends before submitting my work for critique. you WILL see pics and Hear clips when I tie it all up though...
I am using a multi switch to control 4 different SS JFet preamp stages: 18 Watt, JCM800, Thunderchief, and the DR Boogie. All of this fits into my old, nasty Crate GX-15 chassis and quite honestly, saved it from a horrible death as I couldn't stand the way it sounded out of the factory. Now I actually enjoy putzing around on it with so many different sounds. The little 20 watt LM1875 does a pretty good job of torturing the 8" factory speaker the amp originally came with. Yes, this is all for guitar, and I still have another 20 watt amp to figure out what I'm going to do with...
My kit went together very well and has been performing solid ever since. The documetation was pretty good but could use more information on power supplies and how to wire them up, but outside of that, was a very solid kit and I would do again a million times over..... The kit is an outstanding value for the performance it provides....
I already double checked it and touched all solder connections with the iron again.... Still the same result..... I'm wondering if a diode or two are shot.... I've seen stranger things happen.... I'm gonna get this damn thing if it kills me.... I hate these flaky things that go wrong... LOL All In Alll though, it was a very easy build outside of this .....
They're installed exactly the way it shows in the instructions.... I'm gonna put it away for a bit to clear my head.... If you guys think of anything, go ahead and post it.... I'll come back to it after the storms come through.....
ok.... I went back through everything.... 12.6 out of both sides of the transformer.... 8.1 volts out of the diodes... That's where I'm losing the voltage.... This is without the amp circuit connected and just the power supply and transformer... I've been through everything 10 times at least checking for errors.... I haven't found any bone-headed mistakes anywhere... polarity on the caps is right as well.... Any other suggestions to look at?
Ok... Got my kit about a week or two ago and had other things that needed to be addressed.... I put it together over the weekend and am having an issue.... with a 12.6 - 0 - 12.6v transformer I'm getting +- 8v... Is this correct?

Another problem... I'm smoking transformers... The first went up in a puff of smoke and andcetthe second smells like it's burning up after about 15 seconds or so... I am getting sound out of it however and it sounds good.... Just wondering about the voltage and where to look for the transformer issue....

The transformer is hooked up 12.6v on the +... center tap 0 as the ground and the other 12.6v on the negative side of the circuit....
I'll post a new thread with the entire build process of the amp with sound clips. If worse comes to worse, I'll use the sim as a line out feature on the amp, but I will record a bunch of clips so you can hear everything through the build both mic'd and direct. My donor amp is the Crate MX15R practice amp that I despise so much, but I'll be keeping the circuit board intact to play frankenstein with again if this experiment goes awry.

Now, off to reading the documentation that Teemuk forwarded. looks like it could be some cool reading...
Thanks for the input Teemuk! I'll take a closer look at that documentation on Wednesday and make adjustments to the circuit board as needed. I will post what I come up with just to confirm. I plan on building this into my Solid State using the DR Boogie as the preamp, just to see what happens.

Is everyone in a wait and see mode to see what this will do sound-wise? or no interest?