MJK’s Jordan JX92S OB with a Goldwood GW-1858 Woofer in an H Frame

[ttan98]

Hi TT,

True, this small enclosure does not cover the last octave or two, depending on how low you consider to be adequate, i.e., a 16Hz organ pedal note. I've been using them on a pair of Studio Tech Ultra 24" stands. In my living room they are quite good down to 50Hz and maybe a bit lower, then they drop off pretty quick (confirmed with a signal generator driving them while setup in the actual listening space).

Imaging is really very good, but as it is a single driver, high frequency dispersion does suffer as you move off-axis and the Fostex datasheet shows response for 30- and 60-degrees. Nothing really new here.

As for high frequency extension, I bought a pair of T90A tweeters intended to pair up with these. However, once I had these playing, I found no real lack of response for the last octave or so, hence I've not used them yet. Of course, others may feel differently and prefer to bring in a super tweeter for the last octave. With some really good analogue recordings, the sizzle on cymbals is crisp and even brushes on a snare drum sound quite natural.

Hope this helps.

Regards, KM

thks for the info, you see I play with the Fostex 167E before, I found it to inadequate in a number of areas, hence so many questions.

I think the F120A is a different beast better than or superior to FE167E in more areas than one sonically.

to keep into prospective the price difference is
FE167E - about $60
F120A - about $200

 

[MJK]

Any idea how the Seas CA26RE4X woofer would compare to the Goldwood GW1858 for this application in an H-Frame?

David,

Sreten is correct in his assessment. The low Qts and the low efficiency are going to be a problem. If you want bass from an H frame with the SEAS driver you are going to need to apply EQ to the low frequencies and a boost to all frequencies. You are going to have to force it to work in the H frame. The Goldwood driver will work naturally in the H frame. The Godwood driver would probably not work so well in a bass reflex or sealed enclosure where the SEAS driver would be happier.

 

[hifimaker]

Thank you Martin for the insight. I'm a noobie when it comes to building speakers, and this is my first real speaker project.

I have a pair of MOTH's as a gift from Nelson, and looking to build an OB speaker with a woofer. Your H-frame design is very exciting and looks great as well! I like the fact I can keep the H-frame woofer and continue to experiment and replace the full range driver.

A really terrific design and a heavy contribution to the hobbyist community!

Thank for the help and sharing your work.

-David

 

[InclinedPlane]

The 120A and 200A I think are the most beautiful fullrange drivers out there. They look vintage but also have a look of modern precision.

 

[MJK]

David,

The Moth driver in an OB sitting on the H frame should work fine. The only thing you need to pay attention to is the relative efficiency of the two drivers. I had to apply 6 to 10 dB of boost to the H frame to match the efficiency of the Lowther ML TL, so you probably will need to use an active crossover. The reason I have been focused on smaller full range drivers is that they are less efficient so in the future there is the potential for a passive crossover option.

Thanks for the positive feedback,

 

[kmaier]

The 120A and 200A I think are the most beautiful fullrange drivers out there. They look vintage but also have a look of modern precision.

Hi IP,

I've not seen the F200A except in pictures... but yes, a pretty driver. The same goes for the F120A. Attached is a link for a group of pics I snapped last year unwrappng a F120A and a Feastrex D5nf... a picture is still worh a thousand words, enjoy.

http://good-times.webshots.com/album/561454797HMqgje

Regards, KM

 

[InclinedPlane]

Ah! you're killing me. I'll never have enough money for Feastrex, d'oh!

 

[maxro]

I am interested in this driver F120A, the price in Australia is quite attractive AUD$196 = US$135 each cheaper than those sold in the States!

Yeah, I saw that too. Major Music appears to have mis-priced them at $100AU less than they should be. I emailed to ask if they would ship to Canada (their shopping cart system does not list Canada as an option). They said that it would be no problem and they would get me a shipping quote if I would let them know how many I wanted. I emailed back with a request for one pair of F120A drivers. That was on October 10th and I have yet to hear back from them.

I suppose one pair of drivers isn't worth their effort. Perhaps a group buy is in order?

Edit: Sorry about the OT.

 

[chrisb]

Hi IP,

I've not seen the F200A except in pictures... but yes, a pretty driver. The same goes for the F120A. Attached is a link for a group of pics I snapped last year unwrappng a F120A and a Feastrex D5nf... a picture is still worh a thousand words, enjoy.

http://good-times.webshots.com/album/561454797HMqgje

Regards, KM

Having held each, there is one thing the best photos in the world can't completely convey, and that is the almost sensual quality of fabrication detail.

