Which pt2399 delay to build?

[the3secondrule]

I've had no luck with the echo base or cave dweller ( both had that blub blub blub noise a high delay times, as well as being noisy.

I just played a pt80 however, and as far as an analog emulation goes, I'm impressed! I'm not looking for anything too fancy, with modulation etc, just a good sounding analog-alike, without the hassles of dealing with low headroom on v3205's or sourcing legit mn3005/3205s.

Anything aside from the pt80 I should be looking at?


J

[midwayfair]

Try my Hamlet if you have major headroom concerns. Otherwise, all the Zero Points are awesome, and the Multiplex is amazing.

[jkokura]

Quite frankly, they're all going to suffer at long delay times. It's one of the reasons I can't stand the PT2399. The PT80 is pretty clean because it uses Companding.

Don't go for the Cavedweller. You could try the Hamlet, Multiplex, or the Zeropoint. The last two use dual PT2399s to help get longer delay time with cleaner repeats.

Jacob

[the3secondrule]

Try my Hamlet if you have major headroom concerns. Otherwise, all the Zero Points are awesome, and the Multiplex is amazing.

It's not so much the headroom that concerns me ( although I have been eyeing up the hamlet - who is selling the boards?) more the garbage noise that seems to be inherent with the pt2399. Companding seems to be the way to go ala pt80, but I really should check out the ZPs and mplexes. I guess the echo base just put me off PTs in general...

[culturejam]

In my experience, there are two main factors that mitigate the "hash" noise in PT2399 circuits:

1) Aggressive low-pass filtering. This is absolutely clutch. Forget fidelity, as the 2399 isn't capable of anything approaching "clean" for delay times beyond about 150ms. The bandwidth just isn't there, so there's no reason to chase it. Filter the shit out of the delay line and don't look back.

2) Chip selection. 2399s vary widely on noise. Many are moderately noisy, a few are terrible, and a smaller few still are pretty damn nice sounding (even at longer delay times). If you are determined to get long times, you need to test the chips the old-fashioned way: with your ears. Try out half a dozen or more 2399s, and keep the one with the best noise characteristics.

Also, using multiple chips in series may not always help reduce net noise if one of the chips is especially noisy. The noise is cumulative and gets multiplied as it goes through the iterative chips. So again, look back at #1 above. Filter early, filter often. Shaving off of the high-end distortion progressively is critical to the multi-chip setups.

Another thing to think about is a dual-gang pot for delay time. Use one gang for Time, and the other as a tone control to drop the cutoff frequency of the LPF as delay time increases.

[GhostofJohnToad]

So what is this PT80 chip? Never heard of it before this.  I'm intrigued.

[kothoma]

No PT80 chip. It's a delay using a PT2399 and NE570 compander. It is modelled after the classic Ibanez AD-80 but without BBD.
See
http://deewm.com/All/PT80/pt80.html
http://uk-electronic.de/onlineshop/index.php?cPath=105_195_352&language=en

Edit: See also
http://www.generalguitargadgets.com/projects/20-modulationecho/125-pt-80-delay

[Cortexturizer]

I became fed up with pt2399 very quickly just like Jacob...I mean it's okay for clarinots and similar noise makers, but for a good delay that doesn't get lost in the mix, especially with distortion, I'd look elsewhere.
Still, I'm gonna build a Hamlet with tap-tempo once it becomes available.

[chromesphere]

I've only built two pt2399, a rebote and the sea urchin. They both have similar sort of characteristics, although I would say the sea urchin has better filtering.  Unfortunately as stated already, the pt2399 suffers from nasty distortion in the +300ms region and I don't think it matters which layout you use your not going to be able to get around that.  Their still a bit of fun though and if your into building pedals definitely should build one!  They also compliment a more professional delay pedal.  I have a damage control timeline (timeline version 1 you could say) and I like to put the sea urchin in front of it to extend swells, or to combine short and long delays together.
Paul

[jimilee]

Hamlet and deprofundis are 2 fantastic builds. Very clean

[midwayfair]

Try my Hamlet if you have major headroom concerns. Otherwise, all the Zero Points are awesome, and the Multiplex is amazing.

It's not so much the headroom that concerns me ( although I have been eyeing up the hamlet - who is selling the boards?) more the garbage noise that seems to be inherent with the pt2399. Companding seems to be the way to go ala pt80, but I really should check out the ZPs and mplexes. I guess the echo base just put me off PTs in general...

Like Forrest says, the PT2399 just doesn't have the bandwidth to do "clean." Companding only helps manage signal levels going into the chip -- if you avoid feeding it a signal that will exceed the 5v power rails, then you can avoid overdriving the PT2399, but you won't make it sound cleaner.

The Hamlet "cheats" in multiple ways ... it feeds the chip an attenuated signal (rather than what's done in something like the Deep Blue Delay where the signal is boosted before it goes to the PT2399), it has an LED cap on the current of the PT2399 itself (which prevents the audio signal in the chip from ever exceeding 1.7V but doesn't distort because it doesn't clip the audio), and it has severe filtering which is then reamplified and tone shaped by a stage that's completely separate from the dry path (getting around the issue most delays have where they mix the delay signal raw back in). I'm not trying to puff up my design, but it's WAY simpler than using a compander, uses a 2c indestructible diode instead of a $5 chip that blows up when you look at it wrong, and the topology allows a delay line that still SOUNDS bright but is clean for most of the dial.

Also, re bandwidth concerns, it's not like even MN3005s are that high fidelity to begin with. It takes two of them, preceded by a compander, severely band-passed, running on 15V, to put out a "reasonably" clean 500ms. The Zero Point SDLX's analog mode is astoundingly good, and it does all this other stuff, too ...

[kothoma]

... Companding only helps manage signal levels going into the chip -- if you avoid feeding it a signal that will exceed the 5v power rails, then you can avoid overdriving the PT2399, but you won't make it sound cleaner.
...

To be acurate, companding not only reduces overdriving, it also reduces the added noise (as in S/N ratio) a bit.
Totally agree otherwise.