Advent modification

[Zilch]

Bump

Bump WHAT?

The "very reasonable" measurements I got were because there was NO FILTER. Without one, the alignment conforms to theory rather nicely. Once connected to the crossover, the stock BSC kicks in to produce the results you have deemed dubious here.... :yes:

 

[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.

Yes series is fine.

 

[Pete B]

Bump what?

The "very reasonable measurements" I got were because there was NO FILTER. Without one, the alignment conforms to theory rather nicely. Once connected to the crossover, the stock BSC kicks in to produce the results you have deemed dubious here.... :yes:

And the curve for foam fill previously mentioned included the crossover then? You need to state your conditions more clearly.

 

[Zilch]

And the foam curve previously mentioned included the crossover then? You need to state your conditions more clearly.

That's BS. Read the thread. How could I possibly illustrate what I did there without the filter being included?

Further, you assert that additional BSC is required over and above what is provided stock (which you claim is "none,") even with boundary reinforcement, and I believe I've seen at least two citations now where your findings have all been derived using the stock crossover; you just repeated that twice immediately above here.... :yes:

 

[Pete B]

That's BS. Read the thread. How could I possibly illustrate what I did there without the filter being included?

Further, you assert that additional BSC is required over and above what is provided stock (which you claim is "none,") even with boundary reinforcement, and I believe I've seen at least two citations now where your findings have all been derived using the stock crossover; you just repeated that twice immediately above here.... :yes:

Calm down dude with your claim of BS.
You stated:"The "very reasonable measurements" I got were because there was NO FILTER."
Then above you state: "That's BS. Read the thread. How could I possibly illustrate what I did there without the filter being included?"
So which one is it?
Is this through the crossover or not: http://audiokarma.org/forums/attachment.php?attachmentid=94451&d=1213056841
I'm asking is the curve for foam filling linked in that post also without the filter? Again, your conditions are not clearly stated so it is difficult to make sense of your measurements.

 

[Pete B]

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.

Zilch, can't believe I'm talking to a guy by this name here, LOL!

I answered your demand already, have some respect for my position and stop harassing me. Do you understand, as time permits? It is about as low on my priority list as it gets. I'm not a curve junky like you.

Pete B.

 

[Pete B]

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:

You've got some interesting Advents there. The OLA most often had fiberglass, yours has foam as I read you above? The NLA, always, as far as I've seen, had foam, yours has fiberglass. Are you actually comparing NLAs to OLAs?

Are these measurements through the crossovers?

Pete B.

 

[Zilch]

I'm asking is the curve for foam filling linked in that post also without the filter? Again, your conditions are not clearly stated so it is difficult to make sense of your measurements.

It is through the filter. You can see the three HF attenuation settings shown there for both units measured.

It makes sense if you read the thread, but more significantly, it's central to your BSC thesis that the presence of the stock filter is irrelevant, and I have just expended several hours here re-measuring to demonstrate that NOT to be the case. Let's see your measurements posted here, Pete, and we can have a rational discussion of our comparative findings. Have you ever done a nearfield measurement? Have you ever measured an Advent woofer without the filter? In fact, have you ever measured an Advent anything, or is your whole "passing interest" BSC project formulated around an interpretation of the CBS Labs curves?

I'm not on a crusade to discredit you or your work, Pete, but when you come to this thread and assert that Atkinson's and my findings are bogus without reasonable objective evidence to the contrary, I'm given to wonder if the basis isn't merely that they conflict with your beliefs.

If your position were that there is not enough BSC in the stock Advents for them to sound good in free space, that might be rational, subject to verification and personal preferences, but further supposition that there is "magic" here is, well, a bit of a stretch....

 

[Zilch]

You've got some interesting Advents there. The OLA most often had fiberglass, yours has foam as I read you above? The NLA, always, as far as I've seen, had foam, yours has fiberglass. Are you actually comparing NLAs to OLAs?

The OLAs have stock foam. The NLA [LA, actually,] boxes had stock foam, and are shown early in the thread. I removed the foam in the NLA [LA] cabs and installed the fiberglass as described in the post.

Are these measurements through the crossovers?

Today's measurements? Yes, except for the Cyan, which is the woofer only in the NLA [LA] cabinet with fiberglass.

