Advent modification

[wank]

Wow, this has been a fun read. Two measurement-philes going at it, and unable to agree. While in other areas of life, I lean strongly to the objectivist viewpoint, in speakers I lean to the subjectivist (I've said many many times "If you like the way it sounds, then it sounds good." This is true because the response curves of ears vary widely). This thread seems to vindicate that concept.

Incidentally, I guess I committed a hit-n-run, but I left for the holiday after my comment about Zilch. I suppose it would be more accurate to say that Zilch doesn't like nearly any speaker he hasn't measured and tweaked with a horn.

Also - Zilch, this is by far the most politic thing I've ever seen you post, and I commend you for it:

I have not yet discovered any exploitable benefit to stacking.

Struck me as funny as hell.

 

[NOHDjunkie]

Pete,

I'd be interested in your thoughts of the NLA's as I will be getting a pair at the end of the month.

You say they are "different". How? better, worse, the same but different? Just curious. I've haven't heard the LA's nor the NLA's.

Same goes for Zilch. I'd also like to hear your thoughts on them if you have any.

 

[markus]

Wow, this has been a fun read. Two measurement-philes going at it, and unable to agree. While in other areas of life, I lean strongly to the objectivist viewpoint, in speakers I lean to the subjectivist (I've said many many times "If you like the way it sounds, then it sounds good." This is true because the response curves of ears vary widely). This thread seems to vindicate that concept.

YES . . . you said it . . . "the response curves of ears vary widely" . . . measurements can level the playing field only so much. Sure, they allow you to quantify the physics of what that speaker is doing, but when it comes down to it, it's PSYCHOACOUSTICS . . what do you hear ? what do I hear ? don't get me started on system synergy

so many variables . . . . all we can do make incremental improvements towards the perceived perfect system . . ..

and to close, another (wank) quote : "If you like the way it sounds, then it sounds good" :yes:

 

[Pete B]

Pete,

I'd be interested in your thoughts of the NLA's as I will be getting a pair at the end of the month.

You say they are "different". How? better, worse, the same but different? Just curious. I've haven't heard the LA's nor the NLA's.

Same goes for Zilch. I'd also like to hear your thoughts on them if you have any.

The woofers, while modernized, perform the same as the originals.
The OLA tweeter rolls off fast above about 15 KHz, partly due to the moving mass. The NLA tweeter uses ferro fluid which allows for a shorter, and lighter voice coil, so that the high end is more extended. However, the ferro fluid seems to be the old thick type where the viscosity changes strongly with temperature. The tweeters sometimes need to be warmed up to bring them into spec, or perhaps I had some defective samples. The tweeter has a different voice coil that provides a lower impedance so that they could make it even hotter sounding than the OLA.

I've A/Bed the two and the OLA on extended is close to the NLA in the normal position. The ferro fluid tweeter with a higher Fs allowed them to simplify the crossover with it being simply first order in the NLA. I felt that the woofer and tweeter were not as well integrated as compared to the OLA in A/B listening tests, but it was a subtle difference that probably would not be noticed without an A/B comparison.

The NLA dips to about 3 ohms in the tweeter range in the Extended position and should not be used in parallel pairs unless your amp can drive 1.5 ohm loads. It is about 6 ohms in the decrease position.

I'd listen to the NLAs with the switch in the decrease position if you do not use BSC. Normal if you do use BSC, or experiment to your liking.

Pete B.

 

[Pete B]

YES . . . you said it . . . "the response curves of ears vary widely" . . . measurements can level the playing field only so much. Sure, they allow you to quantify the physics of what that speaker is doing, but when it comes down to it, it's PSYCHOACOUSTICS . . what do you hear ? what do I hear ? don't get me started on system synergy

so many variables . . . . all we can do make incremental improvements towards the perceived perfect system . . ..

and to close, another (wank) quote : "If you like the way it sounds, then it sounds good" :yes:

Even if our hearing is different, we've all adapted to our hearing response and if the system produces a reasonable approximation to the original event then it will sound real to all people. I find that others usually hear the same flaws that I do.

I actually read that Dyslexics have more sensitive hearing in that they are particularly annoyed or jumpy with loud sounds. Perhaps they're more sensitive in other ways also.

Pete B.

 

[markus]

I'd listen to the NLAs with the switch in the decrease position if you do not use BSC. Normal if you do use BSC, or experiment to your liking.

Pete B.

I've bypassed the factory crossover in my refoamed OLA's, using just a simple 1st order x-over for the tweeter, 16uf of vintage oil cap goodness . . .

sounds really nice. . . . I'd be interested to see what a little BSC would do :scratch2:

 

[Zilch]

I'm not familiar with the CLIO mic, do you know if it is a Panasonic capsule?
I believe that JA uses Mightly Mic which is a Panasonic. It does have some distortion issues at high SPL.

