DIY speaker build using Waveguides...looking for advice - AVS Forum
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post #1 of 1040 Old 04-18-2009, 06:43 PM - Thread Starter
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I have DIY ribbon designs, now I want to try waveguides. Reading everything that Geddes has done has me wanting to use more TD12S drivers with a matched Compression driver and some sort of wave guide.

Yes, I could just buy the Geddes kits but I want to find out what waveguide choices are out there and how they match up with compression drivers.

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post #2 of 1040 Old 04-18-2009, 07:04 PM
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Hey Penn, haven't used waveguides with compression drivers, but modded the waveguides to work with 1" soft domes. There's some high efficiency 1" domes that handle gobs of power in the passband and are pretty efficient. The Vifa DX25 come to mind at 93db and handles upwards of 100w from 2k up, probobly more with waveguide mounting which will lower HD allowing for a lower XO point. The new tweeter from SB acoustics looks like it will probobly become a top DIY dome once it's readily available. Looks like the perfect match to a 6.5 waveguide and a 10" pro woofer. See Zaphs tweeter mishmash for more info. Here's the link to the madisound store. It's gonna be about $50 each.

http://www.madisound.com/catalog/pro...oducts_id=8540

I've used the SEAS 27TDFC with these waveguides and they sound fantastic...clean and loud down to 1.5khz

http://mcmelectronics.com/product/DI...M-H-65-/54-580

I'm doing a pair of the Zaph WG TMM's sealed with the CA18RLY woofer right now for reference level playback to 80hz, with bass bins underneath. Will be working on a WG TM using the SB acoustics when it's available with the Peerless exclusive for reference level high fidelity playback.

http://www.madisound.com/catalog/pro...oducts_id=1605

See Zaphs TidBits section on the performance of this driver.
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post #3 of 1040 Old 04-18-2009, 07:31 PM - Thread Starter
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Thanks! My one requirement is that my speaker sensitivity has to be high, 95dBs or higher but your links look like great matches for the TD12S, anyways!!

I found this kit from 18sound.. I didnt know 18sound had kits on their site. Pretty cool. I wish B&C have some.

http://www.eighteensound.com/staticC...ound_kit12.pdf

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post #4 of 1040 Old 04-18-2009, 07:40 PM - Thread Starter
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I've used the SEAS 27TDFC with these waveguides and they sound fantastic...clean and loud down to 1.5khz

http://mcmelectronics.com/product/DI...M-H-65-/54-580

Did you modified the waveguide the same way Zaph talked about on his site?

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post #5 of 1040 Old 04-18-2009, 07:58 PM
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Quote:
Originally Posted by penngray View Post

Did you modified the waveguide the same way Zaph talked about on his site?

Not really. I made the jig and used the router to get the same height and correct hole size but that's it. For mounting, i cut a cardboard shipping tube and press fit it onto the backside of the waveguide. Then i poured clear epoxy resin into the tube up to the level of the hole. Then i do a quick pass with the router again for a flat surface, and simply screw the tweeter through the back directly into the hardened epoxy. Very dense.. the waveguide assy sounds like stone when you knock on it. I also used a piece of felt in between the guide and the tweeter as a pseudo gasket.

PE also has the 10" waveguide version that Zaph tested and was too deep for the application. Both the DX25 and SB acoustics tweeter are larger due to the rolled surround and would allow for a much shallower profile and probobly much better results. I may give the 10" a whirl, removing the mounting lip with a lathe an gluing in directly into the baffle. Some seem to think that the profole edhe of the PE guides creates some of the issues so removing it along with the shallower depth SHOULD produce much better results. If you're gonna use a DCX, i'm sure you can shape it to taste. I've worked in the Pro-sound field for years as a live sound engineer and i must say that IMO dome tweeters are WAAAY smoother than Comps to my ears, especially in smaller spaces. The directivity of a horn lens or WG with anything less than 20ft of radiation distance is simply ear melting!, to me anyways. Geddes adresses this with his foam phase plug thing, but unitl i see some HD and FR plots nearfield i'm not convinced that the added dynamics of the higher sensitivity is worth the SQ tradeoffs. The first pair of sealed WgTMMs i built for my brother were capable of 120db as a pair in room....what more do i need!
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post #6 of 1040 Old 04-18-2009, 08:01 PM
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Quote:
Originally Posted by penngray View Post

Thanks! My one requirement is that my speaker sensitivity has to be high, 95dBs or higher but your links look like great matches for the TD12S, anyways!!

