Introducing Denotiva DIY speakers!

[Bryguy]

Oh, that's definitely too high for my desired use. Is that after filtering?

I was under the impression most woofers lose about 6db when tossed on a typical bookshelf baffle but apparently not? I think I'm missing something here.

It depends on how much BSC you implement into the crossover. If none, you can reach basically the manufacturer stated sensitivity, you'll just have weaker bass than you would have on an infinite baffle. The -6dB is just a generalization for how much the bass tends to taper off, and if you want to compensate for that you need to attenuate the rest of the driver's bandwidth equally. Baffle step only really affects lower frequencies. The wavelengths at higher frequencies are small enough that the baffle remains effectively infinite. Some designs incorporate very little BSC into the crossover, and thus preserve the manufacturer stated sensitivity. Most of the times I see speakers with a -3db BSC, and usually only see the full 6dB for speakers with an emphasis on bass. That's just a generalization though. The new Dayton Opal1 for example has close to 6dB BSC (fwiw most folks on the diy forums seem to think it was too much, but that's mostly for IMD reasons. If you plan to use the Sig180 only at lower frequencies then 6dB BSC should be fine, not to mention the sig180 won't play as low as the epique)

Btw, this is why it's generally frowned upon to add a woofer to a pre-existing 2 way speaker. The crossover designed for the 2 way will have treated the MW as a woofer, not a midrange.

 

[RickS]

Oh, that's definitely too high for my desired use. Is that after filtering?

I was under the impression most woofers lose about 6db when tossed on a typical bookshelf baffle but apparently not? I think I'm missing something here.

No filters were used. Pretty confident in result but rarely measure sensitivity as it gets very loud.

p.s. after rechecking my measurement rig, found I have moved the mic to somewhat over a meter. So my original sensitivity estimate was low and likely closer to the SIG180 spec. In any case, is in line with VCAD's diffraction tool.

 

[RickS]

Modeling the bass reveals a more promising vented f3 in the mid 50s. The sealed f3 (no bsc) is in the high 90s and low Qtc. So, not going there. Will mount a vent tomorrow and see how it does.

 

[RickS]

Went to capture driver spins with sealed cabinet and broke something in my test rig.

Am down while I figure out what is causing.

 

[Bryguy]

Went to capture driver spins with sealed cabinet and broke something in my test rig.

Am down while I figure out what is causing.

Oh no! Good luck with that

 

[Ktacos]

It was me, I did it.

 

[RickS]

May have been the minidsp as switched to passive crossover and did better. Mounted a 2x7 port and it sounds much better. Need to redo driver measurements without the minidsp in the loop and get back to r2. Will have to wait until next week as Buckeye has some work for me.

 

[RickS]

Hit a snag on amp testing, so am switching back to speakers. Before I switch my test stand over to r2, did some listening and some more measurements on this speaker. On the positive side, is putting out about 88 dB at 2.83V/1m sensitivity and the bass sounds decent. However, this is partly due to the usual crossover tricks and tuning that extends the bass rolloff. F3 is around 60 Hz but was expecting much lower. Might have to wait and see if PE improves it.

As it stands, might squeak out some more bass with a slightly larger cabinet and/or bringing in closer to the front wall. The cabinet is not available until October but the next round of SIG180s should be available again in August. Think I will shelve it for now.

 

[Ktacos]

about 88 dB at 2.83V/1m sensitivity

So probably a bit too loud for tebm46.

 

[Dave Bullet]

Where have you designed BSC to kick in? I know it's baffle / woofer dependent, but your transfer function graph starts at 200Hz so hard to see. I usually have mine starting about 100Hz. May help explain the weak bass. Are these ported or sealed? (sorry if I missed an earlier post). Can't tell as the impedance also starts at 200Hz.

PS: Looks like a very nice design.

 

[Ktacos]

BSC seems to largely just happen on its own if you're filtering the woofers properly. I can't say I've ever really actively tried to correct the losses.

I cn be hard to get accurate low end data, so most people take Close mic measurements and apply baffle loss to match the 1 meter measurement. Vcad can do all this.

 

[RickS]

Am taking advantage of some baffle step but the bass performance needs to be addressed holistically and, while could give up more sensitivity (and still may), the bigger issue is the SIG180 not making spec. I have approached PE on the much higher Fs and was initially challenged that the driver needs more burn-in. As I did an initial burn-in cycle and have been playing the speaker for months, I am skeptical. The Fs is claimed to be 40 Hz and is still measuring in the low 50s. I have not had other woofers that required more aggressive burn-in. Also, if I compare the spider to other comparable midwoofers, it is rather stiff. I am waiting for an update from PE and we will see.

While the SIG180 looks like a decent value, PE needs to show that it can make at least close to its spec. Otherwise, there are plenty of other woofers available and will switch to one of them.

 

[ernperkins]

Don't expect PE to budge. Here's another set of measurements for the Sig180: Fs of 50 and 52 Hz. https://diy.midwestaudio.club/discussion/comment/47092/#Comment_47092

 

[RickS]

Don't expect PE to budge. Here's another set of measurements for the Sig180: Fs of 50 and 52 Hz. https://diy.midwestaudio.club/discussion/comment/47092/#Comment_47092

Thanks, those are @Wolf’s measures and he mentioned in the SIG180 thread. Have a good track record of getting vendor’s to pony up and PE is usually very responsive. Like others, they may not always publicly admit a defect. Juggling several projects and this one can wait.

 

[Ktacos]

I'm kind finding I'm not a fan of whatever is going on around 700hz with the sig 180. PE shows distortion there, as do my measurements. Don't even have to bring it up in level to see it. I find the rs180 has some of advantage over the 180 in terms resolution, but I'm not even going to try to define what I mean by that because I don't know what I'm hearing here.

 

[a4eaudio]

Don't expect PE to budge. Here's another set of measurements for the Sig180: Fs of 50 and 52 Hz. https://diy.midwestaudio.club/discussion/comment/47092/#Comment_47092

Here are my measurements - Fs of 47 and 49Hz

New Dayton Signature Series (Sub180-4 etc) - Page 2

Looks like they’ve respawned a driver series just to fill the holes left by Tymphany. I’m looking elsewhere

diy.midwestaudio.club

 

[Bryguy]

Will be interested to hear how PE responds.

 

[Ktacos]

Another pass with comparable directivity but flatter overall....

View attachment 356370

Gave it a listen with my favorite tunes and sounds pretty good too!

Meanwhile a friend prototyped one with closer driver distances. Ofc, it involves trimming the tweeter waveguide. See what you think...

View attachment 356374

would love to know the screws you used, seems like they are a great fit for the drivers holes.

 

[RickS]

would love to know the screws you used, seems like they are a great fit for the drivers holes.

Those are not mine. Torx are too fancy for me.

Will have to ask @carbidetooth.

 

[RickS]

Before I do another follow-up with PE, thought I would give the woofer another round of break-in. I did bring the Fs down to around 48 Hz after some extended sessions of driving it at 20-60 Hz. This is way more than I have done for any other woofer and much more than my (now discontinued) Dayton ES180s.

The woofer got reviewed in Voice Coil and the measured Fs was 45 Hz. That is still over 10% higher than spec and am not expecting to even get to that mark.