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post #661 of 11156 Old 12-19-2010, 04:27 AM
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Does this discussion about roundover assume there is no baffle? I assume the design still has a flange to attach the waveguide flush to a baffle.

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post #662 of 11156 Old 12-19-2010, 06:35 AM
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Quote:
Originally Posted by penngray View Post

Does this discussion about roundover assume there is no baffle? I assume the design still has a flange to attach the waveguide flush to a baffle.

Penngray, there is suppose to be a flange to attach it flush with the baffle.

I'm not sure if the post from jzagaja has anything to do with that or not though.

There's a chance that I will order one with a flange and one without. I'll have to check on pricing for that. If the back side of the roundover was flat, someone could always attach 1" long screw posts with a female end on them. Drill holes in the baffle that correspond to those posts, and the WG would fit real nice, just put screws in through the back posts to hold it in place. But I'm not sure how easy that will be on this first round. It wouldn't be hard for a DIY guy to rig up those posts if they wanted too.

Honestly, if the back side of the WG was solid material, then it wouldn't be hard to figure a way to put the screws in through the back.

I'll find out.

If there's time later today, I might draw a cut away side view of how this should mount to the baffle. If anyone wants to beat me to that, go for it! But I'll try.


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post #663 of 11156 Old 12-19-2010, 09:42 AM
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Quote:
Originally Posted by penngray View Post

There is always a risk of splitting hairs to far in the discussion. Also "windows of opportunities" never stay open for ever. The longer the discussion goes on the more the inherent risk of failure increases.

Lets remember someone is ready and waiting. There is no time frame set but I would never risk prolonging the discussion and risk that window closing for unforseen reasons.


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Originally Posted by coctostan View Post

I agree with all of that I just believe we are at the point where the differences are so small that no amount of simulation or discussion is going to improve on it.
If you look at the success of the QSC WG, I'm confident this one will also be successful. It is very similar, but improved in a number of ways with no real downside other than higher cost.


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i'm with penn whose wisdom comes from business experience, getting it 98% right and getting it done is better than getting it 99% right and never getting it done.

my final thoughts in #638. as for any remaining decisions...the advice is simple, go conservative, i.e. "don't f... it up", but lets end the committee meeting.

who has the ball and what is the next step?

Sorry, I have been in and out the past few days. I did not realize that we had fine tuned to the point that we are ready. If we are, then pull the trigger and let's get one made and more importantly measured.

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post #664 of 11156 Old 12-19-2010, 12:27 PM
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Sorry to do this now, but just came across this today by Geddes (post #117 here http://www.whatsbestforum.com/showth...eguides/page12 )

"the ideal for an elliptical waveguide is to have a phase plug in the driver that has an elliptical outlet. Going from cicular to elliptical is ideally done in the phase plug. Then the waveguide becomes exactly an Ellipsoidal geometry. To make an elliptical waveguide which matches to a circular throat requires some "tricks". Tricks that I am not prepared to disclose."

Presumably this just isn't that important, or the known good sounding elliptical WG's like 18Sound's incorporate some appropriate measures in their design.

So, question for jzagaja: is the round-to-elliptical transition taken care of in the SEOS WG geometry, or otherwise accounted for in your simulations?

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post #665 of 11156 Old 12-19-2010, 02:08 PM
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We don't know how smooth transition from circular throat to elliptical mouth affects directivity - I simply cannot simulate these things. We must build prototype to see. I haven't seen elliptical drivers. JBL 476Be seems best type for WG:

http://www.harman-japan.co.jp/jbl/hi...mg/sys04_l.jpg

I think it's easy modify an existing driver to any kind of aperture - using conventional lathe remove an existing phase plug then insert rapidly prototyped plastic phase plug like in 476Be but with elliptical aperture.
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post #666 of 11156 Old 12-19-2010, 02:29 PM
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BTW: There's also E-JMLC-1000 that expands rapidly horizontally and provides loading vertically. All JMLC horns are standalone, can rival OS, EOS and SEOS.
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post #667 of 11156 Old 12-19-2010, 03:06 PM
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Quote:
Originally Posted by jzagaja View Post

Minimum required roundover for removing "axial dip" depends on coverage. With 90deg coverage it is 12cm, with 50deg - 3cm and these values were used in SEOS-15-9050-N4. Now if you need vertical height to be 8" we need rV=4.5cm and 60deg coverage. Should I draw and simulate SEOS-15-9060-N3?

