My vote is to with the bigger size. Any time the woofer-box Qtc is above 0.9, there is a risk of an overly fat bass. Sometimes it happens, sometimes not. But there is no point in pressing our luck with a Qtc of 1.0 .
The classic golden ratio box for 85 liters gross would be 28 H x 17.25 W x 10.75 D (inches internal) and 29.5 H x 18.75 W x 13 D (inches external), assuming 0.75 inch wall thickness and 1.5 inch thick baffle. Internal modal ratios are 1: 1.6: 2.6
j.
Yes, I think I may have to resign myself to wait until they come in and get real T/S parameters. I'll likely make the cabinet out of Birch plywood rather than MDF or particle board, so the possibility of making a cabinet that may not actually work would be a little silly.
I had thought about this, but it conflicts with one of our design goals that it be easy for a beginner to build. I think we underestimate just how intimidating building a speaker can be for a beginner. BUT...if the T/S parameters really do measure unfavorably we can come back to this. My guess is that it is fairly straightforward and I could make a quick video.
One other thought I had was going aperiodic. Do you have experience with that?
I don't get why you want to use the Peerless woofer, maybe a didn't read that post. It is cheap made and was well priced at around 50$ a while ago. At the current price in the US, you get much more value from some Dayton Audio for example. Plus you buy "made in USA". It has a too high Qtc, too high Fs and too low power rating to build something interesting from it.
Dayton isn't USA made, Dayton is an brand from Parts Express that buy's OEM drivers made to their specs from big OEM builders, mainly in asia and partly also Europe. The US does not have big OEM builders anymore i thought, just some smaller specialised builders. Some brands make their speakers still in the US, but that is inhouse production and not the cheap ones.
Some political posts not related to speaker pricing have been removed.
I thought I read somewhere made in USA. Even as I didn't belive it. Anyway, in the US they have a very good price/ performance ratio. In Europe they are too expensive. Also you need not trust their TSP data, but should measure them yourself. Like with hardly any driver.
This is exactly correct. We started with some Dayton drivers as options but decided to exclude them as we are trying to closely control the total price in both USD and EUR. We also had to exclude Monacor and a few other brands not available in the US.
It is increasingly complicated to find products that are available in Europe and the US/ Canada/ South America and have compareable prices.
If I was in Brasil I would sure use other drivers than in Germany.
So in the end we would have a set of speakers that are more a retail price than a performance decission.
If I was in Brasil I would sure use other drivers than in Germany.
So in the end we would have a set of speakers that are more a retail price than a performance decission.
More busy work over something so clearly stated in the rules. Is it time to start looking at alternate ways to manage it?
So... getting back on a promise. And getting back on the 3d order box, which the Germans actually have a name for, being GHP:
This is the 830669 in 2,2cft with the specs from the Peerless website. Black is ordinary 2nd order, red is with 940uF (2x470uF) in series with the woofer. I accounted for a slight series resistance.
What can be observed is that the -3dB point shifts downwards about 5Hz and the 1,5dB hump of the rather highish Qtc goes down to reference level. Not that spectacular, but not totally irrelevant either.
Next to a bit of low extension, an effective subsonic protection can be had. Red curve is normal box, green is with series cap. While it dips a bit in the 30Hz region (only one and some dBV), you gain a lot in subsonic region. Plus, hefty bonus coming: you gain effective DC-protection of the woofer. As we all know, parties come with amps burning and deceasing. Et voilà, no woofer breakdown on amp failure.
Just my 2 ct. Oh yeah, blue curve is max SPL half space at 1m, driver operating in linear region. Not bad for the money.
This is the 830669 in 2,2cft with the specs from the Peerless website. Black is ordinary 2nd order, red is with 940uF (2x470uF) in series with the woofer. I accounted for a slight series resistance.
What can be observed is that the -3dB point shifts downwards about 5Hz and the 1,5dB hump of the rather highish Qtc goes down to reference level. Not that spectacular, but not totally irrelevant either.
