Khanspire / RS WmtW Build

[Moejoe]

Hi all,

Recently I had another thread in this forum where I got some great advice. Work has now commenced, so I decided to start a new thread now that I know what I'm building and my other thread had become a bit disjointed. Hope that's ok!

I have everything here (excluding the drivers and crossover components) and I'm well on my way building a single OS MTM. I'm sure glad I did this for practice since I'm not experienced with woodworking so several mistakes have been made

Now with the Khanspires, I asked briefly in my old thread and e-mailed CJD about the port since I can only get 70mm and 100mm flared ports (dayton not precision), not the stated 3". Unibox was telling me 70mm could be too small, but CDJ kindly assured me it would probably be fine but he prefers overkill.

I Have since ordered and received the 100mm ports. Holy cow these things are huge!

So here's my concern. In my mind with a larger diameter, wouldn't it require more airflow for resonance/output to occur? So will it require higher volumes/driver displacement before the port starts to do it's job? I hope this makes sense.

One other concern I have is that I bought some Monacor 35mm spiked feet, but with such a heavy enclosure wouldn't these be prone to ripping out of the MDF base if someone leaned on it?

I really appreciate the help you guys offer.

As a side note, I included a picture to show the size of the port but also to show CJD I too like overkill. (I greatly underestimated how much 2kg of filling is, and I could only get a 14m roll of denim insulation) That's a 2ft Ruler in-between the ports for reference :lol:

[JonMarsh]

Your concern isn't founded about the port. A larger port, tuned to the correct length, just means the amount of air movement is reduced for a given SPL- remember, it's area times displacement that creates output. As long as the net turning is correct (larger diameter port requires longer length for the same box tune), you're fine.

Good luck with your build, and of course, feel free to post early and post often about how it's going- pictures are always appreciated.

[---k---]

Looking forward to your build progress. :t

I think Jon answered the port question. Regarding the spikes. Not sure how big those are. I'd suggest using plywood for the base where the spike screw in. Mdf is weak for pull out. And even with plywood I'd be somewhat gentle. These are big 50kg+ speakers. Somewhat top heavy.

[TEK]

I guess these are the spikes you were wondering about?

http://www.monacor.co.uk/categories/speaker-feet/vnr/129130/

From what I can understand these are memt to be mounted from the bottom. They also seems to be fairly high. I would be very sceptical to that construction if I were you. For direct downward fore I think everything is OK, but it will require little force sideways to there those nuts out of the MDF.
Maybe if you could mount the nuts first, preferrable glued in place with some epoxy or simular - and then add a 3-5mm of plywood (or another quite dens material) above it - glued to the MDF and with holes drilled where the spikes is going through, that would give you a sturdy solution.

[Steve Manning]

I've had good luck replacing the inserts that typically come with spikes, like the ones TEK listed, with threaded inserts from these guys, http://www.ezlok.com/. I usually use the brass inserts and drop some CA or epoxy in the hole to lock the inserts in place ..... works pretty well.

[JonMarsh]

I've had good luck replacing the inserts that typically come with spikes, like the ones TEK listed, with threaded inserts from these guys, http://www.ezlok.com/. I usually use the brass inserts and drop some CA or epoxy in the hole to lock the inserts in place ..... works pretty well.

+1 on that- just ordered a bunch more ez-lok inserts and driver tools

[wkhanna]

i used those for mounting my drivers, too.

[Steve Manning]

i used those for mounting my drivers, too.

Same ...... biggest trick is getting them in perfectly straight.

[wkhanna]

yep!

[Steve Manning]

Cool Bill ...... I just ran across this while looking for another video, https://www.youtube.com/watch?v=EszFoi7c_Y8. I think it's a good idea though I would put his notch in the middle of the board and not the end. That way you don't have to apply pressure to hold the board down and it could easily straddle driver cutouts.

[wkhanna]

that is a good method.

i use one of these:

[Moejoe]

Wow, thanks alot for all the replies guys and I hope you all had a wonderful Christmas and new year.

