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Old 7th May 2015, 07:55 PM   #1
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Default Advise on mid range driver

I am at a turning point in my speaker building journey. Having recently heard the Grimm LS1's i am re-evaluating the need for mid range horns which i currently use. I have the Beyma TPL's which i like alot and am considering a sealed mid range driver to replace the midrange and midbass horns, allowing me to drop one way out my rig.

I have seem the beyma 12P80Nd in a sealed configuration, recommended to go with the TPL. I have access to a pair of beyma 122Nd's which to my untrained eye seem very similar just a slightly lighter cone, higher fs ( not the same power rating - but don't need 700w domestically).

From some simple calcs messing with Qes i seem to be able to get a similar response for both drivers with a f3 of around 90hz. in a sealed cabinet for a Q of 0.7. It all seems to good to be true, or am i compromising the performance for the price of a pair of drivers? (Is the 122Nd - not in same league as the 12P80Nd sonically?)

From recent posts it looks like what i am aiming to build has been done already in the tweek geek BMF1, excepting i am changing all the drivers except the TPL. (peerless XLS 12" for the bass)

I have looked at the faital 12FH530 driver that was used in the BMF1, but am not sure if going to marry with TPL as well.
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Old 8th May 2015, 03:38 AM   #2
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The Beyma 122ND has an Xmax of just 2mm. The Beyma 12P80Nd has an Xmax of 7.5mm. Very different motors.

THE USUAL SUSPECTS:
1--My favorite is the Lambda TD12M because it has the lowest harmonic distortion and matched polar at 1600Hz(and I own a pair)
2--From the datasheet, the Faital 12FH530 also looks excellent. Low Le shorting ring on the pole. Dampeded cone breakup. Good SPL polar match to TPL horn.
3--From the datasheet, the Beyma 12P80Nd has the highest BL=23.1 and BL/Mms(56g). The cone uses composite paper plus carbon fiber. The mirrored(2-spider) suspension is linear to 7.5mm xmax. The datasheet SPL shows cone breakup ~2Khz which suggests a steep slope active Xover is beneficial. The Qtc=0.17 offers motor controlled speed with accuracy which several say is necessary to match the TPL-150.
4--From the datasheet, the 18Sound 12NMB420 also looks excellent. Low Le, just 34g Mms, dampened cone breakup. Good SPL polar match.

FOR WOOFERS:
==== Sd ====
18" 1220 cm2
15" 855 cm2
12" 530 cm2
10" 345 cm2
8" 225 cm2

The large cone area of an 18" woofer provides high efficiency bass with modest distortion generating displacement. Side-to-Side physically connected woofer pairs use counter-forces to dramatically reduce vibrations. Two 18" woofers can provide high quality room-equalized bass from a sealed box alignment with modest watts. Two 18" woofers like (Faital 18FH500, Peavey LoRider18, Beyma 18LX60 rev1) which have modest Mms (140-180g) and Qts~ 0.37 connected in parallel in a sealed 9cuft volume can provide Qtc=0.7 alignment with F3=60Hz before equalization extends the bass to the 20-30Hz range... 30Hz at 100db SPL with 20 watts of power. I have sims if you are interested.


THE ITALIAN CONNECTION: Faital 12FH530 and two Faital 18FH500
probably the best overall driver pairing
Attached Images
File Type: jpg 12FH530.jpg (115.2 KB, 850 views)
File Type: jpg 530.JPG (125.7 KB, 851 views)
File Type: jpg 500.JPG (134.1 KB, 835 views)
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Old 8th May 2015, 03:46 AM   #3
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Quote:
Originally Posted by LineSource View Post

THE ITALIAN CONNECTION: Faital 12FH530 and two Faital 18FH500
probably the best overall driver pairing
And the new 18 XL1800 ??
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Old 8th May 2015, 05:41 AM   #4
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Quote:
Originally Posted by vinylnvalves View Post
(Is the 122Nd - not in same league as the 12P80Nd sonically?)
I ran a simple sim on the 122Nd which estimated that with 2mm Xmax at 90Hz it can generate ~ 101db @1m maximum SPL before the distortion would increase from out-of-gap over extension. Xdamage is 16mm, so increased distortion would probably be the main concern for high SPL transients.

The 122Nd SPL/freq curve in the datasheet shows ~5db increase jump at the primary cone diameter resonance(400-500Hz) which you would want to check with your own measurements before constructing a crossover.

========Subwoofers====

From the datasheet, the NEW Faital Pro 18XL1800 looks like a great high power, high output woofer capable of scary SPL deep bass. MMs = 245g, Le=2.04mH, Qts=0.40.

Simulate two 18XL1800 in a sealed 9cuft box with a 20Hz Linkwitz transform and see how much power is required for 100db SPL @30Hz.

