Modding the Zu Omen MKII

Hi all

I am a bit courious as to if anyone else went down the DIY mod path with their Omens?

What are your experiences?

On my mod list (so far)
- New Double xover capacitators
- Adding a parallell resistor to the tweeter
- Stiffening of the cabinet
- Painting the insides with noise-x
- New internal cabeling
- New bolts and fastenings for main elements.

They now sound fantastic! And play in a different league!

And probably more mods to come! ;-)
Why don't you call Sean? I am sure he'll give you lots of ideas for things to work on. In fact, I think he kind of likes it when owners do modding.
Congrats on your mods.  Which x-over caps did you use?  By double x-over caps do you mean using a bypass cap?

I'm not a modder but from what I've read Sean will offer lots of ideas to improve Omen performance.  I kind of like the sound of mine as is and I've compared Omens directly with Zu models up the chain, so I'd be afraid to mod mine too much, but that's just me.  I did the ClarityCap upgrade myself and that hits the limits of my modding ability.

Zu used to use a parallel resistor but then I believe for Omen Mk II they switched supertweeters and found it was no longer necessary.
Hi guys,

Yes I may actually at some time contact Sean, I have been considering changing the elements entirely! 😁

I started with the clarity cap, a decent upgrade it is. But after reading on misc forums, I ended up with Mundorf Supremes 1uf and with a 0,1uf in parallell. I must say, a HUGE difference over the clarity cap!

I added a 63ohm Duelund graphite resistor across the tweeter, that really helped the tweeter relax, without negative effects really..


What did you use for internal wire and how did you get the binding posts out to rewire them?
After intense and red-eye forum nerding, I landed on coated solid copper wire, 2x1,5mm for each binding post. Warning, that is stiff and a bit hard to work with, but sounds great!

I unfortunately broke the posts removing them, installed a plate and new copper terminals.
I own the Zu Omen Def mkii’s. I did the Radian Tweeter upgrade. Big improvement over the stock tweeter. 

Please tell me me more about how the sound changed from stiffening and adding the noise x to the cabinet.   And can you tell me how you stiffened the cabinet and the process to apply the noise x?
I added a solid 1x1 inch oak dowel right underneath the main element towards the back wall. Made it a snug fit, had to force it in place, and glued it in place with epoxy glue. 

Prior to this, I used about 1L of noise-x sound paint (for each speaker) in 3-4 layers all over the insides.

aldso adding new bolts with nuts torqued from the back side of the front plate, allowing for much higher torque.

made the cabinet «talk» vanish, and a much more dynamic sound all over. Good improvement in imaging as well!!
Hey zuangbro, 

Could you be a real pal and give me some specific links to the parts you've used? I'm really interested in these mods! And the things I'm wondering about: 
- resistor
- capacitors

I had trouble finding the correct ones. 

AND: have you done any more mods? I've also considered changing out the full range drivers.
effect placebo, if you won to hear difference , make change in one speaker , leave second one as this , and  try to listen difference.
The human sound memory is short
Did I do more.....yes, I probably went over the top..

I changed the stock tweeters for a pair of these;

Radian 475-beryllium

added a suitable Lpad using Mills wirewound resitstors..

those speakers now play in a whole different league.

oh,btw, you can buy a bracket/adaptor for the 475’s and they will fit nicely with the current Omen lenses....
Hahahaha I love it 

thanks for the awesome tips! I’ve been thinking of switching tweeters. Why did you pick those over the radian 850s?

and what’s an Lpad?

I got the 475’s primarily due to avoid the woodwork, keep the cost down and make sure the speakers can be returned original if I for some reason would want to..  

the larger Zu lenses are $$$

also, the 850’s are not really well behaved in the high frequencies, the 475-be are beryllium, they are superb for tweeter duty!
L-pad is an arrangement of resistors to match your tweeter to your main driver. If you go this path there are a couple of things to take note of....
What did you use for the L-pad and how do you set it up? 
I'm thinking your reasoning on the 475s is very good. 
This is the values I used for the L-pad;

2 x (RES-M1115) - 3R 12W MRA12 Mills Resistor - £9.18 (£4.59 each)
SKU: RES-M1115, Location: AA04, Tariff Code: 8533210000

2 x (RES-M1135) - 4R7 12W MRA12 Mills Resistor (4.7R) - £9.18 (£4.59 each)
SKU: RES-M1135, Location: AA04, Tariff Code: 8533210000

These values are a result of scaling compared to what I know Zu use to match the 850’s with the 103nd drivers, accounting for the differences 260drivers.

note; these values will work for the 8Ohm 475-be radians.

if you go for the 16ohm Radian 475 version, different values will apply...
Also, there are plenty of L-PAD calculators available online.