Interestingly, it would seem that it would play flat in 2-Pi alignment with no filter, and thus would require BSC in freespace, not only to restore the bass, but also to balance with the tweeter. We have at least one member here who has bypassed the lowpass filter entirely like this. I put in the filter, and it plays just like the stock OLA, except ~2 dB damped at the peak, presumably because of the fiberglass.

The question is whether the stock filter provides enough BSC for use in freespace, largely irrespective of whether the damping is foam or fiberglass, and I suggested earlier in this thread, that would depend upon whether one wanted to retain the equivalent of boundary-augmented bass in that alignment.... :yes:

 

[Pete B]

It is through the filter. You can see the three HF attenuation settings shown there for both units measured.

It makes sense if you read the thread, but more significantly, it's central to your BSC thesis that the presence of the stock filter is irrelevant, and I have just expended several hours here re-measuring to demonstrate that NOT to be the case. Let's see your measurements posted here, Pete, and we can have a rational discussion of our comparative findings. Have you ever done a nearfield measurement? Have you ever measured an Advent woofer without the filter? In fact, have you ever measured an Advent anything, or is your whole "passing interest" BSC project founded in an interpretation of the CBS Labs curves?

I'm not on a crusade to discredit your work, Pete, but when you come to this thread and assert that Atkinson's and my findings are bogus without reasonable objective evidence to the contrary, I'm given to wonder if the basis isn't merely that they conflict with your beliefs.

If your position were that there is not enough BSC in the stock Advents for them to sound good in free space, that might be rational, subject to verification and personal preferences, but further supposition that there is "magic" here is, well, a bit of a stretch....

Look at the date of my posts concerning JA's work at the Classic Speaker Pages - nothing to do with your assertions, so drop the assumptions and accusations. Stop trying to guess what work I've done or not done. You do come across as on a crusade, making demands left and right. I've noted that some people don't seem to get nearfield measurments right and you seem to be one of them, but refuse to look at the facts. I've been doing nearfield woofer measurments for over 25 years, yes I know how to do it. I've stated repeatedly, I'm not addicted to curves as you are. I have no interest in debating with a guy who slaps out messy curves right and left.

You tell me to read your thread, go read mine and find the bode curve, it's really very simple. And don't forget that I offered 1 to 6 dB as options when you try to prove that it can't work. The fact is that you have ignored my points about the complexity of the in room response. Yes some say that in room is actually as bad as anechoic, due to destructive interference with the room boundaries. I've said this several times and you repeatdly miss it on your mission to prove what exactly? I don't know? Oh yes, that you are never wrong. Again, I trust T&S theory, CBS labs, Keele, but not work by a trolling internet junkie going by Zilch. I really believe that you are BSing at this point in desperation. The change from foam to fiberglass is really very small, yet you state that you fixed the boom with fiberglass. There was no boom, you heard the (incorrect) curve that you measured, LOL!

You don't set my priorities, so back off.

 

[archie2]

The OLAs have stock foam. The NLA boxes had stock foam, and are shown early in the thread. I removed the foam in the NLA cabs and installed the fiberglass as described in the post.

Today's measurements? Yes, except for the Cyan, which is the woofer only in the NLA cabinet with fiberglass.

Interestingly, it would seem that it would play flat in 2-Pi alignment with no filter, and thus would require BSC in freespace. We have at least one member here who has bypassed the lowpass filter entirely like this. I put in the filter, and it plays just like the stock OLA, except ~2 dB damped at the peak, presumably because of the fiberglass.

The question is whether the stock filter provides enough BSC for use in freespace, largely irrespective of whether the damping is foam or fiberglass, and I suggested earlier in this thread, that would depend upon whether one wanted to retain the equivalent of boundary-augmented bass in that alignment.... :yes:

Both my OLA's have stock fiberglass and my NLA's have stock foam.

 

[Pete B]

The OLAs have stock foam. The NLA boxes had stock foam, and are shown early in the thread. I removed the foam in the NLA cabs and installed the fiberglass as described in the post.

Today's measurements? Yes, except for the Cyan, which is the woofer only in the NLA cabinet with fiberglass.

Interestingly, it would seem that it would play flat in 2-Pi alignment with no filter, and thus would require BSC in freespace. We have at least one member here who has bypassed the lowpass filter entirely like this. I put in the filter, and it plays just like the stock OLA, except ~2 dB damped at the peak, presumably because of the fiberglass.