The F120A (and F200A) are certainly examples of Fostex's best work, but the Feastrex are in a class by themselves. Analogies are worthless trying to describe it.

Hopefully someday before my hearing is completely shot I'll actually get a chance to hear the Feastrex in the appropriate cabinets.

 

[planet10]

I suppose one pair of drivers isn't worth their effort. Perhaps a group buy is in order?

At that price i might even be able to afford a set... they'd be 10 weeks on a boat thou.

I suggest everyone in Oz, quickly buy a pair before they figure out their mistake... that is more in line with what one would expect FX120 to cost,

dave

 

[Aengus]

Maxro said:

I suppose one pair of drivers isn't worth their effort. Perhaps a group buy is in order?

Hey, Max, I might reconsider.

We could always ask an Aussie member to do the buy and ship them to Canada. It wouldn't be too onerous if they just had to accept the carton as shipped to them, and readdress it to a Canadian address.

Come to think of it, I've got some (somewhat distant) relations in Australia. If there's insufficient response here, let's get together and see what we can work out.

Regards.

Aengus

P.S. I got busy so haven't done anything with the EVs yet. And I too apologize for the O/T.

 

[ttan98]

Spoke to the sales personnel at Major Music in Aussie land.

F120A is out of stock, takes 3-4 weeks delivery, the Internet price incorrect, correct price AUD$241.

 

[Aengus]

correct price AUD$241.

Which is about US$161 - Madisound lists them at US$227. Still a good deal.

[edit] ttan98, thanks for checking.

 

[maxro]

We could always ask an Aussie member to do the buy and ship them to Canada. It wouldn't be too onerous if they just had to accept the carton as shipped to them, and readdress it to a Canadian address.

Ah, but if we ordered them directly, we would circumvent the Australian sales tax.

 

[dublin78]

Would these work in an H frame?

http://www.alphard.pl/en/product/79/61

short info: Woofer with a paper cone on a stiff suspension. Ventilated magnet.
Power [ Watt Max ] 250 W
Power [RMS] 125 W
SPL [dB] 97 dB
Impedance 4 ohm
Frequency range [Hz] 27-2500 Hz
Cone material Cellulose
Dumper Textil
Frame Steel
Speaker dimension [inch/mm] 18" / 460 mm
Cone diameter 383 mm
Mounting depth 194 mm
Coil diameter [inch / mm] 2,5" / 65 mm
Coil carcass Aluminium
X-max [mm] 4 mm
Magnet[mm] 169 mm x 20 mm
Weight 5,84 kg
Fs [Hz] 27 Hz
Qts 0,46
Qms 4,46
Qes 0,51
Search:QUALITY POLICY

 

[InclinedPlane]

Sure I Think they'd be fine. The specs look good. I'd like to see a slightly higher Q though. The 18" size with its huge surface area will help.

I think I'm going to head in a different direction and try this driver:

http://www.usspeaker.com/beyma sm115k-1.htm

run by a subwoofer amp. That way the low Q won't be a problem for my OB with its healthy xmax, low FS and much higher motor strength vs moving mass compared to the high Q drivers normally used in OB. Downside is: $500 for a pair.

 

[MJK]

dublin78,

If it was me, I would look for a driver with a Qts of about 1.0. I am afraid that the lower Qts of the driver you selected might compromise the bass performance unless you use some EQ. To really see how it would work I would model it before spending any money and let the calculated results guide your choice. If you look at the design studies on my site you will see the impact of lower Qts on bass performance and the differences between OB, U frame, and H frame responses.

 

[InclinedPlane]

That reminds me. Aren't the woofers on Jamo's R909 low Q units? I wonder how they did it.

 

[vaughn]

I am quite enamored with the open baffle speaker and have an off brand 18" woofer
I would like to experiment with(GLI Pro ZX-18200, looks like it might be a Goldwood oem).

I am curious which active crossover you are using, Martin. I would like to have the flexibility of
being able to experiment with different drivers for the top end. I have been doing some research
in an attempt to find a solid recommendation but it seems that most avoid using them.

 

[MJK]

vaughn,

I am using a dBx DriveRack PA crossover. It will run two or three way with slopes between 6 and 24 dB/octave, can strore quite a few configurations for recalling later, and has some EQ cabability.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=246-170

I am sure it is not the best but it seems to work well for me and I have been happy with the performance. The direct competitor is the Behringer DCX unit which has similar features and a computer control hook up which would be really nice. Both of these use XLR connectors and my three identical 200 W SS amps and my SS preamp also have XLR connection capabilities. I picked up eight 10' long XLR cables from an e-Bay store at a great price and they have made connecting and reconfiguring really a snap.