Port question?
Hi, I'm not sure if anyone will see this since it's been a while. Anyways, I have built the NOMEX 164's; they came together a little faster than I thought. I guess that's what happens when you work on them every free second because you're so excited
.
My question is this: the design calls for a tuning frequency of 45hz which is a port length of about 3", I cut my port to 3.75" for 42hz based on Pascal's recommendation because it's easier to take more off than to add length. What is the effect of a lower tuning frequency? Slight hump and faster roll-off? slightly looser bass? These things have a surprising amount of bass and they have a clear but meaty sound when called for, but I feel like they might be just a touch loose at times.
They only have about 6 hours on them so I won't be making any adjustments until they are broken-in, but I just wanted to get a handle on the tuning effects.
I have been taking a lot of photos and will post a build thread when they are broken in and finished; I still need to add the side fillets and finish the veneer.
Thanks,
Evan
Hi, I'm not sure if anyone will see this since it's been a while. Anyways, I have built the NOMEX 164's; they came together a little faster than I thought. I guess that's what happens when you work on them every free second because you're so excited
. My question is this: the design calls for a tuning frequency of 45hz which is a port length of about 3", I cut my port to 3.75" for 42hz based on Pascal's recommendation because it's easier to take more off than to add length. What is the effect of a lower tuning frequency? Slight hump and faster roll-off? slightly looser bass? These things have a surprising amount of bass and they have a clear but meaty sound when called for, but I feel like they might be just a touch loose at times.
They only have about 6 hours on them so I won't be making any adjustments until they are broken-in, but I just wanted to get a handle on the tuning effects.
I have been taking a lot of photos and will post a build thread when they are broken in and finished; I still need to add the side fillets and finish the veneer.
Thanks,
Evan
If anything the opposite happens. Lowering the tuning frequency will reduce the output and remove any hump, should there have been one there to begin with. It will also lower the group delay for a given frequency, so if anything, will give the perception of 'tighter' bass.
The good old boom boxes of yore are really a thing of the past, what with the advent of decent CAD software. If you're getting a feeling that the loudspeakers aren't as tight as they should be, then I would look more towards to room placement.
What were your previous loudspeakers? If these loudspeakers have significantly lower extension, this can be perceived subectively as being less tight, that is, when compared to say a small book shelf design with nothing decent below around 80Hz.
The good old boom boxes of yore are really a thing of the past, what with the advent of decent CAD software. If you're getting a feeling that the loudspeakers aren't as tight as they should be, then I would look more towards to room placement.
What were your previous loudspeakers? If these loudspeakers have significantly lower extension, this can be perceived subectively as being less tight, that is, when compared to say a small book shelf design with nothing decent below around 80Hz.
You know I was thinking about it after I posted. They actually are not loose, kick drums and stand-up bass are actually quite tight, what I think I meant is that at certain frequencies there is a slight resonance. Not sure if it supposed to be in the song or not because it seems to fit when it happens.
So are you saying that a lower TF would be preferable?
Cotdt-
I do like the extention. I built the 40L version hoping that I can use them for stereo w/o my sub and that is exactly what I am finding is now possible. I have a pretty decent sub, but noticed that it still adds a little slop with music. I did try stuffing the port though and I found that it just made them sound a bit thinner.
Thanks
.So are you saying that a lower TF would be preferable?
Cotdt-
I do like the extention. I built the 40L version hoping that I can use them for stereo w/o my sub and that is exactly what I am finding is now possible. I have a pretty decent sub, but noticed that it still adds a little slop with music. I did try stuffing the port though and I found that it just made them sound a bit thinner.
Thanks
Sorry, 5th Element, I didn't read the rest of your post. My previous speakers were Kef iq5. They are supposed to play to 43hz, but the NOMEX are much fuller sounding. They are closer than the KEF's were to the wall. Kef's front port, 24" from baffle to back wall, NOMEX rear port 24" from baffle to wall, 12" from port. I could pull them out a few more inches.
Thanks, I'll try it again; I only tried it for a second before. So should I leave the port tuning at 42 or should I use the recommended tuning of 45hz. 45 will require cutting the port shorter.
Another thing, can the 18 ohm resister be adjusted to attenuate the tweeter? I have tried them with it in place and out. I like the sound with it in place much better; they sounded way too aggressive when the resistor was removed, but with it in place the highs are pretty recessed. I feel like I would it bumped up just the tiniest bit. Or maybe they will open-up with more break-in?
