High efficiency speakers, low efficiency speakers

Loudspeakers
22

Well, the Jensen speakers have much higher Q and so I’m not surprised that you feel like they have more bass, as there will be some peaking around resonance. According to studies from the BBC and others, a little bump around 80-100 Hz like this is “a good thing” in a bandwidth limited system (no subwoofer used) but, since you mentioned using subs, I would recommend a flat response there, for easiest integration.

Also, those Jensen woofers have very limited excursion (+/- 1 mm) and a lot of cone breakup, being designs for guitar use and there are now better options.

23

Well, there are a few different philosophies on this and both Geddes and Toole have some good recommendations. It relates to the speaker directivity and the acoustic properties of the room (how much absorption/damping there is).

Toe in effects the intensity of the near wall reflections and, as humans, we’re very sensitive to these lateral reflections both for things like spaciousness, localization and apparent source width. You’re basically trading one of the other a little. More toe-in and more lateral absorption decreases spaciousness but increases localization (ability to locate a sound in space).

The same goes with more directional speakers. They are “drier” sounding, as you’re getting more direct sound from the speaker relative to the reverberant field of the room and they take more energy to excite the room and so can change your toe-in your toe in and absorption strategy to favor spaciousness more.

Paul, in particular enjoys spaciousness and so the rooms here are designed with that in mind (minimal /no toe in and a good amount of QRD diffusers laterally and the speaker’s a healthily distance from boundaries to emphasize later reflections).

However, there is a certain amount of user preference involved in these decisions.

24

Good afternoon Chris!

Everything you said about the Jensen speakers, is true.

Granted that this sounds very big, but a little over 16 years ago, I pulled this grate feet off without a hitch!

I built hifi speakers using the Jensen P15N woofers.

But however, I used them as mid bass drivers.

I also used 18ench woofers that were mint for the electric bass to fill in what was missing from the P15N woofers.

I put 300watt amplifiers in the cabinets with their own built in active crossovers in there with them.

I used the P8Q woofers as mid ranges, and air motion transformers for tweeters.

I made 30 pares of them, and sold every single one of them.

I done that from 2005 to 2008.

The thing that stopped me, is my house got destroyed by a tornado at the time.

I’m wanting to get back there where I once was in doing that.

I made a killing off of my designs.

But I also want to try my hands at building amplifiers too as well.

I understand how they work, but I wish to build amplifiers using radio transmitting tubes like the 816 tube.

I don’t know about any company that’s making amps like that for hifi use.

But I think it can be done.

6182CC72A5244A45AB824DAE605FB0B9.png
6182CC72A5244A45AB824DAE605FB0B9.png708×1 82 Bytes

1 Like
25

Thanks Chris, yes, directivity, off-axis-response, near wall reflections all goes in the same direction and influences sound staging or you say spaciousness/imaging. It certainly also influences tonality a bit, but I always considered it a rather bad advice to react to tonality changes within the setup by changing toe in (simply because imo with toe in one should match the speaker towards its optimal or preferred imaging potential in the respective room, which would be worsened by adjusting tonality with it.

26

Yes, you’re right. I like Stereophile a lot as a publication but they do mention that pretty often (to use care in toe in to adjust tonality), where it would be better to have a speaker with less issues in this regard.

27

So, whizzer cones don’t block the high frequency break up of the cone at all. It does extend response by being attached directly to the voice coil former and mechanically decoupling and resonating at high frequency.

There is a phase shift at this point, as if there was a passive crossover in place. You can see it in the phase plot of this lowther driver at about 3.5 Khz. Lowther EX3

The polar response of whizzer cones is terrible and, while they can sound a little better than they measure, I would generally avoid them like the plague for hifi applications.

Thiel speakers actually developed a similar sort of structure but with a small rubber suspension and a metal dome in the center of their mid in the CS2.4. It decoupled at higher frequencies and extends past 20 KHz. This actually worked remarkably well, though apparently it was challenging to manufacture (getting the compliance right for the dome to decouple and sum correctly) and still not up to the performance level of the best coaxial.

2 Likes
28

So why would a designer use a whizzer cone? Is it a cheap solution to a need? Or is it a designer who’s knowledge has only gone just so far? By your description, it sounds like a very inelegant design.

2 Likes
29

Well, for some designs, it is 100% cost driven. One of the more prolific uses of them is in cheap commercial paging and background speaker systems like these: Dual cone driver | 25V/70V Transformer | 810-T72 | Lowell Manufacturing
or older OEM automotive speakers. A cheap 1-way is cheaper than a cheap 2-way.

A second is more of a belief system that a single driver full range is better in the midrange by eliminating the crossover or pushing the crossover above the vocal range. When you combine this with wanting high sensitivity and 8-10" woofer, you get things like whizzer cones. The smaller single driver full ranges (like the jordans, markaudio, fostex, tangband etc.) still have power response issues but are a lot less problematic than their larger, high efficiency brethren with whizzer cones.

There is also a lot of history here and whizzer cones existed back in some of the earliest designs and so some drivers, like lowthers and voxativ drivers are kind of a super-retro thing but taken to the nth degree. It’s hard to find proper measurements of these things because the drivers smooth the data and don’t show the off axis performance.
Here are a few measurements of a voxativ, though no polar data is shown.

These eminence Beta12 LTA drivers with the whizzer cones where originally use in some budget acoustic instrument amplifiers and things from Fender, I think (and later some higher end models like the Euphonic Audio “Whizzy” models and others) and for that sort of thing they’re fine.

