Hi all,
I've been wanting to play around with some full range drivers lately. No particular reason other than I have a couple pairs for projects and I have scrap plywood laying around. I like the sound of full range drivers and I love the simplicity of using them for simple applications where I don't have to get into crossovers and can simply integrate with subwoofers and have a full range system. Anyhow, I have a pair of Visaton BG20's (8" full range drivers, typically good from 40hz to 18khz) that are about $40 a piece and was going to do an open baffle with them but then decided I wanted to play with some monitors or bookshelf class cabinets. I toyed between bass reflex, tapered horn and sealed and ultimately I opted to go sealed and limit them to a small enclosure volume as they would be integrated with a sub so I didn't need to push extension. Cabinet shape, I went with an almost cube and I found that with 0.5 ft^3 they would roll off after about 80~100hz which was about my goal for simple integration with subs, F3 was closer to 82hz if I recall when I modeled. I measured later to see what it was.
Applications: Stereo listening, heights, atmos.
I'm currently listening to them in a stereo field on a simple setup with a sub integrated and just listening to my typical music. My first impressions are positive. I had no expectations for these but ultimately I find them to present vocals naturally and dialog in general quite nicely. They do exhibit some beaming in terms of dispersion, expected of an 8 inch driver like this, however from just listening and moving along angles I found it to be pleasing and acceptable to listen to up to 15 degrees off central axis in total, or 30 degrees total dispersion centered on axis and still felt like it was a good listen and the treble didn't die off. After 15 degrees it definitely falls off rapidly, so not good for wide dispersion needs, but totally good for applications that have the seating within 30 degrees of central axis, at least, to my ear. I may measure later to see what it's doing. But it wasn't mission critical.
Long term I think I will be using these for height channels and/or atmos channels. They don't need a lot of range. They're not mission critical for output and are really just for ambient effect. They came out to about 12lbs each, so they're not too heavy and can mount on the walls easily with some metal mounts that articulate. But I will do that later. For now, I'm just listening to them in a stereo setup with music and a sub.
Finished cabinets with drivers:
Cutting, Assembly and Finish:
Some 3/4th inch thick birch veneer plywood (4x4 feet scrap)
Wen track saw with track
Assembly is just wood glue (Titebond) and clamps. I had just enough clamps to do both cabinets at the same time. I need more clamps!
Home made jig and measured with the hand router and an up cutting spiral bit for making the driver holes.
Calked all the insides at all joints.
Terminals pushed through some drilled holes.
Finishing:
A coat of Minwax Natural
Next, a coat of satin poly
Wiring, Gasket, Stuffing, Driver Installation
I made some basic cables with spades and hoop terminals.
Hot glued them after installing just to give them another level of "stay put."
Same thing on the hoops internally on the terminals, threaded down some washers and nuts and then got glued them to keep from vibrating loose.
Very best,
I've been wanting to play around with some full range drivers lately. No particular reason other than I have a couple pairs for projects and I have scrap plywood laying around. I like the sound of full range drivers and I love the simplicity of using them for simple applications where I don't have to get into crossovers and can simply integrate with subwoofers and have a full range system. Anyhow, I have a pair of Visaton BG20's (8" full range drivers, typically good from 40hz to 18khz) that are about $40 a piece and was going to do an open baffle with them but then decided I wanted to play with some monitors or bookshelf class cabinets. I toyed between bass reflex, tapered horn and sealed and ultimately I opted to go sealed and limit them to a small enclosure volume as they would be integrated with a sub so I didn't need to push extension. Cabinet shape, I went with an almost cube and I found that with 0.5 ft^3 they would roll off after about 80~100hz which was about my goal for simple integration with subs, F3 was closer to 82hz if I recall when I modeled. I measured later to see what it was.
Applications: Stereo listening, heights, atmos.
I'm currently listening to them in a stereo field on a simple setup with a sub integrated and just listening to my typical music. My first impressions are positive. I had no expectations for these but ultimately I find them to present vocals naturally and dialog in general quite nicely. They do exhibit some beaming in terms of dispersion, expected of an 8 inch driver like this, however from just listening and moving along angles I found it to be pleasing and acceptable to listen to up to 15 degrees off central axis in total, or 30 degrees total dispersion centered on axis and still felt like it was a good listen and the treble didn't die off. After 15 degrees it definitely falls off rapidly, so not good for wide dispersion needs, but totally good for applications that have the seating within 30 degrees of central axis, at least, to my ear. I may measure later to see what it's doing. But it wasn't mission critical.
