Bjorn

Thanks for the information.

Hi Langston. Did you find a measurement that correlated with your experience? I've used class D amplifiers for a while and have not really recognized the same. There are some people here in Norway who AB tested the best class D vs the best measurable class AB and they haven't able to hear a difference. Here's an intermodulation measurement of a Vera Audio power amplifier. Showing left and right channel. You mentioned Bill Whotlock and his expired patented CMRR solution. Vera Audio used a similar design and developed it further. The CMRR of this amp is at least 89dB@100Hz and better than 94dB@1kHz.

An off-topic question. Does anyone know which DSP the new Jubilee is using?

Here's the raw measurement of the Celestion Axi2050 in the K-402 horn at 85 cm distance. 1/24 Oct. smoothing. And here's a measurement at 1m distance of AXi2050 (green) vs Radian 950BePB (red). 1/24 Oct. smoothing. As can be seen, the Celestion AXi2050 needs more boost in the highs. Or simply lower the frequencies below to get a flat response before adding the desired shelving. It's a large driver with a 5" voice-coil. While the AXi2050 does give more level in the lows, it drops quite significantly below 250 Hz in the K-402 horn. Meaning a crossover of 4th order much below 500 Hz here might not be ideal, but this is up for discussion and is best to test by listening. The Radian 950BePB is best to crossover around 600 Hz if it's a 4th order. A steeper crossover might enable a little lower crossover for both. Depending on the distortion and directivity.

Thank you Chris. Still of interest, though it's an older Cornwall speaker. And 1m distance with absorption on the floor is great. I'll send you a PM with email address. Surprisingly very difficult to find measurements of these speakers, considering they have been in the market a long time.

Has anyone measured one of these speakers and can post at least the frequency response? Anechoic, gated or nearfield measurements would be best, but even in room responses would be interesting to see. Preferably one of the later versions but older models are also ok.

It uses a 5" voice coil.

I'm not allowed to share any such information here. That would kick me out of here.

No. I haven't tested TAD drivers. Today I'm using Radian 951BePB (1.4") exit with a horn that I got developed together with Don Keele. Picture below and the best horn I've heard by far. But I know some who have tested Radian Be (950 I think), different JBL drivers with Truextent Be (i.e. 2451) and different TAD drivers and have also measured them. If I remember correctly they were basically very close and perhaps not possible to distinguish audibly after applying EQ, apart from TAD 4003 which the person found to be slightly better than JBL 2451 Be (I don't think he tested Radian 951BepB). TAD 4003 is also the driver that measures overall best and seems to both go a bit lower in frequency and has more level/SPL in the highs. Unfortunately it's an exceptional expensive driver (not sold new anymore) and I assume we're talking about a minor improvement after equalization. The horn is certainly way more important, which the person who has tested these drivers also agrees to.

Found a measurement at 2.3 m distance with both drivers that includes EQ. Hope that answers your question. Red=Radian Blue=Celestion 1/12 oct. smoothing.

I'm certainly now talking about the frequencies around 16.5 KHz. I said upper midrange and treble. Obviously it's quite difficult to pinpoint what frequencies one is hearing the difference at, but my experience was this was also lower than only the very highest frequencies. Besides, my distortion measurements confirmed that the distortion already above 550 Hz was higher for the Axi2050. Below 180 Hz I saw lower distortion with Axi2050. Actually, when listening to AXi2050 in the beginning I didn't notice it. When listening more I starting asking myself if something wasn't missing and it lacked some openness. I then started doing more serious AB listening tests and with various music material it became very evident. That being said, I'm a critical listener and details might be bigger for me than many others. So your mileage may vary. I know of two others in Norway have tested the AXi2050 with different horns and they came to the same conclusion as me by the way. One ended up using a tweeter crossed at around 4 KHz (bad place to cross IMO). Below is a raw measurement of both drivers at 1 m distance. I need to look at EQ setting or measurements to answer your question, but I don't really think the super high frequencies are relevant here. Red=Radian Blue=Celestion 1/24 oct smoothing. The cancellation at 700-800 Hz for Radian seems to be something with the combination of the driver and K-402. I haven't seen that with other horns.

I tested the AXi2050 on K-402 in 2019 and did a direct comparison to Radian 950BePB. Back and forth for several days both in mono for quick comparisons and listening in stereo, though swapping for stereo takes time when you only have one pair of speakers. My experience was quite different from Chris'. The Radian with Be sounded considerably clearer and more open in both the upper midrange and tweeter. Distortion measurements confirmed this. Crossover lower was nice though and mye experience her was also different. While it didn't experience this as night and day, it was still more than a subtle improvement in a coherent sound stage and vocal presentation. But overall, the Axi2050 sounded dull in the upper frequencies making it boring to listen to compared to Radian. But I'm not surprised Klipsch is choosing such a driver for a commercial speaker and that solved issues with the bass bin they use.

Stacking AMTs will cause both comb filtering and serious vertical lobing. That's simply physics with large center og center spacing, thus "small gap" doesn't help much here. How much that bothers people probably depends a lot on references and what's being compared to as well as the benefits. Almost all commercial speakers suffer from this to various degrees. It's something best to try out and hear for yourself.

A poly isn't really considered a proper diffuser anymore. It focuses the sound at certain directions at certain frequencies strongly, thus doesn't evenly spread out the sound like a good diffuser will do. It can diffuse spatially well however, if several units with a weird dimension are placed next to each other. But it will not offer any temporal diffusion either way and is IMO an outdated product that's been replaced by something better. Obviously I can't argue with you if you like the effect of it.

Chris A: You forget that a speaker which has a good power response, reflections don't contribute negatively anymore. Just ask Toole and his followers! Kidding and sorry couldn't help myself. But it's quite disturbing and sad to see that what I wrote above is considered by many as science now and isn't even ut for debate! Just read some of the posts in the discussion I had with amirm and Toole at audiosciencereview forum.