Wampler - Faux Analog Echo Delay

[GodSaveMetal]

i see in the forum there is a topic about the Faux Analog tape delay... this was missing

[alexradium]

i see in the forum there is a topic about the Faux Analog tape delay... this was missing

very similar to the rebote,as BW said once

[Intripped]

very similar to the rebote,as BW said once

yes, all these PT2399-based delay circuits are similar one to the other - main differences are on the filtering
i like a lot the TONE pot, this allows you to get the sound you like; and i guess it's easy to add it to the rebote circuit or echo base also.

the only thing that i don't like is that you have some hiss that you can clearly hear under the repetitions - same as echo base (i don't know about rebote - never built it up)

anyway if you set the TONE quite dark, this hiss becomes very subtle, and the sound of the pedal is good and convincing

NOTE- I forgot to say: the cap marked as CXXX is not present on the board. also the value (100pF) is not correct.

[indyguitarist]

i see in the forum there is a topic about the Faux Analog tape delay... this was missing

very similar to the rebote,as BW said once

to be accurate though, the rebote is basically just the datasheet schematic material.

[MoonWatcher]

the only thing that i don't like is that you have some hiss that you can clearly hear under the repetitions.

anyway if you set the TONE quite dark, this hiss becomes very subtle.

the cap marked as CXXX is not present on the board.

To decrease the hiss, try increasing C8 and C21, and put a cap in the empty spot at CXXX. Aim for low pass filters that are roughly an octave lower than the hiss frequency, at least to start. A graphic EQ is good for a quick and dirty way of determining this, and might even help you decide on the exact frequency to cut.

Since you have 3 places to cut treble in the circuit, it should help to attenuate the hiss so that it doesn't sound like you're cranking a tone control all the way back. Socket the 3 cap locations for swapping.

And if you get those 3 values tweaked nicely, you could potentially even decrease C7 a bit, since it will no longer have to do the lion's share of filtering out the treble.

You may not need to start cutting treble a full octave below the hiss center frequency, and the LP filters at those 3 spots need not all be the same.

You may want to look at some Boss pedals or other common stuff to see how they cut the hiss with delays/trems/etc., and try their LP filter freq's to serve as a starting point. If you never use full range up to 5 khz or higher, it won't be critical if it's always cutting a little more treble than other pedals typically might.

[skywise]

very similar to the rebote,as BW said once

to be accurate though, the rebote is basically just the datasheet schematic material.

Yep. The Rebote 2 is the datasheet "application circuit" with an added op amp for input amp and output mixing.

Just about all the PT2399 circuits are going to look a lot like the datasheet. There is a basic footprint needed for it to work. What matters is what you do with the input and delay line filtering, how feedback is controlled, fun stuff like modulation, etc. Also, pre-selecting the delay chips is a big help in reducing noise. Some are much quieter than others.

[indyguitarist]

very similar to the rebote,as BW said once

to be accurate though, the rebote is basically just the datasheet schematic material.

Yep. The Rebote 2 is the datasheet "application circuit" with an added op amp for input amp and output mixing.

Just about all the PT2399 circuits are going to look a lot like the datasheet. There is a basic footprint needed for it to work. What matters is what you do with the input and delay line filtering, how feedback is controlled, fun stuff like modulation, etc. Also, pre-selecting the delay chips is a big help in reducing noise. Some are much quieter than others.

You hit the nail on the head -- the datasheet basically says "this is how to connect things to make a delay", and the difference in the different 2399 designs are exactly as you describe. Also, one of the big things we do is trash a huge amount of 2399's because they are just too noisy, or outside of our "specs".

[MoonWatcher]

very similar to the rebote,as BW said once

to be accurate though, the rebote is basically just the datasheet schematic material.

Yep. The Rebote 2 is the datasheet "application circuit" with an added op amp for input amp and output mixing.

Just about all the PT2399 circuits are going to look a lot like the datasheet. There is a basic footprint needed for it to work. What matters is what you do with the input and delay line filtering, how feedback is controlled, fun stuff like modulation, etc. Also, pre-selecting the delay chips is a big help in reducing noise. Some are much quieter than others.

