Hi @Lament. It would be good to know the status of these drivers as the TD-2002 is listed as still available, which might support your probably well founded suspicion that they are just selling off NOS from inventory. IIRC the TD-4003 was still listed as available untll late last year, the TD-2001 has been gone for as long as I have been checking their page. (A couple of years.)
I got a reply from a TAD representative today;
Dear Sir
Thank you for contacting TAD.
The supply of parts has been unstable for a while.
TD-4001 and TL-1601B remain in production.
Sincerely
TADL
So I owe @kevinkr and everyone else reading this thread an apology for being so assertive earlier.
Very good news though for anyone looking for new TAD drivers 🙂
Dear Sir
Thank you for contacting TAD.
The supply of parts has been unstable for a while.
TD-4001 and TL-1601B remain in production.
Sincerely
TADL
So I owe @kevinkr and everyone else reading this thread an apology for being so assertive earlier.
Very good news though for anyone looking for new TAD drivers 🙂
@Lament it takes a pretty big guy to admit being wrong, particularly in public. You are awesome. 😀 😀
I didn't ask about that, but if you head over to https://www.proaudiodesign.com/search?type=product&search=top-products&q=tad you will find prices for TD-4001, TL-1601B and more.
Huh. Although pricey at US$1750, the TL-1601B isn't that far off the Great Plains Audio 416-Alnico at US$1240 each. Both are several times the price of up-to-date prosound 15" drivers.
The TD-4001, at nearly US$5000 each, is something else. Whew!
The TD-4001, at nearly US$5000 each, is something else. Whew!
Last edited:
As the nearest drop-in alternative, the JBL 2450J is available new for approx. US$1,500 each, plus $500 each for a BeX4016 diaphragm...
At 2/5 of the price, you get (JBL2450J vs. TAD TD-4001):
- near identical internal throat structure (10 degree exit angle, Fc = 220Hz exp equivalent)
- likely more advanced "coherent wave" phase plug
- stamped vs. vapour-deposited Be dia
- glued mylar vs. integral Be surround (resulting in lower Fs)
- Neodymium vs. AlNiCo magnet (lighter and less susceptible to demagnetization)
Last edited:
How do they look considerably different inside? To me they look identical. If you mean the darker diaphragm of the SL, this is aquaplas coated titanium.
You asked about this a couple of days ago in this thread, I replied;
https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-757#post-7294575
You asked about this a couple of days ago in this thread, I replied;
https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-757#post-7294575
Sorry, I'd missed that. But it seems to be available elsewhere, e.g., here: https://usspeaker.com/jbl 2450H-1.htm
Can you explain that a little more? How do you arrive at the Fc and equivalent?
The 2450SL has a treated Aquaplas diaphragm and a 1.5" exit where the 2450J is straight titanium and has the 2" exit snout.
I have both and use the 2450J with the 2450SL diaphragm in my 150hz horns.
I have both and use the 2450J with the 2450SL diaphragm in my 150hz horns.
Thanks. But there are these ventilation groove/slots which look depper in the 2450 but maybe this is because of the video quality or because of a dirty surface.
Is there a recommendation to search for 2450SL? It seems to be a good compromise with the 1.5" exit.
The equivalent exponential flare rate (and cut-off frequency) of the internal throat may be calculated based on its input surface area (at the phase plug exit), output surface area (at the 2" throat exit), and length. The throat is really conical, but it you assume (*) that it is exponential, and set those three values, then there is only one Fc that fits the exponential equation.
(*) a reasonable (if imperfect) assumption, since the two expansion profiles (conical and exponential) are very very similar over the first few cm of length, especially for relatively slow flare rates (i.e., low Fc).
Yes I agree, it looks like the machined grooves are deeper, but probably just because of dirt like you say.
I own a pair of 2450SL and I'm very happy with them, I have aquaplas coated titanium dia's, beryllium dia's and Radian 1245 dia's for them and I think they all bring their own quality. I also have a pair of alnico 2441 that sound really wonderful with the beryllium dia's. I will use these if/when I get some Yuichi's.
I'm keeping my fingers crossed that you and fluid decide to make the A290 V2 design publically available, or plans/step files available for purchase 🙂
Note that used TD-4001 with original Be diaphragms can be acquired for less than $3K a pair, admittedly this is still rather expensive, and there is always the risk that the seller was not honest with you. (I had a very good purchase experience with mine, but can't guarantee the same for anyone else.) Perhaps used JBL 2450J with new Be diaphragms might be another good avenue to consider.
That said I am delighted with my pair of TAD TD-4001s and am really happy finally to put the unwanted excitement of the past few months behind me.
That said I am delighted with my pair of TAD TD-4001s and am really happy finally to put the unwanted excitement of the past few months behind me.
I agree with @kevinkr, there are some risks to be aware of when shopping for TD-4001. One thing that has already been mentioned is demagnetization. This is very real, I got mine remagnetized by GPA and the difference in HF response was very apparent on REW measurements.
Another thing that I have not seen mentioned anywhere is the very fine machining tolerance for the VC gap. This is a beautifully machined driver, but the VC needs to be very precisely centered in the gap to obtain optimal magnetic force and at the same time not rub and produce distortion. There are a number of very thin plastic shims/spacers between the diaphragm and driver, located on the mounting holes. On my pair of drivers these had been tampered with, and the result was poor HF response and distortion. It was a hell of a job aligning these to get the optimal balance between HF response and low distortion.
So if you own TD-4001, have REW and a mic, I suggest taking some measurements. This is probably not an issue for most 4001 drivers though.
Another thing that I have not seen mentioned anywhere is the very fine machining tolerance for the VC gap. This is a beautifully machined driver, but the VC needs to be very precisely centered in the gap to obtain optimal magnetic force and at the same time not rub and produce distortion. There are a number of very thin plastic shims/spacers between the diaphragm and driver, located on the mounting holes. On my pair of drivers these had been tampered with, and the result was poor HF response and distortion. It was a hell of a job aligning these to get the optimal balance between HF response and low distortion.
So if you own TD-4001, have REW and a mic, I suggest taking some measurements. This is probably not an issue for most 4001 drivers though.