For nearfield, you crank down the SPL. Most common measurement mics are 120 dB SPL max, as I recall.

CLIO protests when you've exceeded the SPL limit.

I've been wanting to set up to try Small's in-box protocol. I can't do outdoors here (urban,) and I don't have big space to do groundplane indoors....

 

[Zilch]

Wow, this has been a fun read. Two measurement-philes going at it, and unable to agree. While in other areas of life, I lean strongly to the objectivist viewpoint, in speakers I lean to the subjectivist (I've said many many times "If you like the way it sounds, then it sounds good." This is true because the response curves of ears vary widely). This thread seems to vindicate that concept.

Naw, Pete and I are debating what IS is, not how it sounds.

Under controlled conditions and given a range of choices, listener preferences are remarkably uniform, and correlate well with measurements.

Generally, if it measures poorly, it also scores poorly with listeners, but good measurements are no guarantee of sonic quality. Speakers can measure well and still sound terrible -- it's the objectivists' job to figure out why. :thmbsp:

 

[archie2]

"I felt that the woofer and tweeter were not as well integrated as compared to the OLA in A/B listening tests, but it was a subtle difference that probably would not be noticed without an A/B comparison." Quote from Pete.

I have 2 pairs of OLA's and 1 pair of NLA, all three pairs have been refoamed and recapped. At one point I stacked the OLA's with the NLA's so not only could I hear mixed stacked Advents, I could A B them. I found the NLA's to be a bit on the harsh side and had less bass. They did reach higher than the OLA's but to my ears it made them sound shrill in comparison. The OLA's are smoother, less fatiguing and are my preferred Large Advent. This surprised me because all the professional reviews gave the NLA's superior marks over the OLA's. Of course the new polyfilm caps may have had something to do with it plus the fact that all my tonal switches don't work in all positions on both sets. They all work in the extended position which is where I A B ed them.

 

[Pete B]

For nearfield, you crank down the SPL. Most common measurement mics are 120 dB SPL max, as I recall.

CLIO protests when you've exceeded the SPL limit.

I've been wanting to set up to try Small's in-box protocol. I can't do outdoors here (urban,) and I don't have big space to do groundplane indoors....

Just noticed this, you changed the stuffing to fiberglass and got very reasonable nearfield woofer results, however you used sinusoidal as compared to MLS methods with the foam stuffing. I have measured Qtc and Fc for both foam and fiberglass and was surprised to find very little difference. I believe that there is an error in your MLS measurement, and also with JA's at Stereophile:
http://www.audiokarma.org/forums/showpost.php?p=1934896&postcount=52

The small rise is expected due to Qtc being greater than .707 and that this is measured through the woofer crossover. People should remember that nearfiled measurements are not valid above 300 Hz or so for a woofer this size.

Pete B.

 

[archie2]

I built Pete's BSC circuit and I'm not sure how to take it. My OLA's are about 8 feet apart on 10 inch stands and a foot and 1/2 from the back wall toed in toward the listener some 14 feet away. From what I'm hearing the BSC is pulling the sound toward the center, sort of condensing it. The speakers do indeed "disappear" to a greater extent but there is no extension of sound behind and in front of the Advents in the slightest. Also the Advents sound a bit muted as if the highs were taken down. I haven't listened to them long enough to see if there is a difference in actual pin pointing of the instruments. Pete, here's a picture, not the neatest job but I made sure no wires are touching where they aren't supposed to.

 

[Pete B]

I built Pete's BSC circuit and I'm not sure how to take it. My OLA's are about 8 feet apart on 10 inch stands and a foot and 1/2 from the back wall toed in toward the listener some 14 feet away. From what I'm hearing the BSC is pulling the sound toward the center, sort of condensing it. The speakers do indeed "disappear" to a greater extent but there is no extension of sound behind and in front of the Advents in the slightest. Also the Advents sound a bit muted as if the highs were taken down. I haven't listened to them long enough to see if there is a difference in actual pin pointing of the instruments. Pete, I can post pics to see if I've wired everything correctly.

Sure that's fine if you'd like to post pictures.

Interesting that you say it brings the sound in toward the center, is this for vocalists or lead instruments which should not extend from speaker to speaker. I would agree that it brings the soundstage into focus, in a good way.

Let me also say please listen to at least 10 high quality cuts that you're familiar with, and give it time. You've probably gotten used to the Advent sound, and perhaps you *will* want to go back to it but for me it is the opposite, once I heard it I would never go back.

Do you have the speakers on extended?

Be sure to use them with the grilles on.

How much power do you have, and SS or tube? What model pre and power amps?

Please also try them without toe in, or with very little. I find that many systems image much better *without* toe in.

Pete B.

 

[archie2]

Pics posted in edited above post.

 

[archie2]

Sure that's fine if you'd like to post pictures.

Interesting that you say it brings the sound in toward the center, is this for vocalists or lead instruments which should not extend from speaker to speaker. I would agree that it brings the soundstage into focus, in a good way.