Please! This should satisfy those that want SEOS, but prefer the the taller height closer to the EOS-15

EDIT: Was not logged in and therefore did not see you already did it, thanks. If possible can you simulate the horizontal and vertical FR so we can compare it to the original EOS-15. Beyond that I think it's decision time.
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post #668 of 11156 Old 12-19-2010, 04:52 PM
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Updated Mock-ups with all profiles

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post #669 of 11156 Old 12-19-2010, 07:41 PM
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Quote:
Originally Posted by jzagaja View Post

I think it's easy modify an existing driver to any kind of aperture - using conventional lathe remove an existing phase plug then insert rapidly prototyped plastic phase plug like in 476Be but with elliptical aperture.

Is it really that easy?

What about keeping chips out of the CD? Or maybe the part to be machined is removable.

For a part the size of a phase plug, rapid prototyping is probably an affordable way to produce them in quantity.

But is phase plug design so straightforward that one try will produce one that performs properly?

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post #670 of 11156 Old 12-19-2010, 09:34 PM
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Quote:
Originally Posted by penngray View Post

I believe audio can have style to it, no doubt its a little harder with waveguide designs since "wide" is hard to pass off as stylish when thin is in and "Monkey coffins" are not

I don't think so, necessarily. It depends on depth. A wide, shallow speaker is probably easier to integrate into a room than a thin, deep one.

Also, I suspect a large number of people who end up signing on will be using them with projectors, and a wide, shallow speaker is ideal to hide behind a screen.

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Originally Posted by penngray View Post

Waveguides do not need a tone of screws, The 18sound waveguides have the best flanges I have seen comercially.

I like the 4-point squared-off flange, too.

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Originally Posted by LBDiver View Post

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One thing I've not seen discussed (though I could have missed it): what's the relative depth of each WG? Are the SEOS's deeper than the EOS's? Shallower?

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post #671 of 11156 Old 12-20-2010, 04:40 AM
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I'm agnostic to flange or no flange. I don't care much about appearance. No flange probably looks better though.

I vote for SEOS-15 90x60 (or50) N-3 rH=12.5cm rV=4.5cm...#4 on LB'd mockups.

I say we put the elliptical phase plug discussion on hold for now, but it would be fun to go back to it once these WGs are in production.
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post #672 of 11156 Old 12-20-2010, 04:48 AM
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Going over some old waveguide discussion I remembered/found Geddees answer to why no one sells OS waveguides

http://www.diyaudio.com/forums/multi...ml#post2100010

Quote:
Originally Posted by Geddes View Post

Just to be clear, I did, but I found that there was no value in it for me. I believe that this is why there aren't any on the market right now. It seems like a simple part, and maybe it is if you have a lot of money for tooling, etc. but in small lots its very expensive and people just don't want to pay a price that is interesting to a manufacturer.

Some time ago there was a long thread about making waveguides. The overwhelming postion at that time was that they would be easy to make and that I was just gouging the market. OK, where are they then? That thread was the reason that I stopped selling them. Simply put the waveguide, foam plug and mounting plate are the key to what I make and sell and represent the greatest value-added by far. I am not willing to give this away without due compensation for this value added.

