Tannoy floorstander progress

[mpmarino]

I've been wanting to build these for a long time.

After many models and designs I just couldn't make up my mind. I went and built something that I could change easily if I wasn't happy.

My system will be sub augmented so the low lows weren't that important to me but I did want some good extension. So , what I ended up with is a 3ft3 sealed enclosure that I can vent later if I like. In fact I can swap both front baffles and the rear baffle with a little effort. At this internal volume both sealed and vented tracked almost equally in winisd so I'm starting sealed.

It is made of mdf/birch ply/oak ply and the speaker baffle is cotton/carbon impregnated phenolic that I found somewhere (looks like carbon fiber he he). All wood materials were scrap from the garage. There are several coats of lacquer at the moment that will get rubbed out at a later date when it's done curing.

No passive Xover...all active. Whadya think?

 

[mpmarino]

'nother

..................go

 

[mpmarino]

and another

waiting...................................................................go

dang!

........now.

 

[mpmarino]

'tis it till thier done.....

goin to flip the record then hit 'submit'.

ok

 

[mpmarino]

OK,

I fired them up today. GARBAGE! There was no bass, I mean NONE. Sounded like a 5" Vifa. So bad that I thought there was an issue with my active xover and my amps input impedance. A quick swap to my old speakers proves that there is not an electronics issue.

Obviously either winisd didn't plot it right(doubt it) or the parameters I have are way off(probably). While they were playing I removed the rear baffles... Now we're getting somewhere! With the rear baffles removed the extension is surprisingly good . But I hear a resonanse somewhere around ??100-150hz??

I think what I am gonna try next is popping a vent into a rear baffle and experiment there.

If I don't get anywhere there I'll try an aperiodic vent where my future reflex vent goes.

If I don't like that I'll take the rear baffles off entirely and try and tame the resonance... hum, maybe I should start with that ??

any comments appreciated

 

[GM]

Greets!

Without knowing the driver model and the specs you used, it's kind of hard to comment other than they look nice.......... That, and the cavity resonance will be ~6780"/internal height.

GM

 

[mpmarino]

thanks for chiming in GM, I was lonely

Yeah, not a lot to go on here. I wish I had the facility to come up with the parameters but I can't take the time to get it together. In other words, I don't know how and I don't have the time to learn it at the moment

So, I'm flying by the seat of my pants. The people over at yahoo tannoy say it's a k3148/k3149

Qts=.4
FS=32Hz
VAS=9.54ft3
Re=5.6R
BL=22
SPL=92dB
12 inch driver

I have no idea how accurate this is....

Thanks for the quick formula, that would put the cavity resonance at ~180hz. I guess my ears aren't too far off

 

[Salas]

I think you dont employ BSC in your active crossover. Is it right?

 

[mpmarino]

I think you dont employ BSC in your active crossover. Is it right?

I am pretty sure you are correct, although my understanding of BSC is not too good.

 

[Salas]

If you dont employ baffle step correction, please follow this experiment. Screw back your back baffles and connect a 1mh coil in series with each woofer. Reduce your HF amp output by 3dB. Listen to decide if you are heading towards some better balance. Let us know so to see for further steps. This must be the Tannoy used in monitor red? SRM 12?

 

[mpmarino]

This must be the Tannoy used in monitor red? SRM 12?

Yes, this is my understanding.

hmm, I don't have a 1mh coil handy nor will I get one real soon. I see where you are going here....

Do you feel this driver should be suitable in this size closed box?

 

[Salas]

Yes its ok. Please use 5cm thick absorptive material in the back only so to deaden the internal resonances somewhat. What is the input impedance of your bass amp? We can emply BSC by using RC filter in its input. Also give me the front baffle dimensions and the driver center distance from top of box face.

 

[Salas]

In any case a good starting point is to feed your bass amp with 220R//1.5uF in line with signal hot and 1uF from hot to cold just after the aformentioned RC. This will give you 4dB BSC. Reduce your HF amp output by 4dB and listen. See ya!

 

[mpmarino]

Thanks for your time salas.

I will say that I often swap amps out so depending on the ip imp of the amp would be a mistake as a permanent solution. in fact I usually have balanced inputs. I currently have the Krell Ksa50 Klone in there which I believe to have a 23k input impedance single ended.


baffle:
990mm high
369mm wide

216mm center of driver to top of baffle.

thanks
marc

 

[Salas]

Good. The values I gave will work. If single ended signal use one network. If balanced signal mirror it. Test. Good luck.

 

[Salas]

...

 

[AndrewT]

Hi,
those T/S params you posted look very suspicious.

A DC Tannoy with a Qts=0.4 does not seem right, particularly in view of BL=22.

Most of the domestic range tend to have T/S of similar values with Bl=15 to 20 and Qts = 0.2 to 0.25

The 12inch may has a higher Fs but jumping up to 30 from the 22 of a 15inch again seems wrong.

I get the impression the params you have quoted are for a commercial small PA model not a DC type, where efficiency is gained at the expense of deep bass.

 

[GM]

thanks for chiming in GM, I was lonely

So, I'm flying by the seat of my pants. The people over at yahoo tannoy say it's a k3148/k3149

Greets!

You're welcome!

These specs are pure BS and I couldn't reconcile them enough with the extra ones here to be of any use with any degree of accuracy: http://www.hilberink.nl/codehans/tannoy61.htm , so unless I missed something, then without actual measurements the only way to get a tonally balanced FR is to use some form of EQ such as BSC to trade as much efficiency as required to get the desired BW whether sealed or vented. That, or build huge BLHs and damp them down as required.

GM

 

[richie00boy]

I don't think the issue is BSC, I've built loads of speakers without it and none were that bad. Also most budget speakers don't have it. Have you checked all drive units are wired for correct phase?

 

[mpmarino]

Thanks all,

Salas, I tried your circuit. Unfortunately no appreciative improvement. I even tried my sony dsp processor's parametric with a slope boosting the lowest bass about 12db and sloping down from there...no good. 5"vifa territory This box can not make bass with this driver sealed up. Thanks so much.

Tried a couple of length vents in the rear baffle based on the TS parameters. More garbage

Andrew and richieboy, thanks I've hoped you would join in

Pulled the rear baffles off.

Except for the resonance it is exactly what I am looking for !

The bass is crisp and tight. The type you can feel in your chest. I dialed a little eq in similar to a LT and they really 'snap'. Although not very deep, I like it. Please remember a sub will come to play..crossed in low.


Plan X is to kill/minimise the resonance.

Other than cabinet mods that I am aware and that you good fellas will suggest, what do you think of a notch filter?



richie, yes all are in phase.