Oris front horn & dipole bass system - finally working!!

[jdunham]

Given the interesting thread on dipole bass recently, and relevant comments in the "Ultimate DIY speaker ideas", I thought I'd post some pictures for anyone who might be interested.

These are my "ultimate" speakers (well until the next ones anyway......) - within the bounds of my current budget, skills, room and spouse factors etc!

They are my interpretation of a system using a directional mid/top together with dipole bass to get the best of out of my room/space available.

My design criteria were: high efficiency, compact design, aesthetics that would suit an old house, can be played loud when required, easy to obtain non "high tech" materials.

See what you think:













I have a lot of tweaking and changes to make still. For now I'm using my 2A3 SET to drive the Oris/AER full-range, into a passive line filter, then into the bass amp (IcePower 500w modules), Lambda TD15S units for the bass. As you can see - minimal baffle area - compact and generate fewer resonances, but heavy weight!!

So far with this set up they sound great, better than all-comers in my room (various electrostatics, conventional, high-efficiency and a number of other horn-loaded systems over the years).

The lack of room excitation on the bass is just uncanny. They create a huge sound stage but without the room joining in!

The position for the units I've adopted sound the best so far, the listening postion is towards the back of the room (3.6 x 5.6m). There are modes along the room which are apparent as you'd expect - in the middle especially.

I've been trying to get more time to do further measurement and improvements, but for the last 2 weeks I can't stop listening to my music collection! D

Anyway, enough of my ramblings for now, do let me know if you have any comments, observations or ideas on how to improve things.

Regards to all,

Jonathan

PS. Thorsten, if you see this, then yes, this is what we were discussing (via email) over 18 months ago!!:

[Pan]

Jonathan,

is it a TacT there on the floor?

In such case, how much does it "better" the dipole performance?

/Peter

[Nuuk]

I thought I'd post some pictures for anyone who might be interested.

Just a few thousand of us then Jonathan!

There are not many speaker systems that I would want in my room but yours would certainly be a candidate.

Are those Lambdas (very) expensive?

[Josephjcole]

Well I have to admit to a somewhat overwhelming sense of jealousy...

I do have some questions though about your open baffle set up... Do you need to use a large amount of correction circutiry with a baffle that small? What kind of low end extension do you get with them? Any guesses on how much power they need, I know you have 500 watts, do you think you are using all 500, or are you just leaving yourself adequete headroom?

just curious
Joe

[ThorstenL]

Konnichiwa,

Originally posted by jdunham
PS. Thorsten, if you see this, then yes, this is what we were discussing (via email) over 18 months ago!!:

Did someone call the Evil ones name? Yes, I'm reading. It turned out real nice and smart. Excellent work. And of course I'm pleased that you like the end results.

Sayonara

[jdunham]

Hi guys, many thanks for the kind words.

A couple of replies:

Are those Lambdas (very) expensive?

No, I was lucky enough to buy them in the Lambda closing down sale, they were around £100 each landed. These are the LE models, which were cheaper (but probably perform the same at the frequencies I use them at). Until the Lambda option, I was going to use some Precision Device drivers - easy and pretty cheap to get in the UK, or some Beymer's. Even low cost Eminence drivers I'm sure would be fine. For a slightly deeper footprint you could use two 18" drivers, and maybe two cheaper ones might be better than 2 most expensive 15" drivers.

Dipole bass seems to be all about the amount of air you can move for the least cone excursion. The reproduction of kick, floor and snare drums have to be heard to be believed!

is it a TacT there on the floor?

Not quite (i.e. a thousand pounds or so cheaper!), its a BehringerUltra curve, but it does a similar job. In terms of performance, see below.

Do you need to use a large amount of correction circutiry with a baffle that small? What kind of low end extension do you get with them? Any guesses on how much power they need, I know you have 500 watts, do you think you are using all 500, or are you just leaving yourself adequete headroom?

Actually, I started using the Behringer until I realised that I was dialling in so little EQ, and now am using it without! Even getting a flatter in room response with the UC, it took away more than it added (due to the AD/DA stages, and added buffer stages at a guess). I'm sure a TacT would be better, but I don't really need one for the mid/highs anayway.

I will post some measurement plots later, but basically its amazingly flat in-room down to around 35hz. There is a small roll-off from 100hz down, but no-where near the predictions.

I may add a monopole sub at some stage for 35hz and below.

On amp power, I was leaving myself adequate headroom, but also based on the theoretical calculations on how much power I'd need to EQ them flat!!

Regards,

Jonathan

[Brian Clark]

Great stuff Jonathan! Good to see you making the best possible use of my "old" AERs
Don't forget you have a package to pick up here ....

Brian

[ThorstenL]

Konnichiwa,

Originally posted by jdunham
Even low cost Eminence drivers I'm sure would be fine. For a slightly deeper footprint you could use two 18" drivers, and maybe two cheaper ones might be better than 2 most expensive 15" drivers.

From Experience, the Eminence Kappa 18 (fairly cheap stamped frame 18" from Eminence) works excellently in a dipole. A pair per side will be enough for fairly large rooms. Add a little mass to the cone and a little series resistance to get the Qt up and you have an excellent dipole.

The room where the two dual Kappa 18 Subs are implemented houses two harpsichords, a small pipe organ, an electronic organ and a Piano Grande, to give some idea of the size, with around 500 Watt per channel there is enough bass down to around 30Hz to seriously fill the room.

I suspect even a pair of Eminence Delta 15 LF could prove sufficient if cost is an object.

Sayonara

[jdunham]

Thanks for the reply Thorsten, I'm certainly very pleased with the results so far (and I know there's more to come).

I haven't done a lot on positioning yet, by turning the drive units face on. But have tried it with the drive units being swapped over. i.e. the null facing into the corner, vs facing into the back wall. The difference is quite marked between the two.

The room where the two dual Kappa 18 Subs are implemented houses two harpsichords, a small pipe organ, an electronic organ and a Piano Grande, to give some idea of the size, with around 500 Watt per channel there is enough bass down to around 30Hz to seriously fill the room.

That sounds like an awesome listening room! I'd love to hear a large dipole in a large room. I'll probably have to wait until I build my own extension (4.5m x 9M with cathedral ceiling are on the current plans!) for that I guess.

What was/is being used for the mid/high range in that set-up?

Cheers,

Jonathan

[eRiCdWoNg]

Very nice, I'd like to try something similar....