Rebote 2.5 delay with tails and modulation (another epic journey thread)

[deadastronaut]

brilliant, cheers tubeguy, i'll give that a go...

so the same for 2-3 pt's then..

when you had your 800ms delay going did you end up with 'cleaner delay at say 4-500ms then?...compared to just 1 pt

[Kipper4]

Yep I see it now thanks Rob. How did I miss that?

[tubeguy]

brilliant, cheers tubeguy, i'll give that a go...

so the same for 2-3 pt's then..

when you had your 800ms delay going did you end up with 'cleaner delay at say 4-500ms then?...compared to just 1 pt

yep... the same for 2 or more pts.

Again, yes; the sound coming from a pair of pt2399 each having 400ms its alot more clean that one pt alone with 600ms for example.
The trick is to calculate the filters properly.

[deadastronaut]

ok, here is tubeguys schematic (thanks man) for the dual pt2399's = 800ms delay..

however i have this on breadboard with the required 5v voltage reg/and divider for Vb.  but still no delay..

this should work right?..i breaded it twice, checked over it...hmmmm...

[deadastronaut]

aha, got it going, it was the '1' cap from pt1 to pt 2 pin 16 misled me.....i thought it would be 1nf...turned out it was 100nf...voil'a

so i have delay now...

now for the tweaking of this @#$%er..

[tubeguy]

my mistake, sorry  . mix multiple nomenclatures on the values ​​of capacitors and resistors making it difficult to identify them. But, well, the thing is already sounding.

[tubeguy]

By the way, the cap is not 100nF, is 1uF poly o electrolitic no polarized. think that 0.47 poly can be used.

[Kipper4]

I'm following this. good work guys.

[samhay]

Glad you got it working Rob.
Are you using a dual-gang pot for the delay or 2 separate pots?

[deadastronaut]

cheers tubey.. 1uf it is then.  

@sam, i'm using 2 seperate trimmers on bread board at the mo...as my board is more crowded than a crowded thing on national lets get crowded day..

last night i burnt the midnight oil and tried the fet switch for tails... success!!!!

then added an lfo  (led/ldr) success.....using 2 breadboards now..


?..which part of the filters are responsible for the sound thinning out on repeats?.

? and which part of the filters are responsible for the initial first delay?..

[samhay]

I guess you should ask tubeguy, but...

^?..which part of the filters are responsible for the sound thinning out on repeats?.
Usually you lose trebble in the repeats, which is mostly a necessary evil, but if the repeats are 'thinning' does that mean you are progessively losing base content? If so, try increasing the 220n cap on the repeats pot's output.

^? and which part of the filters are responsible for the initial first delay?..
All of the delays are filtered by the RCs on the right hand side of the PT2399s.

I found this quite useful - http://sound.westhost.com/project26a.htm

[deadastronaut]

cheers sam..

very interesting article, the guy obviously spent some time with the pt's..

one particular sentence jumped right out at me, ....

''As it transpires, the circuit can be simplified quite dramatically. So much so, that I've tested the delay with no filters at all, and there is no audible noise''

i may have to try this crude test just to see how it behaves...if it does, then 4 pt's are going in series, with filters at the in and out...

[samhay]

Thought you might like that.

[deadastronaut]

 

btw, are their any other long delay chips about?...i mean the pt2399 has been around for a while, just wondered if they had been updated...made obsolete by a better performance chip?

[tubeguy]

For avoid the thin sound, change the cap of .47 to 1 uF electrolitic or poly (at the out of first opamp) and the same with the cap de 100n above mentioned (for 1 uF).
even the .22 cap maybe 1uF... test it and listen.
Good idea test in the breadboard put only filters of input and output... remember to configure opamps of the pt as unity gain amps (2 res of 10k its ok)

[Kipper4]

Quick derail question
Can i just add the fet switching momentary to the plain ol' rebote 2.5 and expect to get tails?
being as i have a rebote already made ,but am waiting to do the tails mod.

[deadastronaut]

hi guys, so something like this?..in a crude form..

btw the delay is definately cleaner at normal rebote settings, and can get longer with 'acceptable' noise...but if we slip in 1 or 2 more pt's it should be really clean at long stuff...and the shorter (normal rebote long delay) will be even cleaner.

that's the theory anyway..




@rich:  hmmmm i guess you could do it, you would have to slip drain and source  between op amp pin 7, and the 1uf..

but the switching might be mad as you would need another switch to turn off (bypass) the fet tails switch too...hmmmm...

[deadastronaut]

around 4.5 seconds of delay-ish..

https://dl.dropboxusercontent.com/u/7464107/delay%20test%203.mp3

[haveyouseenhim]

around 4.5 seconds of delay-ish..

https://dl.dropboxusercontent.com/u/7464107/delay%20test%203.mp3

   Count me in.

[psychedelicfish]

Sounds awesome! I've always found the max delay from a single PT2399 to be pretty unsatisfactory. It's just slightly too short and slightly too distorted to be useful.

When using several PT2399s in series, have you noticed any more noise/noise build up? I'm thinking it would be worthwhile taking a few extra steps to reduce noise with something like this. I see you've connected the digital grounds to the analog grounds. I'm no mixed mode circuit expert, but its probably better in terms of noise to connect the digital grounds to the analog grounds through a small resistor (10r or so), or even a small inductor, say 10uH (the type you get in resistor-like packages). Whether it would be better to connect all digital grounds together and then to the analog ground through a single resistor/inductor or to use a resistor/inductor for each chip's digital ground I don't know, so I'll leave that to those more expert than I.

Another thing you might consider is the LED used in Jon's (midwayfair) Hamlet Delay, where he puts an LED in parallel with the capacitor on pin 7, anode to pin 7 and cathode to ground. This supposedly makes it impossible to overload the digital sections of the PT2399 (you can still overdrive the onboard op amps though).