Let me also say please listen to at least 10 high quality cuts that you're familiar with, and give it time. You've probably gotten used to the Advent sound, and perhaps you *will* want to go back to it but for me it is the opposite, once I heard it I would never go back.

Do you have the speakers on extended?

Be sure to use them with the grilles on.

How much power do you have, and SS or tube? What model pre and power amps?

Please also try them without toe in, or with very little. I find that many systems image much better *without* toe in.

Pete B.

I'll follow your suggestions re: placement. I have the OLA's switch extended and with grills on. I'm driving them with a SS Yamaha CR 2020, 105 WPC.
I'll also try various music renditions and give it time. Thanks.

http://www.audiokarma.org/forums/attachment.php?attachmentid=98580&d=1215566882

 

[justw]

Generally, if it measures poorly, it also scores poorly with listeners, but good measurements are no guarantee of sonic quality. Speakers can measure well and still sound terrible -- it's the objectivists' job to figure out why. :thmbsp:

Well said!

 

[archie2]

Heh, I just looked at my pic. What a rat's nest. But it does work and as sloppy as it looks there is no contact where contact should not be.

 

[Pete B]

I'll follow your suggestions re: placement. I have the OLA's switch extended and with grills on. I'm driving them with a SS Yamaha CR 2020, 105 WPC.
I'll also try various music renditions and give it time. Thanks.

http://www.audiokarma.org/forums/attachment.php?attachmentid=98580&d=1215566882

Your build looks fine, however the disk cap is a ceramic. CGO and NPO ceramic types are fine whereas Z5U and X7R are not. That is probably a Z5U as they are more common, perhaps someone else can comment as to what RS stocks for their disk caps. You can read more here on page 8, Figure 2: http://www.johnhardyco.com/pdf/990-2007.pdf
A mylar cap is fine; I believe RS stocks mylar types of that value.

Pete B.

 

[archie2]

Your build looks fine, however the disk cap is a ceramic. CGO and NPO ceramic types are fine whereas Z5U and X7R are not. That is probably a Z5U as they are more common, perhaps someone else can comment as to what RS stocks for their disk caps. You can read more here on page 8, Figure 2: http://www.johnhardyco.com/pdf/990-2007.pdf
A mylar cap is fine; I believe RS stocks mylar types of that value.

Pete B.

Don't see any .0047uF mylar caps in RS inventory. They do have .01uF mylar caps though. I can wire 2 of those in series.

 

[Zilch]

Look, I am not on trial here, I said this was a casual experiment, and I gave a table of values for 1 to 6 dB of compensation clearly recognizing that all rooms are not the same.

You have framed your challenge for me to provide my ideal compensation curve when I have clearly stated that it will depend on the room and placement. I do not know the ideal curve for your or anyone elses room, obviously.

Cool. So post the Bode plot of your FAMILY of BSC transfer functions, then.... :yes:

I'm planning to do a more complete web page on the LAs and I might do some SPL measurements for it, however this will be as time permits.

That'd be good, but we'd probably rather see them now, please.... :thmbsp:

Just noticed this, you changed the stuffing to fiberglass and got very reasonable nearfield woofer results, however you used sinusoidal as compared to MLS methods with the foam stuffing. I have measured Qtc and Fc for both foam and fiberglass and was surprised to find very little difference. I believe that there is an error in your MLS measurement, and also with JA's at Stereophile:
http://www.audiokarma.org/forums/showpost.php?p=1934896&postcount=52

The small rise is expected due to Qtc being greater than .707 and that this is measured through the woofer crossover.

The stock filter's already generous BSC is doing it, actually. See below.

People should remember that nearfiled measurements are not valid above 300 Hz or so for a woofer this size.

Your references Keele and D'Appolito say different, but I would agree, in general. In any case, I've rolled all of these measurements off 24 dB/octave at ~1.5 kHz for the sake of clarity. Red is stock OLA in all cases, and it doesn't matter how I measure it, the results are the same. NLA has the fiberglass which provides ~2 db more damping than the OLA foam at the peak:

Edit: "NLA" in the legend is actually LA cabinet, NOT NLA.

 

[Pete B]

Just noticed this, you changed the stuffing to fiberglass and got very reasonable nearfield woofer results, however you used sinusoidal as compared to MLS methods with the foam stuffing. I have measured Qtc and Fc for both foam and fiberglass and was surprised to find very little difference. I believe that there is an error in your MLS measurement, and also with JA's at Stereophile:
http://www.audiokarma.org/forums/showpost.php?p=1934896&postcount=52

The small rise is expected due to Qtc being greater than .707 and that this is measured through the woofer crossover. People should remember that nearfiled measurements are not valid above 300 Hz or so for a woofer this size.

Pete B.

Bump, How do you explain the drastic differences in your previous comparison?