Selah Integrity DIY Speaker Kit Review

[goldark]

Good article on what Jeff meant to the community and how his passing was felt all around the world: https://www.washingtonpost.com/nati...g-kidney-failure-he-couldnt-beat-coronavirus/

 

[Rick Sykora]

Very very sad that Jeff Bagby passed away
I had the pleasure of talking with him on speaker design and he was indeed the kindest and most enthousiastic man.
I hope one of his own designs will make it to the testbench here one day.
He was for instance very happy with one of his latest designs the Helios: https://www.facebook.com/groups/462464294109413/post_tags/?post_tag_id=784134678609038
I'm sure that one would test very well here for a 2-way.

Will add Helios to the future list, but it is more than a bit over budget. At $850 for one, unless the membership really wants to fund, will have to settle for the Mandolin I have on order for now.

 

[Kustomize]

Will add Helios to the future list, but it is more than a bit over budget. At $850 for one, unless the membership really wants to fund, will have to settle for the Mandolin I have on order for now.

Can’t wait for the Mandolin! Mandolin 2 MTM have been on my wishlist!

 

[Rick Sykora]

I'm not saying it's definitely a problem, or a problem for all amps, or a problem for all content. But it could be a problem for some amps playing some content at high volume levels.

If it is a problem, you would need a new amp if you plan to use it with any common 2-way vented bookshelf.

Most of them have a very comparable phase dip in the bass just as this speaker does. Fortunately, it usually happens at in narrow range of high impedance and is not much of a concern.

 

[Selah Audio]

There was some speculation on the difference in the response curve versus the Buchardt S400 that exhibits the peak in the midrange. I used the same passive radiator and if you look at the impedance curve both speakers show a tuning right around 40hz. The S400 cabinet does have less internal volume (I'm guessing about .4 cubic ft.) but has no bracing. It may be a difference in the bracing and / or damping material.

I chose the woofer for low bass extension in a compact enclosure and the tradeoff is lower sensitivity. If you compare the response versus other speakers (using woofers of similar size) you'll notice a flat extended tuning with no peaking. The impedance is also reasonable (7 ohms nominal / 5.5 ohms minimum) compared to others like the S400 that dips down to 3 ohms.

 

[Beave]

If it is a problem, you would need a new amp if you plan to use it with any common 2-way vented bookshelf.

Most of them have a very comparable phase dip in the bass just as this speaker does. Fortunately, it usually happens at in narrow range of high impedance and is not much of a concern.

I've seen dozens of speakers that hit -40 to -50 degrees but few that approach -70 degrees. Some B&W models might.

 

[Rick Sykora]

I've seen dozens of speakers that hit -40 to -50 degrees but few that approach -70 degrees. Some B&W models might.

As Amir states in his review post, "Impedance is around 5.5 ohm which is higher (better) than typical small speaker". I have measured fewer speakers than Amir, but I concur. Plus or minus 45 degrees is considered worst case, so your statement means that dozens of speakers are just as bad (or worse) than this one.

 

[Beave]

As Amir states in his review post, "Impedance is around 5.5 ohm which is higher (better) than typical small speaker". I have measured fewer speaker than Amir, but I concur. Plus or minus 45 degrees is considered worst case, so your statement means that dozens of speakers are just as bad (or worse) than this one.

Do those other speakers (with lower impedance magnitude) also have the low sensitivity of this speaker?

When assessing the difficulty of a loudspeaker load, the sensitivity, the impedance magnitude, and the impedance phase all play a role.

If "plus or minus 45 degrees is considered worst case," but this one goes to nearly minus 70, then I'm not sure how you deduce that "dozens of speakers are just as bad (or worse) than this one."

 

[Rick Sykora]

Do those other speakers (with lower impedance magnitude) also have the low sensitivity of this speaker?

When assessing the difficulty of a loudspeaker load, the sensitivity, the impedance magnitude, and the impedance phase all play a role.

If "plus or minus 45 degrees is considered worst case," but this one goes to nearly minus 70, then I'm not sure how you deduce that "dozens of speakers are just as bad (or worse) than this one."

Agree that the loading is dependent on the impedance and phase angle. Sensitivity does play a role, but so then does room size and listening levels.

Sensitivity is often not all that high with small woofers in any case. Music is dynamic and singling out one dip in the overall load is nitpicking IMO. Notably, since the segment has comparable characteristics (small. vented designs with low impedance woofers and negative phase swings in the bass region), they are likely to present comparable loads to amplifiers. Context is important here, so not sure what your samples are, but I looked at my own data and the ASR measurements for small, vented speakers.

Btw, worst case amp load being +/- 45 degrees is not from me, but from Rod Elliott (and others). See here: https://sound-au.com/patd.htm#s11

 

[Chrispy]

@amirm Forgive me if already provided, but what are these "speaker killer" bass tracks?

 

[amirm]

@amirm Forgive me if already provided, but what are these "speaker killer" bass tracks?