TEK, yes those are the spikes I have which is why I asked about them, I'm really not comfortable with them, they will tear straight out with a little nudge. So I've ordered the smaller ones instead.
Thanks for the great advice with the inserts, I already have some I'm going to be using for the access panels but I hadn't thought of using them for the drivers and spikes as well.

Absent of my drivers and electronics I've done as much as I can to the OS MTM, would you guys mind telling me if my lining is sufficient? I know paul 'lightly stuffed' his, so I'm trying not to go to crazy.

Finally, before I dive in on the khan's and start massacring some wood. Does my MDF look ok? strange and stupid question, but it's... green. Looks less dense etc.

Nice tool there wkhanna, bet mine would still end up wonky though!

Many thanks guys

[---k---]

I notice that wkhanna's photos show the inserts going into plywood. I personally, being paranoid, wouldn't trust any insert into MDF for spikes on a speaker this big. I'd use plywood for the base with the speakers. You can laminate it to MDF if you like. If you go MDF, I'd at least use some Minwax Wood Hardener on the MDF and epoxy the inserts in. MDF is great for somethings, but your right in fearing fastener pull out.

Can't say if your MDF is right or wrong from a photo. MDF will vary based on manufacturer. I've had light brown and dark brown before. I swore at times one was better than the other, but think that was only my anger due to my most recent mistake. There are probably some minimum standards for MDF out there, and I doubt manufacturers are exceeding them much. I'm sure it is acceptable. Remember, MDF is used because it is cheap, very machinable, and dense.

Your OS speakers lining look good to me, but I haven't built those or any of Paul's speakers. I'd probably try and cover the areas not covered. You may or may not still need to add a handfull or so of loose poly stuffing in the middle. Every designer is different in what they like. You might also want to vary the amount to taste. But, that can be done after the baffle is glued on and you listen to them.

[Steve Manning]

I notice that wkhanna's photos show the inserts going into plywood. I personally, being paranoid, wouldn't trust any insert into MDF for spikes on a speaker this big. I'd use plywood for the base with the speakers. You can laminate it to MDF if you like. If you go MDF, I'd at least use some Minwax Wood Hardener on the MDF and epoxy the inserts in. MDF is great for somethings, but your right in fearing fastener pull out.

Can't say if your MDF is right or wrong from a photo. MDF will vary based on manufacturer. I've had light brown and dark brown before. I swore at times one was better than the other, but think that was only my anger due to my most recent mistake. There are probably some minimum standards for MDF out there, and I doubt manufacturers are exceeding them much. I'm sure it is acceptable. Remember, MDF is used because it is cheap, very machinable, and dense.

Your OS speakers lining look good to me, but I haven't built those or any of Paul's speakers. I'd probably try and cover the areas not covered. You may or may not still need to add a handfull or so of loose poly stuffing in the middle. Every designer is different in what they like. You might also want to vary the amount to taste. But, that can be done after the baffle is glued on and you listen to them.

To add a little bit of info ..... I recently found out about what is called "cabinet grade mdf". I got it from an actually lumber yard. It is used in building kitchen cabinets ..... it is denser, you can tell the difference in weight and will take a finish a lot better than the Lowes variety. Cost was within a couple of bucks of what you get at Lowes as well.

One other comment ..... my 1071's are made from mdf and are a pretty good size speaker and I used threaded inserts for the spikes and have never had an issue with tearing them out. The biggest reason for that .... I remove the spikes prior to moving. I don't think it's wise to drag speakers around with spikes in place, regardless of what they are made from. You actually see companies like Wilson and Magico (their cabinets being aluminum) put wheels in place to move the cabinets around and only spike them once your done tweaking the final position of the speakers.

[Moejoe]

perfect, thanks alot for the info!

I'm stuck with the wood anyway, all I know is it's heavy!

I'll be back soon with some photo's and no doubt more questions

Cheers guys

[TEK]

+1 on that- just ordered a bunch more ez-lok inserts and driver tools

Where do you buy these from?

[Steve Manning]

Where do you buy these from?

TEK, you can get them from a number of places though I got my last order from Amazon, cheapest I've found so far ..... of course in your neck of the woods I'm not sure.