I found this kit from 18sound.. I didnt know 18sound had kits on their site. Pretty cool. I wish B&C have some.

http://www.eighteensound.com/staticC...ound_kit12.pdf


Except for the ported design, those look pretty awesome! Those 18sound drivers are $$$. I'm not sure if the value is there for home use but when considering live sound apps and thermal power limits combined with replacement costs definately.
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post #7 of 1040 Old 04-18-2009, 08:23 PM
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For bang/buck I don't think you can beat the 18Sound XT1086.

It measured very well with a BMS 4552ND; even Geddes said so.

Noah
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post #8 of 1040 Old 04-18-2009, 08:43 PM - Thread Starter
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Quote:
Originally Posted by mayhem13 View Post

Not really. I made the jig and used the router to get the same height and correct hole size but that's it. For mounting, i cut a cardboard shipping tube and press fit it onto the backside of the waveguide. Then i poured clear epoxy resin into the tube up to the level of the hole. Then i do a quick pass with the router again for a flat surface, and simply screw the tweeter through the back directly into the hardened epoxy. Very dense.. the waveguide assy sounds like stone when you knock on it. I also used a piece of felt in between the guide and the tweeter as a pseudo gasket.

PE also has the 10" waveguide version that Zaph tested and was too deep for the application. Both the DX25 and SB acoustics tweeter are larger due to the rolled surround and would allow for a much shallower profile and probobly much better results. I may give the 10" a whirl, removing the mounting lip with a lathe an gluing in directly into the baffle. Some seem to think that the profole edhe of the PE guides creates some of the issues so removing it along with the shallower depth SHOULD produce much better results. If you're gonna use a DCX, i'm sure you can shape it to taste. I've worked in the Pro-sound field for years as a live sound engineer and i must say that IMO dome tweeters are WAAAY smoother than Comps to my ears, especially in smaller spaces. The directivity of a horn lens or WG with anything less than 20ft of radiation distance is simply ear melting!, to me anyways. Geddes adresses this with his foam phase plug thing, but unitl i see some HD and FR plots nearfield i'm not convinced that the added dynamics of the higher sensitivity is worth the SQ tradeoffs. The first pair of sealed WgTMMs i built for my brother were capable of 120db as a pair in room....what more do i need!


So you prefer dome tweeters with waveguides for in home audio because Compression drivers give high sensitivity at the expensive of SQ (measured HD and FR issues?)

From all my cost comparisons it does seem that dome/waveguide have a huge performance/$$$ advantage over the more expensive comp. stuff.

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post #9 of 1040 Old 04-18-2009, 09:05 PM
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Other than the one from Geddes the only decent waveguide is the DDS-ENG.

Everyone copying Zaph's MCM WG idea fails to see he hasn't published any off axis measurements. Reason being they look pretty bad. Also problematic is the MCM WG is too small in diameter and only works down low, so it's really a waste to go to the time and trouble. As they say been there, done that, shouldn't have wasted the time and money.

The SB Acoustics concepts works because each WG is custom machined for the specific tweeter
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post #10 of 1040 Old 04-18-2009, 09:12 PM - Thread Starter
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The SB Acoustics concepts works because each WG is custom machined for the specific tweeter

What is that concepts, are they purchased together?

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post #11 of 1040 Old 04-18-2009, 09:25 PM
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Sorry I was referring to SP Technology, not SB Acoustics
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post #12 of 1040 Old 04-18-2009, 10:31 PM
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Quote:
Originally Posted by noah katz View Post

For bang/buck I don't think you can beat the 18Sound XT1086.

