Originally Posted by Russdawg1
They use two different Raal’s and if you check out Raal’s website they compare the frequency response if each one, and not two are alike. From this I would expect them to sound similar, possibly unnoticeable, but slightly different. Dave might have something to say on this. Speaking of which, I’m headed to SoCal and plan on hearing quite a bit of the lineup!
I am not fully comfortable jumping into this thread, but I thought it best to answer this question as there is quite a bit of discussion. First off, I reached out to Dennis personally when I first heard of the sad news. While we are "competitors" - we have been "friendly competitors" for quite some time and we personally share a lot of common ground.
This is not an industry someone enters to make money, it is an industry that survives on the shoulders of those who have deep passion for it. As a small business grows, so do the headaches and stresses, when those elements bite into one’s passion and especially one’s health – it is time to step away from it. Being in this industry since 1985, I have been down this road more times than I care to remember.
I also apologize in advance if my message is somewhat incoherent, I caught a very nasty sinus infection and the combination of cough medicine and antibiotics isn't sitting well with me.
The 70-20xr (a modified version of which is used in our towers) is really an entirely different beast than the tweeter in our S2 or the 64-10 used in the BMR. Besides having over twice the radiating surface area, The 70-20, according to Aleks – is the best they manufacture and uses a unique and ingenious method to dampen the ribbon diaphragm of which I am under obligation not to discuss the technical details of. It is the reason this tweeter is not available over the counter and also why a contract must be executed in order to purchase it.
I have extensively evaluated every RAAL ribbon tweeter, and have worked directly with Aleksander on the design of the tweeter in our S2, which eventually brought forth the OEM 64-10 (used in the BMR’s, Salk Song 3’s and many others), and I must agree with Aleks, the 70-20xr is the best they offer. The frequency response is exceptionally linear, and the horizontal polar response is shockingly good. It can also be crossed quite low and can handle insane amounts of power, thanks in part to the way it is damped.
That said, assuming crossover adjustments to compensate for frequency response deviations between the two tweeters – from about 3500Hz on up, the two tweeters sound very similar provided the 64-10 is operating well below its max thermal and dynamic capabilities. Even within that operating range, the 70-20xr does have a smoother overall sound (thanks to how it is damped) and does provide more detail due to the transformer design. The 70-20xr uses a higher performance transformer with less saturation and less core loss, this is even further reduced in the 70-20xr if upgrading to the 70-20xram, which uses an amorphous core transformer.
Of course, the big question comes in – are these differences actually audible? We have had customers who can easily detect differences between these 2 different RAAL’s – and we have had customers who have not been able to. Heck, we have also had customers who haven’t been able to hear a difference between a quality dome and a RAAL ribbon. As always, it really comes down to your own hearing. From a technical standpoint, the 70-20xr / 70-20xram is quite superior but that does come with a cost, as the 70-20xr is a significantly more expensive tweeter, even more so when upgrading to the Amorphous core option.
Now all that stated, even with a high crossover and steep slope, power handling and dynamics on the 64-10 is limited compared to the 70-20xr, and this is where the audible differences between the 2 tweeters becomes extremely evident.
Both of these tweeters are excellent, but they are in very different price brackets and I would say that within their price brackets, as good as it gets.
Please feel free to contact me directly if any further questions arise as I am not on AVS very often these days.
Hope this makes some sense!