I don't make stand alone waveguides, they are molded into a custom baffle. It is extra work for me to cut them out. I have, and will, sell the baffles with foam plug and mounting plate. Just contact me on the side because I do not advertise this. But be fore warned, they are not cheap


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post #673 of 11156 Old 12-20-2010, 04:50 AM
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Quote:
Originally Posted by jzagaja View Post

BTW: There's also E-JMLC-1000 that expands rapidly horizontally and provides loading vertically. All JMLC horns are standalone, can rival OS, EOS and SEOS.

I think we have posted this before but people are not interested in JMLC horns. I get that you have the prototyped and maybe some built but we should keep the discussion on SEOS.

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post #674 of 11156 Old 12-20-2010, 04:54 AM
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Quote:
Originally Posted by Erich H View Post

Penngray, there is suppose to be a flange to attach it flush with the baffle.

I'm not sure if the post from jzagaja has anything to do with that or not though.

There's a chance that I will order one with a flange and one without. I'll have to check on pricing for that. If the back side of the roundover was flat, someone could always attach 1" long screw posts with a female end on them. Drill holes in the baffle that correspond to those posts, and the WG would fit real nice, just put screws in through the back posts to hold it in place. But I'm not sure how easy that will be on this first round. It wouldn't be hard for a DIY guy to rig up those posts if they wanted too.

Honestly, if the back side of the WG was solid material, then it wouldn't be hard to figure a way to put the screws in through the back.

I'll find out.

If there's time later today, I might draw a cut away side view of how this should mount to the baffle. If anyone wants to beat me to that, go for it! But I'll try.

Thanks, the roundover discussion is a little confusing so I want to make sure its known that most will be installing this flush on baffle.

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post #675 of 11156 Old 12-20-2010, 05:50 AM
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Quote:
Originally Posted by coctostan View Post

I'm agnostic to flange or no flange. I don't care much about appearance. No flange probably looks better though.

I vote for SEOS-15 90x60 (or50) N-3 rH=12.5cm rV=4.5cm...#4 on LB'd mockups.

I say we put the elliptical phase plug discussion on hold for now, but it would be fun to go back to it once these WGs are in production.

Coctostan, there might be more options than what LBDiver posted though. I'm not sure he covered every option with those 6 mock ups. Let's not zero in on those unless they have covered every option.


It's time for the heavy weights to weigh in here. I need to get all the info to the builders.


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post #676 of 11156 Old 12-20-2010, 07:35 AM
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It sounds like it should be either

SEOS-15 9060 N=3 (rH=12cm, rV=4.5) Elliptical flange

SEOS-15 9050 N=4 (rH=12cm, rV=3) Elliptical flange


I think Zilch would be happier to help out with the second choice because the CTC is better and will cause him less problems.

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post #677 of 11156 Old 12-20-2010, 08:07 AM
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ok, lets put some numbers out there for the two presumeably most popular choices; SEOS-15-9050-N4 & SEOS-15-9060-N3.

The height of the SEOS-15-9060-N3 is 8" according to jack. Let's assume we use a 12" woofer and a 0.5" space between waveguide and woofer. That means CTC distance is 10.5". That corresponds to roughly 1250hz. So by Linkwitz's rule, in order to have a 60º vertical lobe the waveguide has to load down to 1250hz. If you use a 15" woofer you need the waveguide to load down to 850hz (impractical probably).

The SEOS-15-9050-N4 is roughly 6" tall (although according to Jack's drawing the above one is only 7.2" tall, not 8" for a comparable figure). This means a CTC of 9.5" and needed loading to ~1400hz. Though, since the SEOS-15-9060-N3 is larger it will likely load down further, a sort of balancing act between CTC and directivity control.

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post #678 of 11156 Old 12-20-2010, 08:25 AM
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Why wouldnt we just keep the same height as what already exists with the QSC HPR-152i, which is 10"?? Of course I didn't see that size listed.