It measured very well with a BMS 4552ND; even Geddes said so.

I agree with this. Good recommendation.

ND1090 and Beyma CP385ND is nice as well.

Best Regards
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post #13 of 1040 Old 04-19-2009, 02:53 AM
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Quote:
Originally Posted by noah katz View Post

For bang/buck I don't think you can beat the 18Sound XT1086.

It measured very well with a BMS 4552ND; even Geddes said so.

but it only holds directivity down to about 2k, no?

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post #14 of 1040 Old 04-19-2009, 02:54 AM
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Originally Posted by NoBS View Post

Other than the one from Geddes the only decent waveguide is the DDS-ENG.

this is incorrect information.

edit: janowitz had ordered some for use in a kit on which he was working. the fabrication was of such poor quality, the waveguides were deemed "unusable".

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post #15 of 1040 Old 04-19-2009, 03:00 AM
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Quote:
Originally Posted by penngray View Post

I have DIY ribbon designs, now I want to try waveguides. Reading everything that Geddes has done has me wanting to use more TD12S drivers with a matched Compression driver and some sort of wave guide.

Yes, I could just buy the Geddes kits but I want to find out what waveguide choices are out there and how they match up with compression drivers.

if you want something relatively inexpensive, but with great performance, have a look at the "econowave" over at audiokarma. it is a jbl waveguide that you can purchase from their pro parts group for $10 and a selenium d220ti driver that you can get for about $40 from parts express. crossover details are provided as well.

http://www.audiokarma.org/forums/sho...d.php?t=150939

another option would be the horn on the pispeakers 4pi. it is an eminence horn and you could use the cheap eminence driver or upgrade to a b&c driver. wayne has written on his design extensively, has his own forum where you could ask him questions, and has posted a lot of information in the "econowave" post mentioned above.

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post #16 of 1040 Old 04-19-2009, 03:50 AM
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You are about two projects ahead of me Penn, One of the things that got me interested in a waveguide is the possibility of using a tiny class A amp. Something like a LH0001 and see what it could do. Getting ready, I am looking on e-bay for the equipment to measure IM. My HP 209 is single tone. Lots of comment here on how clean CD's can be, but I have only heard crappy ones, so measurement time!
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post #17 of 1040 Old 04-19-2009, 06:54 AM
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Originally Posted by LTD02 View Post

this is incorrect information.

Unlike you I have hands on experience with the DDS-ENG. Should you choose to explore a little further than simply reading a few forum posts, you'll find companies like Emerald Physics have evolved from the generic 12" WG to using the DDS-ENG in their most expensive speakers. Wonder why???

As I type this I'm listening to DDS-ENG waveguides paired with the B&C DE250's. I've also used them with the BMS 4540ND. And unlike the 18Sound XT1086, the DDS-ENG don't have a characteristic horn like sound.
Quote:


edit: janowitz had ordered some for use in a kit on which he was working. the fabrication was of such poor quality, the waveguides were deemed "unusuable".

Janowitz ordered a single pair and decided against using them based on problems with that particular pair. Had he exchanged them instead of posting a knee-jerk reaction he would have received a usable pair.

Quote:


if you want something relatively inexpensive, but with great performance, have a look at the "econowave" over at audiokarma. it is a jbl waveguide that you can purchase from their pro parts group for $10 and a selenium d220ti driver that you can get for about $40 from parts express. crossover details are provided as well.

I have 2 pair of the JBL Eco-waveguides. The build quality isn't all that great, and they don't sound good even when paired with a high quality compression driver.
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post #18 of 1040 Old 04-19-2009, 07:10 AM - Thread Starter
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Quote:
Originally Posted by LTD02 View Post

if you want something relatively inexpensive, but with great performance, have a look at the "econowave" over at audiokarma. it is a jbl waveguide that you can purchase from their pro parts group for $10 and a selenium d220ti driver that you can get for about $40 from parts express. crossover details are provided as well.

http://www.audiokarma.org/forums/sho...d.php?t=150939

another option would be the horn on the pispeakers 4pi. it is an eminence horn and you could use the cheap eminence driver or upgrade to a b&c driver. wayne has written on his design extensively, has his own forum where you could ask him questions, and has posted a lot of information in the "econowave" post mentioned above.