Long term I think I will be using these for height channels and/or atmos channels. They don't need a lot of range. They're not mission critical for output and are really just for ambient effect. They came out to about 12lbs each, so they're not too heavy and can mount on the walls easily with some metal mounts that articulate. But I will do that later. For now, I'm just listening to them in a stereo setup with music and a sub.
Finished cabinets with drivers:
Cutting, Assembly and Finish:
Some 3/4th inch thick birch veneer plywood (4x4 feet scrap)
Wen track saw with track
Assembly is just wood glue (Titebond) and clamps. I had just enough clamps to do both cabinets at the same time. I need more clamps!
Home made jig and measured with the hand router and an up cutting spiral bit for making the driver holes.
Calked all the insides at all joints.
Terminals pushed through some drilled holes.
Finishing:
A coat of Minwax Natural
Next, a coat of satin poly
Wiring, Gasket, Stuffing, Driver Installation
I made some basic cables with spades and hoop terminals.
Hot glued them after installing just to give them another level of "stay put."
Same thing on the hoops internally on the terminals, threaded down some washers and nuts and then got glued them to keep from vibrating loose.
Very best,
Gasket liner for the driver to sit on. I didn't do recessed because my circles are not perfect so there was no point trying to do a pretty rabbet bit recession. Maybe next time. I cut some liner down to about quarter inch and placed it on to help seal the driver.
Wired them up. Tested them. They worked. So time to stuff and install.
Stuffing. I used some left over polyfil. I measured about half a pound and came to about 228g and I got the same amount in each cabinet.
Installed
Measurements and Thoughts
From my cabinet dimensions, my internal dimensions are:
Top to Bottom: 264mm
Standing waves: 650hz (plus harmonics, 1.3khz, 2,6khz, 5.2khz, 10.4khz, etc)
Left to Right: 264mm
Standing waves: 650hz (plus harmonics, 1.3khz, 2,6khz, 5.2khz, 10.4khz, etc)
Front to Back (ignoring the driver's motor and magnet): 209mm
Standing waves: 821hz (plus harmonics, 1.64khz, 3.28khz, 6.56khz, 13.12khz, etc)
I didn't design the enclosure dimensions to achieve a golden ratio for standing waves, but rather, I figured knowing about them and seeing if they show up in a meaningful way might matter and if we can eliminate them if they do surface.
DATS (Impedance Measurements):
First impedance sweep, no stuffing in the enclosure (I just wanted to see before & after stuffing changes here). The impedance spike is where it was predicted.
I see a ripple spike just after 800hz, which may be a tiny result from the predicted 821hz standing wave.
I see two ripple spikes together around 1.3~1.5khz which may be results from the predicted 1.3khz standing waves.
They are quite tiny, so I don't imagine that they will matter much.
After I stuffed both enclosures with 228g of polyfil, I measured them both and here are both of their results:
Significant reduction in the impedance spike near 100hz.
Most of the potential predicted standing wave ripples were reduced to gentle humps.
Frequency Response:
I set up for some far field measurements, not something I do often. I placed the driver center at the halfway point between my ceiling and floor (96 inches) and so the center of the cone is around 48 inches off the floor. I setup the microphone (Umik-1) at 1 meter distance from the driver center.
So the driver is 1 meter from the microphone for the direct wave.
The reflected wave will travel 1.3m reflect and another 1.3m to the microphone (2.6 meters).
So the 2.6m reflection minus the 1 meter direct wave is 1.6m
Speed of sound is 343m/s and if I divide this with my distance of 1.6m I get 214hz as being the lowest frequency I could potentially measure and gate to remove reflections.
Here's the response, but no impulse response gating applied at this time and smoothed with psychoacoustic smoothing.
For now though, it rolls off as expected, mids are fine, treble rolls off heavily after 16~18khz as expected.
Here's the ungated response, far field, 50hz to 20kz, ugly:
Working through impulse response gating:
Gated response limited to 200hz (knowing 214hz is my lower limit that it would be accurate to via the calcs before):
Near field measurement, 40hz to 300hz. I will align around 250hz or so, above the lower limit of the impulse gated 214hz limit I calculated.
