Klangfilm L307/Siemens LSP15p horn design help

[SETorbust]

I am planning to build some type of horn enclosure for these great 8.5” 15 ohm German drivers but not sure what design to use.

I have been enjoying them on open baffle with Raal tweeters the last five years but now itching to try something different. They do everything right except lower bass so I currently use 12 “ powered drivers in sealed enclosures to augment from around 100 down to guessing around 40hz. Now I would like to get the bass in horn form as well as curious how they sound in enclosures (guessing will lose huge soundstage and gain in imaging). I do also have a second pair I can fool around with as a possible add on.

So hoping for any guidance on a folded horn design or maybe even Karlson if that suits it better. The other problem I have is not being able to find any parameters on the driver to design the enclosure. Also I would like to keep the enclosure relatively short around 30 inches to accommodate the tweeter, narrower the better but don’t mind a deeper design.

 

[methodarn]

First of all, you need to measure T/S parameters of these drivers
I can't find any T/S on this drivers, but I guess that speakers will work properly in OB design only. If my assumption is true, horn is the last place where these speakers should be used.

 

[SETorbust]

Yeah I couldnt find any measurements either.
Any reason you feel a horn enclosure is not appropriate?
If I cant get data I might just try to copy another design that utilizes an 8 inch light cone and maybe incorporate an adjustable throat.

 

[methodarn]

Cause these alnico magnet looks very small, i almost shure these speakers have a large qts and bad motor strenght. First of all, for back loaded horn design you need motor which can drives horn's throat and Qts of driver which can place in reasonable size of horn chamber.
Typical Qts of driver for OB design is about 0.8-1.2qts
Typical Qts of driver for BLH is about 0.15-0.35

Sorry for my bad english, hope I was explained properly.
Regards, Dima Kohan

 

[planet10]

First of all, you need to measure T/S parameters of these drivers

Without the T/S we would only be guessing as to an appropriate enclosure.

As far as horns go, small is not a term usually associated with them. A horn for an appropriate 8” is going to be large.

dave

 

[Scottmoose]

And even larger [as well as pointless] for an inappropriate 8in. When you factor compact into the equation, probably not likely to turn out well.

 

[SETorbust]

I see.
I could drop the compact height requirement but it sounds like from what everyone is saying the main issue is the driver.
Might the Karlsonator be a better option?

From what I read this driver was always used open baffle or open back enclosure so maybe I might not waste my time with this horn idea. I had hoped in addition to trying out conventional point source since I have a second pair it crossed my mind an easy experiment would be to stick a second driver in open baffle form on top of whatever enclosure should I build it hoping the positives outweigh the negatives of dual driver issues.
Another easy experiment I thought to try would be to flip the enclosure so the enclosed driver fires upwards underneath the second driver ala Tekton Sigma (actually I currently am doing that now but with both open and it sounds better than one single driver with a more meat on the bones sound)

 

[IG81]

Best would be do use ARTA/LIMP and build the impedance jig to measure the parameters. Short of that, I would try it in a large-ish sealed or aperiodic enclosure with lots of stuffing (adjust to taste). ~40-50L or so should not be too bad for a (most likely) high Qt 8" driver.

The Karlsonator being a vented enclosure, and a more complex one than regular bass reflex as it's essentially BP6, you'd need the parameters as well. Your driver is likely not suited to this type of load anyway IMO.

 

[GM]

Cause these alnico magnet looks very small, i almost shure these speakers have a large qts and bad motor strenght. First of all, for back loaded horn design you need motor which can drives horn's throat and Qts of driver which can place in reasonable size of horn chamber.
Typical Qts of driver for OB design is about 0.8-1.2qts
Typical Qts of driver for BLH is about 0.15-0.35

Sorry for my bad english, hope I was explained properly.
Regards, Dima Kohan

True, but it's only part of the 'story' as one wants a driver that has an effective* upper mass corner that rolls off the horn [acoustic XO point] where the room's baffle step corner is, so as it's moved from pi on back to 0.5 [free space to corner loading] the Qts' increases, requiring a larger filter chamber, shorter horn, ergo in most cases a low Qts driver must be coupled to a high output impedance to perform best overall in room.

At some point then, at each extreme is the long horn [low Qts'] has too much mids comb filtering with the driver's, requiring excessive damping/potential dip in the critical [lower] mids response [AKA telephone bandwidth] large enough to negatively impact vocals, etc., and at the other extreme is such a large throat that the horn is too short [high Qts'], forcing IB, OB loading if corner loading isn't a viable option.

* Qts' = Qts + any added series resistance: mh-audio.nl - Home

GM

 

[SETorbust]

I can’t get TS parameters and with everyone expressing concerns regarding what looks like a high qts driver in BLH I think I might then set my sights on building the suggested aperiodic enclosure.
I’m thinking since it may or not work so to make it a cheap easy build I will use the minikarlsonator thread foam core build idea for sides except for the front baffle.