driver/amp recommendations for dual mono sub

[Wang1]

I currently have lowther dx4 in BLH cabinets, which bass is rubbish, my first plan will be to try and EQ some bass using Nelsons EQ board, if this works, great.

If not then i have 3 thoughts:

1. leave the drivers in the BLH cabs and build/add a couple of subs

2. make and transfer the drivers to open baffle and build/add a couple of subs

3. make and transfer drivers to TQWT (or ML voigt)


Would appreciate any thoughts/recommendations

Thanks

 

[mayhem13]

Depends on what you mean by Rubbish Wang…..is it poor quality or quantity?………

Anyway, I would NOT add open baffle subs to a horn or enclosure loaded FR, they won’t integrate very well at all

Boosting the LF of a driver like the Lowther with only 1mm xmax will end badly……likely destroying your drivers over time not to mention the harmonic distortion every time the coil travels outside of the gap.

Please share what size room you’re trying to load so we can better assist you with the best option. My instinct tells me your issue is not enough extension and bass output……one sealed subwoofer enclosure located between your two horns with opposed drivers might be all you need. Ive been very successful with this method when not much is needed……say 60hz on down to 25 or so overlapping the existing output which is likely there but down 20db

 

[Wang1]

You are correct, not a very objective description.

The bass is just lacking as you say not enough extension, mids and highs sound great, from what I've read recently missing bass is a trait of full range drivers especially Lowther.

I'm not looking for thumping bass, just nice, tight bass to give more body to the the rest of the music.

Its interesting you mention sealed box, I have an old SEAS CA25FAY which i have had for years but never used, i was planning to get a new surround for it., and put it in a sealed box, have tried to model it in Hornresp (first time tried).

I have attached the data for this and comments welcome if this is correct or not.

My room is aprox. 4m x 4.5m (speakers on short side).

I would appreciate any advise/recommendations you may have and if i did try the sealed box route first, how would i integrate it, what type of x-over/amplifier, etc would be suitable.

Thanks

 

[Wang1]

I remodelled as an infinite baffle, not sure if this is correct, i was looking for an air suspension model.

 

[Wang1]

i attach also model of current driver/cabinet

 

[Wang1]

I just read further your earlier post and realise you are referring to opposed drivers in the same box, can this be modelled in hornresp

 

[mayhem13]

The CA25 is better suited to a ported design due to the low ish QTS and limited xmax. If you could source another?……

A dual opposed sealed essentially would be doubling the modeled output of a single unit in Hornresp if you chose a sealed alignment. The opposed drivers just counter momentum rocking of the system and reduce distortion as the system behaves in a more linear fashion.

 

[mayhem13]

i attach also model of current driver/cabinet

View attachment 1286016

So here’s the thing……you could remove the Lowther and then mechanically block off the horn path creating a new, sealed chamber for the fullrange driver. Then for each cabinet, add a baffle to cover the horn outlet and install a woofer in each……you’d need to do some calculating as to the internal volume but I guess somewhere around 2.75 cuft or 75 liters.

You could choose to port it out the back or source and use a sealed woofer…..stuffing the horn length as best as possible to absorb the back wave of the driver as much as possible…..a ‘tight’ system with quick impulse response equals very articulate bass.

Your room isn’t exactly small and it appears that the horn opening in your existing cabinets could support up to a 12” driver. Two of these would load your space quite nicely. The newly sealed chamber for the Lowther would have a relatively high Q and a 2nd order acoustic rolloff………I’d say a crossover of 2nd order electrical from a electronic high pass would be a great match around 120 hz……..the Lowther would now be far more linear in its operation and handle more power……would make for a great system overall.

There‘s other creative options to explore with your existing cabinets as well….the one i‘ve outlined would be the easiest and would require an additional 2 channel amplifier and a 2x4 DSP unit for the crossover control and bass EQ as well as a high pass filter for the Lowther drivers.

 

[wchang]

Have you tried the BLH in reverse as a tapered TL, driver (DX4) at the horn mouth on styrofoam baffle? (If you try a cardboard baffle you must be very careful because the "innie" Lowther foam surround is completely unprotected on the inside from sharp cutout edge.)

I have PM2A Ticonal in Fidelio close to wall/corner with decent bass; also had PM6A in makeshift TLonken (tapered TL with front slot); DX3 in midsize bookshelf etc. It isn't easy to integrate subs with ultrafast Lowther. I once used resin-coated carbon fiber with PM6A both sealed. The $20 pair of old 10" Chinese ringed paper cones (I'm listening to right now) could do it too. Phase must be well aligned If using bi-amp (aircore inductor) or sub plate-amp (continuous phase adjustment knob).

https://www.diyaudio.com/community/threads/full-range-speaker-photo-gallery.65061/post-7629178

 

[Wang1]

So here’s the thing……you could remove the Lowther and then mechanically block off the horn path creating a new, sealed chamber for the fullrange driver. Then for each cabinet, add a baffle to cover the horn outlet and install a woofer in each……you’d need to do some calculating as to the internal volume but I guess somewhere around 2.75 cuft or 75 liters.