I post a couple of them earlier: https://www.audiosciencereview.com/...rity-diy-speaker-kit-review.15695/post-501087

I have a third one but is not in that playlist.

 

[restorer-john]

Apologies for nit-picking, but the terminology should be sub-bass, not subsonic bass. Subsonic generally refers to the speed of sound, ie, being below the speed of sound, not the frequency of sound. (The terms subsonic has also been used to describe sounds below the threshold of hearing - but in amplitude, not frequency. However, I don't see this in any 'official' definitions, so it may be an incorrect usage.)

One could also use infrasonic bass, but that's generally reserved for frequencies below 20Hz.

Yep, it's totally nitpicking.

Most amplifiers and preamplifiers labeled the switchable filters as a Subsonic filter. A few (NAD) called them Infrasonic filters. I don't have a problem with it, we all know what it means. Sub as a prefix means under. Under what we hear. Infra means below. Below what we hear.

 

[restorer-john]

I have a third one but is not in that playlist.

Ah, I know that one! Amir's low level resolution test- AKA, The Speaker Killer.

-80dBFS 1KHz tone you have to turn right up, with a secret 19KHz 0dBFS tone to take out the tweeters without hearing anything. Then while the listener is scratching his head and wondering why his tweeters are smoking, a 15Hz 0dBFS tone to kill the woofers.

 

[BostonJack]

I've been wanting to try my hand at some curved pieces. Anyone have any idea how they made the front left and right piece? Is it gentle enough that one can form some plywood with soaking and time or is it just easier to kerf it? Or maybe just some other technique I am not aware of?

I'm guessing, but I believe that the top facet is a flat piece that could be done on a table saw (would require epoxied pieces to build out behind the baffle). If I were doing the side curved pieces, I would do two straight angled cuts, draw the curve with a template and then shape with a belt sander. Maybe use a template in some hardwood as a guide (or even Al plate). This would require some finesse.

A really clever person might just CNC that part.

I am Jonsing to build this speaker.

 

[Beave]

Agree that the loading is dependent on the impedance and phase angle. Sensitivity does play a role, but so then does room size and listening levels.

Sensitivity is often not all that high with small woofers in any case. Music is dynamic and singling out one dip in the overall load is nitpicking IMO. Notably, since the segment has comparable characteristics (small. vented designs with low impedance woofers and negative phase swings in the bass region), they are likely to present comparable loads to amplifiers. Context is important here, so not sure what your samples are, but I looked at my own data and the ASR measurements for small, vented speakers.

Btw, worst case amp load being +/- 45 degrees is not from me, but from Rod Elliott (and others). See here: https://sound-au.com/patd.htm#s11

But isn't that what we do here (nitpicking, singling out small measurable issues)? I mean, we argue over little frequency response variations, small regions of increased THD, relatively small directivity mismatches, etc. Why not point out similarly small issues in the impedance plots?

I still don't understand your reference to 'worst case amp load being +/- 45 degrees' or your referenced link. +/-45 degrees is probably typical for a small two-way, not worst-case. This speaker is worse than +/-45 degrees, although it's ameloriated by the magnitude being around 5-6 Ohms where the phase is so low.

 

[Beave]

Yep, it's totally nitpicking.

Most amplifiers and preamplifiers labeled the switchable filters as a Subsonic filter. A few (NAD) called them Infrasonic filters. I don't have a problem with it, we all know what it means. Sub as a prefix means under. Under what we hear. Infra means below. Below what we hear.

I remember my brother having a receiver with a subsonic filter. Probably wrong terminology then, and wrong now.

Subsonic is below the speed of sound. Supersonic is above the speed of sound.

Infrasonic is below, but in frequency. Ultrasonic is above, in frequency. Think infrared and ultraviolet - they're referring to frequency.

Yes, I know it's nitpicking. I had an audio professor who pointed out the common misuse and insisted we use it correctly.

 

[richard12511]

I post a couple of them earlier: https://www.audiosciencereview.com/...rity-diy-speaker-kit-review.15695/post-501087

I have a third one but is not in that playlist.

How about this organ piece? Someone else shared it a few days ago, and I had some fun with it. Might have to turn it up a bit, but be careful. Low note is at the very end.

 

[amirm]

How about this organ piece? Someone else shared it a few days ago, and I had some fun with it. Might have to turn it up a bit, but be careful. Low note is at the very end.

THat link doesn't work for me. Even if it did, I need a track I can play in Tidal, not youtube stream if that is what it was.

 

[Trouble Maker]

Ah, I know that one! Amir's low level resolution test- AKA, The Speaker Killer.

-80dBFS 1KHz tone you have to turn right up, with a secret 19KHz 0dBFS tone to take out the tweeters without hearing anything. Then while the listener is scratching his head and wondering why his tweeters are smoking, a 15Hz 0dBFS tone to kill the woofers.

Change out the 15Hz for something in the 5-9Hz range to add injury to insult.

 

[restorer-john]

Yes, I know it's nitpicking.

This has to be the cutest nit-picking.