[Steve Manning]

Where do you buy these from?

I just found this, http://www.ezlok.com/sales-contacts, info at the bottom might be good for you.

[Moejoe]

TEK, mine are not as high quality as those ez-lok ones but they were the closest I could find here in the UK, as Steve said, amazon or ebay is the place to be. The ones I got were these http://www.ebay.co.uk/itm/1916328271...%3AMEBIDX%3AIT

I assume we are allowed to link ebay etc? I apologise if not!

[wkhanna]

I assume we are allowed to link ebay etc? I apologise if not!

no worries on the ebay link, provided you are not the seller

[Moejoe]

Hello All! Hope your all well.

Thought I would stop in with an update and a few questions. I've got my OS MTM up and running in my parents living room and its a huge improvement thanks a lot Paul.

I'm sure glad I did the OS MTM to start with as well, having very little experience with woodwork I learnt a lot with the smaller build first and saved myself a lot of time and wood with the larger build. Everything is going to plan so far. Never used a router before, what a tool! I've attached some pics of my progress. I've gone so far over my original budget that I even cheapened out on the clamps and made some with threaded bar.

A few questions, Is it possible to paint the pointy coney bit (good technical term) of the rs225? I'm guessing probably not a great idea due to the movement and sound quality but it would be nice if I could.

I'm going to be painting these with an air gun and my plan is to seal the MDF with a 1-1 mix of PVA/water and straight PVA on the end grain before I fill and sand. Is this correct? I see so many different approaches it gets a bit confusing

Thanks for all your hard work and as always I appreciate any feedback,
Karl

[---k---]

Vent pole.
I'm not recommending it. But, I believe the vent poles unscrew and you can paint them so long as you don't close up the gap between the pole and the driver. I swear I've seen someone do it once. A very light spray should be okay. You probably should experiment on a spare driver. This might be where the Y in DIY comes into play.

[rvsixer]

Sorry just chimed into this thread. Regarding drilling straight holes for the inserts, I used these drill guides with great success on my last build:

https://www.biggatortools.com/drill-guides.html

Also handy for other tasks such as drilling straight and centered holes through pipes, etc.

[Moejoe]

Thanks K, I didn't realize the 'vent pole' was separate to the cone, It feels like your right and it should unscrew but I could not do it with finger force and I don't have spares, so think I'll just leave that one.

Sorry but I have another boring question that I'm sure your sick of. with the inductors, I have seen the picture showing the acceptable distances and orientation but it does not mention placing them at 45 degrees. Is it possible? I assume there is still going to be an unacceptable amount of cross talk.

Please see my picture to understand what I'm asking. I have seen the 3 coils close together before but I'm unsure about the middle one. Would really like to try and keep it all on one board for easy access.

As always I greatly appreciate the help, I'm really enjoying this project.

[---k---]

Yes, we've all seen the dos-don't graphs. I think there is good and good enough.

It looks like you're trying to combine all the crossovers on one board. I separate mine out for a couple of reasons: 1) it makes laying out and checking the crossover easier in my mind. Just dealing with one thing at a time. 2) it avoids some of these issues. My tweeter crossover is in the tweeter box and the mid and woofer are behind the bottom woofer, and probably too close to each other and to close to the woofer.

I'm confused by your photo though. I count 7 inductors. The Khan crossovers only have 6 inductors for each speaker. Is that two mids and one tweeter? Maybe this is just theoretical? But even if this is an external crossover, I'd absolutely definitely suggest you not put the right side crossovers on the same board as the left side crossovers. You got to keep them separated. Not really, but the logistics of checking and maintaining is easier.

I've been told that 45* is better than nothing. This is my mid-crossover. I've never been chastized by CJD or anyone else, so I think it falls in that good enough category. You'll note the inductors are at 45*. They are a fair distance away, so I'm good with it.




I've learned most everything I know about crossover layout by staring for hours at photos of crossovers by Jon Marsh, CJD, and a few other gurus. I've stared at them, traced the graphs, and really tried to understand what goes where and how the ground wire loop works, etc. I think I understand them pretty good now. It just takes putting in effort.

