Harmony - My attempt to clone the Synergy Horn

[goldyrathore]

I wanted to build a speaker with high dynamics, good soundstage/imaging ability and also one that blends better with the room in the bass region.

Tom Danley's synergy horn provides constant and narrow directivity for the mids and highs hence my attempt to clone it.

The idea is as below:-

On the top is a typical 2 way Synergy horn. Mid to high xover is at about 1300hz. Mid to low xover is about 300hz. Below the horn are bipole woofers with passive radiators to extend the lows down to lower 20s. To smooth bass in the room, bipole arrangement, with offset drivers, was chosen.

Its an active 3 way build. To pull this off it requires so many different priciples to work in harmony.

This thread will document the journey to realise the harmony.


Goldy

 

[t.antony]

Goldy. this is a unique and very interesting build. Subscribed!

 

[Hari655]

Goldy Sir..best of luck If you work on weekends please let me know so that i will also sit and understand the whole process.

 

[navin advani]

I wanted to build a speaker with high dynamics, good soundstage/imaging ability and also one that blends better with the room in the bass region.

Tom Danley's synergy horn provides constant and narrow directivity for the mids and highs hence my attempt to clone it.

I wold strongly suggest using the 8" woofers in push-push config and also coupling the PRs back to back on opposite sides of the cabinet.

This will reduce movement/vibration of the cabinet and tighten focus.

 

[mileojule]

i will also sit and understand the whole process.

 

[Hari655]

i will also sit and understand the whole process.

:lol:

Actually me and goldy are from same city and i have met him couple of times also...so this time i wanted him to work on weekends so that i can see his work, calculations in person at his place..

 

[grubyhalo]

Very interesting! Thanks for starting this thread. I take it that you are familiar with the following threads:

Index of DIY Synergy and Unity Horns

DIY Synergy/Unity spreadsheet

 

[goldyrathore]

t.antony,
Thanks for the kind words.

Hari655,
I plan to work on them by whatever time I can steal so cannot let you know in advance , however, if I manage to plan early then will surely inform you. Alternatively, you are welcome to visit and check out the progress. And yes, thanks for wishing me luck, I need it, this is a challenging build atleast for me.

Navin,
There are two competing factors here :-
a) To smooth out bass one needs drivers far apart. This is what I have attempted in this design
b) To cancel vibration opposite back to back mounting works well as you ve mentioned.

I favoured the first giving more importance to having bass sources separated in space. The active drivers handle the higher bass (where wavelengths are comparatively shorter) but then the excursion is less and the moving mass of cone is about 35gms only so vibration transmitted to the cab would be less. The PRs will have heavy mass and undergo more excursion but handle longer wavelenghts (below 45hz) so the opposite PRs are still oppositely coupled mechanically. I know its not perfect. Does it really work? I hope so. Only time will tell.


grubyhalo,
Yes Ive seen those threads. There is a great deal of info in those as well as some others.

 

[Hari655]

Goldy Sir,

What is the compression driver you are using?

Thanks,
Hari

 

[goldyrathore]

Goldy Sir,

What is the compression driver you are using?

Thanks,
Hari

BMD-450 II -> P.Audio System Co., LTD

Goldy

 

[goldyrathore]

Compression driver

Here is the compression driver.
The spec sheet suggests 1.5k lowest xover. Considering that its a PA driver being used in a home setup in a narrow angled horn, xover of 1.2k-1.3k will not be an issue.

 

[goldyrathore]

A test horn

Here is the test horn.
Its a 15" wide and 12" high horn.

Next step: Find a suitable midrange.
Certainly not easy. There is already a thread at diyaudio discussing a suitable mid.

 

[goldyrathore]

Choosing the mid drivers

Here are the two drivers being considered.

On the left is a 2" driver. This one has an Fs of ~250Hz and a cloth surround. The high Fs indicates a very light cone and a light cone actually helps.
On the right is a Sony 2.5" driver. The Fs is ~130hz and a rubber surround.


Since the mids operate in a bandpass alignment, it needs an Fb thats at the center of the passband. For the usable bandwidth of 300hz to 1200hz we want the Fb to be ~600hz. We know that when a driver is boxed its Fs becomes Fb .

So next step is to seal both the drivers and measure the Fb. We'll now see how each one performs in a bandpass alignment. For the time being they will be outside the horn for measurements.

