HELP PLEASE : Diy alternative to Deflex sheet

[mad-moon]

This stuff was hunted down by Geoff (Walpurgis)...Deflex sheet...but it's only available in Canada...too far away and to expensive to get it here...Alternative suggestions please on a post card..

This is a dense foam rubber type material...I would like something similar..with the ridges..or does anyone have 2 Deflex sheets lying about...(long shot)

http://i236.photobucket.com/albums/ff281/spooneymoon/SPEAKER%20_zpsvhr5extk.jpg (http://s236.photobucket.com/user/spooneymoon/media/SPEAKER%20_zpsvhr5extk.jpg.html)

[walpurgis]

Hi Alan. I may have identified the damping material. But I'm not sure that I'd be using it myself. I have no idea if Roksan applied it during manufacture or whether a former owner may have decided it was a good idea to do so. Delflex is not something I would use for such a purpose. I reckon the drivers are likely to be fine without it.

[struth]

the yellow stuff is Petal Rubber Drive Shaft Coupling Insert Spider Cushion ...maybe ;)

[Reffc]

Hi Alan. I may have identified the damping material. But I'm not sure that I'd be using it myself. I have no idea if Roksan applied it during manufacture or whether a former owner may have decided it was a good idea to do so. Delflex is not something I would use for such a purpose. I reckon the drivers are likely to be fine without it.

That's a correct assumption/concern Geoff, Roksan didn't use this. What Roksan did was to use an aluminium/timber laminate crossbeam behind the drive unit tapped for a through bolt, then threaded a pointed bolt though to press onto the rear of the drive unit to couple it to the cabinet, distributing cage resonances into the beam and cabinet. The cab was then stuffed to achieve a Qts of 0.71

[danilo]

Try Felt Or Duco cement ?
Seems as a popular fittment with those trying to make cheap drivers pretend they are not.

[mad-moon]

That's a correct assumption/concern Geoff, Roksan didn't use this. What Roksan did was to use an aluminium/timber laminate crossbeam behind the drive unit tapped for a through bolt, then threaded a pointed bolt though to press onto the rear of the drive unit to couple it to the cabinet, distributing cage resonances into the beam and cabinet. The cab was then stuffed to achieve a Qts of 0.71

Yep...I've got the pin bolt screwed up to the magnet...with about an extra quarter turn..and siliconed it to the brace so it can't move...so this deflex sheeting is totally unneccessary??... ...They were like that when I bought them...Since putting a pair of 50watt drivers back in to the cabs...I feel as though there is a bit ring from the cab..which wasn't present when I had the drivers in with the deflex adhererd to the magnet/skeleton..what should the cabs be stuffed with?

[walpurgis]

If the screw is bracing the back of the drive unit, the structure of the driver should now be pretty inert and not require added damping. Don't over tighten it though. You could distort the driver chassis.

Surely you have the original damping materials in the boxes? If not, I'd suggest lining the walls with about 40mm of poly foam and adding loose teased wool in the main part of the enclosure below and behind (not touching) the bass driver. You might need to experiment with quantities.

[mad-moon]

If the screw is bracing the back of the drive unit, the structure of the driver should now be pretty inert and not require added damping. Don't over tighten it though. You could distort the driver chassis.

Surely you have the original damping materials in the boxes? If not, I'd suggest lining the walls with about 40mm of poly foam and adding loose teased wool in the main part of the enclosure below and behind (not touching) the bass driver. You might need to experiment with quantities.

Yes Geoff they have damping material..on all the inner surfaces of the cabs..I'm wondering if this is original or not..it's approx 20mm thick like a hairy polyester wadding...there is an extra 60mm thick piece of wadding which I wedged in at the back of the cab up to 50% height behind the bass mid...when I put the higher watt drivers in...the speakers were excellent..until I recently blew one of the 80 watt drivers...I've put 50 watts units back in..and find they are a little on the ringy side..unless i'm mistaking brightness for ring...the 80watt drivers are warmer than the 50 watters...still exceptionally nice mind you but that little bit brighter...I feel like i'm starting all over again...it's frustrating..

[struth]

The xovers may not be quite right for the driver change.. the any vibration stuff may be on there because there was a problem with the driver initially of course... try turning the driver 90 degrees.

[Audio Advent]

Higher power handling implies (to me anyway, no way an expert) a heavier coil made of thinker wire. That can effect efficiency, their impedance response, DC resistance, probably Q and their excursion etc etc etc . I wouldn't be surprised if the 80W drivers sound warmer because they aren't acting as the speaker was designed and now that you've got used to THAT sound, the originals now sound bright in some area in comparison (but actually you're hearing a flatter response).

Once you get used to a sound it becomes the reference to the brain, even if it's an incorrect sound.

[walpurgis]

I doubt if you have ringing drivers. It may be that you just need to let your ears get used to the new balance.

However, if you still feel there's a problem, there may be things that can be done. I could be wrong, but I believe the crossover was pretty simple on these, using no roll off on the bass driver and relying on coil inductance to drop output higher up its range. It could be that the tweeter section values should be revised to raise the point at which the tweeter rolls in to match the change in bass units, as the drivers could be overlapping in output a bit too much now producing an upper mid hump. An 'L' pad could work, but this would drop output across the whole treble range, reducing upper treble a bit too. My inclination though would be to not do anything unless absolutely necessary.

