Quote from: joecool85 on October 31, 2006, 02:31:49 PM
As far as small practice amps go, I really haven't heard anything that I like better than my K-20X.

I bought a used Vox DA5 this weekend.  Super nice amp with great effects.

Any more kits available?

Quote from: joecool85 on October 22, 2006, 08:02:20 AM
Awesome!  Do you have any sound clips/pics?  Sounds like you've made yourself quite the amp.  It's good to know that those LM1875 kits are going to good use.   

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

Opamp and judging by the pin count probably a dual OPamp like a TL072.

http://focus.ti.com/lit/ds/symlink/tl072.pdf

And yes it looks like a buffer to provide a high impedance (1m ohm in this case) input for the input jack.

Yea, I'm a tube amp guy but I don't have one at the moment.  I kick myself every day for selling my Marshall 50 watt several years ago.

The Spider III was really impressive for a solid state amp.  As technology advances, I believe you won't be able to tell the difference between a tube amp and a solid state one but right now there is a noticable difference.  For instance, I played on the new Mesa Boogie Stiletto Ace and that is THE best sounding amp I have ever played on.  The one I played on was a 50 2x12 combo and it made the hair on my arms stand on end.  But of course it has a wicked price of $1869.  It should make the hair on your arms stand on end!  I also played on a B-52 2x12 100watt combo which was a very nice sounding all tube amp.  Price was $749 but Harmony Central has a lot of user posts with reliability issues.

I'm in the market for a 50watt all tube combo but just haven't found what I'm looking for yet.

Quote from: rockgardenlove on October 29, 2006, 01:57:14 AM
These amps sound really terrible...
Horribly digital tone. 

I played a new Line 6 Spider 3 yesterday.  That thing sounded really good.  Over 400 presets and several artists favorite presets.  Nice sounding amp.

I'd post it in the diyuadio.com Musical Instruments forum.  Might get a few more looks at it.

Just got my two free sample LM4780s from National in yesterday.  I was thinking that my next project would be a Stereo 55W guitar amp.  Run it through a stereo 2X12 or 4x12 cabinet.  Would a bridged LM4780 configuration be a better idea?

I wonder if there is a plus/minus power supply version of either of these two?

Can't help you but I've got an 1875 project that needs to be put together as well - after my 3875 project of course.  Post up what you find or use.  I'm interested!

Yea, I made a PCB of the ESP Project 27 preamp.  I made a few changes.  After I get the amp all together I'll see if it sounds as good as it does with a +-9V supply as a stomp box which is how I tested it.

I have the same transformer.  Doc from the Avel web site.

Well I tried putting a dual power supply on a Sans Amp Preamp and it didn't like it.  Great distortion but not a whole lot of change between all of the different settings.  Someone with more electronics background is going to have to sort this one out.  I went ahead and used the ESP Project 27 premap.  I used my own circuit board and made several options for the clipping diodes (diodes, LEDs and soft/hard clipping).  It sounds pretty good.  I need to change a couple of caps to get a bit more low end out of it though but other than that it sounds pretty good.  I'll probably go with this config for my LM3875 Chip Amp.

Quote from: Stompin_Tom on August 31, 2006, 11:02:34 AM
I see... yes, that's the sort of solution I was looking for... How would you change the components if you needed a different voltage, I wonder?

Did you decide on a preamp, turbo?

Well, I have two preamps built and ready to go.  The Sans Amp GT-2 from www.tonepad.com which is a converted stompbox preamp and I've also built the Project 27 preamp from ESP.  One of these should work I'm guessing.  I'm hoping the Sans Amp preamp works like I want it to.  I need to find a nice high gain preamp to play with as well.  Anyone have suggestions?

You can change the resistore to suit the amount of power you need.  The schematic above is set up for about 50 milliamps at +-15v.  35V / 680 = .0515.  If you need more power than that, you can drop the power resistor value some and if you need to change the voltage, use a different value Zener diode.

Check out the preamp schematic in ESP's Project 27.  He uses a power resistor and a Zener diode.  That's how I'm powering my preamp.

Quote from: RDV on August 28, 2006, 02:09:27 PM
I'm using a 160VA 22 + 22 volt toroid to power two and it does fine but that's about as low as you can go for two. The 220 VA would give you all the power you'd need.

What size fuse do you have on the mains?