Recommendation of 8-Inch Woofer + Real Tweeter - Page 2 - diyAudio
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Old 5th April 2014, 07:38 AM   #11
lexer98 is offline lexer98  Argentina
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Selenium 8MB4P can fit in a relative small enclosure ... here is a simulation with a box of 18LTS - Sealed box with fill to lower the QTC ... but the results aren't good, high QTC and F3 (very bad bass response)

Click the image to open in full size.
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Old 5th April 2014, 11:14 AM   #12
system7 is offline system7  United Kingdom
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Quote:
Originally Posted by lexer98 View Post
Selenium 8MB4P can fit in a relative small enclosure ... here is a simulation with a box of 18LTS - Sealed box with fill to lower the QTC ... but the results aren't good, high QTC and F3 (very bad bass response)

Click the image to open in full size.
These JBL Selenium drivers all seem to have very high Qts, which does make for problems with small boxes, and I don't think they are designed for that application. But some of it is actually the nature of this type of speaker. You simply have to lower your expectations of deep bass with cloth surround high efficiency drivers. You might not want the bigger magnet versions either, which are moving away from the concept of an easy to filter Le around 0.6mH, IMO. They usually have a low Xmax too, and don't have a lot of excursion in the bass.

I got lucky with this Sony cloth surround driver:

Click the image to open in full size.

It has only a very light transparent cloth dustcap, as opposed to some of the more solid paper ones. You can see the magnet through it.

Troels did something similar to my own light filter with this Supravox 8" driver. He missed a trick by not using a KEF type third order tweeter filter wired in negative polarity though, hence the need for a waveguide in his experiments to line up the acoustic centres better:
Supravox 215GMFHow to tweak this driver to better performance

THIS is how you do it, IMO, It's easy:
DIY with Kef and Celestion

8 inch bass is a very difficult one to get sounding nice without the KEF filter trick. It's the phase problem with a big woofer. What sort of tweeter you use depends on what you think sounds nice. It depresses me that people always seem to follow the conventional wisdom and go out and buy soft domes without really noticing how harsh and bad they sound though.
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Old 5th April 2014, 01:22 PM   #13
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The problem here is that the OP will not end buying what he wants because of foreign taxes. So the best thing is to spend his money wisely in a kit of considerable quality for a low price.

BR-1 Kit Components | 300-641 (for $130.86)
Kit includes:
Two Dayton Audio DC160-8 6-1/2" woofers
Two Dayton Audio DC28F-8 1-1/8" silk dome tweeters
Two crossover boards
Two 47 F non-polarized capacitors
Two Dayton Audio 0.1 F by-pass capacitors
Two 8 ohm 10W resistors
Two 1.8 mH 18 AWG air core inductors
Four Dayton Audio 6.2 F polypropylene capacitors
Two 4 ohm 5W resistors
Two 10 ohm 5W resistors
Two 0.5 mH 20 AWG air core inductors
One 8 ft. 16 AWG speaker wire
Twenty-four .205" (16-14 AWG) female disconnects
Two 24" x 18" sheets of acoustic foam, 1-1/2" thick
Twenty-two #6 x 3/4" Phillips pan head screws
Speaker terminal cups NOT included

More Parts Express Speaker Kits here
-------------------------------------------
Other interesting drivers from overseas (some more expensive).
Dayton Audio RS225S-8 8"
Dayton Audio RS225-8 8" Reference Woofer 8 Ohm
Amazon.com: Dayton Audio RS225-8 8" Reference Woofer: Electronics
Vifa P21W0-20-08 Woofer
Vifa P21W0-20-08 Woofer
http://www.madisound.com/store/manuals/p21wo20-08.pdf
ScanSpeak Classic 21W/8555-00
The Madisound Speaker Store
Monacor SPH-200KE
SPH-200KE
Monacor SPH-200KE
Monacor SPH-200KE Kevlar Cone 8 inch HiFi Woofer from Monacor 75.01 IN STOCK (5 Apr 2014)
Seas L22RNX/P
H1252-08 L22RNX/P
Seas L22RNX/P H1252-08 Woofer - Prestige Series Woofer
Seas Excel W22EX001
E0022-08S W22EX001
Seas W22EX001 E0022 Linkwitz LX521 & Orion Woofer
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Old 5th April 2014, 09:46 PM   #14
system7 is offline system7  United Kingdom
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I'm a bit dubious about a 6" driver with a 10W per channel amp, Inductor. They DO tend to be inefficient! It's down to the large coil you need and the nature of 6" drivers.

I've built a lot of variations on the 8 inch bass theme, Here with a typical sort of rubber surround bass:

Click the image to open in full size.

Morel CAT 298 soft dome tweeter. Not exactly smooth and unfatiguing. Usual spit and sizzle.

