thread: DBX 163X
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Old 15th February 2011 | Show parent
  #49
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Summary of this thread

Hi. This is my first post in this forum and I just wanted to start by saying thank you to the people who provide this valuable assistance, in particular Jim Williams.

I have a 163X that I now (from reading this thread) realize was made in Hong Kong. I've put together a summary of all the questions and answers in this thread and hope to get a little clarification. Here's what I've gathered from this thread:

DBX 163X Upgrade:

1. The 163x (made in Hong Kong) has the C1252H2 (IC1) like the 160x.

* Jim Williams: That's the older marker for the same vca chip. Yank it, drop in
a that 2180A and remove the 47/51 ohm resistor at pin 4 and remove the
100k trim resistor off the vca trim pot to pin 4.


2. The 2nd chip (IC2) is a C1253H2. Should it be replaced with the 2180A, like the C1252H2?
Damn Yankee replied with: I answered my own question about the other chip.

However, I don't see the answer to this one and I'm a newb to these types of mods. Can someone confirm if it's supposed to be replaced with the 2180A also? If not, what chip should it be replaced with?


3. Do I yank R9 (47k) & R10 (100k) and what do I do with R11?

Or do I yank R10 (100k) & R11 (47k) and what do I do with R9?
R9 & R11 are both 47k...

* Jim Williams: Snip out R9 (47 ohm) and R10 (100k ohm). Leave the 1253,
it's the RMS detector. R11 the trim pot can stay.


4. Is it okay to substitute the THAT 2180A with a THAT 2181?

* Jim Williams: The 2180 is pre trimmed. The 2181's are not and so you would
need a decent distortion analyzer to set it for lowest THD. The A grade is
their best.


5. What exactly does the the cutting of R9 and R10 do? (i assume from the discussion they are cut, not jumpered). are they something that is done only with the upgrade to the 2180 chip or are their effects heard with the stock chip.

* Jim Williams: Those resistors are for the that 2180A replacement only. Leave them if the original VCA is kept. The dual input opamp can be swapped for a National LME49860NA and the output 5534 opamp can be a LME49710NA or a ADA 4898-1 or similar. Replace the small 470 uf mains caps with 1000 uf or 2200 uf if you can fit them.


6. Would these 470uf mains caps be C14 and C21? (i'm going to assume the 1M50E1 @ C13 and C20 are fine as-is). Going to assume 25v is what they should be since it looks like they are running to the +/- 24v, but i'll double check what's currently in there. I’m also going to put in some sockets for the input/output IC's. So far the 10 bucks per unit for the THAT 2180 seems to be worthwhile, hopefully 20-ish total for new vca, in/out op amps, and mains caps will be a big step from the original unit.

* Jim Williams: For real low noise use a AD8599 or a BB OPA2211 for the dual and a AD8597 or OPA211 for the single, those are very low noise opamps. They are S0-8 only so use a Brown Dog or Aries adaptor into a millimax machined socket.

* Against88: the 470uf caps to be replaced by 1000 or 2200 are c28 and c29.


7. The last question was not been answered directly: "Just to be sure, on mouser, OPA211 and OPA2211 are the to names for the same opamp. So John, did you mean "OPA2111 for the single" ? Or is it the same for the tow opamps?" However, looking back at Jim's initial response, I think it's clear.

* Unanswered.
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So the only questions I have are:

1. Can the 2nd chip in IC2, a C1253H2, be replaced with the 2180A, like the C1252H2 chip in IC1?

2. Does anyone have any good sources for the parts discussed in this thread:
- 2180A chips
- National LME49860NA
- LME49710NA or a ADA 4898-1
- Capacitors: has anyone verified if there are particular 1000uF or 2200uF that will and won't fit?

3. An answer to #7.

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Thanks. I hope I didn't miss anything and I hope that summarizing this helps others who stumble upon this thread in the future. My honest intention is to help by consolidating all the info, so hopefully that's what I've done.