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PostPosted: 05 Feb 2016, 21:19 
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Location: Australia
Not sure if I have mentioned this before but having enjoyed my 12" Beymas so much I bought the even more efficient 15" drivers. These are 99db efficient and though they are happy in quite a small box I am putting them in a 170ltr box with to huge ports on the rear. Also there is a open box brace down at the the 60ltr mark. If these speakers don't produce good bass I can block off the last 60ltrs and mount a 12" woofer there. All the calcs tell me these will easily go to 40hz. There is diagonal bracing on the sides and the open box brace 3/4 the way down.

So far the boxes have been lined with bitumanised heavy Al tape and Dacron. My base and box building mate Don is doing all the grunt work. About two more weeks until complete.
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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
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PostPosted: 13 Feb 2016, 07:34 
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Got the boxes home now and have done a rough assembly to take a listen. The boxes will be painted and finished next week. Big sound, better bass than the 12" Beymas.
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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
Website: retro-thermionic


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PostPosted: 13 Feb 2016, 15:02 
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Looking good! :thumbsup:

Wouldn't call them that big, though :confused:

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PostPosted: 13 Feb 2016, 17:04 
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Geek wrote:
Looking good! :thumbsup:

Wouldn't call them that big, though :confused:


My wife does and that's all that matters. Lol.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
Website: retro-thermionic


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PostPosted: 20 Feb 2016, 21:10 
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Retro-thermionic "VoXGrandious" re-assembled, painted and now driven by my new repaired 300B. Different bass response with nodes at 80, 63 and a slight fall at 50 to come back at 40 and now with better output at 31hz. My DIY 300B (The Silver Dragon) produces 8W but excellent bass response with 30W Hammond OPTs.
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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
Website: retro-thermionic


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PostPosted: 24 Feb 2016, 20:27 
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Nice work Mark. At 99dB you will get high SPL with low powered amps. How close are they to the wall? You may want to fiddle with the positioning to try and flatten the bass response. The boxes with drivers look pretty heavy. What do they weigh in at?

Cheers

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PostPosted: 24 Feb 2016, 21:42 
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I have no idea what they weigh. More awkward than heavy. I added a double layer of Dacron down the front baffle board into the bottom chamber. I also added another layer behind the speaker. I guy test my speakers yesterday and they goods to 30hz (-3db). With pink noise across the concentric drivers there is a 2db gain at the tweeter. This just gives them some sparkle.

Also my speaker budding mate, Ron, said the tweeter wasn't working as it should. After a lot of stuffing around we removed the Lpad from the tweeter after the Xover and put a 10ohm resistor before the tweeter Xover only. I'm by-wired. The tweeter came to life like I'd never heard it before. Try it yourself.

Also with two 15cm ports at the back midrange was coming out of the ports and muddying voice. The additional Dacron has stopped that. The box was just underdamped. Something I would never usually do. The bass is even better and even tighter now. Goes real low.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
Website: retro-thermionic


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PostPosted: 01 Mar 2016, 07:08 
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Gio, weighed the speakers today. I had them out to put the name plates on, "VoXGrandious", and take some photos for my blog. More images to come.

They weight 40kg or 88lb. Not too heavy.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
Website: retro-thermionic


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PostPosted: 01 Mar 2016, 17:38 
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Some better images.
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Attachment:
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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
Website: retro-thermionic


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PostPosted: 24 Jun 2016, 20:21 
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I have been driving these very high efficiency speakers with low power tube amps. But a week or so ago I hooked up one of my Class D amps. I've built 7 and sold 6. This is the least best sounding of the current Ds I have been making and didn't expect much. It is based on the IRS2092 gate controller chip and the board can be bridged at the flick of a switch. It delivers 250W into 8 ohms. The PS is linear with two massive 47,000uf ultra low ESR Mundorf caps which can deliver 700A each.

I expect the sound to be too bright and over detailed. I got the opposite. Deep well controlled bass, balanced mids and bright highs. With a result there is a number of tube amps sitting around gathering dust. A great combo and I just can't stop listening to it. A pleasant surprise.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
Website: retro-thermionic


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