6w Per Channel stereo Guitar amp Layout Inside. Also, Orange MKII emu Layout.

[nelson]

I saw someone request some more amp projects in the "what project would you like to see" thread.


Plus, I want a little stereo bench amp.

So, I layed this out tonight, thought I might aswell share it.

http://www.yourfilelink.com/get.php?fid=77728

(link will die if no one downloads it for 30 days)

The layout is unverified.

You can use the single Preamp layout as a Jfet Emulation of the Orange Graphic MKII minus FAC and Boost pot, although they could easily be added in, I havent provided pads.


The power amp is based on the TP1517NE Stereo power amp IC. Basically lifted straight out of the datasheet, with minor modification to remove standby and mute functions. I have provided a seperate Power amp board layout and PnP blue graphic for those who want to use their own preamp.

I am looking for ideas on a suitable low parts count compressor limiter circuit to insert between the preamp and power amp.

Stereo effects loop can easily be added.

Runs on 18v Wall wart. Dunlop sells a good one for $19.99.

Any suggestions for a suitable compressor/limiter, glaring mistakes and any huge criticisms most welcome.

Thanks.
Nelson

[nelson]

90 views, and not 1 comment?

[Joecool85]

Neat!  I like it a lot.  Do you think you could post it at ssguitar.com?  Or if you don't want to, can I post it there?

[phaeton]

I saw someone request some more amp projects in the "what project would you like to see" thread.

me! me! it was me!

Thanks for the link... i'm going to pore over it tonight (unless beer gets in the way).  I always wondered why there aren't more stereo combo amps on the market, with all the stereo effects that are available.  I realize that physical separation is key, but even putting a pair of speakers at 45-degree angles or back to back facing sideways makes a difference.

Btw, what program did you use to draw this up with? gschem works, but I find it sometimes lacking. Thanks for sharing.

Someday I want to do the whole hex pickup/6 amplifier thing, but coming across 6 identical speakers without blowing a huge wad on new stuff is the killer.

[Zero the hero]

MANY THANKS, Nelson!
I've just spotted this thread, I haven't seen it before!
If I find this IC I think I'll build it, cause I'm looking for a simple amplifier for driving a synth I'm building (top secret!  )

[Lurco]

TDA1517 ?

[Mark Hammer]

A place near me "recycles" computers, and has bins of cards of various types (nic, video, etc.).  I can vouch for the fact that if it was a low end sound card from 6 years ago or more, and had a jack for powering speakers directly, the chances are very good it used a TDA1517 (if it didn't use a TEA2025) for powering the speakers.

If you can't find a supplier nearby, see if you can find a junk box of old sound cards somewhere and cannibalize it for the 1517.

[nelson]

TDA1517 ?

TPA1517NE

Its manufacturted by Texas Instruments.

There were free samples available last time I checked. Well, thats where I got mine.

[nelson]

Neat!  I like it a lot.  Do you think you could post it at ssguitar.com?  Or if you don't want to, can I post it there?

Post Away. I posted it here for public consumption.

Thanks for asking permission.

[nelson]

MANY THANKS, Nelson!
I've just spotted this thread, I haven't seen it before!
If I find this IC I think I'll build it, cause I'm looking for a simple amplifier for driving a synth I'm building (top secret!  )

And here was me thinking you had gone to the darkside of Retro computing!



LOVE the pic on the main page btw.

[George Giblet]

If you want critical comments I can say there's a good chance it will sound muddy, particularly for clean.

The pre-stages have speaker sim low-pass filters *and* the power amps feed speakers so there is double roll-off happening.

Most guitar amps have low damping add further treble boost and some bass boost.

The correct balance depends on thre final speaker but, as is, I suspect it's not voiced correctly for the majority of speakers.

[nelson]

If you want critical comments I can say there's a good chance it will sound muddy, particularly for clean.

The pre-stages have speaker sim low-pass filters *and* the power amps feed speakers so there is double roll-off happening.

Most guitar amps have low damping add further treble boost and some bass boost.

The correct balance depends on thre final speaker but, as is, I suspect it's not voiced correctly for the majority of speakers.

