DR-ZEN2 Limiter Build
- Thread starter bgrugle
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Help Support GroupDIY Audio Forum:
Hi I built this unit some years ago. As far as I remember I haven't found any incorrect instructions and the unit works fine and actually sounds pretty great. Most complicated part was the calibration of the unit with the fixed resistor calculations. What is the issue with the PSU? Does the PSU work without the circuit engaged? Do you have the +/-28V at the output of the PSU board ?
Hi Undo, nice build!! I’m working on my unit right now. One channel sounds pretty good so far but the other one produces super loud popping sounds when in fast attack…!? I wonder if you might have an idea where to look for the reason? Could it be because of bad matching of the four 1N5231B diodes?
Another thing: when I put the unit in bypass I get a loud clipping sound as if there would not be diodes at the relays…. But they are. Do you also have that issue?
Thanks for your advice!!
Another thing: when I put the unit in bypass I get a loud clipping sound as if there would not be diodes at the relays…. But they are. Do you also have that issue?
Thanks for your advice!!
Hi axl85. Have you tried swapping the zener diodes with those of the working channel? I would try this first, as these parts are probably the most critical in the circuit. For the other issue (bypass). My unit has not this problem. It‘s been a few years since I built the unit and actually don‘t remember the details so I‘m probably not much help.
Hi
This is my build. It was one of my first ever build compressors. Tok me one week 12-14h everyday.. Matched all resistors (tok me 12houres).
Check the two points here on the PSU
Yeah, the cabling could be better. But for my first build i'm happy.
Best,
Fab
This is my build. It was one of my first ever build compressors. Tok me one week 12-14h everyday.. Matched all resistors (tok me 12houres).
Check the two points here on the PSU
Yeah, the cabling could be better. But for my first build i'm happy.
Best,
Fab
What 1N751A's did you all use?
I'm just about to start a DR-ZEN2 build and the 1N751A's in my mouser cart are £1.50 each so they're going to cost a fortune to buy in bulk to find 4x matched pairs. I've been doing some reading on Zenner limiter builds and have realised using the right 1N751A is critical.
I'm just about to start a DR-ZEN2 build and the 1N751A's in my mouser cart are £1.50 each so they're going to cost a fortune to buy in bulk to find 4x matched pairs. I've been doing some reading on Zenner limiter builds and have realised using the right 1N751A is critical.
I used these in this build: https://www.mouser.de/ProductDetail/512-1N5231B
The DIYR - BOM also mentions them as alternative.
The DIYR - BOM also mentions them as alternative.
I went with 1N5231B's in the end and have got a 4 matched pairs.
I've got one more question about the Zen 2 build how do you mount the TO3's. I've never used TO3's in a build before and just wanted to check how to mount them properly as I cant find any info on mounting to a PCB? There's load of info out there for metal chassis mounting but nothing for PCB's.
I'm assuming as the TO3 case is the collector there is no need to use a insulator underneath them or insulating bushings on the screws?
I've got one more question about the Zen 2 build how do you mount the TO3's. I've never used TO3's in a build before and just wanted to check how to mount them properly as I cant find any info on mounting to a PCB? There's load of info out there for metal chassis mounting but nothing for PCB's.
I'm assuming as the TO3 case is the collector there is no need to use a insulator underneath them or insulating bushings on the screws?
Rob Flinn
Well-known member
They are not T03, they are T066. You don't really need heatsinks on these transitors for this box, they don't get hot enough to need them. What I did when using them was use some M3 nuts & bolts through the pcb. Use crinklle washers & put the bolts in from the non component side. Use a couple of nuts on the component side then you can stand the transistors away from the pcb so they get plenty of air around them, bolt them down & solder the 2 legs.
flyingeyepro
Active member
nice job
I finally finished all the wiring in my Zen 2 this morning and fired it up to check the PSU voltages before connecting the main boards and there was no magic smoke which was a bonus.....
I checked the +v and -v voltages and they were around 18v, when I started to trim up the -V and got to 28v the fuse blew. I popped in a couple more fuses which both blew straight away, so I tried a 1000mA fuse slow blow fuse instead of the 500mA one that was in the project cart and the transformer made a buzzing noise for a second before the fuse blew.
Can anyone confirm what rating the fuse should be as it's not specified in the BOM? Also what are the chances I've damaged the transformer with it buzzing?
I checked the +v and -v voltages and they were around 18v, when I started to trim up the -V and got to 28v the fuse blew. I popped in a couple more fuses which both blew straight away, so I tried a 1000mA fuse slow blow fuse instead of the 500mA one that was in the project cart and the transformer made a buzzing noise for a second before the fuse blew.
Can anyone confirm what rating the fuse should be as it's not specified in the BOM? Also what are the chances I've damaged the transformer with it buzzing?
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I've just done some more testing as I to try and figure out what the fault is.
I disconnected the PSU board from the toroid and when I turn the power on the toroid buzzes for a split second before blowing the fuse. I'm now using 0.63a slow blow fuse as I've had issues in the past with toroids blowing 0.5a fuse due to the power up spike of inrush current.
I followed DIY Racked's diagram when wiring up the toroid and have just double checked and everything is as it should be, as the fuses are blowing when the only thing connected to the power the toroid is the only thing that could be at fault????
The toroidal is 25v, 50Va and I'm in the uk so supplying it with 240v.
I disconnected the PSU board from the toroid and when I turn the power on the toroid buzzes for a split second before blowing the fuse. I'm now using 0.63a slow blow fuse as I've had issues in the past with toroids blowing 0.5a fuse due to the power up spike of inrush current.
I followed DIY Racked's diagram when wiring up the toroid and have just double checked and everything is as it should be, as the fuses are blowing when the only thing connected to the power the toroid is the only thing that could be at fault????
The toroidal is 25v, 50Va and I'm in the uk so supplying it with 240v.
Attachments
Hey folks,
I finally came back to to this build and am almost there. My unit is passing audio in bypass, all the LEDs and meters are lit, and I'm getting the correct 28/-28V at the PSU and the 20/-20V on the boards. But when the unit is engaged, it's not passing audio and all I hear is white noise.
Does anyone know what I should be reading at the various test points? Something funky is going on in channel 1 at test points E, F, and G, but without a schematic I'm in the dark. I've triple checked all my components, orientations, wiring, and reflowed my solder points.
Channel 1
I finally came back to to this build and am almost there. My unit is passing audio in bypass, all the LEDs and meters are lit, and I'm getting the correct 28/-28V at the PSU and the 20/-20V on the boards. But when the unit is engaged, it's not passing audio and all I hear is white noise.
Does anyone know what I should be reading at the various test points? Something funky is going on in channel 1 at test points E, F, and G, but without a schematic I'm in the dark. I've triple checked all my components, orientations, wiring, and reflowed my solder points.
Channel 1
- A: 0 V
- B: 12.8 V
- C: 12.8 V
- D: 5 mV
- E: 0.5 V
- F: 0.5 V
- G: 1.15 V
- A: 0 V
- B: 10 V
- C: 10 V
- D: 8 mV
- E: 15 V
- F: 19.7 V
- G: -10 V
Hi desol, there's a couple on youtube.
Sounds very good, that's what got me considering building a zener limiter for mastering.
The Zen2 is out of my budget though, so still researching on possible other candidates.
Everyone's build looks great, all the best with it!