They will however give you other values than what I proposed above...
Alright. Thank you very much!

lastly, this bracket to make the tweeters fit, where can I get some?

did you explore switching out the full range driver?
I got the bracket of a local supplier, but you can probably buy it together with your 475’s from the same supplier. Just make sure it fits the threads on the original Zu lens. 

The original eminence asd1001 driver has 1 3/8in (18ext.) threads.

did not change the main drivers as I am very happy with the sound right now...
Hey man,

I spoke with radian and zu. They were skeptical. How does this work with the throat being deeper on that lens? Opposed to more flush like the larger zu lens. 

Basically not figuring this thing out over here :) 
I don’t really understand what they are saying there.

with the bracket the distance will be the same as for your current driver...

if the laws of physics don’t change, when you change the driver, the speed of sound coming from the new driver will be the same as from your old....
hm. I see your point! Thank you.

I had a look at the ASD 1001 Eminence drivers. They come in a B-version with that bracket off... So yeah. That would be the same thing.

Thanks, man! :)

Do you set up the L-pad like this? 1+1 resistor, and 1 capacitor for each?

Sorry for all the questions, man, I don’t know jack ... I at least know basic soldering.
Yes, exactly like that! The cap is the same value you already have.

No worries, this is a bit outside most people’s comfort zone :-)

Thank you!

spoke again with radian. They said it would be fine if you’d make it fit. And they said performance would hardly if at all be affected. 

Also. Zu said the 850s would be hard to fit in there even with making a bigger hole. If at all possible. They said no. 
Just to be clear, I stuffed the 475-be drivers in there, using the linked bracket. (Or similar) It all fits with no mods, bracket is 1in internal diameter, fits with the Radian 475-be 1in exit. That assembly once mounted will screw right into the Omen MKII lens with female 1-3/8in threads.
The 850 will fit, but it will involve purchasing new (expensive) lenses from Zu, and some woodwork... 

There is no way back once you do that.

Using the 475-be’s it can all be returned to original, and you can sell the drivers separate if you like.
Now, remember to put the larger resistor value in parallell/across the teeeter binding posts, and the smaller in series after the cap!

Like this? 

- Do the Mills go in this order, or switched around? OR in parallel?
- Are there any other errors?

I also ordered ClarityCaps before I read this. 
Skip the Duelund (that is for the original tweeter) replace that with the larger value Mills, and you’r good
@zuangbro Did you experience needing any burn in? It sounds kinda muffled now. The whole speaker. I guess especially the FRD.

Or maybe I've messed something up.
Sounds strange...

If you did this right, it should sound anything but muffeled.

if you replaced the caps, they will break-in over the next 30-50 hours, and sound great after 200.

make sure that all polarities are correct, + to + all drivers and speakers...
If you have new compression drivers, they may need 10-50 hours of break in aswell, depending og how loud you play..
@zuangbro - You really have me intrigued with your Radian 475be upgrade. I'm thinking of making the same leap with my Omen DWs. I recently replaced the Clarity caps with Duelund tinned copper caps (I know, I know, it was one of those what-the-heck shelter-in-place moments) and the Omens took on a whole new presence and holography. So that got me thinking, and googling, and here I am...

Would you do anything different with the resistor values you mentioned? Any regrets with the 475be? Any other mod updates?
Just bought Zu Dirty Weekends. Out of the box they sounded boxy. Could hear what I thought were internal resonances and the need for more damping. I caulked the wood joints with green glue, Applied a few coats of acoust-X paint, a layer of 1/2 inch foam and 2 dowel braces between tweeter and full range. Much better, even my wife who really does not care noticed. Much cleaner sounding. I am shocked Zu lets these out of the factory without addressing these issues.
Hello, I saw this post and recently purchased the Zu Omen DW’s with Jupiter cap upgrade and I’m very interested in the 475-be tweeter replacement for the stock ones in the DW speakers.  I’ve been reading the post and are these the parts I’d need to replace the stock tweeters?
1.  475-be tweeters 
2.  Lpad using Mills wirewound resitstors [I have no idea what these are]
3.  P-Audio PC-20 Adaptor - 1" Small Format Bolt On to 1" Screw-in Horn [How many will I need] 

I have never done a DIY before, but I’m trying to reinvent myself by telling my foolish self that I could do it! I’d appreciate any help with the parts I need to replace the stock tweeters with the Radian 475-be tweeters. Could I fit the ZU 2" HFL-1 TWEETER LENS in the DW’s and are these lens compatible with 475-be tweeters? Sorry for all these questions.

