dbx 160vu clone

[damnyankee]

AC,

A couple things:

Mike on another board says when converting from the vca can to THAT says: "Yes it will need a PCB(2181) to mount where old VCA was...If you go with the 2181A it needs a couple of trim pots.."

Mike Harris/Harris Audio Systems on the 160VU power supply: "Les Tyler of DBX confirmed with me the crappy power supply contributes to the unique sound...watch the lamp as you cross threshold....first clue...."

Also, I tried to call Mouser to see if we could get a cross reference for the BC263 & BC361 in the power supply.  They're closed on the weekends.  Digi-key was open but only had one tech and I was on hold in line for her for quite some time so I hung up.

 

[damnyankee]

AC:

I'm checking for some replacements for the BC263 & BC361 for the power supply and it appears they are available:

BC263 appears to cross reference to NTE159 and Mouser has these in stock:
http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search?OpenForm
http://www.mouser.com/Search/Refine.aspx?Keyword=NTE159

BC361 appears to cross reference to NTE129 and Mouser has a 2 week lead time:
http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search?OpenForm
http://www.mouser.com/ProductDetail/NTE/NTE129/?qs=JV7lzlMm3yIGUPDEmxLAgQ%3D%3D

Can you or Matthias double check this to see if this is indeed correct???!

Thanks!

DY

 

[abechap024]

excellent! Great info Damnyankee. Looks like that NTE129/8 can be used for the output transistors. Not the easiest to source but they are out there.
So I'll bite the bullet and  build on the PS. But I'm going to leave on the jumpers for outside power, so there will be some options.

Besides that its starting to look like a genuine PCB...

looks like mouser has 233 of the nte129 in stock. http://www.mouser.com/Semiconductors/Replacement-Semiconductors/_/N-76qhk?Keyword=nte129&FS=True

 

[TheGuitarist]

Seems like the best bet would to have this project as pcbs with hard to find components, or full kits for obvious reasons.

 

[damnyankee]

AC:
I think jumpers are a terrific idea - if someone wants to plug in their own power supply, then so be it.  Great job on the pcb!!!

The Guitarist:
Actually, all these transistors are out there.  I'll bet you can find an old retired tech in town who will probably have some.   There are literally 10s of thousands NOS of each of these around but alot of them seem to be located in overseas inventories - so they're out there.  

DY

 

[damnyankee]

AC:

We are going with LEDs for the GR? 

Secondly, what are you going to do for the switches (meter)?  Are you going to leave them for the LEDs?

 

[Rybow]

I really like the idea of LED metering vs getting an original meter. Mainly as a cost/availability concern.

It is also amazing what you can find for parts at various electronic repair shops. There is a shop here that has all sorts of crazy old stuff in stock all the time.

This project is looking very promising! Thank you guys so much for all the great work so far!

 

[damnyankee]

Hey AC...

I just took a closer look at Matthias' 200 VCA file and:

Q2 (BC179B or BC263C) was actually stuffed with BC456 & 545C stuffed on those VCAs.
Q3 (KE3687) was stuffed with U2749.

So we have a few more transistor options in those spots.  However, R11 & R13 were not stuffed on the boards either; so I don't know if it had to with the transistor changes or not.

Just something we need to be aware of...

DY

 

[damnyankee]

I really like the idea of LED metering vs getting an original meter. Mainly as a cost/availability concern.

It is also amazing what you can find for parts at various electronic repair shops. There is a shop here that has all sorts of crazy old stuff in stock all the time.

This project is looking very promising! Thank you guys so much for all the great work so far!

Glad to do it.  There's not much in these and they shouldn't cost *too* much to build.

By the way, I think some of those BC263s we're having issue sourcing in the U.S. may be in Canadian inventories...so if you'd like to give us a hand (since you live there), would you consider putting some feelers to some electronics distributors up there?

 

[damnyankee]

Good news!  We have a few more options from Matthias' 200 VCA files:

His Q2 (BC179B or BC263C) was actually stuffed with BC456 & 545C.

BC456 cross references to NTE229:
http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search
http://www.mouser.com/ProductDetail/NTE/NTE229/?qs=JV7lzlMm3yJ4L%252b3Ct5XkBg%3d%3d

(BC545C does not have a NTE cross reference.)

