Sentinels

[meb46]

Has anyone on the forum had any success on equivalent Avalon Sentinel designs? Specifically with the 3 separate enclosures? I see a few attempts at this from European DIY'ers, but havent found any threads on this forum. Can anyone point me in the right direction?

Thanks

[Bear]

I think an Isis-type build that was never finished is the closest anyone here has attempted and published along these lines. There are a few designs running around that use the C79 mid, though.

[meb46]

The Isis version is of interest too and obviously a bit easier. I'm currently considering abandoning my current design due to a panel issue. My curved plywood sides are delaminating due to the humidity... I have poured a serious amount of time into them... so attempting not to get too down about it by focussing on my next challenge.

Any links to "proven" Sentinel or Isis... possibly even Time series clones or similar would be a great deal of help.

Cheers

[Bear]

The Isis version is of interest too and obviously a bit easier. I'm currently considering abandoning my current design due to a panel issue. My curved plywood sides are delaminating due to the humidity... I have poured a serious amount of time into them... so attempting not to get too down about it by focussing on my next challenge.

Any links to "proven" Sentinel or Isis... possibly even Time series clones or similar would be a great deal of help.

Cheers

Time is really just an up-scaled Indra. For that, I send you to our resident expert (and founder of Avalon, in a way) JonMarsh and his, er, EvilTwin:

http://htguide.com/forum/showthread.php4?t=33995&highlight=ardent

http://htguide.com/forum/showthread.php4?t=33490&highlight=ardent

For the Isis clone, just look at Evil Twin's thread history...

[meb46]

Bear... both of these threads dont seem to reach any valid conclusion or project completion... I was hoping to essentially consider proven designs and avoid the risk of "failure" Is the general design of JonMarsh's Ardents able to be scaled up for dual 10" woofers or would the Mid/Treble be significantly adversely effected?

Will continue my trawl of the Forum and see what else I can find. Essentially my brief is an Avalon style enclosure and build complexity (Build complexity if my forte'), utilizing larger Dual Bass drivers... either 10" or 12".

[meb46]

One version I found drawings for on the forum is as attached... I think this is one of "Jeds" designs? Correct me if i'm wrong? Any other information lurking about?

[Hdale85]

That wasn't a speaker Jed actually ever designed. It was just a drawing he did up of a concept I believe. Unfortunately changing the Ardent's drivers would require a new crossover.

Something you could do is build the cabinet you want, and then use some sort of active crossover, maybe a Mini-DSP or a DSX or something. Gives you a chance to tinker with some crossover features without getting into the components and what not. The down side is that for a 3 way design you will need 3 channels of amplification for each speaker.

I would love to see a split cabinet design like that though, it's been something I've wanted for quite some time (I think I may of even been the one to post that picture?) but it's a pretty complicated design, and so not likely someone is going to just make for the community.

[Vilbig]

Extreme bang for the buck....

https://sites.google.com/site/undefinition/tarkus

[meb46]

Thanks for the feedback - I am trying to get more information on Jed's "Duet 10's" as they seem the most relevant to what I require. I would have preferred dual 12" base drivers, but there seems very few proven designs of this style.

I have just spent the last few days coming to grips with Google Sketch. It's time I went 3D instead of my old 2D packages... wow... Sketch-up is fantastic!!!! Drawing some complex boxes and shapes within a few hours. Top marks to Google for that one!

[Hdale85]

Well the Duet 10 design isn't an "open source" design so to say. And I don't think he offers that kit at all anymore. I think the only kits he offers now are the Dynamic kits. So I'm not sure he'd share much with you? Maybe.....

[meb46]

Fingers crossed...

Definitely not after a kit... I want to essentially start from a proven front baffle/driver selection (Or as close as possible) and work from there... I have a CNC Router eagerly awaiting some complex matrix style internal bracing... my imagination is my limitation...

[Hdale85]

Well, you couldn't change the baffle shape or anything either, the crossover wouldn't match if you went from say a regular box cabinet to something like the picture posted. Honestly I think your best bet is going to be to go active or try and find someone that will build a crossover for you if they are close by. Where are you located?

[meb46]

I'm based in Singapore... so "local" support is a little difficult

I'm thinking of replicating the front baffle dimensions of the Avalon Time and using the same Mid/Treble Drivers, and then some different dual Base Drivers... possibly Aurasound NS12 or similar.

For the crossovers I would probably seek help from the lads at Madisound...

I would broadly assume the Avalon Time Mid/Treble + Front Baffle dimensions are a proven combination with the variation then coming from the rear enclosures.

[Hdale85]

There is someone else that does custom crossovers as well, I think they are a bit better known for high end crossovers but I can't think of who it is. Honestly the best way to design a crossover though is designing it in the cabinet with real driver measurements.