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post #679 of 11156 Old 12-20-2010, 08:27 AM
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Has a ballpark price been given for these units yet?
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post #680 of 11156 Old 12-20-2010, 08:35 AM
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Quote:
Originally Posted by Erich H View Post

Coctostan, there might be more options than what LBDiver posted though. I'm not sure he covered every option with those 6 mock ups. Let's not zero in on those unless they have covered every option.


It's time for the heavy weights to weigh in here. I need to get all the info to the builders.

Erich-

I'm aware of that, I just think that the SEOS-15 N3 90x50 or 60 rV=12.5cm and rH=~4.5cm is the sweet spot. LB happened to have it mocked up. It should give us the best combination of CTC, roundover, and axial dip. Concerning cosmetics I will defer to the majority on that one.

AudioJosh-

My calculations show the lobe being at 30deg down for a 15" woofer on the 8" tall WG and a 1000hz crossover. I'm not sure where you are getting 850hz. IMO, a 1000hz crossover for a 15" woofer makes it pretty much ideal. 1250hz for a 12" is great as well. The nulls are spread apart and directivity should match nicely right around there.

BTW: This is what I'm using for calculations based on Linkwitz's formulas: https://spreadsheets.google.com/ccc?...xVTZQX1E&hl=en
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post #681 of 11156 Old 12-20-2010, 08:41 AM
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I'm aware of that, I just think that the SEOS-15 N3 90x50 or 60 rV=12.5cm and rH=~4.5cm is the sweet spot

Is it? Im not interested in XOs at 1200Hz and above that is pushing all these larger woofers to high. I definitely would lean towards 90x60 more then 90x50.

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post #682 of 11156 Old 12-20-2010, 08:49 AM
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Quote:
Originally Posted by A9X-308 View Post

Has a ballpark price been given for these units yet?

A9X, there has not been a ballpark price given because the manufacturer is still unknown at this time.

The prototype is coming from the people who are doing the waveguide group buy over diyaudio.com but long term the costs of shipping from Poland is just too high imo.

EricH is in control of that though and our job is just try and get an agreed upon prototype.

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post #683 of 11156 Old 12-20-2010, 09:05 AM
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Quote:
Originally Posted by penngray View Post

Is it? Im not interested in XOs at 1200Hz and above that is pushing all these larger woofers to high. I definitely would lean towards 90x60 more then 90x50.

Penn-

I know you aren't interested 1200hz crossovers but by my calculations we should get pattern control down to around 1000hz. If you want to crossover at 800hz I really can't say if a 15" wide WG will hold pattern. We'd have to measure it to really know. I'm pretty sure the 15" width is settled. Nobody else seemed to want something wider.

How does that not match up to your requirements then?

When I say "Sweet spot" I mean that it pleases most people here well enough. None of us know the exact ramifications of small changes from this middle ground. Which N value is best? We are all guessing. Same for roundover.

90x60 matches the QSC waveguide and that allows appropriate CTC spacing if the vertical height is similar. This configuration has proven to be versatile enough IMO. In essence we are designing a SEOS version of the QSC with a better throat match.
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post #684 of 11156 Old 12-20-2010, 09:32 AM
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Originally Posted by coctostan View Post

AudioJosh-

My calculations show the lobe being at 30deg down for a 15" woofer on the 8" tall WG and a 1000hz crossover. I'm not sure where you are getting 850hz. IMO, a 1000hz crossover for a 15" woofer makes it pretty much ideal. 1250hz for a 12" is great as well. The nulls are spread apart and directivity should match nicely right around there.

BTW: This is what I'm using for calculations based on Linkwitz's formulas: https://spreadsheets.google.com/ccc?...xVTZQX1E&hl=en

I can't access that link right now. However, my numbers do need to be checked. I was calculating the corresponding 1-wavelength length based on the assumed CTC spacing. I had seemed to recall Linkwitz's rule of thumb was 1-wavelenght of seperation equaled 60º vertical lobe. That is what I likely misused.