I favor 18" woofers with modest Mms(like 170g), modest Le(like 0.9mH) and smaller box Qtc(like 0.37 ) which in a 9cuft box plus 20Hz LinkWitz transform can generate 100db @30Hz with 20 watts of power(without room gain added). A philosophy of power efficient bass over monster high SPL bass.
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Old 8th May 2015, 06:32 PM   #5
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Thanks for the detailed responses.

Understanding what you are saying about the midrange, the 122nd is possible but there are compromises, unlikely to go above 100db in my 5m x 4m listening room, the response isn't as flat as the other options, but thats correctable with my DSP. ( maybe should have said i intend to run active).
Your mentioning the TD12M's reminded me i have some Altec 414'z in the cupboard gathering dust, they are low qts, so may sim them in IB.
This idea of replacing my midrange horn (200Hz Le cleach with JBL 2482 crossed @ 350hz) is not one of not likeing the horn, but i feel the integration below it is a weakness, that i have unsucessfully not solved, following 3 years of experimenting ( currently running a horn loaded super cardiod with 2 x 15" drivers per channel). Integrating IB is easier and taking the x-over below 100hz makes that even less challenging. So this midrange IB going upto 1300Hz has a lot to live upto.

I have considered the MT-E500M AMT, which can go as low as 300 Hz, but from PK's experience would need at least 2 per side to get the impact/dynamics. But again its crossing in a critical frequency band - so i may not sucessfully solve my integration problem.

Another option i have pondered are the BMR's - for midrange duty only.

On the subwoofer duty - are you suggesting 2 x 18" drivers per channel - it certainly will have impact, a 9 cuft cabinet just for subs is to big for my room. I would have thought the peerless 12" xls drivers with their extended travel would displace enough air. I appreciate the 18" would move less so lower distortion, but it the art of compromise.
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Old 8th May 2015, 11:25 PM   #6
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Quote:
Originally Posted by vinylnvalves View Post
a 9 cuft cabinet just for subs is to big for my room.
You have a 38" wide 200Hz LeCleach midrange horn.... how can you whine about a 9cuft woofer cabinet? Just built around the horn and go UP. Paint the cabinet the same color as your wall, or put a pretty picture on it... speaker camoufloge :-)

Your DSP can provide room equalization and time alignment for the dual 18" woofers, and also time alignment for any horn tweeter choice above the JBL 2482 in the big LeCleach.
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Old 9th May 2015, 05:11 PM   #7
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My midrange horn - isn't that big - its a 200hz horn crossed at 350hz - 68cm diameter. The attached image shows what space i have to play with, with respect to my current speakers. The wave guides on the TPL's are signficantly larger that the production ones and allow the crossing to be lowered to around 1200hz. Also they are firing into a 2 ltr box which is fully stuffed, which has lowered the distortion.

Doing the sums, for the proposal of 2 18" drivers in a 9 cuft box will need a 6" deeper and 4" wider box to get the internal volume. My current arrangement with 2 15" drivers move enough air, it just doesn't go low enough (40hz with equalisation). Maybe i will look to see if there are any suitable 15" sub driver (last time i looked they were either midbass or heavy coned subs)

I have seen a clone of the Daniel Hertz M1 mentioned in the past using a single 18", i assume the cabinet would need some structural considerations as there isn't the second driver to cancel the vibration effects.
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Old 9th May 2015, 05:23 PM   #8
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forgot to attach the picture ...doh
[IMG]Click the image to open in full size.[/IMG]
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Old 10th May 2015, 06:36 AM   #9
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SWEET LeCleach! Wish I had one :-)

Have you experimented with using a small horn tweeter like the Fostex T90A or T500A? They were designed for integration with a round midrange horn. There are several positive feedback reports. You can locate the Fostex just under your LeCleach front edge and use your DSP for time alignment.

The Beyma TPL-150H has a 80H x 30V horn pattern. They are often mated to sealed boxed midrange speakers which gradually beam to +/- 40degrees around 1600Hz. This creates a smooth directivity function that provides a natural soundstage in many homes. Geddes has a good whitepaper. http://www.gedlee.com/downloads/directivity.pdf

I suspect you have enough spare stuff in storage to build a speaker like the BMF-1 around your TPL-150H. If you constructed a separate sealed woofer box you could also test it with your current LeCleach system.
Attached Images
File Type: jpg T500A.jpg (104.2 KB, 717 views)
File Type: jpg Directivity Model.jpg (85.9 KB, 200 views)
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Old 10th May 2015, 09:07 AM   #10
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I think the point of me wanting to replace the midrange is being missed. I have thougth that the TPL and a round horn don't work that well some time ago. What I do know is that integrating anything below the midrange horn is more challenging. I have some BMS 4592's. I used in the horns no integration issues at the top, my 10 ft listening position wasn't far enough back for them though to be on axis. So that's why I think the horn needs to be replaced, to ease integration, but what I replace it with needs 99% of the qualities of a big CD in a big horn, is this an impossible ask?
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