I browsed through the "econowave" stuff a couple of weeks ago, its one of the reasons I want to try a wave design. Other reasons are because I want compare them vs my Ribbon designs and I have extra TD12S to try new things with.

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post #19 of 1040 Old 04-19-2009, 09:59 AM
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Quote:
Originally Posted by NoBS View Post

Unlike you I have hands on experience with the DDS-ENG. Should you choose to explore a little further than simply reading a few forum posts, you'll find companies like Emerald Physics have evolved from the generic 12" WG to using the DDS-ENG in their most expensive speakers. Wonder why???

As I type this I'm listening to DDS-ENG waveguides paired with the B&C DE250's. I've also used them with the BMS 4540ND. And unlike the 18Sound XT1086, the DDS-ENG don't have a characteristic horn like sound.
Janowitz ordered a single pair and decided against using them based on problems with that particular pair. Had he exchanged them instead of posting a knee-jerk reaction he would have received a usable pair.

I have 2 pair of the JBL Eco-waveguides. The build quality isn't all that great, and they don't sound good even when paired with a high quality compression driver.

Please try not to critisize people for their subjective opinions, interjecting yours as fact. It's kinda childish. I think Penn is just trying to explore some options. I'm sure he'll analyze measurements and hard data when the time comes if he decides to start a DIY waveguide project. You may very well be right that the Geddes waveguids and the DDS are the only options......UNTIL some other DIYer tries some different combos with favorable results in the home environement.

Maybe you could enlight us with some nearfield measurments of FR,CSD and HD on the geddes and B&C loaded DDS to confirm your CONCLUSIVE statement. Otherwise, relax yourself and let Penn enjoy his search for an alternative to ribbons in a high efficiency design.
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post #20 of 1040 Old 04-19-2009, 10:50 AM
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Quote:
Originally Posted by NoBS View Post

Unlike you I have hands on experience with the DDS-ENG. Should you choose to explore a little further than simply reading a few forum posts, you'll find companies like Emerald Physics have evolved from the generic 12" WG to using the DDS-ENG in their most expensive speakers. Wonder why???

As I type this I'm listening to DDS-ENG waveguides paired with the B&C DE250's. I've also used them with the BMS 4540ND. And unlike the 18Sound XT1086, the DDS-ENG don't have a characteristic horn like sound.
Janowitz ordered a single pair and decided against using them based on problems with that particular pair. Had he exchanged them instead of posting a knee-jerk reaction he would have received a usable pair.

I have 2 pair of the JBL Eco-waveguides. The build quality isn't all that great, and they don't sound good even when paired with a high quality compression driver.

your arguments are shooting all over the place, but have nothing to do with what i posted.

let's recall, you said the only good waveguides were those by geddes and dds. i suggested that wasn't correct information. there are lots of people all over the place who are getting great results with a number of different waveguides. i never said that the geddes or the dds don't sound good.

your opinion about the jbl econowaves runs contrary to most everyone who has them. it is good to hear all perspectives though, so thanks for weighing in with your experience.

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post #21 of 1040 Old 04-19-2009, 11:31 AM
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"but it only holds directivity down to about 2k, no?"

Looks like closer to 1K from this:

http://lscon.tripod.com/xt1086/

"And unlike the 18Sound XT1086, the DDS-ENG don't have a characteristic horn like sound."

You're the first I've heard say this.

Noah
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post #22 of 1040 Old 04-19-2009, 11:58 AM
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Quote:
Originally Posted by noah katz View Post

"but it only holds directivity down to about 2k, no?"

Looks like closer to 1K from this:

http://lscon.tripod.com/xt1086/

fair point noah...i suppose it depends how particular one is. the waterfall does begin to collapse just under 2k (and this is also reflected in the falling directivity measurement below), but if that doesn't matter so much for the given application, the usable lower limit could be lower.

