PT2399 motorboating problem with new ICs

[Mick Bailey]

I've just bought a batch of PT2399 and decided to test them in an old but reliable Rebote 2. This is a fairly quiet pedal (apart from the usual noise that is inherent with longer delay times), but with the new ICs, when the delay time is increased beyond 12 o'clock the pedal 'motorboats' loudly at a fairly low frequency - sort of a put-put-put-put-put sound. This is irrespective of any signal input and is a constant noise. The older ICs don't do this.

Has anyone come across this problem -  any ideas?   

[Morocotopo]

Does the motorboating vary with the time pot? I used a 100K pot in my rebote 2.5, and at the longest times (from about half rotation on up) the thing starts making all kinds of funny cyclic background noises. If that´s the case, it´s just the nature of the beast, at the longest delay times the quantization/filter/whatever noises start to show up.

OK, I see you already answered my question (me, smart, me).

Fake chips maybe (If that´s the case I also have fakes...)? I think there are Holtek workalikes but that have less "quality" sound.

[Suicufnoc]

I got the same sound from my cheap Tayda pt2399's.  I don't have any good ones to compare to, though.  I'm currently messing around with a compander setup like the PT-80, and the sound is sufficiently squished into the background.

[Jorge_S]

bump!

Can someone confirm if Tayda's 2399's work "different" than regular IC's?

I was planning on buying several from them, but now I am scared I might pay for chips that don't work the right way...

Thanks!

[Mick Bailey]

I've carried out further checks with the ICs;

1. The delay time is substantially reduced compared to my 'originals' when the delay control is at 12 O'clock.
2. Anything beyond 12 O'clock produces a lot of shifting background noise - like tuning between radio stations.
3. The sound quality is very much reduced overall.
4. At longer delay time the noise level is serious and unusable.
5. The chips lock up on power on (all of them) and require numerous power cycles to get them running, otherwise they sit there getting hot. (I know this is a problem with low resistor values on pin 6, but the Rebote doesn't suffer this)

I have some ICs left over which I ordered from Banzai in Germany about 5 years ago and they don't show any of these problems. Even on the longest delay I just get some low-level background chuffing between repeats which is lost in a band situation.

It's clear that these new ICs are either production rejects, fakes or damaged in some way. The marking is the same as the older Banzai chips (not the serif printed white marking).

I've ordered two more lots from different suppliers, but one of these is Tayda, so probably not good according to subsequent research. I'll let you know how I go on.

I've also tried decoupling the 5v line with more filtering, floating the digital ground, experimenting with caps etc., and nothing works.

Does anyone have a supplier of reliable, consistent ICs?
 

[LaceSensor]

Hmm I'll have to check my pt2399s now. I bought 10 or more from tayda due to cheapness, assumed they were quality.  I used one in a deep blue delay and it sounded ok to me but yeah the repeats did seem dirtiier at longer delay times.  I have some pt from another supplier I'll have to do some tests, will be very annoyed if the tayda pt are bad news...

[LaceSensor]

Hi

I agree that this is an issue, I have some older PT2399 to test in a deep blue delay clone.
The old one sounds much better than these new ones from Tayda.
also the IC die is obviously different. The PTC logo looks wrong compared to two old ones I have, the print is different, and the ic doesnt have a recessed circle on.
I have 20 "new" Pt2399 from Tayda, I tested a few, all of them motorboat like you have described.

I dont know what to do. This is $11 worth of IC from Tayda that I cant consciously use due to poor quality sound.
Guess its only enough to just write it off as a failed endeavour.

The other place I know that does good PT is either Banzai or Dr Tweek in the UK...

[Jorge_S]

also the IC die is obviously different. The PTC logo looks wrong compared to two old ones I have, the print is different, and the ic doesnt have a recessed circle on.

Can you please post a picture or a scan of both logos so we can compare before we purchase? it will be of great help!

thanks!