1 Like
30

@Chris_Brunhaver I am just a dummy watching from the sidelines who wants to thank you for sharing a little of that lifetime of knowledge here. You are obviously another great addition to the PSA fold.
Thanks again
Vern

3 Likes
31

Well, Paul has talked about wanting to do subwoofers in the future. They won’t be our first products, though that may have been a valid strategy.

As you mention, subs are are a great way to combine some of our core expertise in amplifiers with some of the low distortion/long throw driver technology I’ve been working with.

32

Now get back to making the FS a home run,
Chris. :slightly_smiling_face: Seriously, the design sidebars are interesting and the solid rationals for the design choices make the upcoming speakers even more interesting.

1 Like
33

Thanks! Back about 12 years ago, I actually interviewed Thiel and they flew me out to Kentucky to meeting with the team and spend time with Jim Thiel for a few days and (meet Kathy and Dawn). It was very interesting to see his process and I have tons of respect for the rigor, ingenuity and passion that he brought.

One thing that I didn’t know at the time, that was an issue is that I thought that I was interviewing to work with Jim and not replace him. I was sad to see what happened to him and later his company/legacy.

2 Likes
34

Well, I took a little bit of a sidebar today. We’re waiting on some samples and so I’m currently working on some new stuff/additional models, which is exciting.

3 Likes
35

How ironic is that. they were looking for you to replace Jim. I never got to meet him but heard wonderful things about him.

His nickname was Gentleman Jim. One great story I read about him was how he literally conceived the design of the coincident driver in the 2.7’s and

3.7’s (which I have) in his head and then went and built it right then.

It was so sad when he passed. I have been a loyal Thiel guy since 1985 and am on my 5th and obviously last pair.

Working with the PS team has got to be so great. I am sure that when they come to market,

You will cause a lot of speaker companies a lot of sleepless nights.

Good luck to you.

Kent Tager

President

The Hub Limited

2921D Battleground Ave.

Greensboro, NC 27408

Toll free: 866-482-5836

Phone: 336- 545-6535

Fax: 336-545-6534

Elie Wiesel:

We must always take sides. Neutrality helps the oppressor, never the victim. Silence encourages the tormentor, never the tormented.

1 Like
36

Yeah, I think that they knew that they would need multiple people to replace him. He designed their website and ERP system in excel and a bunch of scripts, designed and made their pen plotter measurement system, programmed CNCs, helped fix and troubleshoot the subwoofer amplifier returns.

I was there right when they were assembling the first 3.7 with the cast aluminum tops. They had tried to make it out of bent aluminum (from a company making bent aluminum school chair/desks) but the company had overpromised about their dimensional accuracy so Thiel had to tool a huge aluminum casting for about $40k. That is why some of the early photos of the 3.7’s had anodized aluminum tops and the later ones had powdercoat.

The folks at FST speakers in China were making the drivers for the 3.7 (based on Jim’s detailed design and documentation). At one point, after they went out of business, and before I worked here at PS Audio, I thought that it may be interesting to resurrect the Theil driver designs with them (as a vendor) but the vendor didn’t have much interest.

Working here is great and I’m very excited to get these products to market! Hoping to find some good homes for these babies.

2 Likes
37

What a great story. If you need any of the coincident drivers to study, I have two extra that I got when I bought the 3.7’s from Rob Gillum three years ago though I doubt you need them at this point.

https://www.coherentsourceservice.com/

Jim must have been a brilliant man to have done all he did. His brother Tom is a neat guy and very active on the Thiel thread on Audiogon.

It would take an incredible speaker to make me want to part with the 3.7’s, but I suspect your babies are going to be killer and could do it.

Good luck Chris.

Kent Tager

President

The Hub Limited

2921D Battleground Ave.

Greensboro, NC 27408

Toll free: 866-482-5836

Phone: 336- 545-6535

Fax: 336-545-6534

Elie Wiesel:

We must always take sides. Neutrality helps the oppressor, never the victim. Silence encourages the tormentor, never the tormented.

38

is there anything folks won’t use Excel for?!

also, to add my thanks for all the info, it is hugely appreciated interesting stuff :slight_smile:

2 Likes
39

What magic do you think listeners pick up on with Zu or similar designs? Dynamics? Timing?

Based on measurements I should have been in love with my former Triton 3+’s but when I first heard the Zu Omen I was shocked how much I had been missing.

I’m very curious if you can manage to combine good measurements with a “live” sound without killing the presence and impact.

40

Well, the Eminence woofers are well designed and have low distortion, low power compression, high sensitivity but somewhat limited bass extension (due to the sensitivity).


Even with all of the problems (huge port resonance/cancellation, raggedy response and directivity) of the older druid speaker, in these measurements, you can see that distortion is less that 1% in the bass at 95 dB/ 2 meters, (101 dB at 1 meter) which is awesome.

Here’s the goldenear 3+ at 90 dB (5 dB less) and you can see how much more distortion there is. Yes, the goldenear is playing lower extension-wise (which penalizes you from a distortion perspective), but you can see that it is as much as 10-20 dB (10-100X) more distortion.

Done right, these kinds of speaker could sounds really effortless and dynamic, but they need to have a flatter/smoother response and even directivity (different tweeter/horn/crossover) and a port/enclosure without the crazy resonances etc. .

2 Likes
41

Since Zu speakers sound so very good, are reviewed so well, sell so well, have been purchased by reviewers for their own collections, like Herb Reichert, it would be reasonable to conclude that Sean Casey must know more than you seem to think he does. Don’t you think?

2 Likes