@kevinjkim, Congrats on picking up the Omen DW’s with the Jupiter cap upgrade! I’ve enjoyed mine (with the Clarity caps) for a couple years and decided to upgrade to the Radian 475 beryllium tweeter over the summer (along with variety of other mods). A list of the mods I performed:

  • Upgraded to Radian 475 beryllium tweeter
  • New high-pass filter network with Duelund tinned copper caps and Path Audio resistors
  • Upgraded to Zu’s 103ND full-range driver
  • Changed all screws and mounting hardware to t-nuts
  • Applied sound-deadening material to interior
  • Epoxied dowels laterally and between the full-range driver and tweeter
  • Added 2-inch thick butcher block platforms hard-mounted with stainless steel set screws

I tried to document the process as much as I could here:

And I put together a list of parts I used here:

If this is your first DIY project, putting together the L-pad (or high-pass filter network) might be the hardest part since that requires soldering. Refer to the parts list for the values of the resistors I used (credit goes to @zuangbro for the values). I verified the resistor values from page 12 of Zu’s upgrade manual for the Druid IV (note that the schematic uses a 16-ohm Radian tweeter, whereas I used an 8-ohm version):

Being that the Radian 475 is a much heavier tweeter than the stock Eminence ASD:1001 (6.4 lbs vs 2 lbs) I would highly recommend upgrading the mounting hardware for the tweeter lens. I believe Zu doesn’t recommend removing the tweeter lens at all because the stock wood screws will strip the threads in the MDF cabinet, which is what happened to one of the screws on mine. Upgrading the mounting hardware to t-nuts, lock nuts, and new button head stainless steel screws will make the tweeter lens/cabinet interface rock solid.

The 2-inch tweeter lens won’t work on the Omens. With a lot of work it might, but then you’d have to use the much heavier Radian 850, which is a 16 pound tweeter. I used the P.Audio PC35 flange adapter to pair the Radian 475 to the Omen’s stock tweeter lens and it works seamlessly.

Overall I had a blast modding the Dirty Weekends, definitely one of the highlights to an otherwise difficult year. It was a great summertime shelter-in-place project, and as we go into winter with more lockdowns likely, I hope more DW owners will get the modding itch.

Btw, on *that other* audio marketplace website, there’s someone selling a pair of Radian 475 berylliums. Make a deal and save some bucks! Good luck!

Dear, SlowLearner28

Thank you so much!  I’m going to check up on all these parts and start this project!  Thank you so much for the detail information!  I’ll keep ya posted!  I’m going to save all the pics on my iPad and start looking up on parts!  A lot of things to study! 
@kevinjkim So glad I can be of help! I made comments on some of the photos on dropbox, providing more context and detail where I could. Feel free to ask questions. DIY will change your life. :)
Just chiming in here. I today finished up all the mods that @slowlearner28 mentioned. First, several months ago, I inserted the dowel bracers and applied the auto sound deadner. That tightened up the bass somewhat.

Last month I replaced the stock drivers with the 103ND. That brought greater clarity and dynamics to the mid-range.

Over the past few days I installed the Radian 475 aluminum tweeters (I couldn’t afford to spring for the beryllium versions). I did an A/B test with installing a Radian in one speaker and going back and forth with the balance control on my amp. It seemed to my ears that the new tweeter adds more presence to the high end. I have to listen a bit more - there’s definitely a difference, but I can’t pin down what it is yet, as dumb as that sounds. Today I put the remaining Radian tweeter into the other speaker.

Some advice:

If you can afford it, I’d go with the Acoustic X coating instead of the auto mat stuff. I’m sure they both worth fine, but I think applying the coating might be easier and cover every square inch. The auto-mat stuff is heavy, can get in the way of the dowels, and takes a while to flatten completely out with a roller. I know Zu uses the Acoustic X type stuff. 