Thanks,
Evan
Another thing, can the 18 ohm resister be adjusted to attenuate the tweeter? I have tried them with it in place and out. I like the sound with it in place much better; they sounded way too aggressive when the resistor was removed, but with it in place the highs are pretty recessed. I feel like I would it bumped up just the tiniest bit. Or maybe they will open-up with more break-in?
Thanks,
Evan
Hi Satx,
Glad to see that you have completed your build so fast
I found that the sound of the medium become nicer after some hours of break-in. What about the tweeter level ? Is it right for you in your listening room ?
I still think it need a little attenuation of ~0.5 db, i'm waiting a week and i wil do some tests again with a equalizer and then il will change the L pad resistors if necessary.
Sound is OK at low level, but when you increase de volume, i think a little attenuation of the tweeter is needed to have a correct tonal balance.
Have you increase de volume at the level where you become to "feel" the bass
Sale advice than 6L6 : Leave it out and let everything break in. Re-visit it in a couple weeks, sound is still evoluting after two weeks IMHO.
One more thing, i think this speaker need just a little toe-in, try with no or just little toe-in, 10/15°.
Glad to see that you have completed your build so fast
I found that the sound of the medium become nicer after some hours of break-in. What about the tweeter level ? Is it right for you in your listening room ?
I still think it need a little attenuation of ~0.5 db, i'm waiting a week and i wil do some tests again with a equalizer and then il will change the L pad resistors if necessary.
Sound is OK at low level, but when you increase de volume, i think a little attenuation of the tweeter is needed to have a correct tonal balance.
Have you increase de volume at the level where you become to "feel" the bass
Sale advice than 6L6 : Leave it out and let everything break in. Re-visit it in a couple weeks, sound is still evoluting after two weeks IMHO.
One more thing, i think this speaker need just a little toe-in, try with no or just little toe-in, 10/15°.
Last edited:
Hi,
I actually may have to try tweeter attenuation again, but I will wait a couple weeks. I actually think I had a problem when I was testing with the 18 ohm in and out. On one of my speakers the positive wire for the tweeter had moved and was touching the ground in the crossover so I wasn't getting any sound from the tweeter; compared to that in an a/b test, the speaker with the resistor removed sounded super aggressive. It was driving me nuts because the soundstage was shifted towards the speaker with the working tweeter. I was messing with placement and toe-in and then finally got out my multi-meter to test my amp channels, that's when I noticed the tweeter. Sounds fabulous now. I stayed up way too late last night listening. They are so much fuller sounding than my old speakers, even when the sub was on. The sub definitely has more bass, but not nearly as good sounding. The NOMEX seem to have more than enough bass without a sub; I built the 40L version. It's not just in the bass though, voices are richer, but clear, and now, I can really hear the body of strings and of instruments; I sound stupid trying to describe sound.
Evan
I actually may have to try tweeter attenuation again, but I will wait a couple weeks. I actually think I had a problem when I was testing with the 18 ohm in and out. On one of my speakers the positive wire for the tweeter had moved and was touching the ground in the crossover so I wasn't getting any sound from the tweeter; compared to that in an a/b test, the speaker with the resistor removed sounded super aggressive
. It was driving me nuts because the soundstage was shifted towards the speaker with the working tweeter. I was messing with placement and toe-in and then finally got out my multi-meter to test my amp channels, that's when I noticed the tweeter. Sounds fabulous now. I stayed up way too late last night listening. They are so much fuller sounding than my old speakers, even when the sub was on. The sub definitely has more bass, but not nearly as good sounding. The NOMEX seem to have more than enough bass without a sub; I built the 40L version. It's not just in the bass though, voices are richer, but clear, and now, I can really hear the body of strings and of instruments; I sound stupid trying to describe sound. Evan
Troels tends to voice his speakers a bit laid back and with higher port tuning which results a bit bass heavy sound. Propably due to his large living room that can/will absorb that bass. And 2.5-way has built-in 6dB baffle step compensation (the whole idea of 0.5 woofer). In smaller rooms that might result in too much bass. I've built his Ellam25 (XT25TG and 2x 15W/8530-K00 in 2.5 alignment, no longer available in his site). With the standard tuning they sound too bass heavy in my living room. I had to stuff the other port (Ellam25 has two port per speaker) resulting lower cabinet tuning. That helped. To get similar result in Nomex164, you might try one of the following: 1) leave the port a bit longer or 2) if you already have shorter port, stuff it with sonofill (or equivalent) or styrofoam. with styrofoam (or felt for that matter) You could also try to just line the port walls 1/4" or 1/2" thick sheet which effectively reduces the airflow resulting in lower tuning.