Click the image to open in full size.

Mylar dome tweeter. Quite nice but a bit BRIGHT at times.

8 inch bass IS efficient in general. I don't have a particular preference really. They all work quite well. Lots of bass for sure.

I really don't notice the theoretical lack of dispersion around 3kHz crossover. It's a sweet high efficiency design.

I'd be willing to take on almost any 8 inch bass driver.
60W 8in Shielded Bass Mid Range Speaker | Maplin
80W 8in Shielded Bass Mid Range Speaker | Maplin

These are cheap Chinese imports. But i think I could do something with either. The smaller magnet version would need less filtering.

I can particular commend a simple tweeter like this Monacor HT22/8. It sounds very good on a third order filter:
HT-22/8

You've probably never heard a cone tweeter with a good sophisticated crossover, as opposed to the usual simple cap, but they sound SO NATURAL when done properly!
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Last edited by system7; 5th April 2014 at 09:51 PM.
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Old 5th April 2014, 10:53 PM   #15
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Your very best link was already posted for the OP.
Pi Speakers - Prices, Dimensions and Specifications ($180-00 for 2x one Pi bass reflex kits)
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Old 6th April 2014, 10:28 AM   #16
system7 is offline system7  United Kingdom
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Quote:
Originally Posted by Inductor View Post
Your very best link was already posted for the OP.
Pi Speakers - Prices, Dimensions and Specifications ($180-00 for 2x one Pi bass reflex kits)
AFAIK, Wayne Parham of Pi Speakers uses a second order and Zobel on the bass for a SET suitable flattish impedance on the Eminence Alpha 8 driver and crosses over at a lowish 2kHz to a third order treble with positive polarity on the wiring. It would need a good tweeter to pull that off, IMO.

But building kits isn't really my idea of diy audio at all.

The Sony E44 originally used just a 2.2uF non-polar capacitor on the mylar dome wired positive. That was it!

Click the image to open in full size.

A bit Mickey Mouse IMO. It sounded merely OK. I adapted the much better KEF type circuit below for it. I got away with 0.7mH and 8.2uF on the bass. The filter is like this.

Click the image to open in full size.

Very good sounding speaker. I give an analysis below. 5kHz Bass cone breakup is well controlled. No-one will be interested in the phase plot except me, I expect. But it's EXCELLENT at crossover.
Attached Images
File Type: png Typical_8inchBass_Filter.PNG (26.8 KB, 56 views)
File Type: png Typical_8inchBass_FreqResp.PNG (20.5 KB, 69 views)
File Type: png Typical_8inchBass_Phase.PNG (24.7 KB, 44 views)
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Old 10th April 2014, 01:47 AM   #17
krafty is offline krafty  Brazil
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Hi folks, back in the thread here, I see that there are lots of suggestions, I will go through all of them, so far I thank you all the contribution. Folks here also helping me out on another thread, very good
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Old 13th April 2014, 03:00 AM   #18
krafty is offline krafty  Brazil
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I thought I would share the current state of my cabinet:

Click the image to open in full size.

I did some tweaking today on these drivers. Added a series 11R/20W resistor and replaced the series 4.7uF bipolar capacitor for a 100V polyester one. I was wondering what kind of coil filter I would need for the woofer (8HTS500 - datasheet).
I noticed improvements already... piezo not that bright as it was, and allowed me to now bring up mediums from the hardware equalizer - the previous setup was making the piezo deal with a great amount of medium frequencies - that is why I could not tolerate the mediums in the hardware equalizer!

But as I was doing this, I was thinking... why NOT use this same cabinet with the new drivers? I would have no work at all around the cabinet besides lacquering or painting it brand new. All I would have to pick is the exact woofer and tweeter to fit in here. The portuguese folk hinted this case might be 19 Liters net. I will measure it from inside.

Does the foam inside the cabinet affect this measure or is a cabinet like this supposed to work without any foam at all? Because in practice, if you foam stuff into it, there is less space....

By the way, the BR-1 Kit components looks very affordable! Thanks Inductor. Will look into this.

Last edited by krafty; 13th April 2014 at 03:28 AM.
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Old 13th April 2014, 03:57 AM   #19
krafty is offline krafty  Brazil
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I've looked at the Dayton RS225-8 and its specifications are listing a 12,4 Litre cabinet as optimal. I would have to eliminate about 6 to 7 liters from this cabinet. Perhaps placing another plywood inside it or maybe even reducing height or placing the front plywood inwards so it gets notched enough.
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Old 13th April 2014, 06:30 AM   #20
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When you can get an extra octave more extension going vented, I would advise not shrinking your box smaller. Using an 8" to 66Hz as the lowest seems like a waste to me.

Later,
Wolf
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