Be very careful with installing the t-nuts if you’re adding those to the mix. Make sure the t-nut cones fit properly in the drill holes and accept the screws without locking up before you put them in the cabinet. I had one t-nut get stripped or something when I screwed in the 103ND and it was a huge headache - the screw got 3/4 of the way down the t-nut but then would turn continually without tightening or loosening. I had to get a pair of bolt cutters to snap the screw head off and ended up scratching the aluminum perimeter ring that goes over the driver. I had a similar problem with one of the smaller t-nuts for the tweeter, but at least that time I had learned my lesson and tried them all out before installing them. Frankly, the t-nut installation was by far the biggest PIA of this project.

Finally, the theaded steel studs that came with my tweeter-to-dome adapter were 1/2" too long. They stuck so far out of the tweeter that I couldn’t screw the Radians into the Zu tweeter dome. You need to get 1/4-20 threaded studs that are 1" long, something like these.

Anyway, the project is now finished. I’m hoping to put in some serious listening time in the next day or so.

I want to provide a follow-up to my November 2020 post on the modifications I performed on my Omen Dirty Weekend Mk.II and detail some discoveries I have made since then. It has been 3 years since I completed those mods and the speakers still continue to amaze me. In that time I have gradually upgraded nearly every component upstream and the speakers have allowed me to hear every change—the Zu 103 full-range drivers in combination with the Radian 475 beryllium supertweeters are very revealing and I learned that your upstream components need to be up to the task. I love the tone density and “shove” of the modded speakers—qualities Zu speakers are best known for—but wanted to further push my system to achieve greater transparency, realism, resolution, and holographic imagery through upstream components.

In the past year I have dove into the world of L-pad calculators, first order crossover calculators, and the software Room EQ Wizard (REW). The reason being that while the modded speakers are thoroughly engaging, I have noticed that on some music I was missing a bit of upper-midrange and above “presence” especially in female vocals. Measuring the speakers with REW confirmed my suspicions, and I could see a gradual decline in the frequency response starting at 1.5kHz out to 20kHz. The L-pad I used with 3ohm and 4.7ohm resistors calculates to about 6dB of attenuation to the tweeter, so my hunch was that this was the cause. I suspected that by removing the L-pad and having just the 1uF capacitor (like in a stock ODW) would solve this. Bear in mind that a stock ODW Mk.II uses Zu’s 206 full-range driver and Eminence ASD1001 tweeter. In addition, the L-pad used in a Zu Soul Supreme with the 103 driver and Radian 850 supertweeter also provides about 6dB of attenuation, which lead me to the conclusion that the Radian 475 beryllium is just a very different animal than an 850 aluminum, so using a 475be in combination with the 103 driver requires a different filter network.

While I could have re-purposed the 1uF Duelund tinned-copper capacitors I used in my 2020 mod, I didn’t want to take apart the filter network I soldered together in case my hunch was wrong. So when a discounted pair of V-Cap ODAM 1uF caps popped up on PartsConnexion, I jumped on them. Everything I read about the ODAM caps, with their characteristic grain-free sound quality and holographic imagery appealed to me and I was very curious how they would compare to the Duelunds.

With just the 1uF ODAM cap hooked up between the 103 driver and Radian 475be, built similarly to Zu's stock Erse caps or upgraded Clarity caps, they are simply a revelation. They sound just like people have described—utterly grainless, holographic, and oh so smooth. I thought the Duelund tinned-copper caps sounded wonderful, but the ODAM caps really are on another level. I measured the speakers again with REW and was very relieved to see that the frequency response from 1.5kHz to 20kHZ was now nearly ruler flat. Female vocals now have greater presence, and because of the reduced “grain” sound spooky real. I close my eyes, and my brain is tricked into thinking the singer is in the room. Success!

I uploaded a graph comparing the frequency response of the speakers with the Duelund caps/Path Audio resistors versus only the ODAM caps (measured using a miniDSP UMIK-1 mic at 1 meter, volume set to 75dB SPL, with Psychoacoustic smoothing). I am quite satisfied with how smooth the graph is considering my listening room is untreated. There is a slight dip at around 150Hz, so I’m currently considering why that might be and ways to alleviate it. I suspect there might be some phase cancellation due to my untreated room at the first reflection. Or perhaps I'm just at the DIY limit to what can be improved upon with the ODW's cabinet to reduce resonance.

I will end this post by re-stating something I wrote in a post several years ago: DIY will change your life. It literally changed mine. Thanks for reading.