His Q3 (KE3687) was stuffed with U2749.

KE3687 cross references to NTE457:
http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search
http://www.mouser.com/ProductDetail/NTE/NTE457/?qs=JV7lzlMm3yLbeYVcZXMT8A%3d%3d

(U2749 does not have a NTE cross reference)

So my obvious question is: can use substitute BC456/NTE229 for ALL the BC263 transistors???  Would resistors have to be tweaked?

 

[abechap024]

Great Idea on the LEDs.  I'm going to leave the meter circuit as is for now...so it will be easy to put whatever kind of meter/led one wants.

Remember also that the the unit also has the above threshold and below threshold LEDs.you could probably leave the whole meter section unstuffed if you wanted!!
thats 4 trimmers and a bunch of resistors and 3 gang switch. or just set the meter to GR using jumpers and leave out the switches

From what I understand a majority of the people that really love this unit just set it so the LEDs are "dancing".

Ok got the VCA section done,
Looking on now how to implement the 2180 option.

thank you guys for making it come together!

Also Its going to be a double sided pcb. I know there are those who would rather etch a board themselves - but considering the complexity of the design fitting the RMS/VCA discrete option and the THAT vca option I think its the best choice. Plus I plan on  making the PCBs/kit available for cheap.
But there is still much work to do...

 

[Rybow]

I really like the idea of LED metering vs getting an original meter. Mainly as a cost/availability concern.

It is also amazing what you can find for parts at various electronic repair shops. There is a shop here that has all sorts of crazy old stuff in stock all the time.

This project is looking very promising! Thank you guys so much for all the great work so far!

Glad to do it.  There's not much in these and they shouldn't cost *too* much to build.

By the way, I think some of those BC263s we're having issue sourcing in the U.S. may be in Canadian inventories...so if you'd like to give us a hand (since you live there), would you consider putting some feelers to some electronics distributors up there?

I will see what I can turn up.

 

[damnyankee]

AC:

Do you have enough room under the VCA footprint to creates holes for an 8 pin SIP socket/footprint (where the holes and leads can be etched but not filled if the actual VCA pcb is used)?

And actually AC: thank YOU for doing the pcb.  Now etching for a two sided board this size is probably ruled out, who's going to manufacture these for us?  I have a very bad feeling that a pcb of this size and that's also 2-sided is going to run some serious bucks...

DY

 

[abechap024]

Right Dy so far there is plenty of room. We might have to locate the That option to the side of the discrete VCA option. Also there was talk of having a switch to switch back and forth between VCAs - I think for now we should just have it one way or another...
I just imagine the nightmare of the vcas weirdly interacting with each other....

But as soon as we actually start doing some actual tests with the vcas, I think we'll have one version we like much better or hardly be able to tell the difference......
I personally like the Idea of a discrete VCA... If we find that its not too hard to implement or tweak.
AC

 

[damnyankee]

I have to tell you, AC: whatever you decide, I'm going to go with the THAT2180.  I'm leary about those old transistors needed for the 200 VCA (which are probably 30-40 years old).  I have a dbx 118 in front of me right now with no left channel output.  I've traced the problem back to the VCA...and I've narrowed it down to either a bad cap or transistor - one of the two.

 

[Rybow]

Couldn't find any BC 263 in stock at the 2 major stores in my area. There is only the NTE 159 replacement.

 

[abechap024]

Looks like the NTE replacements are the way to go on all accounts. I wouldn't bother looking for the original transistors, they seem to be long gone.
Here is the updated PCB, well not the final version by any means - I still need to do a final look through and place all the components *exactly$ were they should go. Also I need to make sure I have the right case/resistor/transistor sizes. I also need to build the power supply. But it has been really enjoyable.

Hopefully the PCB will be done soon!

 

[Rybow]

That looks great abechap! Really impressive stuff!

 

[arska]

Using NTE replacements is.....  Take handfull any BCxxxC , select and match hfe Ube , and You have exellent replacements for VCA200 and RMS208.




 

 

[damnyankee]

AC - outstanding job on the board!  Hopefully you can make enough room in the power supply section to upgrade the 35v 470uf caps to 35v 4,700uf FM caps till kill the noise in the power supply.  Those 470ufs just don't cut it.