Build of gr-research X-LS Encore

[Rick Sykora]

Ok, the next stage plans have changed again. Based on your feedback, we are moving towards a more granular approach. Rather than testing a pair built by Danny, I will be doing the roundover and No Rez for the second speaker. I will also build the premium version of the crossover. Since the crossovers were built to be serviced readily, Amir will be able to swap the base crossover for the premium one in either speaker.

The parts just shipped today, so do not expect to get them until mid-next week. Should be able to make the changes by next weekend, so the timing to get them to Amir is about the same as originally planned.

 

[maty]

The premium crossover will have the same measurements, except that you have fine-tuned on the values of the capacitors by measuring them, which is what Danny Richie does. Another thing will be the sound, which I suppose will be much better, especially with acoustic and electrical instrumentation.

No Rez or equivalent. DIY sandwich with damping+absorbent. Better to do it before, although being a big woofer it is easy to put it later. Much more complicated if it is 5.25" or less... if you have big hands.

 

[Rick Sykora]

Ok, the next stage plans have changed again. Based on your feedback, we are moving towards a more granular approach. Rather than testing a pair built by Danny, I will be doing the roundover and No Rez for the second speaker. I will also build the premium version of the crossover. Since the crossovers were built to be serviced readily, Amir will be able to swap the base crossover for the premium one in either speaker.

The parts just shipped today, so do not expect to get them until mid-next week. Should be able to make the changes by next weekend, so the timing to get them to Amir is about the same as originally planned.

Btw, sorry no tube connectors...

Had already built with terminal cups and would have complicated crossover swapping anyway. Since Vandersteen claims terminal strips are best, maybe someone can do an external comparison?

 

[Deleted member 2944]

I thought DR was building a full-on pair to send Amir's way for testing/listening. What happened to that plan???

Dave.

 

[KaiserSoze]

YouTube Building the X-LS Encore: Installing Tube Connectors, by Danny Richie

"... talking about the difference in how they sound vs. the binding posts ..."

I think it is interesting that he does not say outright that the tube connectors improve the sound. Instead, he says "...people start giving feedback, talking about the difference in how they sound vs. the binding posts." See, it isn't his claim. It's something that other people say.

 

[KaiserSoze]

Btw, sorry no tube connectors...

Had already built with terminal cups and would have complicated crossover swapping anyway. Since Vanderseen claims terminal strips are best, maybe someone can do an external comparison?

Since the claim for the tube connectors is with avoidance of ferrous metal, any alternative that similarly avoids ferrous metal should also preclude anyone from claiming that you still didn't build it the way you were supposed to build it. But it sounds like you are already past the point where you could do anything other than the regular binding posts incorporated into the cups. Otherwise, I would have suggested rigging something using some of those copper things they sell in the electrical departments of hardware stores, for ground connections in house wiring and elsewhere. Essentially a couple of small copper plates bent into an angle and using a copper screw to squeeze them together, thereby clamping the grounding wires together. But as I think about it the screw might be steel. And you're past that point anyway so it doesn't matter.

 

[Rick Sykora]

I thought DR was building a full-on pair to send Amir's way for testing/listening. What happened to that plan???

Dave.

@amirm and I kicked both options around and settled on the more granular approach.

He made the final call and am good with it.

 

[Rick Sykora]

Got the shipment and noticed did not have the fancy copper bypass caps, so called GR. Danny said they were optional, but I did not want to cut corners on the premium crossover, so I ordered. Ofc, this will delay things a bit more...

Round over is done and have removed the original damping. Will apply No Rez over the weekend.

 

[Rick Sykora]

The No Rez went in today. It was not too bad, but am sure it is a lot easier to do before the cabinet is entirely assembled. As Danny suggests, it does cut fairly readily on a table saw. However, have to be careful that the adhesive layer does not get under the fence. It can also be trimmed with a razor knife or scissors. As shown below, cutting a hole is tricky. This pic shows my first attempt and a much more successful subsequent one...

The left picture is my first attempt to cut the terminal cup hole with a hole saw. Once through the adhesive layer, the teeth grabbed and savagely tore the foam. Was not happy as did not want to waste any. The trick to get a clean hole was to stop drilling after penetrating the adhesive layer and reverse the drill rotation. This way, the hole saw teeth ground through the foam without aggressively grabbing and tearing it.

I started cutting pieces from the top down and, even with my hole saw hiccup, used half of the sheet. No Rez is an inch thick, so it uses considerable internal space. If you use the flat pack, you can follow the cut sheet from Peter Rawlings. Otherwise, I found it easiest to cut strips to cover the widest areas first. The back panel is to big to fit an entire piece through the woofer hole, so it was done as an upper half and a lower one. Here is the final result:

 

[Rick Sykora]

Remeasured the speaker impedance with No Rez. No major change in this case. The bass tuning peaks were a tad higher and the 275 Hz resonance blip was still present. Previously mentioned the resonance to Danny, but he had no suggestions for the root cause.