I left the speaker sim filters off the actual PCB layout.

I forgot to remove them from the preamp schematic. (basically cut and pasted from the Citrus MKII)



The 2 470R with 10uF cap to ground network on the 3rd gain stage can be tweaked.

[nelson]

If you want critical comments I can say there's a good chance it will sound muddy, particularly for clean.

The pre-stages have speaker sim low-pass filters *and* the power amps feed speakers so there is double roll-off happening.

Most guitar amps have low damping add further treble boost and some bass boost.

The correct balance depends on thre final speaker but, as is, I suspect it's not voiced correctly for the majority of speakers.

I forgot to thank you for your critique.

I really do appreciate any criticism.

Sometimes I overlook things.

[Zero the hero]

MANY THANKS, Nelson!
I've just spotted this thread, I haven't seen it before!
If I find this IC I think I'll build it, cause I'm looking for a simple amplifier for driving a synth I'm building (top secret!  )

And here was me thinking you had gone to the darkside of Retro computing!



LOVE the pic on the main page btw.

  I hope to come back to electronics soon! I'm wasting too much money...

[Joecool85]

Neat!  I like it a lot.  Do you think you could post it at ssguitar.com?  Or if you don't want to, can I post it there?

Post Away. I posted it here for public consumption.

Thanks for asking permission.



Sweet.  I'll post that up later on ssguitar.com, which btw, would be cool if you checked it out and joined :-)

[George Giblet]

> I forgot to thank you for your critique.

No problem.  You've got thing's I mentioned covered!

[Mark Hammer]

I thought I had successfully posted this yesterday but I guess I was wrong.

The old Roland JC120 was much-loved for its rich chorus sound.  One of the reasons the chorus sounded so good was because the dry and wet signals each had their own power amp and speaker.  This nice compact little design strikes me as a terrific way for those who have not tinkered with the delights of stereo or split processing to start doing so.

It could be delay or spring reverb going into one of the channels, or perhaps a modulated delay (chorus or flange) going into the second channel, or perhaps a phase-shifted signal, or merely asynchronous tremolos, or two different fuzzes.  Whatever the case, get into experimenting with using two different sounds coming out of two different speakers.

2 x 6w is obviously not a gigging amp, but a medium-sized package with a pair of decent 6" or 8" speakers could make a nice little studio amp.

[nelson]

I thought I had successfully posted this yesterday but I guess I was wrong.

The old Roland JC120 was much-loved for its rich chorus sound.  One of the reasons the chorus sounded so good was because the dry and wet signals each had their own power amp and speaker.  This nice compact little design strikes me as a terrific way for those who have not tinkered with the delights of stereo or split processing to start doing so.

It could be delay or spring reverb going into one of the channels, or perhaps a modulated delay (chorus or flange) going into the second channel, or perhaps a phase-shifted signal, or merely asynchronous tremolos, or two different fuzzes.  Whatever the case, get into experimenting with using two different sounds coming out of two different speakers.

2 x 6w is obviously not a gigging amp, but a medium-sized package with a pair of decent 6" or 8" speakers could make a nice little studio amp.

Thanks Mark.

Thats the idea.

Any ideas for a nice low parts count compressor/limiter for inbetween the preamp and poweramp?

Ala the vox design.

I dont think this chip will sound too great clipping.

[Joecool85]

I posted this at ssguitar, if you want to ask questions there about adding circuits to it, feel free to, we have a lot of knowledgable people over there that work on this type of stuff.

[Mark Hammer]

Any ideas for a nice low parts count compressor/limiter for inbetween the preamp and poweramp?

Ala the vox design.

I dont think this chip will sound too great clipping.

What you want is either something that uses feedforward, with the amplitude/envelope detection at the input and the attenuation further downstream, or maybe something like what Crate uses with their amps to link the power amp feedback to a Vactrol-based attenuator circuit at the input to the amp.

I suspect the simplest method might be to run a line out from Q1, Q2, or Q3 through a diode to a Vactrol that forms parts of the master voume circuit, or some secondary attenuator circuit after the master volume pot, à la Crate.  In this way peaks could adjust the volume in a downward direction, but without producing full-out compression.