The FR20's Are Here

We aren’t using frequency tapering (a 3.5 way design) on these, though you could certainly do that. Ideally, the drivers would be in separate chambers for this (for measurement purposes) though you ca implement it whiteout that.

A lot of punch and emphasis in the upper bass can be not only the voicing of the speaker but the dynamic linearity of the woofers (large signal behavior) and the enclosure construction.

Sometimes, there is an interaction with the upper impedance peak of a woofer in a reflex system and the low pass filter components that can add some emphasis in the upper bass (but also give some additional punch). However, this interaction also drops the impedance quite low.;


I hope that you didn’t have many steps. I added some boards to help get my slightly lighter TLS1 bases up eight steps. Summer heat helped. Also, my hand truck is small and lacks straps. I think that I would have to hire help for the 2s. My room is sized for the 2s but my budget isn’t.
Piano movers charge per step.

The best part is that I had only one threshhold to climb and had a ramp on that.

Where are you? I’m in Phoenix, AZ.

Just ordered black FR20s…should have them by early March. :grin: :slightly_smiling_face: :laughing:

Will be driving them with M1200s or Atma-Sphere Class Ds.


I have black FR20’s that are driven by my M 1200’s. They are very happy together. I think you will be too!


Congratulations! I’m also driving my FR20s by M1200s. I don’t remember how many times I said “wow” while I’m listening music.


I’m in Tucson, so not very far away. Using m1200s, but the atma-spheres seem interesting. Would also like to try AGDs.

Hi Chris,
I love my FR20s. One can say who cares how it’s made if it sounds great. But I want to understand the design philosophy. It’s not going to change the fact that it sounds great. But I can appreciate more by knowing more.
For that, you’ve explained the design of FR30 and FR20 in great detail in many video clips on YouTube. I really enjoy watching you talking about the speakers.
I have some questions about the design of the FR20 woofer, it would be great if you can explain.
I understand why you change the cone material from FR30 woofer’s aluminum, to improve efficiency. But why did you choose to use the single spider instead of the double that used in FR30’s woofer? Is it also for efficiency, or something else?
And what is a spider with stitched-in lead wires? Does it matter for the performance whether the lead is stitched in or not? I ask because it’s mentioned in the description on the web.

Thank you.

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I love hearing when people are enjoying their speakers and I’m happy to share more about the design.

Yes, we moved to a single spider for the woofer used in the FR20 versus dual spider for the FR30 woofer in order to further reduce the mass. Half of the surround and spider count towards the mass of the moving system and so moving to a single spider reduced the moving mass by an additional 2-3 grams. We still have quite a good suspension linearity/symmetry with the single spider.

As for the lead wires, they are attached to the spider to prevent them from roping and slapping against the cone under high excursion. There is more clearance on the FR20 woofer (reducing the need for this feature) but we are using the same spider as the FR30, where the clearance is rather tight because of the spider spacer ring and the ability of the woofer to move ~1" p-p under very high power in deep bass passages.


One more question, Chris: Can you please explain what an underhung woofer or driver is?
Thanks and I really appreciate your willingness to share your extensive knowledge.

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Overhung vs underhung

This cutaway from this monitor audio woofer shows an underhung structure.

Well, the simple answer is that in an underhung driver, the voice coil length (winding width) is less than the height of the magnetic gap and in an overhung driver it is longer. The main goal of this underhung arrangement is to get more constant motor force (BL product) versus excursion but at the expense of power handling, peak motor force/sensitivity, cost and with generally poorer modulation/magnetic saturation (bigger magnet/pole needed to get the larger top plate to the same flux level/saturation).

Interestingly, the pros and cons listed on wikipedia (about sensitivity with respect to overhung vs underhung) are wrong! Maybe teachers are right to tell kids not to cite wikipedia as a source.

This may need a separate thread on woofer design. We are using neither overhung or underhung in our woofer and are using something kind of in-between the two (but more close to underhung in its performance characteristics.


That’s very interesting and more complex than I would have thought! Thanks.

Thank you very much for the detail.

I don’t think I’ll ever have a chance to play that loud and hard. Strong bass from FR20 can vibrate the rooms even at the moderate listening level.

Don’t leave! Paul, make Chris VP of the speaker division!


We love Chris!


@ejor2 any updates on how the FR20’s sound?

I received my FR20s.


and After

@adifferentpaul now I knew why you were saying “I will not be getting rid of my FR20’s”.
It’s addictive. I feel like captured and drown in the sea of resonances radiated from them. Falling deeper and deeper beneath, comfortably.
I haven’t thought PS Audio speakers are so good. (Sorry, PSA.)
These speaker are not an intermediate stop along the way to the destination, but may well be the destination for me, seriously.


so you think they are significantly better than the Sopra’s? (were those no2?)

I’m loving mine…sounded great after 100 hours, even better after another 100…enjoy !!!

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Sopra No2 are excellent speakers. Unless I do not listen to polyphony vocal music in which I felt something is not right (to my appetites), I might be using them.
FR20 is significantly better than Sopra No2 for me in almost all sonic profiles. What it excels most is expressions of musical resonances in complex mix of multiple voices with rich echoes. They don’t sound like modulated or turbid at all. True resolution, I’d like to call it.
At this moment I feel the bass is a bit shy with FR20s. It should be tuned by some positioning and else.