Lovepedal - Purple Plexi 800 [goop-alarm]  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
Post Reply
User avatar
dap9
Solder Soldier
Posts: 203
Joined: 21 Dec 2007, 03:56
Has thanked: 8 times

Post by dap9 »

Here's a recording of what I've got so far on the breadboard. At first the gain's all the way down and I go through the Frequency knob low to high. at about 0:50 I crank the gain and then again go through the frequency settings. Mine sounds a little fuzzy, but so far I'm having a good time w/ the circuit.

http://www.balderdashrecords.com/tunes/PP%20Clone2.mp3

Ghandi
Solder Soldier
Posts: 160
Joined: 14 Aug 2007, 14:52
Has thanked: 14 times
Been thanked: 28 times

Post by Ghandi »

Jimmy-H wrote:I like that Ghandi : "Blind testing"
Do you also use shades when you are testing? [smilie=a_fro.gif] :ROFL 8)
Just kiddin', but do you really hear a difference? (with or without shades.....uuuhhh 47 uF cap)
of course I hear a difference!!! :shock:
...try it yourselve!

User avatar
unbeliever
Breadboard Brother
Posts: 108
Joined: 15 Sep 2008, 22:48
Been thanked: 6 times

Post by unbeliever »

Ghandi wrote:@Jimmy-H,
0,1uF and 47,1uF filtering makes a difference I hear (at least) in a blind test
A blind test? How have you done this? On the same unit, modded, and listened to at different times? Or different units, where simple part tolerance (especially with electro caps) can easily explain away 'differences'?
and it could also easily explain the difference minatour87 measured with his septrum clone and a real PP800 on his spectrum analyzer.
Again, much more likely to be parts tolerance. Whenever you see an electro, keep in mind the (say) 47uf is a nominal value; it might be 20% less, or 80% (!) more.

Soooo ... what 'differences' do you hear? Can you record samples?

Ghandi
Solder Soldier
Posts: 160
Joined: 14 Aug 2007, 14:52
Has thanked: 14 times
Been thanked: 28 times

Post by Ghandi »

@unbeliver:
I don't have some samples on hand right now, sorry...

but you have build some stompboxes, right?
so, you could add a socket beween V+ and ground and ask a somebody to change the caps while you are playing the guitar.
I think even you will hear a difference...

more filtering makes the sound more focused and it appears to be less warm, to little filtering makes it muddy.
and the difference between 0,1uf and 38,6uf, even with the elco having only 37,6uF with a tolerance of 20% is HUGE!

have you ever tried some changes to your sompboxes yourselve,
or are you just waiting for the next best schematic to come along to clone?

take a tubecreamer clone with a cap 47uF cap from V/2 to ground
and then experiment with the filter cap V+ to ground.
try a 100uF cap and no cap, also a HUGE difference!

peace, love and bananas!
ghandi

User avatar
unbeliever
Breadboard Brother
Posts: 108
Joined: 15 Sep 2008, 22:48
Been thanked: 6 times

Post by unbeliever »

Ghandi wrote:@unbeliver:
but you have build some stompboxes, right?
One or two... not that many I suppose...
more filtering makes the sound more focused and it appears to be less warm, to little filtering makes it muddy.
and the difference between 0,1uf and 38,6uf, even with the elco having only 37,6uF with a tolerance of 20% is HUGE!
It wasn't clear from your post what you were referring to with the cap values; I mis-interpreted your English.
take a tubecreamer clone with a cap 47uF cap from V/2 to ground
and then experiment with the filter cap V+ to ground.
try a 100uF cap and no cap, also a HUGE difference!
It all depends on the current capability of the power supply, and the impedance between the circuit and the power supply; at least in my experience making a pedal or two...

Ghandi
Solder Soldier
Posts: 160
Joined: 14 Aug 2007, 14:52
Has thanked: 14 times
Been thanked: 28 times

Post by Ghandi »

unbeliever wrote: It all depends on the current capability of the power supply, and the impedance between the circuit and the power supply; at least in my experience making a pedal or two...
true, I'm talking about carbon 9V blocks here.

analogguru
Old Solderhand
Posts: 3283
Joined: 26 Jun 2007, 14:58
Been thanked: 110 times
Contact:

Post by analogguru »

Ghandi wrote:
unbeliever wrote: It all depends on the current capability of the power supply, and the impedance between the circuit and the power supply; at least in my experience making a pedal or two...
true, I'm talking about carbon 9V blocks here.
Full, half-full, or near empty ?

analogguru
There´s a sucker born every minute - and too many of them end up in the bootweak pedal biz.

Ghandi
Solder Soldier
Posts: 160
Joined: 14 Aug 2007, 14:52
Has thanked: 14 times
Been thanked: 28 times

Post by Ghandi »

8,954V

User avatar
GuitarLord5000
Posts: 33
Joined: 16 Nov 2008, 17:46
Completed builds

ROG Big Daddy
ROG Grace
ROG Little Gem
ROG Tantalus Project
ROG 3 Legged Dog
DOD 250
MXR Dist +
Easy Face
Fuzz face
Orange Squeezer

Has thanked: 2 times

Post by GuitarLord5000 »

dap9 wrote:I only have some LM386 floating around.
Hey dap9, are you still having that problem with the distortion cutting out when you hold a note for a long time?
I'm very curious about this, because I've had this exact problem with the LM386 chips. I've never gotten a good answer for this either.
Posted is '06:
https://www.diystompboxes.com/smfforum/ ... ic=43962.0

Seemed to be a problem with the chip, and not the circuit. All the chips I tried exhibited this problem when I built ROG Big Daddy, and the problem remained when I built a Smash Drive with them.
Cheers,
Dave

orogeny
Posts: 30
Joined: 15 Dec 2007, 23:18

Post by orogeny »

Uh, oh. That sputtering decay you guys are talking about is a deal killer for me. I was going to build this pedal but now I don't see the point.

