I am in the process of building a pair as well , so please keep us posted. Did you take Steve's suggestion of using the 1/8"felt between the baffle and cabinet to increase the size of the slot?

Larry

I Plan to use the 1/8" felt between the baffle and cabinet and will let you know how it is. Do you think bass will increase as the drivers loosen up .....and what is BSC?
Larry

Hi Big L

BSC = Baffle Step Correction, normally used to compensate for the loss due to small baffles.

Hi NB,

What passive BSC did you use?

Wakanda

Sealing the speaker using rubber tape?

Steve mentioned miking the enclosure to enhance the lower bass.  Any thoughts?

Wakanda: I'll try the broadcast system using my CS2 clones as the broadcast speakers.

Big L: I had screwed the front baffle to the cabinet and used the rubber sealing in between to make the box air tight. I did this because I want to hear the speaker before spending time and money on the finish (read paint and veneer).

I recently built a WO32 and used black 3/4 inch wide foam tape (from local hardware) to seal the top to the bottom assembly.  It compressed evenly under pressure from the screws, made a nice tight seal and looked great.

Thanks for the posts on your build!

Hi Nelson,

Thanks for jumping into the forum with your build results!  I've read your posts with some interest and look forward to the story as it continues.

If you're on the bright side of the holy grail, you may already be there.  It my experience just upgrading speaker wire can lead to another week of tube rolling with the final result being a completely different set of tubes.  That would indicate that a change as major as the speaker might demand the same type of system voicing.

Another thing I've noticed is that A) the DFR-8S (shielded version) has more bass than the DFR-8, and that some amps generate much more weight than others.  Our Torii MK II or MK III for example, has fooled me more than once into thinking I had bass augmentation on when in fact it was off.  

You've been trying different amplifiers so I expect you're already finding favorites.  I enjoyed your comment about being able to instantly hear how much better one amp was over another.  I use these type of speakers when I voice my amplifiers, as I know in 15 seconds what's up whereas if I used a normal pair of hi-fi speakers it takes 15 minutes and a fair amount of guessing.

Also, darkening the room a bit is a great way to pick up the low end.  Hang a couple moving blankets up over hard surfaces some night as an experiment...

It will be most interesting to hear what happens when you mic the chambers, but once you overcome the feedback none of what I've said above will be remembered.

Steve

I failed first attempt yesterday using a Behringer ECM-8000 and a mic preamp. Got acoustic feedback (boom boom) and too much noise from the preamp. I really need more gain (another preamp or a better mic preamp).

I also look forward to read Steves next article about the ZOBs.

I found the ZOB extremely detailed and open but to light/bright for my taste in the long run. I really nead more bass to balance the speakers for all my rock albums.

Though acoustic instruments and live recordings can sound absolutely life like. Stunning!  :)

Maybe the Tang Band W8-1808B 8" Neodymium Full Range Driver will fit? It does have a higher Q than the stock FE207E.

Who makes a good OB sub to use if you mic'd the chambers?

I was thinking if as Steve says the purest ,totally in snyc bass comes out of the chamber port, then using the chambered mic'd feed to some OB subs or even normal subs might be very interesting.

Break in period for the DFR-8's is 40 - 50 hours before they're even usable.  200-500 hours before they are completely done. Base fills out in the 40-100 hour window.

The resonant cavity is usually lightly stuffed.  The more stuffing you use, the wider the "Q" and the lower the gain.  

The chamber under the slider should be left clear to maximize air flow.





Installing mics in the chamber is an interesting journey.

Suspended just below the port opening pointing straight down into the fiber fill is one way.  Adjusting the height of the mic allows it to pick up some ambient information at higher frequencies that are originating from the rear of the driver.

Placed in the port opening so that the mic body touches the cabinet is another way that had good results.

There are no rules yet, after enough people get it to work and compare notes we'll have some usable information.

Feedback is the main issue.  Just about the time you get the mic turned up so you can hear some bass coming out of the broadcast speakers, you get boom.  No matter what, you have to find the level where it booms and back it off some.  The trick is to get the highest level possible.

A simple mixer is a starting point.  It will have the mic preamps and the line level outs you need.  Most will also have a bass, mid, and treble control for each channel.  This can help to reduce feedback.  

The microphones I used were Sure 57's (general purpose instrument mics) although I suspect some small drum mics would be worth trying.

With this simple arrangement, work on placement and type of broadcast speaker and what adjustments you have to get the least feedback possible.  Right now the feedback is helping you to find the best set up.

The tendency is to want to hear the broadcast system too loud.  It should be almost silent to where you have to get your head down by it to see if it's on.  This is usually the right amount ambience.  Remember, low frequency ambience is harder to hear than midrange ambience, so by the time it feeds back you're probably louder than you realize.

When you achieve somewhat usable results, you can either explore a better signal path, ie., mic preamp to replace the mixer, or go for more bass with less feedback.  It the latter is required, you can try a notch filter at the feedback frequency, or even a digital feedback destroyer.

The ideal set up would be a tube mic preamp with and adjustable notch filter.  I will eventually make one of these for myself and then probably for everyone else if enough of these speakers are built.