Aligned levels of near field to far field impulse response gated measurements:
Final response graph, if I did everything correctly. It's not purty and flat, but it shows what I need. I see the spike at 8khz as expected with this driver, the source of its brightness. The roll off is really closer to 80hz so the F3 is lower and this is great, this fully handles full range vocals of human speech. Variation is about 5db which looks ugly on a graph, but in reality it sounds fine.
Listening experience:
I did not really notice a loss in treble. In fact, they sounded a little bright to me. Maybe that spike around 8khz. There is a spike around 8khz in the manufacturer response graph, so this was expected and this validates it. Overall though, I found it to be pleasant. Vocals are natural and detailed. Instruments sounded realistic and fine to me.
I did some listen throughs of:
Pink Floyd - Dark Side of the Moon
Fleetwood Mac - Rumours
Eagles - Hotel California
David Bowie - The Rise and Fall of Ziggy Stardust and the Spiders from Mars
Norah Jones - The Fall
The Cranberries - Bury the Hatchet
Audrey Assad - Heart
Keith Jarrett - The Kohl Concert
Tori Amos - A Piano
Counting Crows - Recovering the Satellites
Tenacious D - The Album
U2 - Greatest Hits
Queen - Greatest Hits
They beam. This is expected of 8" full range drivers. However, it was not unpleasant. I found I could go off axis about up to 15 degrees and the treble would fall off after that. But the rest still sounded fine. So that gives me about a 30 degree central axis dispersion field, going off center axis by 15 degrees either way and it sounded fine to me. Beyond that and it lost treble (as expected). So these are not wide dispersion for a large seating array, but they are fine in a 30 degree cone area which can be figured based on distance--totally fine for stereo listening and I think will be fine for heights or atmos use too with a limited seating arrangement.
My god, 70's rock sounds so good on these, despite not being anything special. It's like nostalgia or something. They sound a lot like how I remember these albums sounding back in the day.
The stereo image is really great. I was pretty much not expecting much but man the imaging is great when sitting in the sweet spot of the beam. The merged image was centered and it was a psychedelic feeling looking into my monitors and hearing everything coming from the middle so nicely like there was something there. Left and right panning effects still came across great and so there was depth and direction, but the stereo imaging was just fantastic. It made vocals feel like you were just standing under the microphone with them on stage (Norah Jones.... melt).
I have these in a stereo field at the moment and while I meant to put them up as heights or atmos, I'm totally happy with them listening to them as stereo and music. My Philharmonics are taking a small break while I listen to these for a while before I mount them up high and see how that is.
Very best,
Wired them up. Tested them. They worked. So time to stuff and install.
Stuffing. I used some left over polyfil. I measured about half a pound and came to about 228g and I got the same amount in each cabinet.
Installed
Measurements and Thoughts
From my cabinet dimensions, my internal dimensions are:
Top to Bottom: 264mm
Standing waves: 650hz (plus harmonics, 1.3khz, 2,6khz, 5.2khz, 10.4khz, etc)
Left to Right: 264mm
Standing waves: 650hz (plus harmonics, 1.3khz, 2,6khz, 5.2khz, 10.4khz, etc)
Front to Back (ignoring the driver's motor and magnet): 209mm
Standing waves: 821hz (plus harmonics, 1.64khz, 3.28khz, 6.56khz, 13.12khz, etc)
I didn't design the enclosure dimensions to achieve a golden ratio for standing waves, but rather, I figured knowing about them and seeing if they show up in a meaningful way might matter and if we can eliminate them if they do surface.
DATS (Impedance Measurements):
First impedance sweep, no stuffing in the enclosure (I just wanted to see before & after stuffing changes here). The impedance spike is where it was predicted.
I see a ripple spike just after 800hz, which may be a tiny result from the predicted 821hz standing wave.
I see two ripple spikes together around 1.3~1.5khz which may be results from the predicted 1.3khz standing waves.
They are quite tiny, so I don't imagine that they will matter much.
After I stuffed both enclosures with 228g of polyfil, I measured them both and here are both of their results:
Significant reduction in the impedance spike near 100hz.
Most of the potential predicted standing wave ripples were reduced to gentle humps.
Frequency Response:
I set up for some far field measurements, not something I do often. I placed the driver center at the halfway point between my ceiling and floor (96 inches) and so the center of the cone is around 48 inches off the floor. I setup the microphone (Umik-1) at 1 meter distance from the driver center.
So the driver is 1 meter from the microphone for the direct wave.
The reflected wave will travel 1.3m reflect and another 1.3m to the microphone (2.6 meters).
So the 2.6m reflection minus the 1 meter direct wave is 1.6m
Speed of sound is 343m/s and if I divide this with my distance of 1.6m I get 214hz as being the lowest frequency I could potentially measure and gate to remove reflections.
Here's the response, but no impulse response gating applied at this time and smoothed with psychoacoustic smoothing.
For now though, it rolls off as expected, mids are fine, treble rolls off heavily after 16~18khz as expected.
Here's the ungated response, far field, 50hz to 20kz, ugly:
Working through impulse response gating:
Gated response limited to 200hz (knowing 214hz is my lower limit that it would be accurate to via the calcs before):
Near field measurement, 40hz to 300hz. I will align around 250hz or so, above the lower limit of the impulse gated 214hz limit I calculated.
Aligned levels of near field to far field impulse response gated measurements:
Final response graph, if I did everything correctly. It's not purty and flat, but it shows what I need. I see the spike at 8khz as expected with this driver, the source of its brightness. The roll off is really closer to 80hz so the F3 is lower and this is great, this fully handles full range vocals of human speech. Variation is about 5db which looks ugly on a graph, but in reality it sounds fine.
Listening experience:
I did not really notice a loss in treble. In fact, they sounded a little bright to me. Maybe that spike around 8khz. There is a spike around 8khz in the manufacturer response graph, so this was expected and this validates it. Overall though, I found it to be pleasant. Vocals are natural and detailed. Instruments sounded realistic and fine to me.
I did some listen throughs of:
Pink Floyd - Dark Side of the Moon
Fleetwood Mac - Rumours
Eagles - Hotel California
David Bowie - The Rise and Fall of Ziggy Stardust and the Spiders from Mars
Norah Jones - The Fall
The Cranberries - Bury the Hatchet
Audrey Assad - Heart
Keith Jarrett - The Kohl Concert
Tori Amos - A Piano
Counting Crows - Recovering the Satellites
Tenacious D - The Album
U2 - Greatest Hits
Queen - Greatest Hits
They beam. This is expected of 8" full range drivers. However, it was not unpleasant. I found I could go off axis about up to 15 degrees and the treble would fall off after that. But the rest still sounded fine. So that gives me about a 30 degree central axis dispersion field, going off center axis by 15 degrees either way and it sounded fine to me. Beyond that and it lost treble (as expected). So these are not wide dispersion for a large seating array, but they are fine in a 30 degree cone area which can be figured based on distance--totally fine for stereo listening and I think will be fine for heights or atmos use too with a limited seating arrangement.
My god, 70's rock sounds so good on these, despite not being anything special. It's like nostalgia or something. They sound a lot like how I remember these albums sounding back in the day.
The stereo image is really great. I was pretty much not expecting much but man the imaging is great when sitting in the sweet spot of the beam. The merged image was centered and it was a psychedelic feeling looking into my monitors and hearing everything coming from the middle so nicely like there was something there. Left and right panning effects still came across great and so there was depth and direction, but the stereo imaging was just fantastic. It made vocals feel like you were just standing under the microphone with them on stage (Norah Jones.... melt).
I have these in a stereo field at the moment and while I meant to put them up as heights or atmos, I'm totally happy with them listening to them as stereo and music. My Philharmonics are taking a small break while I listen to these for a while before I mount them up high and see how that is.
Very best,
Thanks, I realize they're nothing special but they were fun to build and super simple. Nothing like 99.9% of what I normally see around this place.
They heavily remind me of how records sounded to me back in the 70's and 80's on that hardware. Very nostalgic sound to them that reminds me of that.
Very best,
They heavily remind me of how records sounded to me back in the 70's and 80's on that hardware. Very nostalgic sound to them that reminds me of that.