Finally, I'll leave you a picture of Jon Marsh's Modula MTM crossover. I asked him about this once upon a time and don't remember his response. I'm guessing he'd prefer it to be different, but this was good enough and fit the purpose.

[Moejoe]

Thanks again K, your a star.

Well spotted as well, I should have mentioned that those coils were for the RS Centre which uses 7 instead of the khan's 6 however it was just a general question with regards to inductors at 45 degree angles.

I understand your points with regards to spreading them out. I would like to keep each crossover on one board, as this board will be attached to the rear access panel and thus easily accessible but not at the cost of performance.

Thanks for those 2 pictures, that really helps clear it up for me. The layout I showed should be 'good enough' then, though it may still prove completely impracticable in terms of circuit layout. I'll have to experiment

[Moejoe]

Hey All.

Finally got the speakers put together for testing. the Khanspires are sounding awesome, I'm really pleased! However I have done something wrong on the RS WmtW, they do not sound right. The woofers sound about half of the output they should be.

Obviously I need to go through the crossover etc, but could someone just confirm to me how the Woofers are supposed to be wired? Parallel with positive polarity?

As always you have my greatest thanks

[scottvalentin]

If it is lacking bass it is likely that one woofer is out of phase with the other so just try switching polarity on one of the woofers and see if that does the trick.

[scottvalentin]

Great job so far by the way!!

[Moejoe]

Thanks a lot Scott. I'm thrilled with them so far! (going to do a nice paint job. maybe some gold leafing). Sorry I've been away on holiday.

So I connected the drivers one by one to compare, for example the tweeters in the khanspire and the centre to compare. (the Khanspires are sounding great so I'm using them as the control)

The woofers on the centre sound find, sounds like a slightly higher crossover point which I would expect from a small sealed design as compared to the ported khan towers.

The mid sounds extremely muddy (but correct frequency range). I've tried it stuffed and un-stuffed. I'm not sure if this could be due to a poorly sealed/oversized mid chamber? It's definitely not right though.

The Tweeters are very wrong, it sounds like the crossover point is far to high, there are no high ends of the vocals just a few hi hats etc. I have checked all my solder points which look good. This leads me to believe I have messed up on the crossover.

Now please be gentle, I haven't dealt with electronics in many years haha. I'm unsure if I can use the negative loop as I have and If I have taken the Tweeter out from the correct point. I have drawn the tweeter circuit exactly as it is laid out. Would someone mind telling me what I have done wrong.

Many Many Thanks

[_luke]

The 22uF in series with the 1uF looks wrong to me. That will end up as a tiny capacitance. Remove the 1uF and try it with just the 22.

[Moejoe]

oh yeah (embarrassed face). Thanks luke no idea what I was thinking there. that will be just under 1uf instead of 21uf. Hopefully thats the issue!

[Moejoe]

Ok thanks Luke that sorted the tweeter out, don't know how I missed that one!

My last issue is still with the mid sounding muddy/tinny. I connected the mids up to both the khanspire and centre crossover outside of the enclosures and there is definitely an issue with the centre. I'm certain I have not made a mistake on this part of the crossover but I don't see what else could be causing an issue? Any ideas would be great!

Thanks and sorry for my drawing skills

[cjd]

Couple possibilities

1. I believe that was originally designed for the shielded (NLA) tweeter, and the impedance response is different... they're not really interchangeable.
2. It never got a voicing pass since it was a "here's data, hey people design a crossover for me" thing. It may just not be ideal.

Do be sure the tweeter and mid are in phase, and the woofers are reversed (relative to the mid/tweet) as well.

Glad you got the 1uF cap issue sorted. That would have done all sorts of weird.

[Moejoe]

Thanks alot cjd.

Since I sorted the silly cap mistake the tweeter sounds fine. that was me just being a plum.

I know the voicing isn't going to be 100% but even to my experienced ears I can tell something is not quite right. The best way I could describe it would be that there is part of the frequency range missing between the woofer and the mid. It feels like there is no where near as much depth in the centre mid. I could be completely wrong but thats my gut instinct. On my reciever if i boost the low frequency's (<1000Hz) It sounds much better.