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post #685 of 11156 Old 12-20-2010, 10:02 AM
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Quote:
Originally Posted by AudioJosh View Post

I can't access that link right now. However, my numbers do need to be checked. I was calculating the corresponding 1-wavelength length based on the assumed CTC spacing. I had seemed to recall Linkwitz's rule of thumb was 1-wavelenght of seperation equaled 60º vertical lobe. That is what I likely misused.

I used this formula:

half angle between nulls = arcsin (xover freq wavelength/2*ctc spacing)

For a 1000hz xover and 12 CTC my calcs show a 34 deg half angle or a 68deg window. The axis angle and shape of this lobe between the nulls is a function of the crossover.
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post #686 of 11156 Old 12-20-2010, 10:18 AM
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The axis angle and shape of this lobe between the nulls is a function of the crossover.

Can different XO slopes help? I remember a lot of discussion over on HT guide with Augerpro and his build and this is what Catapult posted in the Raptor thread. Maybe this is just an horizontal axis design thought?

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John K suggested a novel way to phase align horn systems. Use a 3rd order crossover down 6dB at Fc. The transfer function is a BW2 plus a BW1. The horn should be 1/4 wavelength behind the woofer at Fc for best alignment. I sim'd it and it worked quite well -- nearly flat with the phase one way and a deep null the other way. I tried it with 5th order (BW4 plus a BW1) and that worked too but the phase had to be the opposite of the 3rd order.

Too bad Catapult and Augerpro are not posting and lurking on AVS these days

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post #687 of 11156 Old 12-20-2010, 10:21 AM
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Quote:
Originally Posted by coctostan View Post

Penn-

I know you aren't interested 1200hz crossovers but by my calculations we should get pattern control down to around 1000hz. If you want to crossover at 800hz I really can't say if a 15" wide WG will hold pattern. We'd have to measure it to really know. I'm pretty sure the 15" width is settled. Nobody else seemed to want something wider.

How does that not match up to your requirements then?

When I say "Sweet spot" I mean that it pleases most people here well enough. None of us know the exact ramifications of small changes from this middle ground. Which N value is best? We are all guessing. Same for roundover.

90x60 matches the QSC waveguide and that allows appropriate CTC spacing if the vertical height is similar. This configuration has proven to be versatile enough IMO. In essence we are designing a SEOS version of the QSC with a better throat match.


Thanks, I think the important parameters have been hashed out I see little reason not to with the

SEOS-15 9060 N=3 (rH=12cm, rV=4.5) Elliptical flange


as the first prototype? Any more thought on the throat being round to match the CD??

At some point we have to bite the bullet and go with something to just get a working model. EricH is ready and I think even if there might be some flaws, they are going to be minor ones. This solution does have great potential. Just to prove Geddes opinion on it being too expensive to produce these waveguides wrong is awesome alone.

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post #688 of 11156 Old 12-20-2010, 10:44 AM
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Quote:
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Any more thought on the throat being round to match the CD??

I believe the throat is circular at the entry and gradually becomes elliptical. It was my understanding this was the design.

I think Geddes is saying that the absolute optimum would be an elliptical CD would be used with an elliptical WG.
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post #689 of 11156 Old 12-20-2010, 10:45 AM
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So it looks like we need conformation on the throat and possibly the way it mounts on the baffle.


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post #690 of 11156 Old 12-20-2010, 10:48 AM
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Quote:
Originally Posted by coctostan View Post

I believe the throat is circular at the entry and gradually becomes elliptical. It was my understanding this was the design.

I think Geddes is saying that the absolute optimum would be an elliptical CD would be used with an elliptical WG.

I read that link and his new site. I have not posted on it and Im not sure I want to...its very Geddes opinion centric. He hates active solutions and is not even aware of solutions like the MiniDSP...sorry for the OT.

Optimum isnt going to help us much since the elliptical CD choices are very limited and probably very expensive.

So the throat is circular and its angle is going to match the B&C DE250??

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