"Every speaker construction should start with a 15" bass driver! JBL knew this already in the mid Nineteen-forties."

[CuteStudio]

These aren't about bass extension, but they do get the dynamics very right, even with fleapower.

This is what I noticed with 12" Eminence Beta 12s, 96dB / Watt or something crazy like that.
Lots of dynamics from very little power!

 

[CuteStudio]

My favorite tube amp has zero global feedback, and terrible bandwidth.

I modified my Class A tube amp to remove the input tube and the transforner from the GNFB loop entirely. There's a good Thorsten Loech post on DIY audio about the reasons. Not just stability, but a bandpass device has little feedback where it needs it anyway. And non linear things (iron) 'do not respond well' to feedback, merely multiplying the harmonics. So now only my driver and output tube are in a loop, just to get the low impedance I need to drive the transformer well. The sound is remarkable. Thorsten was correct! The transformer does a much better job being driven well, and left to get on with the job. Also - super stable!

 

[AnalogSteph]

Troels designs are built to maximize performance of his beloved Vacuum tube amps. The drivers tend to be selected for lowest distortion and broadest dynamics.

He designed an excellent 8" paper cone driver with attention paid to longterm compression effects.

More recent driver designs throw power at the problem.

Which arguably is the more economic approach for most people. Amplifier power is pretty cheap these days (and has been for a while). Good high-efficiency drivers aren't.

 

[Jim Matthews]

Which arguably is the more economic approach for most people. Amplifier power is pretty cheap these days (and has been for a while). Good high-efficiency drivers aren't.

I'm living this practice.

From Direct Heated triodes and high sensitivity drivers to JBL 708p.

I couldn't be happier with the change.

 

[Zvu]

What high sensitivity drivers and design did you use ?

 

[blueone]

Of course Alnico magnets help too: some of the well built tube table-top radios with 6" alnico speakers in them sound so spookily realistic on speech, you'd swear someone else was in the room. Think about it: Class A tube, Alnico speaker - paper (with possible whizzer) and a fully tube tuner and peramp section: we've gone forward in many ways with HiFi, but not always toward the direction of accurate sound.

Alnico magnets make an audible difference? Seriously? I did just think about it, and I'm left wondering what a post like this is doing on a site like ASR?

 

[SIY]

Alnico magnets make an audible difference? Seriously? I did just think about it, and I'm left wondering what a post like this is doing on a site like ASR?

As soon as you see someone rhapsodizing about the wonders of 1950s table radio technology, you know it’s time to smile and slowly back out of the room.

The approving cite of Thorsten Loesch, easily the most intellectually dishonest person I’ve ever encountered, seals the deal.

 

[Jim T]

That's a quote from Troels Gravesen, a super-ultra-mega-productive speaker builder from Denmark. I often check out his website and mostly every time he has come up with a new model..
I admire his work, not even mentioning the super advanced woodwork! That's second to none, and the number one reason I've never dared try one of his designs. Can of course hire a pro woodworker but that's like cheating..

Anyway, just wanted to show some DIY loudspeaker porn..

http://www.troelsgravesen.dk/

View attachment 129208

Very nice. Seems to have a little "Wilson" heritage to it. beautiful cabinets.

 

[Jim Matthews]

What high sensitivity drivers and design did you use ?

BMS 4592/Deltalite 2515 in simple (but enormous) cabinet with an equally imposing SEOS 24 horn above.

I sold those parts off and lived with an Open Baffle 12" from Bastanis with a very crude Compression driver and sealed Deltalite 2512 for bass duty.


That satisfied for 3 years, until the RME ADI-DAC lead me here, and to the JBL 708p.

 

[Zvu]

BMS 4592/Deltalite 2515 in simple (but enormous) cabinet with an equally imposing SEOS 24 horn above.

I sold those parts off and lived with an Open Baffle 12" from Bastanis with a very crude Compression driver and sealed Deltalite 2512 for bass duty.