[LaceSensor]

yeah ill do it tommorow. 1am here now and everything is packed away.

[Mick Bailey]

I've just received 10 ICs from Tayda and they are excellent quality - no motorboating or ghostly whispers and they behave as well as I could have hoped for. The marking is similar to the ones from Banzai and they are every bit as good (possibly even a little better - less background noise).

I also received 5 more today from a different supplier. These are the ones with the printed white lettering and they motorboat at higher delay times, though this is not as intrusive as the worst examples I have and they function OK at shorter delay times. Noise and quality of the repeats are OK, but I still consider them lower quality and wouldn't be happy to use them other than for breadboard experiments.

It would appear that it's a bit of a lottery trying to buy good quality ICs. I've got 27 and only 17 are usable.

[Suicufnoc]

I've just received 10 ICs from Tayda and they are excellent quality - no motorboating or ghostly whispers and they behave as well as I could have hoped for. The marking is similar to the ones from Banzai and they are every bit as good (possibly even a little better - less background noise).

Are these printed with serif font or sans-serif font?  My Tayda chips are sans-serif and motorboat at long times (Probably .5 second plus).

[Mick Bailey]

Sans serif.

[CynicalMan]

Don't let TGP see this!   

"I scored a Mad Professor Deep Blue Delay off Craigslist for $100!"
"Is it a serif-chip or sans-serif-chip model?"
"Sans-serif."
"Don't waste your time with the sans-serif ones, they sound all muddy and ice-picky. The serif ones are much nicer, with warm, sparkly repeats."
"Really? Crap. Well, there's a serif one on ebay for $500, I guess I'll pick that up instead. Thanks for the tip!"

[DavenPaget]

I've just received 10 ICs from Tayda and they are excellent quality - no motorboating or ghostly whispers and they behave as well as I could have hoped for. The marking is similar to the ones from Banzai and they are every bit as good (possibly even a little better - less background noise).

I also received 5 more today from a different supplier. These are the ones with the printed white lettering and they motorboat at higher delay times, though this is not as intrusive as the worst examples I have and they function OK at shorter delay times. Noise and quality of the repeats are OK, but I still consider them lower quality and wouldn't be happy to use them other than for breadboard experiments.

It would appear that it's a bit of a lottery trying to buy good quality ICs. I've got 27 and only 17 are usable.

I went to look into the PT2399 in my Mixer and heck , i don't know what sort of chip i got .
Probably good probably bad , haven't tested this mixer at all .


PS : i flipped the ic out just for you guys .

[LaceSensor]

I've just received 10 ICs from Tayda and they are excellent quality - no motorboating or ghostly whispers and they behave as well as I could have hoped for. The marking is similar to the ones from Banzai and they are every bit as good (possibly even a little better - less background noise).

I also received 5 more today from a different supplier. These are the ones with the printed white lettering and they motorboat at higher delay times, though this is not as intrusive as the worst examples I have and they function OK at shorter delay times. Noise and quality of the repeats are OK, but I still consider them lower quality and wouldn't be happy to use them other than for breadboard experiments.

It would appear that it's a bit of a lottery trying to buy good quality ICs. I've got 27 and only 17 are usable.

Where we're the bad ones from? These and the original ones.  I have a bunch from tayda that suck...

[smallbearelec]

It would appear that it's a bit of a lottery trying to buy good quality ICs.

It can be, depending on the chip.

When I saw this thread, I was surprised that no one mentioned that SBE sells the PT2399, though they are more expensive here in small lots. On checking my Stock List, I was shocked to find that the part was not posted. Apologies! The item had been disabled accidentally. It is back, and we have plenty of stock.

I had gotten a shipment of PT2399 at what seemed to be good price from a source in China. They turned out to be either very shaky or outright bad. Fortunately, the broker was someone I trust and she protected me. The next batch came directly from Princeton; they were much more expensive, but I have had no complaints.