BTW LOTS!!! of pedals seem to do this. The blues driver was the first one that caught my ears. Ever since I heard it, any pedal that doesn't pass the smooth decay to silence test is gone.

User avatar
dap9
Solder Soldier
Posts: 203
Joined: 21 Dec 2007, 03:56
Has thanked: 8 times

Post by dap9 »

GuitarLord5000 wrote:
dap9 wrote:I only have some LM386 floating around.
Hey dap9, are you still having that problem with the distortion cutting out when you hold a note for a long time?
I'm very curious about this, because I've had this exact problem with the LM386 chips. I've never gotten a good answer for this either.
Posted is '06:
https://www.diystompboxes.com/smfforum/ ... ic=43962.0

Seemed to be a problem with the chip, and not the circuit. All the chips I tried exhibited this problem when I built ROG Big Daddy, and the problem remained when I built a Smash Drive with them.

Yeah, unfortuantely. I can't find a source for the JRC 386 chip in the US (at least in the regular mouser/small bear places). :hmmm: I'd love to try that chip out

User avatar
soulsonic
Old Solderhand
Posts: 3750
Joined: 27 Jun 2007, 04:38
my favorite amplifier

Stopped using amps mostly...

Completed builds: too many!
Location: Cortland, NY
Has thanked: 97 times
Been thanked: 299 times
Contact:

Post by soulsonic »

http://www.mouser.com/Search/Refine.aspx?Keyword=NJM386

All "JRC" stuff is now under "NJM". Alot of times the package still says JRC on it.
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran

User avatar
dap9
Solder Soldier
Posts: 203
Joined: 21 Dec 2007, 03:56
Has thanked: 8 times

Post by dap9 »

soulsonic wrote:http://www.mouser.com/Search/Refine.aspx?Keyword=NJM386

All "JRC" stuff is now under "NJM". Alot of times the package still says JRC on it.
Doh! :slap: You (or somone else) already stated that in a previous post :oops:

thanks for the reminder!

minatour87
Posts: 17
Joined: 03 Sep 2008, 00:36
Has thanked: 4 times

Post by minatour87 »

i got a email from pacificsemi.com
they have LM386N-1 NSC 1013 0.25
see ya minatour87

minatour87
Posts: 17
Joined: 03 Sep 2008, 00:36
Has thanked: 4 times

Post by minatour87 »

Ghandi wrote:I know that, look who did reverse engineering. :mrgreen:

I'm asking minatour87 if he used the third 47uF cap on the clone he tested!?
...since there are some schematics which don't show that cap...
reviewing my document for the last version of this pedal i would say yes...
peace minatour87

mrhenry
Breadboard Brother
Posts: 71
Joined: 06 Feb 2008, 16:42
my favorite amplifier

soniccord toad, tweed bandmaster, JTM45

Location: Ft. Worth, Texas

Post by mrhenry »

ciccius,

Hi there. You can use anything that will sub for a LM386 chip, or equivalent. There has been some suggestion that the JRC386 is a better replacement. As always, you should check the data sheet.

http://www.national.com/ds/LM/LM386.pdf

also, for what its worth, you can tweak this circuit quite a bit. I am planning on working with it soon. The data sheet gives nice, clear instructions about regulating the gain at two pins on the IC, and instructions for input biasing. Since this is a low voltage audio power amp, it is pretty interesting to me since i am new at this.

Also, you should take note that this IC can be used in application that power a speaker. http://www.beavisaudio.com/projects/Noi ... k_Rev2.pdf

which makes me think..... :hmmm: Lovepedal used to issue something called the "2 Watt plexi" and also the "Half watt" amp head.... I would be willing to bet that they are merely a tweaked noisy cricket using... :secret: YOU GUESSED IT! LM386 chips.

have fun,
mrhenry

andregarcia57
Cap Cooler
Posts: 458
Joined: 16 Nov 2008, 16:42
Been thanked: 75 times

Post by andregarcia57 »

I put up this little box and I used the LM386, is there any problem or difference to jrc386? I also heard that the gain of the pot is still 0, but lower gain and bass?

User avatar
telecaster
Cap Cooler
Posts: 458
Joined: 17 Jan 2009, 01:57
Has thanked: 174 times
Been thanked: 12 times

Post by telecaster »

Don't turn your pedal to 10.
KindaFuzzy - Looks like a blue nail polish and nutella sandwich.
Freekish - "Our originality is in the basement. Our business is in the toilet"
Guitarlcarl - I did take offence at being called an idiot by a moron.

User avatar
soulsonic
Old Solderhand
Posts: 3750
Joined: 27 Jun 2007, 04:38
my favorite amplifier

Stopped using amps mostly...

Completed builds: too many!
Location: Cortland, NY
Has thanked: 97 times
Been thanked: 299 times
Contact:

Post by soulsonic »

It hisses because it's a noisy design made with a cheap noisy chip.
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran

User avatar
Fuzzer
Transistor Tuner
Posts: 1037
Joined: 16 Sep 2007, 16:17
Been thanked: 19 times

Post by Fuzzer »

soulsonic wrote:It hisses because it's a noisy design made with a cheap noisy chip.
:lol: :lol:
That's totally spot on;

But there are ways to cure it, more to mitigate it.

http://www.wentztech.com/radio/Technica ... ge11_3.jpg
The Freestompboxes Forum search function is soo great, use the search function..., the S E A R C H function.

Post Reply