18sounds has pretty good measurements on their site as well.



http://www.eighteensound.com/index.a...roduct&pid=178
LL

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post #23 of 1040 Old 04-19-2009, 01:24 PM
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that 18 Sound design looks interesting, but where on earth can you buy the stuff? All the online dealers that I can find don't sell those particular drivers
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post #24 of 1040 Old 04-19-2009, 04:51 PM
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Quote:
Originally Posted by penngray View Post

I browsed through the "econowave" stuff a couple of weeks ago, its one of the reasons I want to try a wave design. Other reasons are because I want compare them vs my Ribbon designs and I have extra TD12S to try new things with.

a key point is that waveguides remove many of the negative room effects from the sound. so a direct comparison with ribbons (or domes) is not really possible. also, waveguides are much less sensitive to their surroundings than ribbons...baffle diffractions and the like are much less of a problem with waveguides.

you'll also notice a peculiar crossover strategy used by some of the better waveguide guys. the woofers are run to the point of beaming, something that is typically never done with traditional designs. the reason is to have the soundfield from the woofer match the soundfield from the waveguide (which in a typical implementation will be down 6db at 45 degrees off axis) through the crossover region. larger woofers beam at lower frequencies. a 15" beams -6db at 45 degrees from about 900hz to about 1.2khz depending on the driver geometry. geddes measured the b&c driver that he uses at 900hz. crossover point for the summas? 900hz. it doesn't have to be perfect, but a good match helps keep the off axis sound the same as the on axis sound (lower in db, but spectrally similar), which is a primary reason why the sound is so good.

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post #25 of 1040 Old 04-19-2009, 05:25 PM
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Talk to John J he was talking about working on a wave guild last I spoke to him.

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post #26 of 1040 Old 04-19-2009, 05:27 PM
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Was reading the patent summary and other information on Geddes. Trying to relate to what I think I hear. When I measured horns in the past, they showed very high IM distortion. I guess I am making the bridge that the HOM issues (reflections/refractions) are causing the modulation. At least that's what horns sound like to me. If refractions are the evil problem, how come most PA horns have sharp discontinuities in them? Does not make sense to me. Dispersion more important than distortion?
Anyone wiser than I, pipe in here.

Taking some of his ideas, what if you took a big block of fairly high density absorptive material, like compressed fiberglass, Celotex etc., cut a cone out of it, then put the very low density foam as the good Dr. recommends in it.
Could you get an absorptive horn with the added HOM suppression in the path?

Yes, Celotex. I still remember a very good sounding, very large single driver horn made with it back in college. I was going to play with it but it looks like you can't get it anymore.

The other comment in the paper was talking about how a compression driver relies on a refraction in the throat to set the initial wavefront, but it does cause issues. Would thin not suggest a dome or ring driver to be useful for a hi-fi transducer? I have never seen a good cross-section of a quality CD and horn, so I am guessing a bit.
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post #27 of 1040 Old 04-19-2009, 06:03 PM
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Quote:
Originally Posted by Nasty N8 View Post

Talk to John J he was talking about working on a wave guild last I spoke to him.

Nate

I actually just posted about this on his forum a few days ago. It's something they're working on, but it's gonna be a while.
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post #28 of 1040 Old 04-20-2009, 12:12 AM
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"that 18 Sound design looks interesting, but where on earth can you buy the stuff?"

You can get BMS from www.assistanceaudio.com; I can't remember if I got the XT1086's from them as well.

I haven't done anything with them so I can's say anything about the sound.

Noah
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post #29 of 1040 Old 04-20-2009, 06:44 AM
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You can buy the 18 Sound horn here...

http://www.loudspeakersplus.com/html/18sound_horns.html
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post #30 of 1040 Old 04-20-2009, 07:20 AM - Thread Starter
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Thanks for the link, lots of unknown online speaker sites out there. Every day I find a new one.

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