I can only guess that there are some factory rejects or poor quality clones out there. Sometimes there is a reason why you have to spend a little more to get what you want.


Regards
SD

[Jorge_S]

I've just received 10 ICs from Tayda and they are excellent quality - no motorboating or ghostly whispers and they behave as well as I could have hoped for. The marking is similar to the ones from Banzai and they are every bit as good (possibly even a little better - less background noise).

So basically, it depends on luck? Do you see any cosmetic difference between the good ones and the bad ones?

Seem like even Tayda doesn't know when their chips are good or bad ... I think I'll buy 10 each from 3 different suppliers. Sorry BearElectronics, but your prices a 7+ times higher than Tayda's.

[Earthscum]

So basically, it depends on luck? Do you see any cosmetic difference between the good ones and the bad ones?

Seem like even Tayda doesn't know when their chips are good or bad ... I think I'll buy 10 each from 3 different suppliers. Sorry BearElectronics, but your prices a 7+ times higher than Tayda's.

Luck? No. Unless you define "luck" as putting faith in your supplier to know whether or not they are sending you good parts that fit within the tolerances that you require.

I look at it this way: Steve (smallbear) guarantees that you get a good chip. Now that we're getting into "shakey" builds with some of the projects posted here, It's really no different than buying Germanium. For a generally stable build, use the Tayda chips. For the oddball stuff, buy one from Steve. I don't know about anyone else, but you can guarantee that Steve will get you a good product. Tayda, well... it's a grab bag situation for some of these builds. Just like Germanium, you can get guaranteed parts from a reputable supplier, and pay a little more, or you can buy a grab bag of transistors on the cheap and sort through them yourself.

FYI, my favorite suppliers are Tayda, Mammoth, and Smallbear. I don't use SB as much, but when I need certain parts, or want a part that could be "iffy" from someone else, I won't hesitate. I've been putting off PT chips for awhile now just because I want to get them through SB but I don't quite have enough of a shopping list yet (gotta get some transformers and such).  

ETA: I can confirm I have 3 different chips. First one, from SB, is heavy "script" style with PTC logo, Second, from Mammoth, is the same, but a lighter stroke. Both are white lettering. The ones I got from Tayda are from a different mold, for sure. Lettering is fine, reddish color, and hard to read. I'll crack my other two boxes open and see if I can't get confirmed pictures of each one later. For now, it's the "fiance's" birthday, so I'm out for a couple hours, lol.

[Mick Bailey]

I bought the ICs from the following suppliers;

Banzai (good, but I have not bought recently)
Tayda (all good)
Goodbuy7888 (Ebay seller) Noisy, but ok on shorter delay times. At least they're usable in some form
Thaishopetc (Ebay seller) Total rubbish and unusable.

I'm not suggesting that the vendors know how good or bad these ICs are - they're just commodity items being passed around the world. Unfortunately I left good feedback for the worst ones before I tested them.

Now, it's OK claiming guarantees, exchanges or refunds, but the return postage from here in England is excessive compared to the 'free' postage sending them out from Thailand, Hong Kong, China or Singapore. It just isn't worth sending them back.

The main question is; are they just cheap, or cheap for a reason? There has to be a certain defect threshold in the factory and a number of rejected components for whatever reason. You would think that the ICs would fail prior to being marked up, but are they finding there way out of the back door and getting printed up with PTC markings?

I can accept that we're swimming with sharks on Ebay, so I have to blame myself to some extent. Buy cheap, buy twice, as they say (or three times, ten times or more if you're buying ICs).

Must say though, it's the first time I've ordered of Tayda and they've supplied excellent products.

[Maudibe]

Hi - Steve from Doctor Tweek here. 

I have put a hold on all PT2399 sales until the quality issue is sorted. We are about to build a test circuit to check the current batch. Fortunately only a couple had been sold from the batch.  which have been 'caught'. Will not be selling these until the issue is resolved or identified. 

Best, Doctor Tweek