 

[soundnovice]

There are two competing factors here :-
a) To smooth out bass one needs drivers far apart. This is what I have attempted in this design
b) To cancel vibration opposite back to back mounting works well as you ve mentioned.

what about placement of the woofers? i guess room mode will have too much affect on the bass, as its radiating from both sides. probably placing speaker atleast 2-3 feet away is must to reduce room interaction.

 

[goldyrathore]

what about placement of the woofers? i guess room mode will have too much affect on the bass, as its radiating from both sides. probably placing speaker atleast 2-3 feet away is must to reduce room interaction.

The room modes are different at different bass source positions. So each bass source position has its own unique response when it interacts with the room. Move the bass source a bit and the whole response changes.

With several sources separated in space the differing individual responses average out to yield a flatter response than a single driver/location. So more room interaction (spatially separated) is needed, not less. This design achieves 4 bass sources, each separated horizontally as well as vertically.

I ve used something from Audiokinesis's controlled offset bipole at Controlled-pattern offset bipole revealed - diyAudio,
The Controlled-Pattern Offset Bipole Loudspeaker


And, yes, this needs atleast 3 feet from the nearest wall.

 

[navin advani]

Navin,
There are two competing factors here :-
a) To smooth out bass one needs drivers far apart. This is what I have attempted in this design
b) To cancel vibration opposite back to back mounting works well as you ve mentioned.

I favoured the first giving more importance to having bass sources separated in space.

My idea was to replace the single 12" with dual 8". Hence you would need 4 8" woofers. You might get a little less volume displacement (of air) as while the Sd of 2 8" woofers equals a 12" most 8" woofers dont have the same linear excursion of similar 12" woofers However you would get lower distortion due to cancelling of physical forces.

Something like Dave's (Planet 10) design here.
toobz woofer

 

[Decadent_Spectre]

Best.Thread.Ever.

Really the only worthwhile thread I have ever seen on this entire forum. Props to you Goldy for attempting this, terrific design choice and yes it is quite the challenge.

The synergies truly are "all that" and their reputation is very well deserved. I for one will never be satisfied with anything else after hearing them.

If I may, I do believe best results will be achieved by integrating the bass/mid bass section into the horn as Tom does for keeping things in phase even if you do not get much horn loading down low from the horn due to the small size. One of the major selling points of the Synergy is a time coherent point source so I feel this would be a good choice. Time domain behavior is king, a slightly ragged frequency response people can live with...according to some research narrow bandwidth peaks/nulls are not really audible depending upon the amplitude.

Best of Luck!

 

[goldyrathore]

Best.Thread.Ever.

Really the only worthwhile thread I have ever seen on this entire forum. Props to you Goldy for attempting this, terrific design choice and yes it is quite the challenge.

The synergies truly are "all that" and their reputation is very well deserved. I for one will never be satisfied with anything else after hearing them.

If I may, I do believe best results will be achieved by integrating the bass/mid bass section into the horn as Tom does for keeping things in phase even if you do not get much horn loading down low from the horn due to the small size. One of the major selling points of the Synergy is a time coherent point source so I feel this would be a good choice. Time domain behavior is king, a slightly ragged frequency response people can live with...according to some research narrow bandwidth peaks/nulls are not really audible depending upon the amplitude.

Best of Luck!

Yes, I will be attemting to achieve the phase response that makes the mids/highs appear as a single driver. Since its quite a task, I planned the active xover route.
I have a Xonar D2X based PC setup for the initial trials of xover, once things are set up correctly will convert the xover to op-amp based active (analogue).

And yes, you pointed out quite correctly frequency response aberrations are not that detrimental as thought so. A narrow peak is more audible than a narrow dip. Time domain behaviour is more detrimental. Also quite important is similar on axis and off axis frequency response. Tom Danley's designs excel here. These waveguides/horns will also be filled (partially atleast) with reticulated 30ppi foam if I manage to acquire.

Thanks for the encouragement and kind words.

Goldy

 

[kanwar]

Great Endeavour Goldy, keep up the good work, i really like such threads.....:thumbsup:


Synergy horns are excellent when it comes to phase coherency.

 

[goldyrathore]

Great Endeavour Goldy, keep up the good work, i really like such threads.....:thumbsup:


Synergy horns are excellent when it comes to phase coherency.

Thanks Kanwar for the encouragement.