Expecting some rain tomorrow, so might give me some time to investigate to see if it is related to my cabinet construction (it does exist in both builds).

 

[Rick Sykora]

So, about the resonance that show around 275 Hz (more like 250 after looking closer), I tried several things to try to eliminate it. These are (in order):

1. Stuffing the port with enough foam dampening to approximate a sealed box
2. Using a pipe clamp to try to change the resonance on all 6 sides
3. Remove the woofer and check it in free air.
4. Connected the woofer to the crossover and checked in free air
5. Spread the Acosta-stuf to cover the side-to-side brace (only remaining exposed hard surface)

While other various things were affected, the source of the resonance was still unresolved. So broke out the signal generator and hooked speaker to my new test amp. When I do this, bad resonances are usually pretty audible. This one was not. However, once I started feeling around the cabinet, it became pretty clear that the side panels were vibrating around 260 Hz and not much above or below that. The cabinet design includes an internal side-to-side brace, but either is not enough or could be better positioned (placement was not critical according to Danny, so I roughly centered it to stay away from other parts (port, woofer, etc.).

So, as this appears to be the cabinet design, the good news is that does not appear to be very audible, the bad news is that No Rez did not eliminate it and no clear other remediation is apparent at this writing.

As usual, comments or questions are welcome!

 

[Deleted member 2944]

If this was a cabinet design issue, your test #3 should have eliminated it. Generally, resonances in this driver frequency range are spider/basket related. I think that's what you have here.
I wouldn't chase this anymore. This seems to be inherent in the system and shouldn't be "fixed" for testing process.

Dave.

 

[Rick Sykora]

If this was a cabinet design issue, your test #3 should have eliminated it. Generally, resonances in this driver frequency range are spider/basket related. I think that's what you have here.
I wouldn't chase this anymore. This seems to be inherent in the system and shouldn't be "fixed" for testing process.

Dave.

Fair point, allow me to clarify. For #3, the resonance did NOT follow the woofer in a free air. Since am waiting on the bypass caps, I wanted to be more certain of the root cause. Given the nature of No Rez, expected that it would dampen the resonance. When it did not, I wanted to be sure something I did was not the source of the resonance.

I have edited my earlier post to correct where it misled you.

 

[Deleted member 2944]

Thank you for clarifying. You said, "the remaining resonance blip remained through all of the above scenarios"......so it seemed clear (to me anyway) this was a driver characteristic.

Anyways, I still don't think you need to pursue this obsessively. You've built the box per the dimensions and applied an appropriate crossbrace. Job done.
But, I'm sure some anal-retentive type on the Audiocirclejerk forum will conclude your brace is 1/16" off in placement and the results are invalid for that reason.

Dave.

 

[DIY Newbie 2020]

Fair point, allow me to clarify. For #3, the resonance did NOT follow the woofer in a free air. Since am waiting on the bypass caps, I wanted to be more certain of the root cause. Given the nature of No Rez, expected that it would dampen the resonance. When it did not, I wanted to be sure something I did was not the source of the resonance.

I have edited my earlier post to correct where it misled you.

Thanks for all your work Rick. Could you send one to Danny to take a look at? It may not help?

 

[DIY Newbie 2020]

Thank you for clarifying. You said, "the remaining resonance blip remained through all of the above scenarios"......so it seemed clear (to me anyway) this was a driver characteristic.

Anyways, I still don't think you need to pursue this obsessively. You've built the box per the dimensions and applied an appropriate crossbrace. Job done.
But, I'm sure some anal-retentive type on the Audiocirclejerk forum will conclude your brace is 1/16" off in placement and the results are invalid for that reason.

Dave.

And there are no anal-retentives on this forum?? So funny mate.

As you as saying Rick did a great job trying to remove that blip but if it is there after all the work he put in then it is.

 

[Rick Sykora]

Thanks for all your work Rick. Could you send one to Danny to take a look at? It may not help?

Let’s see what else we find when Amir retests. This resonance does not merit any more time in my mind. They are fairly common in many speakers. Tried to see if anyone else has posted an impedance measure of their build and came up empty. The brace in the flat pack is better implemented, so may help. If not using the flat pack, might beef up the braces and use wood glue rather than Liquid Nails.

Having spent a fair amount of time on other designs with such resonance, if you go to stiffer bracing, the main issue is that you may replace this lower resonance with a higher, more audible one. Another approach would be to use something more viscous than No Rez to line the cabinet inside. Now that the No Rez is in, cannot be readily removed, so not a lot of options left for this cabinet.

This does show why many builders/designers are obsessive over resonance control. But as shown here, you can spend more time and money and not entirely eliminate the unwanted ones. It is also worth noting that you might fix the speaker but other items (equipment, furniture, paneling), are likely resonating around your room as well.

 

[maty]

YouTube Building the X-LS Encore: Final Assembly, by Danny Richie

 

[maty]

YouTube Building the X-LS Encore: Measurements, by Danny Richie

 

[maty]

I think it would be interesting to try with the loudspeakers turned, with the tweeter facing into the room as: