SOLSTICE: Even easier PT2399 reverb!

[merlinb]

Some of you may remember my Equinox reverb: http://www.diystompboxes.com/smfforum/index.php?topic=93868.0 which used two PT2399s in parallel for its reverb sound.

Having proved the concept I decided to simplify the circuitry by putting the PT2399s in series instead, so naturally it had to be called Solstice! It uses many fewer components since only two of the on-board opamps are now required, taking care of both the input and output filtering simultaneously. I also eliminated the fat/bright switch, since I never use it on anything but bright. Tail switching remains, naturalment.

Here is a quick sound clip. I recorded a sample into my computer and played it back through the Solstice, reverb at zero, then 12 o'clock, then maximum. Some EQ added later for a simple cab sim.
http://dl.dropbox.com/u/57831278/solsitce.mp3

Interestingly I think the Equinox sounded a bit more springy, whereas Solstice sounds a bit softer and more like a real hall...

Schematic, PCB and layout can be found here:
http://s81.photobucket.com/albums/j207/merlinblencowe/Solstice%20Reverb/

Also I have put everything (including BOM) into a single PDF:
http://www.freewebs.com/valvewizard2/solstice.PDF

The circuit is a bit big, so here is a basic overview of the topology for quick reference. Lots of fun to be had by varying the feedback and delay resistors. Various room, bathroom and metal box sounds are possible with modding, if not very useful...



It doesn't look much on the outside yet, but I will update when I have finished decorating it (unless you're reading this in a year's time, in which case I have probably gotten around to it   )

[Keeb]

Just today I downloaded the Equinox documents to build for a friend...
Have to give this a try!
Thank you.

[sugonidamaso]

WOW! Another master craftsmanship! Great word merlin! Based from the sample. Equinox is more roomy(?-still love the switch ).

[Earthscum]

That's really neat! I thought about using 2 delay lines before, but never could brainstorm a way to make it work... man, I was way off! I gave up on it when you posted Equinox (that's when the realization hit, I think, that I had lots more to learn about delay stuff in general).

One idea I had that may be feasible is using a BBD like 3207 for the longer delay line, driven by buffered and divided down clock from the PT. I'm thinking (dangerous at times) that the difference in sound from the 2 lines would interact for some extra texture.

[Perrow]

I really like the sound of this, I'll have a listen with something other than my phone speaker, but this might go into my next amp build.

[midwayfair]

This one sounds fantastic, and it's a nice change from all the Benton chip designs.

Your compressor is really cool, too, it's on my build list. This one's a little beyond perfboard, though ... I might have to get someone to etch it for me when I go to build an amp with no reverb.

[mr_deadmaxxx]

another one.

[Jdansti]

This sounds great!  I'm in the process of building it and was wondering if it would be useful to move P2 off board and use a regular pot so that I could control the delay without opening the enclosure.

[merlinb]

This sounds great!  I'm in the process of building it and was wondering if it would be useful to move P2 off board and use a regular pot so that I could control the delay without opening the enclosure.

Sure, knock yourself out! Personally I don't find it very useful, so I just drilled small hole in the bottom of the enclosure so I can twiddle the trimpot with a screwdriver.

[Jdansti]

This sounds great!  I'm in the process of building it and was wondering if it would be useful to move P2 off board and use a regular pot so that I could control the delay without opening the enclosure.

Sure, knock yourself out! Personally I don't find it very useful, so I just drilled small hole in the bottom of the enclosure so I can twiddle the trimpot with a screwdriver.

Good idea. Thanks!

[Jdansti]

Just finished testing my Solstice and it works great!!! (after remembering that my PS is center neg thank you for the protection diode!)

Haven't boxed it yet, but here's the board. Most of my poly caps weren't as small as yours so I had to get creative with the lead bending.



I experimented with the delay pot and decided to keep it off board in case I want easy access to a slappier sound. Thanks for sharing this with us!

[merlinb]

Thanks Jdansti, glad you like it!

I have just finished designing the PCB for a simplified Equinox that is a drop in replacement for the Solstice (no fat switch), so eventually I will post that too. Much smaller PCB than the original Equinox.

[lukatosh]

Great job merlinb!!

i've one question... what do i have to do to make this pedal true bypass and use a 3pdt?

excuse my noob question

[merlinb]

i've one question... what do i have to do to make this pedal true bypass and use a 3pdt?

Like this, but without bothering with the DPDT tails switch (red). The green switch is the 3PDT, with the third pole being used for the LED switching on the PCB.

[garcho]

Thanks Merlin!

[newild]

Hi guys, are you ok? My Solstice doesn't modulate, when I switch on, the sound doesnt change, please help me, thanks a lot!!!

[Jdansti]

Hi guys, are you ok? My Solstice doesn't modulate, when I switch on, the sound doesnt change, please help me, thanks a lot!!!

I just ran into a similar problem I find that mine works for about 10 minutes and then it sounds 100% dry. The 78L05 reglulator becomes so hot that I can't touch it. If completely power it down and wait for about an hour, it works fine again for another 10 min.

Edit:  BTW, welcome to the forum!!!

[greaser_au]

I just ran into a similar problem I find that mine works for about 10 minutes and then it sounds 100% dry. The 78L05 reglulator becomes so hot that I can't touch it. If completely power it down and wait for about an hour, it works fine again for another 10 min.

the 78XX family has a 'thermal shutdown feature, if the device gets too hot it will try to protect itself by turning off the output. overheating is casued by excessive dissipation, so check the voltage across the regulator and current draw (perhaps open LK9 and insert your multimeter).

According to the data sheet, the PT2399 draws 30 to 40mA, so 2 of them draw 60 to 80mA from the regulator output (78L05 max = 100mA).  If you are using a 9V regulated supply, the regulator will have (9V-5V)=4V across it, and will dissipate 240 to 320mW. the T0-92 device has a case-ambient thermal resistance of 200degC/W, so the temperature rise of the regulator chip will be 48-64 degrees C from ambient.  At an ambient of 20C  (68F) the regulator chip is at 68-84C - a bit warm, but still ok.
However - if your PT2399s both draw on the high side, and you use an unregulated supply (say 12V - not unusual for 9V wallwarts) we might see"  0.08A* (12-5V)=0.56W.     0.56W*200=112 degrees. At 20C ambient (junction temperature is now 132C) we are getting a lot closer to shutdown territory.

if everything is normal & works ok otherwise it might be worth replacing the L series regulator with a 7805, simply because the temperature rise will thoretically be only be 25% (case-ambient thermal resistance of 50degC/W).

david

[Jdansti]

I just ran into a similar problem I find that mine works for about 10 minutes and then it sounds 100% dry. The 78L05 reglulator becomes so hot that I can't touch it. If completely power it down and wait for about an hour, it works fine again for another 10 min.

the 78XX family has a 'thermal shutdown feature, if the device gets too hot it will try to protect itself by turning off the output. overheating is casued by excessive dissipation, so check the voltage across the regulator and current draw (perhaps open LK9 and insert your multimeter).

According to the data sheet, the PT2399 draws 30 to 40mA, so 2 of them draw 60 to 80mA from the regulator output (78L05 max = 100mA).  If you are using a 9V regulated supply, the regulator will have (9V-5V)=4V across it, and will dissipate 240 to 320mW. the T0-92 device has a case-ambient thermal resistance of 200degC/W, so the temperature rise of the regulator chip will be 48-64 degrees C from ambient.  At an ambient of 20C  (68F) the regulator chip is at 68-84C - a bit warm, but still ok.
However - if your PT2399s both draw on the high side, and you use an unregulated supply (say 12V - not unusual for 9V wallwarts) we might see"  0.08A* (12-5V)=0.56W.     0.56W*200=112 degrees. At 20C ambient (junction temperature is now 132C) we are getting a lot closer to shutdown territory.

if everything is normal & works ok otherwise it might be worth replacing the L series regulator with a 7805, simply because the temperature rise will thoretically be only be 25% (case-ambient thermal resistance of 50degC/W).

david

David-

Thanks for the information about the regulators. I suspected the same, but I think I saw 5V on the output after the Solstice stopped working.  I'm going to substitute a 7805 anyway and see what happens. If I understand you correctly, the temp rise on the TO-220 case should be small enough to not require a heat sink. Is this correct?

[greaser_au]

David-

Thanks for the information about the regulators. I suspected the same, but I think I saw 5V on the output after the Solstice stopped working.  I'm going to substitute a 7805 anyway and see what happens. If I understand you correctly, the temp rise on the TO-220 case should be small enough to not require a heat sink. Is this correct?

I'd say at regulated 9V you won't need heatsinking.

david