An E2 inspired loudspeaker: Quick but not dirty

[Joe Alesi]

Hello

Great to see all the detail you are posting on your project

I can see you are still on the hunt for the TAD woofers...another possibility if supply is limited would be to try the older JBL 2205. I have heard it said that the TAD was modelled after the 2205 ( I don't know how true that is..I have my doubts).

Still SOME of the specs are not too different, the free air resonance and VAS are very similar. The power handling is different 150W v 300W - although measurement methods used never make this ultra clear. Q 0.22 v 0.3. There appears to be a big difference in Xmax though and the efficiency (1.8% vs 3.5%)

I'm not sure that this would make your woofer quest any easier...you never know. It may be interesting to model them against the TADs.

Ian, I don't recall...Are you goining for a horizontal pair of woofers or vertical arrangement...MTM etc..?

Best
JA

[Ian Mackenzie]

I am only used one woofer per box initally.

[johnaec]

Is this system using TAD drivers similar to what you're designing: http://cgi.ebay.com/ws/eBayISAPI.dll...MEWA:IT&ih=006


John

[Ian Mackenzie]

Wait and see.

[Ian Mackenzie]

As a result of servere shifts in pricing and foreign exchange rates I wont be proceeding with this project basis of the previous discussions.

I just dont see the sense (any sense) in spending AUD $2000 on just two woofers right at the moment.

Okay it breaks a religious tie with using Tad but so what.

Therefore a panel of other drivers has been drawn up and data /response characteristics compared. Discounting the black magic of what may or may not be a great woofer the Altec 416, 515 from GPA and the Acoustic Elegance (Lamba) 15M appear to perform similarly expect for maximum displacement.

The JBL 1500FE also looks good on 3.5 ft 3 tuned to 32 hertz as in the 4800. I have no idea if the 1500FE is available or the pricing of it or GPA drivers. I expect the landed price to be in the order of the Tad 1601s.

This narrows it down to the Lamba driver.

The B & C 15TBX100 is another option (as used by Earl Geddes in the Suma)

The simulations allow for some conservative room gain.

The intent at this stage is to explore the Big Blue project mentioned earlier. This design featured a Tad horn, Tad 4001 driver, a Focal 15VX11 15 inch woofer (which is NLA) in tractrix mid bass horn and is reflex loaded. Its like compact VOT on steroids.

I have shared several emails with Christian Rintelen the designer who has been very helpful with some details.

http://www.nutshellhifi.com/library/europe.html


On paper it has 100 db sensitivity and in room response to 35 hz (-f3).

It was well reviewed in Europe at the Triode Festival in 2004. Any loudspeaker that gets the thumbs up from those guys has to have something going for it.

Its is just a proposal at this point but a very worthy alternative. My 2245H woofers could always be used for LF reinforcement below 40 hertz.

[jbljfan]

Pops up here from time to time for approx. $470 U.S.
http://www.harmanaudio.com/search_br...00000000004338

[richluvsound]

Hi Ian

have you thought about re-coning a 2227 basket with a 1500 fe kit ?

Rich

[Ian Mackenzie]

I doubt any one has

[richluvsound]

Oh dear , and I have 2 2227 baskets hear ready for the same destiny !

Rich

[4313B]

You can get 1500FE recone kits?

[Ian Mackenzie]

In any case 2227 baskets are not that common.

[Ian Mackenzie]

Okay,

After some more analysis on drver selection I am going to trial the Acoustic Elegance (Lamba) TD 15M.

While cost was a consideration in the end the Lamba driver has more features that suit my application and is in that sense better value for money at the present time.

For those not aware the reduction of the AUD cash rate by the Aust Reserve Bank has forced down the dollar from a high a 0.9 to the lows of 0.6. against the US dollar. The end effect of this is a high price and potential for probelms with customs because of the high import cost.

For comparison Lamba drivers are a 50% less then the Tad at the moment and one hell of a lot more use friendly.

What is more interesting is that this driver has some heritage from Altec Lansing in that the cone profile is very similar to that Altec. I did some web searches and it to would seem the Altec cone profile was found to perform the best.

I am sure the forum Altec fans will be pleased to hear this.

TD15M Highlights:
Pro Style Bass-Mid or bass horn
PVA Hand Coated Cloth Edge
Very Light, Stiff, Hand Coated and Sealed Paper Cone
6mm peak xmax, 40Hz~2Khz, 97dB@1w, 8ohm only


There are a number of other things that make this driver comparable to a contemporary JBL driver in the way the motor is set up.

A copper shorting ring is placed on the full length of the pole peice and there are (2) optional aluminium de-modulations rings for further improvements in distortion and reduced power compression. (I have only found these types of enhancements in JBLs top drivers.)

What is quite interesting is that it has a phasing plug that serves several purposes. It acts as a heatsink, it extends the Pole to imrove the performance of the motor and also acts to reduce IM distortion. The pole is 2 1/2 inches in diameter. The MMs is 70 grams and BL is 17.

I will post a link to an article by the designers later on what Xmax and BL mean in relation to driver performance.

There is no dust cap per say and it was found that with such low inductance the driver (0.2 Mh) did not need a dust cap to extend the response out to 4 khertz. The pole is 2.5 inches as I understand it.

Users are advised not to touch the phasing plug under high drive conditions to avoid scorched fingers!

The real draw card is the 19 mm top plate and 25 mm length voice coil. According to the folks at AE with the thick top plate you get a much more broad BL curve than with a thinner plate. The thick top plate also serves to enhance low power compression.

The XMax of the TD15M based on the BL curve and the point at which BL drops to 70% is 6mm apparently

Under test the driver has a good power response out to 2 hertz as a result of the cone profile..

On paper using an extended alignment the -f 3 is 43 hertz. The in room reponse using a modified Colloms room gain curve (a more conservative boost of only +2.5 dB at 50 herts increasing to +3 db at 30 hertz) the f-3 is 33 hertz using a 7 cu ft enclosure tuned to 34.6 hertz

The thermal limit is 133 db and max output as Fb is 128 hertz

Sensitivity at 1 watt is 97.8 db

This allows the enclosure to be placed near the wall floor boundary without the usual bloom that you get from an maximum flat alignment. If more ELF is required the mutiple 2245H will come into play.See graph below.

Is this an E2 inspired loudspeaker ..well I suppose it is ..on a bugdet.

More later.

[4313B]

Pops up here from time to time for approx. $470 U.S.
http://www.harmanaudio.com/search_br...00000000004338

I'm glad to see they are trying not to screw over their Dealers at the moment. There was a time there when they were undercutting their Dealers.

If more ELF is required the mutiple 2245H will come into play.See graph below.

They are pretty tough to beat.

Is this an E2 inspired loudspeaker ..well I suppose it is ..on a bugdet.

As an aside - I suspect that the E2 is the opus. I suppose it is possible that I could be wrong but...

[Guido]

You can get 1500FE recone kits?

No, these are C8RME150 kits

[4313B]

No, these are C8RME150 kits

Ah!