[Bear]

Bear... both of these threads dont seem to reach any valid conclusion or project completion... I was hoping to essentially consider proven designs and avoid the risk of "failure" Is the general design of JonMarsh's Ardents able to be scaled up for dual 10" woofers or would the Mid/Treble be significantly adversely effected?

Will continue my trawl of the Forum and see what else I can find. Essentially my brief is an Avalon style enclosure and build complexity (Build complexity if my forte'), utilizing larger Dual Bass drivers... either 10" or 12".

You should read the Ardent thread in its entirety before saying that it's no help. Since I'm the forgiving kind, here's another to review:

http://www.htguide.com/forum/showthread.php4?t=36370

[meb46]

Definitely wasnt saying they weren't helpful... Jon's notes are great to follow and have been hugely helpful

I have been playing around modeling dual Aurasound NS12's in WinSpeakerz and they seem to be a good option for the Bass enclosure... still trying to get my head around the physic's behind the Avalon facets etc. Thus far I am considering a single cabinet enclosue (not split bin), using Dual Aurasound NS12's + Accuton C90-6-79 + Scanspeak D3004-6640.

[Face]

Do you have a measuring setup? While those are great subs, I'm not sure they'd cross nicely to a C79.

[meb46]

Yes, I have a measuring set up... omnimic etc...

What alternative Mid would you recommend as a better option? I was thinking of using something slightly larger... 6.5" mid...

[Face]

I'd measure the NS12's first and take it from there.

[meb46]

The NS12's seem "on-paper" able to get up to around 1K for the first crossoverpoint, and then roll into the C79... again... "on-paper" so real world measurement would be the way. I suspect I am going to have to run with a cross sectional view of everyones driver tests and then measure the actual drivers once in the enclosure and adapt the crossover from there to suit it specifically.

[JonMarsh]

Definitely wasnt saying they weren't helpful... Jon's notes are great to follow and have been hugely helpful

I have been playing around modeling dual Aurasound NS12's in WinSpeakerz and they seem to be a good option for the Bass enclosure... still trying to get my head around the physic's behind the Avalon facets etc. Thus far I am considering a single cabinet enclosue (not split bin), using Dual Aurasound NS12's + Accuton C90-6-79 + Scanspeak D3004-6640.

A reasonable idea- do uyou have the NS12's on hand, though? I don't think they're easy to find anymore.

As I mentioned in my PM to you, level balance between the frequency sections is a good idea. With dual 10's or 12's on the bottom end, I think you might want to consider the same Accuton Midrange I used in the Modula Xtreme experiment. Substantially more sensitive, and capable of much higher SPL with low distortion, as documented in some of the measurement threads on HT guide. This would be the C173-6-090. Unfortunately, due to China's restriction on rare earth exports to other countries, the price of neodymium has gone through the roof, and the cost of those drivers has literally doubled since I bought the pair.

When you're talking good dual 12s on the bottom end, it's more of an Isis configuration, and the 6.5 midrange is a better match. That's not to say that you can't chose to go otherwise, in a configuration more like the Avalon Time. In that case, a carefully selected 10" might make the most sense, especially if you want to keep the enclosure size reasonable. I expect I'll rebuild the Modula Xtreme into an Isis like project sometime in the next year or two.

As to the reason for the facets, it's to provide a way to minimize the effective baffle size in the mid and tweeter, so that the BSC frequency is moved upwards as high as possible and the office axis power response is improved in the upper midrange/presence region. First did this in the 70's. Avalon's original founder worked for me in the late 70's when he was a physics student at CU, and I was the head engineer at a small pro audio company. I gave him a pair of speakers using this concept and very thick front panels that I'd built, which my new wife didn't want around. Should have kept the speakers and given the wife away. Oh well, hindsight is 20/20!

[meb46]

Jon, lets just hope your wife doesnt read the forum As per your PM, is it possible for you to email me the Ardent details? Thanks

I am trying to chase down 4x NS12's through Aurasounds Hong Kong Office. Seems like the closest sales office to Singapore... no update from them yet.

Will check out the C173 later today and see what the spec's look like in comparison. Alternatively, I could look at using my current D6.8 HiVi mid range drivers and then the scanspeak tweeter... hmmm...

[JonMarsh]

Will get those out to you after work

And in the meantime, this post from one of the driver testing threads may be interesting.


Driver Evaluations for a new project


Towards the end.

[meb46]

First conceptual drawing of the Bass Cabinet ends up at 136L tunned to 25 Hz with the Dual NS12 Aurasounds... Single 100mm port with a length of around 204mm...

