Obsolete parts… did I just waste $12?

K

krupdb8

New member
This is on me for not looking at the BOM before adding The Creamery Compressor (PCB301) to my cart, but…

I ordered the PCB a couple days ago and started to gather parts yesterday. This pedal requires four “KA4558” and two “THAT2159”.

I looked at the datasheets and there are differences between KA4558 and other 4558 variants, so I assume it specifically requires those — though I am guessing any 4558 will probably work well enough.

The big problem is the two THAT2159 chips. They are unobtanium with no alternative, apparently.

Did I just waste $12 on this PCB? Not a big deal and yes, I normally check the BOM before considering a PCB and didn’t this this because I was shopping from my phone.

Cheers,
Ken

PS it would be great if PedalPCB (and other board makers) had some sort of red/orange/yellow status on the PCB product page to note when critical components are obsolete and unattainable and/or there is no available substitute (red—so make sure you have some!), obsolete but still available and there is no substitute (Orange), or obsolete but widely available , or there is an available substitute (yellow). Just a thought. I know this could be a maintenance nightmare for ppcb to try and keep track of the availability of components but thought it might be helpful to shoppers.
 
There’s either an Xvive or coolaudio clone of the chip but it’s also hard to come across. I need a handful of the 2159 chips too, but I always forget about it when they’re available. Regardless, fear not— they might take a while to find, but they pop up often enough
 
I didn’t see that Coolaudio produced a V2159! But it appears as rare as the original THAT2159 these days.

There are a couple of threads here that say the Coolaudio V2181 “might” be a drop-in replacement, and it is currently available from cabintech!

… I just found a post on vintage-radio.net of a manufacturer’s note on using the 2181 to replace 215x chips. It says to eliminate the resistor that goes to pin 2 and the cap at pin 8 can be reduced to as low as 22pF. Also it appears pin 4 is not used on the 2181?? Interesting!
 
I ordered V2181L from cabintech and will try to figure out the proper integration later.

Am I right that any 4558 chips should work fine with this build?

Thanks all!
Ken
 
Not really understanding the question. Is it the THAT chips? I have a Creamery here, I think, so if need be I can pull the chips and get them to you. I loved the comp but it never made it to my board. Still, if I found the chips so they must still be out there.
 
Gordo said:
Not really understanding the question. Is it the THAT chips? I have a Creamery here, I think, so if need be I can pull the chips and get them to you. I loved the comp but it never made it to my board. Still, if I found the chips so they must still be out there.
Click to expand...
Smallbear had CoolAudio v2159s for a bit, but they’ve been out for some time now.

There are some THAT2159s on eBay of questionable provenance from overseas that are pricier than I’d feel comfortable gambling on.

I asked @StompBoxParts if they could source them or the CoolAudio repros a while back, they responded in the negative.
 
benny_profane said:
The THAT2181C is the closest-in-spec replacement for the 2159, but the THAT2180 (pre trimmed) can also be used. Per table 3 in the app note, omit R2 (51R) in figure 1.

Click to expand...
Thanks for the info! I finally got my Uv files ready for my two creamery builds after like 2 years, but I forgot to get the 2159s when they were still attainable. Gotta say though— that’s gotta be the most bizarre font choice I’ve ever seen for a technical datasheet
 
To revive this thread– In the Creamery schematic, if using the 2181 in place of the 2159, R31 is to be omitted as it correlates to the 2181 Design Note Page's R2 for IC2.
For IC5, there doesn't seem to be a connection between pin 2 and pin 4, or rather there is, but it's via a 33k resistor- R23. This configuration however bares similarity to figure 7 and figure 8, which would suggest that R23 is comparable to R3, which the Design Note Page suggests should be calculated for minimum THD via the datasheet, but the fact that pins 2 and 4 have an internal 25Ω connection, and both are connected to Vref in IC5 would suggest that R23 is completely inconsequential since it would no longer be providing any function other than to reduce the internal resistance of pins 2 and 4 from 25Ω to 24.98Ω; that said, no point in omitting it since it doesn't do any harm.
Now– R32 has a lot in common with R3 with regard to IC2, but I can't seem to find in the 2181 datasheet where it says how to calculate what size that resistance should be given the supply voltage– that said 1K for R32 definitely seems way small compared to the 130k-680k values given for R3 when assuming a bi-polar 15v supply, so I'm not sure what, if anything, to change R32's value to.

Anyone else have any thoughts on my observations, or any further insights into what should be changed when using a 2181 in place of the original 2159?
 
Any update on this?

I subbed out r31 for a jumper to no immense effect in my problematic (maybe) build. I don't see any change to make to ic5 as it's not laid out with the same resistor situation to pins 4 and 6.
 
Bricksnbeatles said:
To revive this thread– In the Creamery schematic, if using the 2181 in place of the 2159, R31 is to be omitted as it correlates to the 2181 Design Note Page's R2 for IC2.
For IC5, there doesn't seem to be a connection between pin 2 and pin 4, or rather there is, but it's via a 33k resistor- R23. This configuration however bares similarity to figure 7 and figure 8, which would suggest that R23 is comparable to R3, which the Design Note Page suggests should be calculated for minimum THD via the datasheet, but the fact that pins 2 and 4 have an internal 25Ω connection, and both are connected to Vref in IC5 would suggest that R23 is completely inconsequential since it would no longer be providing any function other than to reduce the internal resistance of pins 2 and 4 from 25Ω to 24.98Ω; that said, no point in omitting it since it doesn't do any harm.
Now– R32 has a lot in common with R3 with regard to IC2, but I can't seem to find in the 2181 datasheet where it says how to calculate what size that resistance should be given the supply voltage– that said 1K for R32 definitely seems way small compared to the 130k-680k values given for R3 when assuming a bi-polar 15v supply, so I'm not sure what, if anything, to change R32's value to.

Anyone else have any thoughts on my observations, or any further insights into what should be changed when using a 2181 in place of the original 2159?
Click to expand...

This thread claims the 2159 is the lowest spec 215x series. https://groupdiy.com/threads/that-2159.2258/

If you look at the design notes for THAT 218x DN137, the Creamery is using a trimmable VCA like the 2181, but omits the trimming resistors in favor of a fixed resistance. It makes more sense to use the pre-trimmed 2180 and omit R23 & R31. There are three grades of both chips. Otherwise you could probably drop in a 2181C and leave it alone, See DN121.

The Coolaudio part is dirt cheap, and correlates to a 2181B. If it was me, I'd omit those two resistors and first try a 2180C. If that's not satisfactory, install those two resistors and and a 2181C. Or, you could plop a trimmer in there and use the Coolaudio part.

If the 2180C works, you could upgrade to the 2180A.

Like I said, I'd start with the 2180.
 
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