That satisfied for 3 years, until the RME ADI-DAC lead me here, and to the JBL 708p.

Getting BMS concentric ring radiator to work as it's supposed to and then blend it with 15" woofer is no easy task. Just making raw measurements for a behemoth like that to be able to tailor the crossover per todays standard is no trivial task.

Deltalite II 2515/BMS 4592/Seos 24 are of premium quality and conceptualy kilometers ahead of 708p concept.

If you don't mind me saying, if you optimized your loudspeaker to measure as 708p does - then it would have been a fair comparison.

I'd use passive crossover between midrange and tweeter and Hypex FA122 per loudspeaker to tailor the response and crossover frequency between woofer and midrange. That way you can use smaller cabinet and tailor the bass response as you see fit and the total cost would be lower than JBL 708p but potential performance would be much better.

 

[restorer-john]

Alnico magnets make an audible difference? Seriously? I did just think about it, and I'm left wondering what a post like this is doing on a site like ASR?

This, found on Lansing heritage site:

 

[Jim Matthews]

I'd use passive crossover between midrange and tweeter and Hypex FA122 per loudspeaker to tailor the response and crossover frequency between woofer and midrange. That way you can use smaller cabinet and tailor the bass response as you see fit and the total cost would be lower than JBL 708p but potential performance would be much better.

The change in approach came after I doubled my money reselling the BMS.
The Open baffle design cost me all of $300 - and a 4 hour round-trip drive.

My desire is to have fewer, smaller and less complicated things.

Could the sound be better, DIY?

Absolutely.

 

[JWAmerica]

I concur. Love my monkey coffins.

Sadly the white/black woofers needed to be replaced and they look a bit plain with all black woofers now.

 

[AudioJester]

15 or 18 inch AE drivers 50-500Hz, my peronal pick in the diy realm. The best I have experienced was with a multidriver point source horn crossing over around 350Hz, combined the subwoofers 60Hz.

 

[DWPress]

I gotta agree because it reinforces my own madness. But my speakers have active XO so the woofers only see 55-350Hz with a LR4 on both ends.

 

[Jim Matthews]

I gotta agree because it reinforces my own madness. But my speakers have active XO so the woofers only see 55-350Hz with a LR4 on both ends.

View attachment 139953

How did you get the forklift in the door?

 

[wwenze]

Maybe one day we will go back to the days of assembling speakers like Ikea furniture.

I'm always a supporter of speakers being part of the furniture, for performance reasons.

 

[King_Pin]

My speakers which all the parts are in the closet still have to be built.
Full front setup L/C/R
Each cabinet houses 2 x JBL 2226h, 2446 CD with a Be diaphragm and a huge waveguide.
I just don't have the room anymore since I moved my work to the basement where the theater used to be.
All measurements and xovers designed by my friend Ryan.

 

[anmpr1]

15" woofers in speakers make little sense.

I suppose it turns on how sensible one chooses to be. JBL applications engineer, the late and great Drew Daniels thought differently. His brew:

[4] 2245H 18" subwoofer drivers
[2] 2220H 15" midbass drivers
[2] 2123H 10" midrange drivers
[2] 2445J 4" compression drivers
[2] 2382 Flat-Front Bi-Radial horns
[2] 2405 Diffraction tweeters

His reasons (that make little sense) can be read here:

http://www.audioheritage.org/html/perspectives/drews-clues/1-intro.html

http://www.audioheritage.org/html/perspectives/drews-clues/3-woofers.html

http://www.audioheritage.org/html/perspectives/drews-clues/2-horns.html

 

[Jim Matthews]

My speakers which all the parts are in the closet still have to be built.
Full front setup L/C/R
Each cabinet houses 2 x JBL 2226h, 2446 CD with a Be diaphragm and a huge waveguide.
I just don't have the room anymore since I moved my work to the basement where the theater used to be.
All measurements and xovers designed by my friend Ryan.

I genuinely hope you build these. It should be epic.

*wowza*