There does not seem to be much information from builders using the SEAS Exotic F8 so here goes. Following on from my satisfaction with the Hemp FR8 reflex enclosure I made in March 2021 I wanted to build what I hoped would be an even higher quality one. I settled on the SEAS Exotic F8 for this.
I considered horn and reflex designs for this project but concluded that the closed box would be the best for the present location. The design is basically the 60L closed box in the SEAS data sheet but I altered the dimensions slightly to better suit my den (small room converted from garage).
I drew up the panel dimensions and routing for joints and got all parts cut by a firm specialising in routing sheet materials. The enclosure is 18mm Birch ply with double thickness front and back panels. The bracing is MDF. The reason to get the work done professionally was that the internal bracing has hundreds of holes. I estimated it would take a week working with hole-saw or router and producing huge amount of dust so it was an easy decision. Assembling the speaker then was a pleasant task which took a week to complete. I intended to make it permanently sealed by gluing all parts so I had to make a good estimation of the damping required. I had a lot of light polyester mesh which I judged to be suitable. I put a layer internally behind the cross braces and a layer round the drive unit part of the enclosure. There is some additional thickness from random pads. The enclosure was painted and the front panel varnished before joining the two together. The finish is the same as for the Hemp enclosure. These builds are not regarded as pieces of furniture and I don’t want them to be veneered. They are for use in my den so function is the aim. I am happy with the varnished fronts and the grey painted enclosure. The finish is perfectly acceptable and very easy to do.
The total cost of the speakers was £1650 in June 2021.
The sound was as expected initially very bright and forward and revealing of detail though thin at the lower range. They are very easy to adjust to your liking in situ as the tuning is done by components in the speaker leads. I added an inductor and resistor as SEAS suggest and then adjusted these values after careful positioning of the speakers in the room.
After months of listening I am very happy with them indeed. They are still a work in progress as I can tweak them. I have a few inductors and resistors wired up with switches to allow easy substitutions. I will also make some spiked stands to see the effect.
I considered horn and reflex designs for this project but concluded that the closed box would be the best for the present location. The design is basically the 60L closed box in the SEAS data sheet but I altered the dimensions slightly to better suit my den (small room converted from garage).
I drew up the panel dimensions and routing for joints and got all parts cut by a firm specialising in routing sheet materials. The enclosure is 18mm Birch ply with double thickness front and back panels. The bracing is MDF. The reason to get the work done professionally was that the internal bracing has hundreds of holes. I estimated it would take a week working with hole-saw or router and producing huge amount of dust so it was an easy decision. Assembling the speaker then was a pleasant task which took a week to complete. I intended to make it permanently sealed by gluing all parts so I had to make a good estimation of the damping required. I had a lot of light polyester mesh which I judged to be suitable. I put a layer internally behind the cross braces and a layer round the drive unit part of the enclosure. There is some additional thickness from random pads. The enclosure was painted and the front panel varnished before joining the two together. The finish is the same as for the Hemp enclosure. These builds are not regarded as pieces of furniture and I don’t want them to be veneered. They are for use in my den so function is the aim. I am happy with the varnished fronts and the grey painted enclosure. The finish is perfectly acceptable and very easy to do.
The total cost of the speakers was £1650 in June 2021.
The sound was as expected initially very bright and forward and revealing of detail though thin at the lower range. They are very easy to adjust to your liking in situ as the tuning is done by components in the speaker leads. I added an inductor and resistor as SEAS suggest and then adjusted these values after careful positioning of the speakers in the room.
After months of listening I am very happy with them indeed. They are still a work in progress as I can tweak them. I have a few inductors and resistors wired up with switches to allow easy substitutions. I will also make some spiked stands to see the effect.
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Very nice build! I built something similar with the SEAS FA22rcz in a smaller sealed 50L enclosure.. I also used the inductor and resistors suggested by SEAS.
I am very happy with the results!
I am very happy with the results!
Hi 11opas, I believe I commented on your build in the FR gallery. It looks very nice. Choosing a single FR unit without hearing it is a bit of a gamble but after my research I felt comfortable going for the SEAS units. The use of the Hemp Acoustics FR8 won me over to single driver speakers. These seem to match into the room so well. We are really happy with all kinds of music through them.
Thanx. We see little on the SEAS exotic because most of us FR guys ar echeap bastards ;^)
MDF is not very stiff so makes poor braces.
When i first saw that SEAS drawing i was very proud that they chose to use the holey brace i have been advocating for decades. All those holes and the tight fit of the driver part of the brace, it can certainly take more time to do the brace than the entire rest of the box, worth it IMO.
Getting the nerve to taking a scalpel to a $750 driver is likely the hardest part.
dave
MDF is not very stiff so makes poor braces.
When i first saw that SEAS drawing i was very proud that they chose to use the holey brace i have been advocating for decades. All those holes and the tight fit of the driver part of the brace, it can certainly take more time to do the brace than the entire rest of the box, worth it IMO.
From experience a phas epug can go a long way towards fixing the HF issues at the source instead of band-aiding with a filter. It is a necessity in the FA22 (and every other whizzer cone FR i have tried).
Getting the nerve to taking a scalpel to a $750 driver is likely the hardest part.
dave
I agree that MDF isn't the best for bracing. To save having to cut all those holes, I got a quote for the braces in MDF. As it was reasonable I asked about the case BB ply and got it all done. If I made them again I would not use MDF anywhere. But the box is very solid though.
I do find that tinkering with the various inductors and resistors gives a lot of possibilities for tuning and I am working towards an ideal tuning. They are great units and I don't feel the need to modify them, but of course I am not able to hear a pair with phase plugs. These are the best speakers I've had and the price is a bargain. The image is very 3D. The music has dynamic clarity and energy. The bass is very well defined and reaches low.
I do find that tinkering with the various inductors and resistors gives a lot of possibilities for tuning and I am working towards an ideal tuning. They are great units and I don't feel the need to modify them, but of course I am not able to hear a pair with phase plugs. These are the best speakers I've had and the price is a bargain. The image is very 3D. The music has dynamic clarity and energy. The bass is very well defined and reaches low.
Great build gcl! I kind of like the utility-grey, do you have a picture of the whole setup as such?
Double-thick 18mm BB-ply rocks, I have this on 142 liters cabs for TD15M. I recently added a bit of bracing still.
I imagine all the hole-sawing could have burned through a regular drill on top of the dust and tedium of doing it yourself.
Double-thick 18mm BB-ply rocks, I have this on 142 liters cabs for TD15M. I recently added a bit of bracing still.
I imagine all the hole-sawing could have burned through a regular drill on top of the dust and tedium of doing it yourself.
IG81 thanks. You're right about the hole sawing, probably wreck a few bits too.
An advantage of the paint finish is that is quick, easy and you can choose many colours. Here in England Dulux have a mixing system for almost any shade. I use a satin sheen emulsion which is tough enough. Two coats of UC and about 5 thin topcoats applied with a high quality 4" roller. Note I mentioned that the build was completed in a week. I was so busy making them I didn't take many pictures. What picture are you looking for?
An advantage of the paint finish is that is quick, easy and you can choose many colours. Here in England Dulux have a mixing system for almost any shade. I use a satin sheen emulsion which is tough enough. Two coats of UC and about 5 thin topcoats applied with a high quality 4" roller. Note I mentioned that the build was completed in a week. I was so busy making them I didn't take many pictures. What picture are you looking for?
Never mind the picture request gcl - I just got that you painted everything but the front baffle, it's not obvious from the setup picture and I skimmed through the text a bit too fast the first time around.
Regarding the MDF bracing, perhaps not the best, but better than nothing.
Regarding the MDF bracing, perhaps not the best, but better than nothing.
It would be interesting to see a freq response of the effect of the removal of the whizzer cone and addition of the phase plug. Have you posted anything on this? Thanks
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I think P10 only suggested dustcap removal though. Whizzer removal would most likely leave you with an extended-range midbass and the need for a super-tweeter if not a full tweeter.
