Turning SR71's into 3-ways

[lunchmoney]

After hearing Mike Z's Beasties, I immediately acquired the big speaker itch...

Mike has generously offered to help design me some big 3-ways, but of course I'd need to pay for the drivers and cabinets.

So having neither the time nor the money to build all new speakers, I had the idea of turning my SR71's into 3-ways...

The tweeters and mids would stay in their existing cabinets as it, and then I would build two additional cabinets with 10" drivers in them... the existing cabinets would simply sit on top of them... leaning towards Dayton Reference 10" woofers, as they are on sale right now.

I like the idea that the mids and tweeters will remain on their narrow baffle, to maintain their great imaging, while the 10's would of course be on wider baffles.

The idea is to design all new 3-way crossovers, and not simply high-pass the SR71's and add the 10's as subs... I've never owned true 3-ways, so I'm looking forward to it.

My SR71 crossovers are external, so it will be simple to go back to them if I ever want to... definitely don't want to lose the SR71's for good, as I'm still a big fan of them.

If you're not familiar with the sr71's, they use the Seas ER18RNX 7" woofer and the Seas 27TBFCG tweeter... here's a pic of one of my SR71's, they are .5 cubic ft, vented:



Please share your thoughts on this. Thanks

[evilskillit]

Re: Turning SR71's into 3-ways

Take a note from Paul Carmody's book on the Tarkus. He wasn't the first but he was the most recent. Build a bin for a big 10 or 12, stick it under there and get to designing your crossover.

[[email protected]]

Re: Turning SR71's into 3-ways

that sounds like a fine plan.

[evilskillit]

Re: Turning SR71's into 3-ways

If you want to go that route then the question is how big do you want your bass bin? How much BSC? How sensitive? and How much money? Then start looking for drivers that will work for you. I'm sure Mike can help make some suggestions.

[Pete Schumacher]

Re: Turning SR71's into 3-ways

The conversion to 3-way will likely mean that the SR71 XO would be tossed. Adding a woofer will eliminate the need for baffle step compensation in the TM section, greatly reducing the tweeter padding. Adding a high pass will also affect the LP section values.

I'd go with a 12" woofer at least, to compliment the 7" mid. Anything less seems wasteful.

[superspeeder]

Re: Turning SR71's into 3-ways

Better not think about it too long... those shielded drivers are dissapearing quickly!

From a cosmetic point of view, I think the RS subs would look better without the phase plug and all (not to mention their higher output capabilities). Pete S. used the 12" RSS315HF-8 sub in his 3-way build to great success, and it's on sale right now for $90!

BTW, your SR71's are dead sexy!

Edit - Pete was typing the same time I was!

[evilskillit]

Re: Turning SR71's into 3-ways

True Pete. What you might not have caught is that the crossovers on those are housed externally. So he can build a bass bin, make a totally new external 3 way crossover, then if he ever wants he can just hook the old 2 way crossover back up. Thats what makes this so feasable. He won't have to wreck that beautiful cabinet or risk not being able to go back if he wants/needs to. So Pete, would you suggest a pair of RSS315s? ;)

[lunchmoney]

Re: Turning SR71's into 3-ways

The conversion to 3-way will likely mean that the SR71 XO would be tossed.

Indeed.

As I said before, we'll be starting over with all new crossovers.

The SR71 crossovers (which are already external) will be put aside in case I ever want to go back to them.

[lunchmoney]

Re: Turning SR71's into 3-ways

If you want to go that route then the question is how big do you want your bass bin? How much BSC? How sensitive? and How much money? Then start looking for drivers that will work for you. I'm sure Mike can help make some suggestions.

These are all issues I'll be working with Mike on, I have every confidence in his abilities. You should hear his Beasties! Amazing speakers.

[lunchmoney]

Re: Turning SR71's into 3-ways

BTW, your SR71's are dead sexy!

Thanks!

Although I cringe when I look at that picture, it was before I had black screws for the tweeters.

[superspeeder]

Re: Turning SR71's into 3-ways

Although I cringe when I look at that picture, it was before I had black screws for the tweeters.

LOL! :D I was thinking that EXACTLY but didn't mention it... didn't want to sound like I was talking down your speakers. I'm sure they look fantastic now with matching screws, and the matte finish on te cabinet is first class! IMO, too many DIY-ers attempt gloss finishes and should go for matte instead.

I also like the roundovers on the vertical edges and the sharp top and bottom - a simple and very clean form.

[evilskillit]

Re: Turning SR71's into 3-ways

These are all issues I'll be working with Mike on, I have every confidence in his abilities. You should hear his Beasties! Amazing speakers.

I would love to, but you guys live too far away :(

[mzisserson]

Re: Turning SR71's into 3-ways

Lets keep this thread going:

Here are the drivers I was thinking about. He listens to a tough range os music to be captured, and is mainly interested in the presence of a tower 3-way as he has a heck of a 12" ref series sub.

I have not modeled, but knowing the timbre of the seas ER18RNX woofers, I am leaning to one of these 3. I kept it to a 10 to keep the size down, I also would like the ER18, to take over at about 150-200Hz. I believe keeping the cone "smaller" does help with transient accuracy and imaging.

1. Dayton ref 10"... Not my top pick, but it will play deep and very accurate.


2. http://www.parts-express.com/pe/show...number=296-434 This is my top pick knowing the accuracy of the Arum Cantus. They also have bountiful body in the "meaty zone" from 60-120, and that is right where the benefit comes into play for both his musical tastes and his room.

3. https://www.madisound.com/store/prod...oducts_id=1654 will also give a great response. I do like the idea of the coated paper. I have herd smaller versions of these drivers and they are extremely articulate in the lower midrange/upper midbass. Expensive though...

Any reccommendations or Ideas?

[evilskillit]

Re: Turning SR71's into 3-ways

I can't really contribute anything useful, but I'll say something anyways ;)

Going with option #3 keeps it all in the family (seas that is) if you're into that sort of thing. It also keeps all the cone material similar/same, which some people also dig on. And finally #3 keeps sensitivity higher, which is always cool. Oh also the 3rd unit with its smaller VAS will probably help keep enclosure size down and WAF up. Its price is the same as the Dayton Ref 10 and only $20 more per pair over option # 2.

Thats it for my mostly useless input, carry on.

[Ryan_M]

Re: Turning SR71's into 3-ways

Subscribed!