When you connect both drivers are they simply in parallel? I think 6dB gain is from combo of double the area and half the impedance. This is usual benefit of taking two 8ohm driver in parallel for 4ohm. 6dB gain for same drive voltage.
I am already there man!
Just listening to the 8in GRS with a 15uF cap and my 8in woofer - man it sounds incredible. That’s a sweet tweeter!
I am already there man!
Just listening to the 8in GRS with a 15uF cap and my 8in woofer - man it sounds incredible. That’s a sweet tweeter!
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Now I want to get on the GRS bandwagon too.
You guys got me excited!
Is there a rule to find the spacing between the two subs? Other than more than 56mm (double XMax).
I don’t often get this excited about a new driver but this is the real deal. It can reach down to 320Hz so could be used as a FAST open baffle with say, an RS225 woofer in a TL crossed circa 900Hz!
All first order transient perfect of course. Plus, the tweeter can be set on top of said existing TL cabinet and simply set back 3in for perfect time alignment.
I'm guessing that with the configuration with the disconnected driver could act like a small sealed enclosure with a passive radiator?
I don't think it's slot-loading, as the drivers are in-phase. Post #34 refers to Linkwitz's description. Seems like black magic! But also used by Celestion in their SL6000 system.
I agree, I don't think this is anything other than two subwoofers summing as one and therefore we are seeing a 6dB rise.
If I took the two of them and put them side by side, we would see exactly the same summing and 6dB rise in output.
All this confirms is that having them in this clamshell configuration doesn't hinder that summing process.
More interesting to me is the slight reduction in distortion, which can only be explained by the clamshell orientation I think.
To me this is simply a nice way to save space and sling the drivers to prevent mechanical vibrations transmitting to the baffle.
It is exactly as linkwitz describes here:
Electro-acoustic models
If I took the two of them and put them side by side, we would see exactly the same summing and 6dB rise in output.
All this confirms is that having them in this clamshell configuration doesn't hinder that summing process.
More interesting to me is the slight reduction in distortion, which can only be explained by the clamshell orientation I think.
To me this is simply a nice way to save space and sling the drivers to prevent mechanical vibrations transmitting to the baffle.
It is exactly as linkwitz describes here:
Electro-acoustic models
Now I am curious why I only got about 3dB increase with the compound dipole. I used 1 amplifier to feed either one or both drivers (they are 16 ohm, so no problem for the amp driving 2 in parallel), you used 1 amplifier per driver, but the effective power (and therefore displacement) of each speaker is the same in both cases.
I tested the single driver without the other driver "obstructing" it (like in your clamshell), maybe that does indeed have an influence as noted by cowanaudio?
anyway, it is great news, because the compound mounting is indeed more compact (than side by side) and easier to hang. SL comments it is ineffective, and indeed maybe one can get the 6dB raise with an enclosure (H-frame) around a single driver, but that will probalby limit the HF output and be more work (a second driver is probably cheaper than the time needed to make the H frame).
And for all the GRS enthousiasts, and because you mentioned line arrays, a link to my latest build, of course still in the fine tuning phase Dipole Line array with GRS Slim 8" and Visaton WS25e
I tested the single driver without the other driver "obstructing" it (like in your clamshell), maybe that does indeed have an influence as noted by cowanaudio?
anyway, it is great news, because the compound mounting is indeed more compact (than side by side) and easier to hang. SL comments it is ineffective, and indeed maybe one can get the 6dB raise with an enclosure (H-frame) around a single driver, but that will probalby limit the HF output and be more work (a second driver is probably cheaper than the time needed to make the H frame).
And for all the GRS enthousiasts, and because you mentioned line arrays, a link to my latest build, of course still in the fine tuning phase
Dipole Line array with GRS Slim 8" and Visaton WS25eHey Erik!! Love your line arrays!
The only reason line arrays are my last speaker type to DIY build is the work involved and size of them!
I have no doubt having scratched the open baffle itch I will probably try a line array build in a few years too - but I am not sure how it could currently top the open baffle circles of doom!