It's cool that the Rebote serves as a fairly complete foundation, so that people tweaking it or designing a "new delay pedal" can concentrate on the latter stuff.

Some are much quieter than others - that's interesting. I've got a bunch of PT2399-based pedals, and none are noisy. I didn't know the chips were so inconsistent. I have a FAB echo that isn't noisy, and that's the cheapest PT2399 delay that I know of. Would Danelectro have a pre-selecting process? What a waste of components - the noisy ones must be discarded altogether.

[skywise]

What a waste of components - the noisy ones must be discarded altogether.

You don't have to get rid of the noisier ones. Just use them in something that does not overly tax the oscillator (ie - short delay times). Most all of them are quiet at less than about 200ms. The hissy ones could be used as a predelay for a Belton-style reverb, or for the various 2399 DIY chorus circuits, or something else entirely (like a slapback-only delay, or short delay with a ton of feedback to make a surf-reverb or something).

[Mbas974]

I'd like to add TAP tempo to this schematic, which DIY one should I use ?

[black03]

Hello, can someone tell me why the PT2399 is ruined often? I measured my power supply and delivery 9v

What is the critical point that causes the pt2399 to break? Can it be reinforced with a capacitor?

[marshmellow]

See here: http://valvewizard.co.uk/smalltime.html

Pin-6 of the PT2399 is a voltage source that rests at half the chip's supply voltage, which is provided by a 5V regulator in this case, so pin-6 will be at 2.5V. The current sucked out of this pin controls the delay time. An important thing to consider is that the current must not exceed 2.5mA when power is first applied or the chip is liable to burn out, so a 1k fixed resistor is included in series with the delay pot.

Also:

There have been reports that some PT2399 chips do not function properly if the digital ground is not connected directly to analog ground -this seems to depend on when the chips were manufactured. I therefore recommend that you short pin-3 directly to pin-4 of the PT2399, i.e., both pins will be grounded.

[black03]

See here: http://valvewizard.co.uk/smalltime.html

Pin-6 of the PT2399 is a voltage source that rests at half the chip's supply voltage, which is provided by a 5V regulator in this case, so pin-6 will be at 2.5V. The current sucked out of this pin controls the delay time. An important thing to consider is that the current must not exceed 2.5mA when power is first applied or the chip is liable to burn out, so a 1k fixed resistor is included in series with the delay pot.

Also:

There have been reports that some PT2399 chips do not function properly if the digital ground is not connected directly to analog ground -this seems to depend on when the chips were manufactured. I therefore recommend that you short pin-3 directly to pin-4 of the PT2399, i.e., both pins will be grounded.

Of course, I use a resistance of 1k, but the problem persists and it was with several pcb and different pt2399, for me there is a problem in the design, which according to the current received damages the pt2399.
what if I would like to know if there is any way to avoid this, something that does not allow the pt2399 to be damaged
If I modify the 1k resistance of pin 6 of pt2399 I think there will be less risk but I will have less delay time and it is not what I want.
What a big problem this is ...

[ppluis0]

Hello, can someone tell me why the PT2399 is ruined often? I measured my power supply and delivery 9v

Hello Black03

But you MUST supply the PT2399 with no more than 5Vdc as can be seen in the previous schematic...!!!

What voltage you have at pin 1 on the delay chip respect to ground ??

[black03]

Hello, can someone tell me why the PT2399 is ruined often? I measured my power supply and delivery 9v

Hello Black03

But you MUST supply the PT2399 with no more than 5Vdc as can be seen in the previous schematic...!!!

What voltage you have at pin 1 on the delay chip respect to ground ??

I understand that up to 2.5v can work well, is this correct? the resistance going to pin 6 determines the delay time and the correct minimum voltage?

[black03]

in this circuit I see that pin 9 and 10 have 150nf and 11 and 12 68nf, in all circuits I see that they place 100nf there, does this influence anything?

[lmkv15]

I'd like to add TAP tempo to this schematic, which DIY one should I use ?

http://uk-electronic.de/onlineshop/prod ... 1d15d1399d

regards Uwe