How would I go about lowering the crossover point for the mid?

Appreciate the help

[cjd]

Are you sure the drivers are wired correctly? That sounds an awful lot like the null you'd get with it wired up out of phase...

Next best suggestion is to do a frequency sweep and record - even a phone app + mic should be close enough to see if there's anything terribly amiss in the range you're referencing. Data goes a long way toward helping isolate issues.

[Moejoe]

Thanks again cjd, and sorry to be a pain.

Your right im just guessing, I've ordered an IMM-6 mic for the phone, hopefully that will be sufficient to provide some kind of data. I'll be back in a week or two with some results.

Cheers

[cjd]

Those are great little mics. The stock one might be enough, but you'll have much better results this way. Also can use it to tune the room. Hopefully this is an easy tweak.

[Moejoe]

Hi, me again!

Right the mic arrived and I've been playing around with it for a bit now (still no idea what im doing).

So the first 3 pictures are of an averaged frequency response over roughly 5 seconds using white noise. The first picture is of the centre and the other two are of each khanspire.

The last 2 pictures are peak frequencies when doing a frequency sweep from 20hz -20khz. Again the first is of the centre, and the last is of one of the khanspires (can only post 5 pics).

I don't know how accurate this is, I've no idea if I'm using the right settings etc (I did upload the calibration file for the mic).

There is clearly a dip around 250hz on all of the speakers, however the centre's is deeper and wider, I found this quite noticeable when just playing around with the settings. Is there anything clearly wrong for you?

Currently I have the centre wired as per the circuit diagram with the mid and tweeter wired with negative polarity and the woofer with positive (and parallel). I will try and get some data with different polarities tomorrow to see if that makes any difference. Do you have any suggestions?
.
Thanks again cjd, and sorry for the messenger widget on the screen, I forgot to take it off

[cjd]

First thought is that maybe only one of the woofers is working on the center, or maybe one is wired out of phase.

The dip around 250 may be room but you can try flipping polarity on the woofers to see, if you're so inclined.

[Moejoe]

Right, I actually think I was using a bad audio file for the frequency sweep. I tried using a different one which sweeps much slower and the graphs look much much better (Centre is first two pictures, Khanspires last two). I also re-positioned the centre ever so slightly.

All the speakers still have that dip at 250hz but no where near as bad. As you say I expect this is due to the room conditions, these are currently in my bedroom which is pretty full with beds and such

Thank you very much for your assistance CJD, I think these are as flat as I'm going to get before I get them into a proper space. They are sounding fantastic!

Now onto the in-khans for the surrounds...

[cjd]

Ahh, the joys of measuring. Center looks slightly hot through the midrange and a bit soft through the crossover to the tweeter (the latter likely the tweeter impedance difference) - but it should do quite nicely with clear dialog at lower output levels. I sure hope so. The exact location of the mic can make a lot of those anomolies move around too, but this is a place where a little EQ can fix it up beautifully, if you find it helpful to do so. And you can now measure the results, which is even better.

I still remember the first listen to the pair of In-Khans. I'd accomplished something a little different on that crossover, and it's now one of my requirements. Subtle, but just a touch magical. Oh, also the accidental shorting out of a well protected power amplifier with the surround wires, which were evidently carrying current as they were let flop around among the steel duct-work... One power cycle later and a little more care, and the sounds were back, and the fear of destroyed electronics gone.

C

[Moejoe]

Howdy folks,

Long time, no see. My apologies but this project has progressed very slowly as I'm sure you can appreciate, sometimes life happens. I Hope everyone has been keeping well and building some cool stuff as always
Quick question for you, I'm about to strip down and prep for paint but I'm questioning my choice of base for the Khanpire towers which have down firing ports. Will a base of this design be acceptable or will it restrict the port and affect tuning? The ports are 4" diameter, flared on both ends (I cant remember the length off hand) and will be approximately 7" off the floor.

Thanks