Troels is a great designer, but his design goals (at least sometimes) tend to value on-axis response rather than power response. Upside is that toe-in has effect on response in sweetspot. downsides of uneven power response on the other hand are non-uniform sound field in the rest of the room. And many others as well. I am not experienced builder/designer so take my comment with grain of salt
Glad to hear others are also interested in Nomex164 build, I have been running circles around it for months as I am evaluating my next build. I acquired the tweeters (D2608/9130) for fair price some time ago and I am trying to find something to build around them. I am in stage "not yet ready for desinging my own" in DIY loudspeakers so I have rely on expertise from more qualified designers/hobbyists
Troels is a great designer, but his design goals (at least sometimes) tend to value on-axis response rather than power response. Upside is that toe-in has effect on response in sweetspot. downsides of uneven power response on the other hand are non-uniform sound field in the rest of the room. And many others as well. I am not experienced builder/designer so take my comment with grain of salt
Glad to hear others are also interested in Nomex164 build, I have been running circles around it for months as I am evaluating my next build. I acquired the tweeters (D2608/9130) for fair price some time ago and I am trying to find something to build around them. I am in stage "not yet ready for desinging my own" in DIY loudspeakers so I have rely on expertise from more qualified designers/hobbyists
Hi, I actually like the tuning on his speakers; that is one on the reasons that I wanted to try out one of his designs. When I changed tweeter attenuation to achieve a flat response (on paper), they sounded really aggressive to me. My goal was to get a speaker that had a lot more body and richness and were not shouting at me. I think these are meeting these goals plus the highs have really opened up and gotten smoother and shimmery after just a few hours. I have a pretty damped room and some speakers really bother my ears, but not these.
I did wonder about power response because he almost never post info about off-axis response, plus he crosses the Nomex pretty high at 3300 and I heard a lot of people complaining about this. I think they sound nice off-axis. I actually think I like them pointed straight out, I tried toeing them in, but I thought the soundstage got smaller and they didn't gain any more accurate imagining, they image well anyways. Plus it led to worse response in the rest of the room.
I cut my vent to 3.75" for a tuning of about 42hz. They are relatively bass heavy,but not in a bad way and I much prefer that to hot in the treble, plus I can fine tune the bass with the port. I have tried stuffing with and without a sub. I like them either unstuffed or just lightly stuffing the one that is nearer to a corner. They do integrate better stuffed and with a sub than my old speakers, I think because the play lower so can cross lower and with less output from the sub.
Sorry for such a long responst
Evan
I did wonder about power response because he almost never post info about off-axis response, plus he crosses the Nomex pretty high at 3300 and I heard a lot of people complaining about this. I think they sound nice off-axis. I actually think I like them pointed straight out, I tried toeing them in, but I thought the soundstage got smaller and they didn't gain any more accurate imagining, they image well anyways. Plus it led to worse response in the rest of the room.
I cut my vent to 3.75" for a tuning of about 42hz. They are relatively bass heavy,but not in a bad way and I much prefer that to hot in the treble, plus I can fine tune the bass with the port. I have tried stuffing with and without a sub. I like them either unstuffed or just lightly stuffing the one that is nearer to a corner. They do integrate better stuffed and with a sub than my old speakers, I think because the play lower so can cross lower and with less output from the sub.
Sorry for such a long responst
Evan
Hi satx,
It would be interresting to make an impedance measurement to check if there is no bad box resonnance and also to check the port tuning.
You can do it with a laptop, REW and and a Jig made as shown in the link below :
Impedance Measurement
It would be interresting to make an impedance measurement to check if there is no bad box resonnance and also to check the port tuning.
You can do it with a laptop, REW and and a Jig made as shown in the link below :
Impedance Measurement
Last edited:
Hi, I'm confused about the impedance measurement diagram. It shows left/right soundcard input. The only inputs I know about are microphone inputs. Mine has 2 microphone inputs plus 5 channel output plus spdif out. Also, it shows the negative speaker terminal to ground. What does this mean? Leave it connected to neg amp of disconnect it or what?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.