Troels performs a whizzerectomy on a 9710
Scroll nearly all the way down to see the results.
Troels performs a whizzerectomy on a 9710
Scroll nearly all the way down to see the results.
removal of the dustcap removes its radiation (highest frequencies, and changes the oil can resonance under the dustcap from half-wabvr to quarter wave mioving that resonance up an octave.
Adding the pjhase plug completely removes that resonance and provides a surface for the HF off the inside of the wizzer to be dispersed more as well as moving any side-to -dide resonance inside the dustcap some octave and a half or so up in frequency.
Lots of picture galleries of dustcapectomies: http://www.planet10-hifi.com/pp-install.html
dave
Adding the pjhase plug completely removes that resonance and provides a surface for the HF off the inside of the wizzer to be dispersed more as well as moving any side-to -dide resonance inside the dustcap some octave and a half or so up in frequency.
Lots of picture galleries of dustcapectomies: http://www.planet10-hifi.com/pp-install.html
dave
I've seen a flat to 10khz 8" full range driver, after removing phase plug it climbed more than 5db 900-4khz then rolled off about that really quickly.
I believe the whizzer helps dispersion by adding an octave, meaning a whizzered 8 has similar disperson as a non whizzered 6-6.5"........
I believe the whizzer helps dispersion by adding an octave, meaning a whizzered 8 has similar disperson as a non whizzered 6-6.5"........
Ah, of course! I jumped to the wrong conclusion. Thank you all for the comments, I'll look up this subject, however I am not contemplating attacking these lovely drivers, my tweaking will be with external filtering.
I would like to give a mention to Joseph Crowe's immensely informative Youtube exploration of the SEAS Prestige 8".
I have made a few changes to the filter and am spending time listening to a few versions; this is the sort of thing. It is so easy to adjust the sound this way.
I have made a few changes to the filter and am spending time listening to a few versions; this is the sort of thing. It is so easy to adjust the sound this way.
Having modelled several variations around this filter I was getting a very enjoyable sound from the speakers. The seamless reproduction through a wide frequency range is engaging. I then removed all the components in the speaker leads and drove the speaker leads directly from the amplifier. The sound seemed “cleaner”, for example, voices had a bit more definition. There seemed to be a smoothing of the high frequencies. I put this down to the improved damping by the consistent amplifier output impedance.
I then added a passive filter between the DAC and amplifier. The passive filter is based on the baffle step compensation method outlined by Rod Elliott where I have shifted the corner frequency to about 1KHz. by using 10nF. The amount of shelf down is adjustable from zero cut to about 6dB. This is easier tweaking than soldering in various inductors and resistors. The components I have used are 10k pot in series with 10k resistor and 10nF capacitor. The buffer is built in but not in use yet (listening without it first).
So now a period of listening to find the preferred filter setting. There is no notch at 3 kHz now and I am not sure it will be necessary.
I then added a passive filter between the DAC and amplifier. The passive filter is based on the baffle step compensation method outlined by Rod Elliott where I have shifted the corner frequency to about 1KHz. by using 10nF. The amount of shelf down is adjustable from zero cut to about 6dB. This is easier tweaking than soldering in various inductors and resistors. The components I have used are 10k pot in series with 10k resistor and 10nF capacitor. The buffer is built in but not in use yet (listening without it first).
So now a period of listening to find the preferred filter setting. There is no notch at 3 kHz now and I am not sure it will be necessary.
Well, none. Of course the speaker response is still rising to some extent and correction has to be done before the amplifier. Now, we are not trying to recreate exactly the filter response of the L and Rs in the leads as the drive conditions and sound have changed a bit. It's an ongoing project.
I have built a little "control Box" to do variable frequency cuts, which is more fun than soldering inductors and other components.
https://www.diyaudio.com/community/...fle-step-compensation-or-hf-reduction.384441/
https://www.diyaudio.com/community/...fle-step-compensation-or-hf-reduction.384441/