Steve

Yes, or the seas exotic which has better xmax, lower fs which should allow the magical Zen enclosure to do even more of its magic.
I am positively stunned by the openness and spaciousness the zen delivers and think with a slight increase in weight and depth it could truly be used stand alone with no subs or miking needed. I am about 100 hours into break-in and like others have found that tube changes, cable changes are clearly heard. If any others have experimented with alternative 8" fullrangers in Steves Magical ZEN enclosure, Please share!!

I am afraid to better the performance of Steves modified DFR-8S is not going to be cheap though, but am coming to the realization that the enclosure has gigantic potential and deserves the best fullrange 8" you can find.

Its more complicated by far than a normal box to make, but with minimal skills and tools and a lot of paying attention to the details, can be done.
What is truly amazing and magical is the spaciousness and clarity you would expect to hear out of a crossoverless open baffle along with real bass and fullness you NEVER would hear out of a 12" wide open baffle.
So Steve has done the seemingly impossible with the Zen OB. He gives you a beautiful high WAF speaker, the incredible open baffle openness,imaging, and lack of box coloration you want PLUS with his genius resonant enclosure below the driver, gives you the fullness and cleanest tuneful bass I honestly have ever heard. And he does all this with an ingeniously simple resonant chamber enclosure/open baffle design that allows you to eliminate all the crossover problems and use a single 8" driver driven directly by a tube amp.
This is what makes me think that using the best possible driver would yield a speaker that is literally untouchable. Even Steve admits that there may be better speakers out there than his heavily modded $300/pair DFR8-S's but none he knows of that are reasonable in cost.
For me personally, this design works so well in so many different areas that there is a gut feeling listening to them that a world class 8" fullrange would truly make the Zen OB the last pair of speakers you ever owned.  Still hoping Steve and others experiment and share their findings with other driver variants in this amazing design.

Yes true and even if it doesn't fit, a very simple replacement baffle could be made . Steve was also ingenious in how he designed the baffle to be removable and replaceable on the Zen OB.

Your project sounds great!  Pictures will be required.

I am awaiting shipment of some Seas X1-08 exotics for the drivers on my ZOB's. I will post impressions as soon as i have them installed in some new baffles. I got a good tip online to use titebond melamine glue as a very high loss adhesive between the two 3/4' sheets of MDF on the front baffle. This will reduce baffle vibration and allow for a clean rock solid launch for the drivers. I also used Medex instead of MDF for the baffle as it is significantly stronger as a driver mounting material than normal MDF. Anyone interested in some brand new almost broken in DFR-8S can contact me.

The Medex I mentioned is a green, formaldehyde free product that when bonded face to face with titebond melamine glue produces an outstanding baffle at a very reasonable price. You could then veneer with any wood you want . Using the titebond melamine makes a very lossy layer between the sandwich which can actually absorb vibration like using an EAR product. Using 2 - 3/4" sheets face to face gives you the strongest, most dense 1.5" thick baffle on earth.

Medex is a "green", super high end, much stronger, version of MDF. It is somewhat harder to find , but is available and for not much more than standard headache causing, weaker MDF.

big L, sorry to call you Al - not sure what I was thinking there.

Out of interest, what is it like to venear MDF/Medex. I haven't ever tried veneering and I heard it wasn't pleasant or easy. How do you find it? Any tips?

Cheers,

Matt

it veneers up easy and beautiful because it is perfectly smooth

Thanks for the Medex info big L.  I'll look into it.  I might use it for the back baffle and rear cabinet.

Keep us posted on your project!
BTW, I've got a couple pairs of Dave's (P-10) eNABled drivers. The cost is well worth it, IMHO!
Best, Don

Guess what is ready to ship back to the US?



He had a set of the other W8s too, but he said the 1808s are better than the 1772s.  

And my carpenter buddy will build the cabinets for the cost of materials.  

Cool.  I didn't even listen to them stock.  I had Dave buy them new and mod them straight out of the box.  He took about three weeks of listening to them to dial them in.  These were the first pairs of the W8 twins he had eNAbled so he took care of me and the other peep, or should I say peepette since she was a repeat customer for Dave too.  

I was about to go with the MarkAudio chr70eN drivers for the Castles design, but Steve finally came through and published the ZOB plans for us, so I went with the ZOBs.  

I think the cool magnet structure of the W8s will only enhance the killer looks of the ZOBs too.  I'm going to use an 8-wire silver/copper hybrid braid for the connecting wires down to the speaker binding posts and I'll invest in really nice binding posts to keep the aesthetics killer.  

I'm really jazzed and looking forward to finally getting my ZOBs built and finishing my new little listening area.  Rearranged the house and moved the home office down to the basement.  I got rid of a ton of crap so I could make room for a little niche and plan to add a couple of Ikea Poang chairs and custom end table/amp rack to hold two of my diy headphone/speaker amps.  They put out about 7W-15W each so they're perfect for my orthodynamic cans and the ZOBs.  

I still need to add the insulation and drop ceiling, then do some smaller Decware traps, but I'll get there.  The journey is 3/4'ers of the fun for me.