"Small" enclosure for Tannoy 15"

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hi guys,

I am about to start a new Tannoy project and need your advice.

The project will be using a set of old Tannoy K3808 (SRM). They will be reconed to K3838 with hard edge, have new HF diaphragms and new filters without controls. Basically only the frame and magnet will remain.

For enclosure I cannot (and will not) build 200 liters+ boxes so my limit is something in the area of 100-150l - and this leads to the question:

Do any of you have experience or information about the following designs for Tannoy 15" taking the relatively small volume into account?

1) Closed
2) Vented with port
3) Vented with acoustic vent
4) Rectangular GRF

Thanks a lot and greetings from Denmark
 
Am I wrong in thinking that the 3808 (SRM M1000) is the hard-edge (folded paper) driver and the 3838 the later soft-edge (rubber) derivative from the SRM M3000?
Will your driver have the TS parameters of the 3808 ,the 3838 or its very own individual set?

Either way in my experience Tannoy drivers do not do particularly well in closed boxes.
I modelled my 3148s and in a closed box they roll off from about 150Hz regardless of box volume. I think something like PeteMcK suggested is your best bet, obviously depending on the actual TS data of your drivers.
Rectangular GRF are about the size of a 300L box btw.
 
Hi guys,

Thanks for the interest and you responses!

@PeteMck
Thanks, this is the similar I get from WinISD Beta. Of course it depends very much of the reliability of the TS data svailable... I have not yet measured the drivers as they are not reconed yet.

@GM
Thanks, I have not joined that group yet - will do :)

@Charles Darwin
The speakers will be reconed to K3838 i.e. everything will be changed leaving only the chassis behind (identical for 3808 and 3838) so I expect the TS to be identical to 3838. I could try with the 3808 first and recone if I am not satisfied however the bass performance of 3808 is not good (and not intended to be either)

@Holty
That sounds great and I missed the Onken on my list. My impression was that Onken primarily is used for bass - would they be suitable all the way down to 1Khz? I really like the energy and punch from those boxes and would be interested if you would share details of your design?

Thanks guys!
 

GM

Member
Joined 2003
Will your driver have the TS parameters of the 3808 ,the 3838 or its very own individual set?

Either way in my experience Tannoy drivers do not do particularly well in closed boxes.

I wondered about this and why I recommended asking the Tannoy cognoscenti, but with Altec or similar it usually means a set of specs that's somewhat different, so ideally need to be measured for best results.

That said, assuming they will still be low Qts and fairly high Vas, how low it will go ~flat for a given net cab Vb will be determined by how much output impedance is used to raise its effective Qts, i.e. trade efficiency for BW. Design a sealed alignment based on a low Qts and drive it with a typical SS amp and it becomes a mids-up speaker as you noted and even a vented alignment will only be a small, high tuned mid-bass.

Anyway, if it were mine I'd just build the biggest cab I could tolerate, tune it to ~Fs and add as much EQ as required to get the flattest in-room response to at least ~42 Hz.

GM
 
hello,
Onkens are made for Altecs 416, but are just regular bass reflex with S = 6.34. The ports on the side help stiffen this big box. IMHO it's useless to calculate an Onken enclosure for any other driver, with an Onken calculator, it's a waste of time and work.
I'm at the moment in search of an enclosure for a set of reconed K3838s. I tried them in the original Onken (277 l): big bump in the bass around 60 Hz, boomy bass. I made the recommended bass reflex like the classic monitor (230 l) but it's not very good , a little smaller bump in the bass but not yet good. I tried various tunings with WinISD but they made only a very small change. I tried a smaller box (160 l) but no big change.
I think i will try the R-GRF in a few days, because this driver doesn't seem to be suited for a bass reflex but for a horn.

jean
 
What specs did you sim with?

GM
I used the specs of the Tannoy brochure, i didn't measure them myself, but i tried different tunings and changed the port dimensions so i think i covered possible variations.

see my results for 2 boxes (90 and 225 l, different vents):
Hébergement instantané d'images - imagik.fr

Maybe i missed something, and i'm willing to learn, i'm not very pleased to have to build a R-GRF to see if it fits.

I met Tannoy at a friend's who owns Westminsters, he even allowed me to take them home for a few days (not easy to move), so when i saw an ad for K3838s i jumped on them. I have a drawing of the westminsters, they're out of my league.

Jean
 
Hey Jean,
The correct Onken design for 3838 is 131dm3. Why don´t you try that if Onken is interesting? F3 will be 49Hz though. Wonder if the original specs are OK?

I made Onkens for Altecs (277 l)in 1982 and they are still in use in my system, i find them to be the best bass i've heard. But in "L'Audiophile" Jacques Mahul, founder of Focal, calculated the parameters of the box and found that it was simply a bass reflex. It's an old design pre-dating TS parameters, based on Jensen enclosure. The good characteristics are the big vent and the doubled sides for the stiffness. If you make a bass reflex with S=6.34 with a large enough vent area, no use to make it with an Onken shape. This particular Onken box is not the only one made by the firm, there's also Onken W with 2 drivers and just 2 holes for vents, another one a copy of Altec A7.

Jean
 
Everyone knows this, it has never been a secret!

You know it, but apparently not many people, so why is there on Onken calculator? Any bass reflex calculator can do the job. You were talking about designing Onkens for the 3838, i just said that IMHO why it was useless.
If eveybody knows it, it should never be mentioned except for the Altec forum. Why are so many people thinking that they are making something special when trying to adapt it to any driver?

Jean

By the way your remark was a little harsh, if things that some people know are declared useless to say then they can shut down every forum, because we are talking about stuff that everybody knows for a long time.
 
Hey Jean and others,

Any news on the quest for the perfect 'small' enclosure. I am still thinking Onken, R-GRF or aperiodic design (closed with flow restricted vent). I am using the aperiodic design with HPD385A and the bass is tight and well controlled (IMHO)

Jesper

I have abandonned the R-GRF which is not suited for my drivers (K 3838) . THe best for now is a 150/200 L bass reflex.
I'm interested in the aperiodic design, i would be interested in some details and drawings.

Jean
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.