Next to a bit of low extension, an effective subsonic protection can be had. Red curve is normal box, green is with series cap. While it dips a bit in the 30Hz region (only one and some dBV), you gain a lot in subsonic region. Plus, hefty bonus coming: you gain effective DC-protection of the woofer. As we all know, parties come with amps burning and deceasing. Et voilà, no woofer breakdown on amp failure.
Just my 2 ct. Oh yeah, blue curve is max SPL half space at 1m, driver operating in linear region. Not bad for the money.
Last edited:
High pass filtering a bass driver works quite well and can make a problematic construction sound deeper and tighter. There is no audible disadvantage compared to a "regular" closed box, the lowered response is followed by a steep decline, protecting the woofer cone from useless movement.
German speaker manufacturer HECO used it in their top of the line "DC" models. Invented was the principle from car audio installers that had limited volume and still wanted deep bass.
There is one catch: Simulating the capacitor value only gives you a first idea of the value needed. The capacitor size you really need should be adjusted by measuring the finished speaker for its response. Otherwise you will not find the best bass extention. Usually your simulation will be +-200uF off.
Next, large caps around 1000uF get expensive if you use overpriced audio grade stuff. You can instead use two identical polar electrolytics in series, connecting both positive ends and get a bipolar cap of half the capacity and the same peak voltage. So two 1000uF 50V caps give one bipolar 5000uF of 50V peak.
It is good practice to use some film foil caps to bypass the electrolytic, in parallel the ad to the resulting capacity.
Last, you can not get this effect in the same way from equalizing. The capacitor enabeles the driver to draw more current below the resonance frequency. Quite a complex process. Equalizing needs to push it with higher voltage the amp may not have.
German speaker manufacturer HECO used it in their top of the line "DC" models. Invented was the principle from car audio installers that had limited volume and still wanted deep bass.
There is one catch: Simulating the capacitor value only gives you a first idea of the value needed. The capacitor size you really need should be adjusted by measuring the finished speaker for its response. Otherwise you will not find the best bass extention. Usually your simulation will be +-200uF off.
Next, large caps around 1000uF get expensive if you use overpriced audio grade stuff. You can instead use two identical polar electrolytics in series, connecting both positive ends and get a bipolar cap of half the capacity and the same peak voltage. So two 1000uF 50V caps give one bipolar 5000uF of 50V peak.
It is good practice to use some film foil caps to bypass the electrolytic, in parallel the ad to the resulting capacity.
Last, you can not get this effect in the same way from equalizing. The capacitor enabeles the driver to draw more current below the resonance frequency. Quite a complex process. Equalizing needs to push it with higher voltage the amp may not have.
Last edited:
Very true. But two bipolar electrolytes 63V DC, which is more than enough, considering this woofer that will run out of juice at about 35V AC, won't set you back that much, about € 16. No need for bypasses, you just take the ESR into account of the crossover (and we're talking about 'woofers' here eh?).
https://www.stereophile.com/content/klh-model-five-loudspeaker-measurements
2000/pair in USA 2021 woofer is 10" sealed box
Rising bass in nearfield tells that baffle step compensation is applied
2000/pair in USA 2021 woofer is 10" sealed box
Rising bass in nearfield tells that baffle step compensation is applied
@bikinpunk 's measurement of the L100 Classic MKII taken from his Near Field Scanner has been uploaded to spinorama.org
TLDR?
JBL specs- Sensitivity 90 dB, Impedance 4 Ohm, Size Width 399mm, Height 636mm, Depth 371mm, Weight 26.7kg (59lbs)
Measured as-
TLDR?
JBL specs- Sensitivity 90 dB, Impedance 4 Ohm, Size Width 399mm, Height 636mm, Depth 371mm, Weight 26.7kg (59lbs)
Measured as-
- Sensitivity: 90.7dB (avg. 100Hz-1kHz for 2.83V measured at 1m).
- -3dB (-6db) point is at 50.5Hz (38.8Hz)
- Horizontal directivity for +/-6dB is (-60.0°, 50.0°) between 1kHz and 10kHz.
- Vertical directivity for +/-6dBis (-10.0°, 30.0°) between 1kHz and 10kHz.
- Tonality (Preference) Score is 4.81 and would be 6.76 with a perfect subwoofer
Last edited: