urei 813b in a waf-friendly enclosure - any ideas welcome!

[katho]

Hi Speakerdave,


Thank you for your much appreciated input!
Before posting, I had checked out another thread (see below) about these monitors, and was under the impression that due to the 'simple' construction and the intense dampening of the original cabinets made it seem like sticking to the exact dimensions was not as critical with these drivers. Am I wrong assuming this ?

http://www.audioheritage.org/vbulletin/showthread.php?26332-Urei-813B-Baffle-layout

I agree completely about using the exact same inner volume as in the original enclosures (does anyone have these at hand, since the brochures don't indicate this clearly ?)

You are right in supposing that my woodworking skills are not topnotch, but I do have a first rate carpenter at hand. Wouldn't want to lose any fingers, haha.


Vincent.

[speakerdave]

Hi,

Welcome to the forums. If I were doing this, I would ask someone with the original cabinets to make some careful measurements so that the internal volume could be calculated as close as possible. Then I would design a cabinet with a taller aspect ratio and smaller footprint, but of exactly the same volume. I would also try to replicate UREI's damped port venting (ask your vendor if he still has it). Otherwise, you will be designing a whole new enclosure with two different bass drivers in one space, no easy task; in fact I think the process would be basically guess, cut and try WITH TEST GEAR. Based on your questions I would bet that is way beyond your skill set, as it would be most people's, including mine.

Build from scratch. Adapting cabinets is a lot of extra work and is difficult to do well.

David



Hi all,

I acquired a complete set of 813b drivers and the corresponding crossovers, but got the no no from the missus when i showed her a picture of how the enclosures usually look like...and I honestly can't blame her. I used to own 809a's without any dismay but these are another kind of breed entirely.

So I will attempt to make some DIY enclosures that would make us both happy...and I'm challenging the minds and creativity of this respectable forum to provide me with ideas.

My listening space is a living area (I'm from Europe, so in metres...) Width: 5 metres, depth about 15 metres, height 2,85 metres.

I would love to make some diy clones of the definition series speakers by tannoy (those are dual driver too), and I have a couple of corner-horns for 12" fullrange goodmans drivers lying around, so I might try to insert the coax units into these.

Would horn-loading these drivers be a possible way to go, or should I stick to a bass-reflex or closed enclosure type? (soffti-mounting is not an option for me, and I have understood that this was a recommended way to use the original urei cabinets)
I might be able to use a dual enclosure per side type of construction (one driver, one box) without getting thrown out, but a really huge construction (like Altec A7 type enclosures- been there, done that, didn't get the approvement and out they went...)

The ideal enclosures would be max. 50 to 60 centimetres wide, no more than 150 centimeres high but might be 80 cm deep... Kind of like these beauties, but with double 15"...

http://nnacoustics.com/img/products/m_4.jpg

Eagerly awaiting your ideas :bouncy::bouncy::bouncy: ,
Aah, and lastly, budget would be between 500 and 750 euro.


Vincent

[katho]

Hi all,

I acquired a complete set of 813b drivers and the corresponding crossovers, but got the no no from the missus when i showed her a picture of how the enclosures usually look like...and I honestly can't blame her. I used to own 809a's without any dismay but these are another kind of breed entirely.

So I will attempt to make some DIY enclosures that would make us both happy...and I'm challenging the minds and creativity of this respectable forum to provide me with ideas.

My listening space is a living area (I'm from Europe, so in metres...) Width: 5 metres, depth about 15 metres, height 2,85 metres.

I would love to make some diy clones of the definition series speakers by tannoy (those are dual driver too), and I have a couple of corner-horns for 12" fullrange goodmans drivers lying around, so I might try to insert the coax units into these.

Would horn-loading these drivers be a possible way to go, or should I stick to a bass-reflex or closed enclosure type? (soffti-mounting is not an option for me, and I have understood that this was a recommended way to use the original urei cabinets)
I might be able to use a dual enclosure per side type of construction (one driver, one box) without getting thrown out, but a really huge construction (like Altec A7 type enclosures- been there, done that, didn't get the approvement and out they went...)

The ideal enclosures would be max. 50 to 60 centimetres wide, no more than 150 centimeres high but might be 80 cm deep... Kind of like these beauties, but with double 15"...

http://nnacoustics.com/img/products/m_4.jpg

Eagerly awaiting your ideas ,
Aah, and lastly, budget would be between 500 and 750 euro.


Vincent

[Mr. Widget]

Would you rather have excellent sounding speakers or would you prefer to play around with this project possibly over and over again for several years? I am certain that any attempt at horn loading or any other serious change from the original will result in a speaker that is objectively inferior to the big ugly black boxes that these things originally came in. Will you have fun messing around? Probably. Will you enjoy the sound of the new design? Initially.

Unless you have decades of speaker building and designing experience the likely outcome is a system that may make you happy or may not depending more on how picky you are and how well educated your ears are rather than the actual sound quality. I have known quite few DIYers who loved every speaker they ever made... no matter how horrible they sounded... and others who could hear the shortfall of every project they ever made... it is more about you and your expectations than the actual design and your results.

Personally I'd follow Dave's advice and copy them exactly... changing only the finish and possibly the proportions.

Widget

[eso]

Would you rather have excellent sounding speakers or would you prefer to play around with this project possibly over and over again for several years?...
Personally I'd follow Dave's advice and copy them exactly... changing only the finish and possibly the proportions.

Widget

Even changing the proportions to much could adversely affect the response. Sure, they're BIG ugly boxes, but they were designed to be soffit mounted so a narrower baffle will probably hurt the bottom end. And an 813 is only flat to ~40Hz anyway (the specs don't say, but that may well be in a soffit placement since that is what they're designed for).

It is my understanding that they are really not ported in the traditional sense. I believe the design is an aperiodic vent that is intended to bleed off cabinet pressure but not resonate the cabinet like a reflex design.

The pair I built really throbs on the bottom. They are great for listening to Rock & Roll. More about that here:

http://www.audioheritage.org/vbulletin/showthread.php?19953-Urei-813b-project&highlight=Urei+813

eso

[Robh3606]

Just a suggestion but since you will be needing a subwoofer anyway why not just drop the helper woofer out of the design. Just build them as 811B. That way you can get them into a much smaller box. A smaller box will definitely help your WAF issues.

Take a look at the schematic all you would need to do is simply transplant the coax and crossover into a new box and leave the helper not connected.

http://www.jblproservice.com/pdf/Vintage%20JBL-UREI%20Electronics/UREI-813B.pdf

Rob:)

[eso]

Just a suggestion but since you will be needing a subwoofer anyway why not just drop the helper woofer out of the design. Just build them as 811B...

I'd say that probably is the better approach for a domestic setting. You will get the wide range coherence of the coax from ~70-17.5K Hz. With the crossover to the sub the low you have lots of options that should integrate well.

eso

[macaroonie]

I think you are on the right track looking at Tannoy's designs.

[eso]

I think you are on the right track looking at Tannoy's designs.

I one wants to completely redesign the Urei Time Align™ Crossover this is a great idea. The Urei crossovers have several filters in addition to the time alignment and all of it is designed for the type of enclosure Urei employed in their products.

If one wishes to make use of the crossovers that came with a system I'd stick with designs as close to those Urei employed as possible.


eso