[Audio Advent]

I'd guess that the damping was there because a previous owner read about it being an upgrade somewhere.. There was a popular dealer's newsletter in the 80s/90s - which can be found online - advocating the use of blue-tac all over driver chassis and I've heard that repeated elsewhere without reference to any original source of the idea. Seems to be one of those "tweaks" that gets around regardless of merit (that's not say it has or has not any).

[Reffc]

Yes Geoff they have damping material..on all the inner surfaces of the cabs..I'm wondering if this is original or not..it's approx 20mm thick like a hairy polyester wadding...there is an extra 60mm thick piece of wadding which I wedged in at the back of the cab up to 50% height behind the bass mid...when I put the higher watt drivers in...the speakers were excellent..until I recently blew one of the 80 watt drivers...I've put 50 watts units back in..and find they are a little on the ringy side..unless i'm mistaking brightness for ring...the 80watt drivers are warmer than the 50 watters...still exceptionally nice mind you but that little bit brighter...I feel like i'm starting all over again...it's frustrating..

As previously mentioned, you cannot swap drivers from the originals in spite of on-line folk-lore as they will not work properly with Touraj's crossover which has quite a dip at crossover (measured to just under 2 ohms). It will upset the balance not to mention the driving amplifier! Darius was a curious design and not at all orthodox in the crossover design especially. In your shoes I'd try to revert them to standard and use a pair of SP1014s (Touraj would do the cone mod for you if you asked him I'm sure), keep the crossover as it is and don't be tempted to mess about with them too much. Because of their design, they are really sensitive to even slight changes. Internally, they should be stuffed to at least 50 to 70% of the volume to achieve the correct Qts. As standard, they had all side, top and bottom sides lined with acoustic wool and had additional wool loosely packed up from the base to behind the drive unit, plus the beam was draped in acoustic wool. I guess you have had to add a bit of a turn to the coupling spike due to the differences in overall driver depth compared with the standard. Be careful, as Geoff has said, over stressing the basket will lead to its warping when you do up the front mounting bolts if you are not very careful.

Finally, and this is not widely enough appreciated by some Darius owners, you need an amp capable of supplying a lot of current for these. Your amp should really be capable of driving a 4 ohm load with excursions to 2 Ohms in the bass to avoid clipping.

[mad-moon]

As previously mentioned, you cannot swap drivers from the originals in spite of on-line folk-lore as they will not work properly with Touraj's crossover which has quite a dip at crossover (measured to just under 2 ohms). It will upset the balance not to mention the driving amplifier! Darius was a curious design and not at all orthodox in the crossover design especially. In your shoes I'd try to revert them to standard and use a pair of SP1014s (Touraj would do the cone mod for you if you asked him I'm sure), keep the crossover as it is and don't be tempted to mess about with them too much. Because of their design, they are really sensitive to even slight changes. Internally, they should be stuffed to at least 50 to 70% of the volume to achieve the correct Qts. As standard, they had all side, top and bottom sides lined with acoustic wool and had additional wool loosely packed up from the base to behind the drive unit, plus the beam was draped in acoustic wool. I guess you have had to add a bit of a turn to the coupling spike due to the differences in overall driver depth compared with the standard. Be careful, as Geoff has said, over stressing the basket will lead to its warping when you do up the front mounting bolts if you are not very careful.

Finally, and this is not widely enough appreciated by some Darius owners, you need an amp capable of supplying a lot of current for these. Your amp should really be capable of driving a 4 ohm load with excursions to 2 Ohms in the bass to avoid clipping.

I'll take all this on board Paul..Many thanks....When I first purchased these..They had in them the SP1014 drivers...several sets...I was sick of them failing...and put in the higher value SP1039...which was a breath of fresh air...the crossover loved them and the speakers were superb, till I got a bit heavy handed with the volume control...they would still be in now..had I not had a failure with one of the 1039's...the speakers that are in now are SP1063a...only difference between these and the 1014's..is the material the voice coils are made from....I wonder if the Aluminium voice coil is giving me that bit brightness...as opposed to the copper coils in the 1014's....?

Just to add Paul...I'm using a forte audio class A pre...and a dual mono 115watts per channel @ 8ohms power amplifier...The modules are From BK electronics......the earlier OMP with the 4 smaller dubellier smoothing caps per board as opposed to the 2 x larger caps of today....it packs a punch..

[mad-moon]

tried a 70% fill...overkill...sucked the life out of them...then 50%...hmmmmm....then approx 30% - 40% ....It's happier at the 30%ish fill with the soft wool.....the ringiness has gone..and I've never had bass like this before....the upper mids have been tamed somewhat..and everything is quite smooth...maybe a tad bass heavy..being super critical...but I'm putting that down to leads....I'm gonna stick with these speakers...lovely jubbly...cheeers everyone for the input...I feel a lot happier now...:DBig Al..





If the screw is bracing the back of the drive unit, the structure of the driver should now be pretty inert and not require added damping. Don't over tighten it though. You could distort the driver chassis.

Surely you have the original damping materials in the boxes? If not, I'd suggest lining the walls with about 40mm of poly foam and adding loose teased wool in the main part of the enclosure below and behind (not touching) the bass driver. You might need to experiment with quantities.