Beyma CP21F match for Beyma TPL150H

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JohnG
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#1 Beyma CP21F match for Beyma TPL150H

Post by JohnG »

I am much closer to producing my first Passive OB Build.
I have 2 x Beyma TPL150H, 2 x Beyma 12P80ND, 4 x Eminence Beta 15's.
I intend on using a 1st Order Xover.
I have been offered 2 x Beyma CP21F with a 1st Order Xover, produced from expensive parts for a very fair price.
My plan so far, is to get up and running and make this a project of discoveries and learning,
in the hope I can end up with a OB that is a 'keeper'.
Would introducing the CP21F into the Baffle, work out as a improvement ?
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#2 Re: Beyma CP21F match for Beyma TPL150H

Post by pre65 »

JohnG wrote: Sun Nov 24, 2019 7:17 am
I am much closer to producing my first Passive OB Build.

My plan so far, is to get up and running and make this a project of discoveries and learning,
in the hope I can end up with a OB that is a 'keeper'.
Go for it. :)
The only thing necessary for the triumph of evil is for good men to do nothing.

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G-Popz THE easy listening connoisseur. (Philip)
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#3 Re: Beyma CP21F match for Beyma TPL150H

Post by steve s »

I have no experience of those tweeters. but a few years ago I bought some bullet tweeters .. They cost a bit more than those, but after a few weeks listening they still had a coarse sound.
one of them is in my daughter's bass rig now, and sounds good enough
As ever you take a chance..
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#4 Re: Beyma CP21F match for Beyma TPL150H

Post by JohnG »

The words of the wise are taken,
I will make my offer for these units.
As I am close to having all the drive units at home, and I make no secret of the fact I am a 'Electronics Numb Nut' would it be a sensible move to purchase a adjustable virtual xover box, to get the initial usage of the Open Baffle Speaker Build functioning ?
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#5 Re: Beyma CP21F match for Beyma TPL150H

Post by steve s »

Just looked up the 12P80ND's, must say I'm very impressed with the specs for a mid driver, a BL of 23, a nice flat output between 200 Hz to 3khz if the specs are to be believed.
Should be a good match with the beyma.
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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#6 Re: Beyma CP21F match for Beyma TPL150H

Post by steve s »

JohnG wrote: Sun Nov 24, 2019 10:40 am would it be a sensible move to purchase a adjustable virtual xover box, to get the initial usage of the Open Baffle Speaker Build functioning ?
That sounds a good idea and easier than me adding / removing wire from inductors
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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#7 Re: Beyma CP21F match for Beyma TPL150H

Post by JohnG »

Hi Steve
I'm glad you approve :D
You are indirectly responsible for my choice of drive units, and you are also the individual who inspired the Vendor of the Drivers that I bought to build there own OB, even though it ended up a active design, but it did have 18" XB's as well.
I am hoping to have a dual role for the Bass Assembly as I would like to attempt to use it with the 57's as well, so a Little planning later in 2020 will reveal a way to achieve this, in the meantime I am looking to be listening for the December Holidays.
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#8 Re: Beyma CP21F match for Beyma TPL150H

Post by chris661 »

I'd consider aiming the additional tweeter backwards, so you've got dipole sound over more of the range.

I did an OB a while ago, using 1x Beyma 15P1200Nd, 1x Faital Pro 10FH520 and 1x EV DH1a per side. It was pretty impressive, but required tri-amping and lots of EQ, particularly at low-frequencies. For me, the presentation was always a little "off", even if the graphs looked good. I found it was because the midrange and bass were dipole (ie, some sound going backwards) while the treble was horn-loaded and only going forwards - the interaction with the room was very very different.

I'll be interested to see how your project unfolds.

Chris
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#9 Re: Beyma CP21F match for Beyma TPL150H

Post by JohnG »

I will keep posting on the progress with the build.
I'm sure there will be a few head scratching moments for all.
All Drivers will be mounted on a rigid board/baffle for the initial learning phase, then later a dedicated design for a Baffle will be produced
I am keen to know the individual Baffle Sizes required when I do the final modular assembly ?
I have very little constraints for a baffle dimensions if room dimensions are OK at 13ft X 14ftt ?
Would a back to back Tweeter Pair be a further improvement as a dipole ?
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#10 Re: Beyma CP21F match for Beyma TPL150H

Post by chris661 »

Back-to-back tweeters would mean it's closer to dipole across the operating range. Linkwitz implemented this on his LX521 speakers, for example.

Chris
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#11 Re: Beyma CP21F match for Beyma TPL150H

Post by Toppsy »

I have 2 x Beyma TPL150H, 2 x Beyma 12P80ND, 4 x Eminence Beta 15's.
I intend on using a 1st Order Xover.
Good luck with that. I doubt very much indeed you will successfully get those base units to work and integrate fully with just a 1st order filter. By that I am assuming you are meaning 1st order electrical with just a single inline inductor as found on most the freeby online XO design downloads and not a 1st order acoustic slope. To achieve 1storder acoustic with those bass drivers will likely mean a minimum of 6 components to achieve. It is not that linear a driver from the FR plots.

You have only to take into consideration the comments Chris posted on his own experiments to realise the futility of do this with 1st order.

When Scott and I did our own 3-way OB experiments we used twin 15" Monacor bass drivers coupled with a 10" coaxial driver. The bass units we used are far more linier than those Eminence drivers and we had to use 2nd order electrical, however the actual acoustic slopes were asymmetric, 3rd order on the high pass & 2nd order on the LF & midrange bandpass.

Good luck with 1st order. Not heard any speaker yet that uses 1st order XO and had proper control of the bass drivers.
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#12 Re: Beyma CP21F match for Beyma TPL150H

Post by IslandPink »

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#13 Re: Beyma CP21F match for Beyma TPL150H

Post by steve s »

Toppsy wrote: Wed Nov 27, 2019 3:06 pm

Good luck with 1st order. Not heard any speaker yet that uses 1st order XO and had proper control of the bass drivers.
I do agree that the Eminence Beta is probably the weak link in John's line up, but probably quite good enough for starters.
But please do explain the link between 'control' and 2nd & 3rd order crossovers colin
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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#14 Re: Beyma CP21F match for Beyma TPL150H

Post by Scottmoose »

I imagine Colin is referring to the fact that many woofers (not all, but many) have significant resonant modes at the upper end of their range, and in those cases a single series inductor often can't provide sufficient suppression, especially if the driver has a rising VC impedance.
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#15 Re: Beyma CP21F match for Beyma TPL150H

Post by IslandPink »

In general I do agree with Colin and Scott that most bass drivers have a rising and ragged response above the midrange that needs taming. The Supravox is an exception.
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