You could choose to port it out the back or source and use a sealed woofer…..stuffing the horn length as best as possible to absorb the back wave of the driver as much as possible…..a ‘tight’ system with quick impulse response equals very articulate bass.

Your room isn’t exactly small and it appears that the horn opening in your existing cabinets could support up to a 12” driver. Two of these would load your space quite nicely. The newly sealed chamber for the Lowther would have a relatively high Q and a 2nd order acoustic rolloff………I’d say a crossover of 2nd order electrical from a electronic high pass would be a great match around 120 hz……..the Lowther would now be far more linear in its operation and handle more power……would make for a great system overall.

There‘s other creative options to explore with your existing cabinets as well….the one i‘ve outlined would be the easiest and would require an additional 2 channel amplifier and a 2x4 DSP unit for the crossover control and bass EQ as well as a high pass filter for the Lowther drivers.

Thanks, just to give you some background, this is the second time i built these speakers, the first time was about 15 years ago using Lowther EX4 and same design cabinet and from what i remember i had no complaints about the bass then, and was very happy overall with the speakers, even compared to a pair of Klipsch La Scala i had before them, (although i did play at a lot higher volumes then).
Anyway I sold the speakers when i went to work abroad, and when i returned a few months ago i decided to build them again using this time DX4 based on the recommendations of Lowther, and now very disappointed with the result.

I have been in communication with Lowther for some advice but to be honest they were not helpful at all saying cabinet was not theirs so basically you're on your own, which i can understand to a certain degree but a bit disappointing all the same having splashed out on the drivers. ( I remember Lowther being alot more helpful the first time round).

Anyhow I like your suggestion of blanking off the throat and mouth of the horn fitting a woofer in the mouth baffle, however i am not so experienced with the technicalities/theory this design would then be based on and if it could be modelled before i went ahead.

The actual volume from throat to mouth is aprox. 140Ltr quite a bit larger than your estimation so I am not sure how this would effect your proposal.

Would you have any suggestions as to drivers and amp that would suite this, for example would it be better to have the cross over and EQ as a separate unit or as part of the amps

many thanks

 

[mayhem13]

So if your confident on your calculation of 140 liters, the yes…..there’s quite a few 12” driver options out there for you.

I would suggest you close off the Lowther portion of the enclosure from the throat and then line that with acoustic felt and a layer of polyester batting.

With 140 liter sealed, at at your intended listening levels, an in room f3 of 30hz is easy with an f6 around 25hz…..healthy for any genre.

 

[Wang1]

Taking your advice i had a look for possible 12" drivers and came up with the Fostex FW305 and put it into hornresp, i used 2.7mtr for Lrc and a volume of 130lts, it seemed to work out ok with a Q of 0.63.

 

[Wang1]

Actually the horn length is 2.4 mtr, not 2.7, this reduces the Q to 0.58, is this too low?

i could bring this up again by reducing the volume with some wood blocks or such like, is this ok.

thanks

 

[mayhem13]

You won’t need anything near a wideband woofer for this design since you’re crossing to a fullrange…..the Fostex qt suggests a ported box and there’s not much linear travel available…….4.5mm I think…..

This would be much better suited to what you’re looking to do

https://www.madisoundspeakerstore.com/approx-12-woofers/sb-acoustics-sb34nrx75-6-12-woofer/

 

[Wang1]

Great, thanks for that.

What's a good Qtc to aim for here, with this driver i get around 0.8, my little understanding is that a lower Q would be better in this application say around 0.6 to 0.7.

My other question is do i really need a DSP, i was thinking of 2 plate amps similar this:

https://www.soundimports.eu/en/mona...J7*MTcxMDU4MDg2NS4xLjAuMTcxMDU4MDg2NS4wLjAuMA..

Also im not sure about the high pass filter, what would be the need for this?

Thanks again for your advice

 

[Wang1]

Ok I see the reason for the high pass filter now, this game to block the low frequency to the full range drivers ( I mentioned I’m a bit new at this game)

can I just use a passive filter of some sort

 

[Wang1]

“I’d say a crossover of 2nd order electrical from a electronic high pass would be a great match around 120 hz…”

can you explain exactly what what you mean by this, I can’t figure it out

thanks