I can't answer your question as to why you only got 3dB increase - I measured at 1M distance on axis of the subs. Presumably you did have an Ohm change in your experiment though? With two subs you had 8 ohm load and with one sub you had 16 ohm right? If this is true then there must be some confounding error with your amplifier and loading I would guess??
What do you think of the GRS planars - are you as impressed with them as me?!
I am going to start doing the 'proper measurements' later this week - along with some proper listening impressions, quick and dirty measurements hint at low distortion and excellent dipole behaviour.
Listening tests are even more impressive than my prototype builds - the sound stage depth and detail is like nothing I have ever heard before (and I have heard very good drivers in decent implementations).
I just don't know if this is room interaction, a property of the naked dipole behaviour, the GRS superiority with their planar engineering or a combo of all the above.....I am hoping measurements will help me quantify this.
But for me, there is no doubt I will be moving my 'Balls of Prestige' out of my man cave. I will be sad to see them go - I much prefer their aesthetics and they have been a daily pleasure for me for nearly five years.......but it is no contest.
The only reason line arrays are my last speaker type to DIY build is the work involved and size of them!
I have no doubt having scratched the open baffle itch I will probably try a line array build in a few years too - but I am not sure how it could currently top the open baffle circles of doom!
I can't answer your question as to why you only got 3dB increase - I measured at 1M distance on axis of the subs. Presumably you did have an Ohm change in your experiment though? With two subs you had 8 ohm load and with one sub you had 16 ohm right? If this is true then there must be some confounding error with your amplifier and loading I would guess??
What do you think of the GRS planars - are you as impressed with them as me?!
I am going to start doing the 'proper measurements' later this week - along with some proper listening impressions, quick and dirty measurements hint at low distortion and excellent dipole behaviour.
Listening tests are even more impressive than my prototype builds - the sound stage depth and detail is like nothing I have ever heard before (and I have heard very good drivers in decent implementations).
I just don't know if this is room interaction, a property of the naked dipole behaviour, the GRS superiority with their planar engineering or a combo of all the above.....I am hoping measurements will help me quantify this.
But for me, there is no doubt I will be moving my 'Balls of Prestige' out of my man cave. I will be sad to see them go - I much prefer their aesthetics and they have been a daily pleasure for me for nearly five years.......but it is no contest.
Yes indeed - one of the several attractions of naked drivers. Also, H-frame runs the risk of cavity resonances - even if only problematic in amplifying high-harmonic distortion products...
Another interesting experiment would be to change distance between the two bass drivers to find what the optimum spacing is. If an arbitrary choice gives 6dB what does the optimum spacing offer?
If the two drivers were at each end of a sealed tube and operating as a dipole, the greater the spacing, the greater the bass output, at the expense of a lower first cancellation.
If the two drivers were at each end of a sealed tube and operating as a dipole, the greater the spacing, the greater the bass output, at the expense of a lower first cancellation.
Hi Cowan - I am no expert (and am frankly surprised at the results), but I would have thought as long as the two drivers are within a 1/4 wavelength they will sum to 6dB, and if they are further than this they may sum a little less?
As Linkwitz himself states:
"The separation 2d2 between them has no influence on the total output as long as it is small compared to the wavelength of radiation. I see no compounding effect other than summing two dipoles, but the two baffles might as well be placed next to each other. "
He seems to see this clamshell configuration as a waste of a driver - as you may as well put one driver in a H-baffle and get the same output.
As Linkwitz himself states:
"The separation 2d2 between them has no influence on the total output as long as it is small compared to the wavelength of radiation. I see no compounding effect other than summing two dipoles, but the two baffles might as well be placed next to each other. "
He seems to see this clamshell configuration as a waste of a driver - as you may as well put one driver in a H-baffle and get the same output.
The Linkwitz article states that the separation just needs to be significantly smaller than the wavelengths of interest.
If the two drivers were connected by a short tube, there'd be a large degree of mechanical coupling, and you'd get an isobaric arrangement - and that would have near-zero effect in the context of a dipole (unlike a box speaker).