Very best,
Yeah, when you consider that most popular music back then was mastered using Altec 604 Duplex systems, then tame the whizzer of a basic 8" 'FR' driver one piece curvilinear cone w/pleated surround and you've basically got a low power half scale 604
and tune it to ~40 Hz in simple reflex to finish it off.
That's an interesting approach for the BG20, well done!
Here is an example what can be done and is published by Visaton BG20 - pentaton-bb
For voices and smoother heights the much more expensive B200 would probably the best Visaton has to offer for a monitor.
B200 - monitor
Some people treated the whizzercone to get rid of the sharpness.
Put a foamring behind the whizzercone and imho some of the sharpness is killed.
In a DIY magazine I found it used with an extra magnet and they removed the whizzercone but also added a tweeter in a short horn.
Up to old hifi standard 5kHz the BG20 guitarspeaker does a perfect job for the price point.
Give the lady more room eg by using a TML or TQWT maybe even a BL horn and it really shines.
Here is an example what can be done and is published by Visaton BG20 - pentaton-bb
For voices and smoother heights the much more expensive B200 would probably the best Visaton has to offer for a monitor.
B200 - monitor
Some people treated the whizzercone to get rid of the sharpness.
Put a foamring behind the whizzercone and imho some of the sharpness is killed.
In a DIY magazine I found it used with an extra magnet and they removed the whizzercone but also added a tweeter in a short horn.
Up to old hifi standard 5kHz the BG20 guitarspeaker does a perfect job for the price point.
Give the lady more room eg by using a TML or TQWT maybe even a BL horn and it really shines.
Hello malveaux, very nice speakers!
Thanks!
Could you post measurement with a 50 or 60 dB scale (50-100 dB)?
Thanks!
I tried to scale it as asked; it looks awful of course. I don't think I did the impulse response gating correctly or something, the ripples look like the ungated measurement; almost looks like a set of harmonics. Probably user error, trying to learn how to measure these things.
Compared to this one, which may be better, but still doesn't seem right. I may have to measure again.
Very best,
Compared to this one, which may be better, but still doesn't seem right. I may have to measure again.
Very best,
The gating as you did seems reasonable.
As this is only one fullrange driver you could also try "farfield" measurement at 50 cm. Nothing axcept the mic should be near the speaker. The first reflection (floor?) should the be more clear then. Adjust the gating window to exclude this first reflection.
As this is only one fullrange driver you could also try "farfield" measurement at 50 cm. Nothing axcept the mic should be near the speaker. The first reflection (floor?) should the be more clear then. Adjust the gating window to exclude this first reflection.
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Yeah. 70ies music works well with pure paper cones.
I do tricks like this with fullranges
https://www.diyaudio.com/community/threads/how-to-make-a-loudspeaker-sandwich-cone.402917/
But 70ies music can be less convincing with sandwich cones.
One reason might be: music was often mixed on loudspeakers with paper cones. They have lots of pseudo bass in the upper bass. With very stiff cones this f region gets less loud and lacks in the response.
I do tricks like this with fullranges
https://www.diyaudio.com/community/threads/how-to-make-a-loudspeaker-sandwich-cone.402917/
But 70ies music can be less convincing with sandwich cones.
One reason might be: music was often mixed on loudspeakers with paper cones. They have lots of pseudo bass in the upper bass. With very stiff cones this f region gets less loud and lacks in the response.
So for that do you start at 10cm and pull back to 20cm and compare to associate the shape of the enclosure?
Very best,
No I mean something between 10 to 20cm measurement distance.
To omit close mic effect disturbing measurement result.
And get the response of the baffle shape represented, too.
Multi way speakers are more difficult to measure because at wider measurement distance you measure the room influence.
I once met someone who was in the production of these RFT goodies and he told me how they were fighting to get temperature resistant glue for the voice coil.
They did not have the patents for special glue. But could not get any from the west.
The voice coil former is made from paper so these 98db RFT3401 had only 10 to 20 watts power handling. Not more.
However I was listening sometimes with 100 watt peak power and they did survive. They measure up to 15k. Very good for 12 inch driver
They did not have the patents for special glue. But could not get any from the west.
The voice coil former is made from paper so these 98db RFT3401 had only 10 to 20 watts power handling. Not more.
However I was listening sometimes with 100 watt peak power and they did survive. They measure up to 15k. Very good for 12 inch driver