The port isnt shown in the attachment yet... and the concept is missing the curved edge chamfers on all of the internal bracing.

I think I might change the bracing a bit and remove some of the thinner braces with solid braces with multiple holes drilled in it. The idea with the heavy internal bracing is to enable me to use 25mm walls and rear panel lined with Bitumen. If I increase the wall thickness too much I end up reducing the overall volume a great deal or alternatively the Cabineet ends up monsterous. Current Dimensions is 1200mm x 380mm x 700mm Total depth.

The top Mid/Treble Cabinet is still a work in progress and I am still trying to work out the baffles etc.

[meb46]

Updated the Bass Bins... pictures attached. These are sized for Dual NS12 Woofers... total volume is 137 Litres Tuned to 25Hz. The internal braces still need the addition of curved/chamfer edges and the base needs a plinth and the addition of the actual port... Further to this, I am still debating the use of thicker sides and rear panels. At the moment, the front baffle is MDF/HDF mix 100mm thick, the top and bottom is 50mm thick and the sides and rear are 25mm thick. With this degree of bracing, it is still recommended to go for thicker sides?

[meb46]

Slight update to cabinet to enable standardized bracing... should end up stronger but also enable a reduction to 5 unique cut shapes (optimised CNC programming requirements). All of the internal bracing will need chamfering (curved), but its easier to machine this with a router after CNC machining.

Plan of attack is to create a test bin to this design, then test one with the Aurasound Woofers before starting to work on the mid-treble cabinet/Crossover details.

The onset of Christmas and holidays may slow my progress

[Bear]

A couple of thoughts:
1) If you are cutting this via a CNC, consider doing the cabinet 'body' as a lamination, rather than as a traditional 4 walls-type box. Think Magico Mini here. This approach allows you to use a couple of standard shapes to build the back of the box in layers, and it also allows you to use those layers to avoid having parallel surfaces to reduce standing waves. If you want to get really crazy, then you can also put a scallop or wave design into the interior to really kill the back wave from the drivers and help midrange clarity. The obvious downside is increased materials usage, but total cost may or may not be affected depending upon the cost of your CNC machine time vs. design time.

Your recommended term for google: translam.

2) With a large cabinet, you also should consider the transmission line effects, especially with a bottom-firing port. Martin King's website will help you with this, though JonMarsh's M8ta design will give you the basic idea from a CAD perspective.

Best of luck!

[meb46]

Bear - thanks for the suggestions, much appreciated. I have looked at the translam style enclosure before, but works out a great deal more expensive on the material/CNC time.

Currently thinking of matching the Dual NS12's with a C173-6-90 and D3004-664000. REALLY dont like the price of the C173's, but they appear to me the obvious choice.

[Hdale85]

The only thing is with the faceted design there would be a lot more shapes then just a couple, because the facets would have probably 30 or so odd shapes just in them selves. Also plan on using A LOT more wood this way as you will have a good bit more waste.

[Bear]

Bear - thanks for the suggestions, much appreciated. I have looked at the translam style enclosure before, but works out a great deal more expensive on the material/CNC time.

Currently thinking of matching the Dual NS12's with a C173-6-90 and D3004-664000. REALLY dont like the price of the C173's, but they appear to me the obvious choice.

Just some thoughts. Every time I've put out a project for bid for CNC work, the cut fees have been enormous. That's why I'm building my own (slowly, ever so slowly). If you are contracting it out, then something this large will definitely be prohibitive. JonMarsh's threads can give you some ideas, though, on how to do an Avalon-style facet job with just a good table saw. No need for the CNC work unless you just want to go that route.

The only thing is with the faceted design there would be a lot more shapes then just a couple, because the facets would have probably 30 or so odd shapes just in them selves. Also plan on using A LOT more wood this way as you will have a good bit more waste.

Do the baffle separate from the rest of the cabinet. Unless you have software that will take a 3D model and create 'slices' for machining (such products are readily available, by the way), creating each slice manually is prohibitive. However, something like Vectric's Cut3D would make quick work of it if that was how someone wanted to do it. The machine time would still be a killer if you were getting it done by a contract house.

[meb46]

Stumbled across this on a Polish Audio Forum... might be of use to any one considering a similar type of design...

[Generic George]

You seem to basically be looking for something like the Galactica from Tony Gee.

It doesn't have a accuton mid, but does have a 12" woofer and a 15" subwoofer.

This is the link for the PDF with the crossover and cabinet information.

http://www.humblehomemadehifi.com/download/Humble%20Homemade%20Hifi_Mezzo%20Galactica_copy.pdf

He does do custom designs FWIW and the last one is pretty dammed close to what you want.

http://www.humblehomemadehifi.com/custom.html