The question is whether the stock filter provides enough BSC for use in freespace, largely irrespective of whether the damping is foam or fiberglass, and I suggested earlier in this thread, that would depend upon whether one wanted to retain the equivalent of boundary-augmented bass in that alignment.... :yes:

The OLA and NLA have completely different values for woofer inductors so again, you leap to the conclusion that the difference is the filling material, ignoring the XO differences. The inductor is even bypassed in the extended position in the NLA, not in the OLA. See my crossover page if you want the values and crossover schematics.

 

[Pete B]

Zilch, everytime I make a valid point such as in the previous post, you throw up a smoke screen with new curves or long winded responses. I'm tired of reading you. The reason I don't post my measurments here is that I have no interest in a pissing contest with you, or any other internet troll. Believe me, I have much more interesting projects, LOL!
And the data I have is on my other computer. They were all done quickly as I did not plan to publish them, I might actually redo them if I ever even bother to publish them. It is time consuming to do it right and I don't like to do a half ass job.

I actually did fairly extensive measurements with different fill materials, Advent foam, fiberglass, wool, poly stuffing, then with all the trolls that come on the net I never published the data, why bother to waste my time explaining? I wasted enough with the BSC, and AR discussions.

 

[Zilch]

The OLA and NLA have completely different values for woofer inductors so again, you leap to the conclusion that the difference is the filling material, ignoring the XO differences. The inductor is even bypassed in the extended position in the NLA, not in the OLA. See my crossover page if you want the values and crossover schematics.

Look again, dood. I specified Rev2 filter right in the legends of all three of today's curves. These are all the original Masonite-surround woofers. Read the thread.

I'm sometimes ignorant; stupid, even, but neither as a matter of policy.

It'll take all of 15 minutes for someone with your vast experience and skill to do an accurate nearfield measurement and post it for AKers to compare.

Who knows? Perhaps there are discoveries to be made here.... :

You are correct that nearfield measurements represent the driver performance into a 2-pi position, however, T&S theory also represents 2-pi performance. So how do you explain the significant peaking, when theory suggests only 1 dB or so? Yes, the CBS measurements suggest no BSC compensation and agree fairly well with the theory, however your nearfield measurment suggests that there is BSC (actually overcompensated) .... something is not right with your measurements, IMO. The CBS measurements look reasonable.

This is real simple:

1) Measure the Advent woofer with no filter. It conforms with theory. It also plays nearly flat when measured nearfield, 2-Pi.

2) Connect the Rev2 filter, and it's plain as day what happens: there is BSC in the crossover.

3) Gobs of it.

4) T&S theory does NOT include a filter. :nono:

5) CBS is 4-Pi

http://audiokarma.org/forums/attachment.php?attachmentid=98592&d=1215573003

 

[wiredbecker]

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.

More accurate but not entirely true. We've measured and listened to a number of hornless speakers from my collection which faired well. Specific models in order of best sound and flattest curves include but are not limited to:

1. B & W DM305 towers (fully stock garage sale find)
2. Polk Monitor 5As! (surprisingly good and often available for cheap)
3. Dynaco A25 (with replaced crossover cap)
4. Baby Advent (had a huge valley in the mid if I remember correctly but still quite nice for cheap)

Horns can sound great. I don't blame him for preferring his own amazing DIY speakers.

Am I forgetting any here Zilch?

 

[Zilch]

Am I forgetting any here Zilch?

Those are the ones I remember.

We should be taking names.

And pics, probably.

[There's Heresys in our future, I am told.... ]

 

[Pete B]

Look again, dood. I specified Rev2 filter right in the legends of all three of today's curves. These are all the original Masonite-surround woofers. Read the thread.

http://audiokarma.org/forums/attachment.php?attachmentid=98592&d=1215573003

NLAs never had Masonite woofers, and they never had Rev2 filters, so WTF are you talking about when calling them NLAs? Also, you cannot put a masonite woofer in a NLA box without cutting. As I said I'm (almost) done reading you.

 

[Pete B]

2) Connect the Rev2 filter, and it's plain as day what happens: there is BSC in the crossover.

3) Gobs of it.

4) T&S theory does NOT include a filter. :nono:

5) CBS is 4-Pi

http://audiokarma.org/forums/attachment.php?attachmentid=98592&d=1215573003

I pointed out that there would be differences with and without the woofer XO, and you've latched on to this and used it as an out for your erroneous measurments.

You say there's "Gobs" of BSC, wrong again Zilch, no way there's anywhere near 8 dB to explain the 10 dB peak in your "with filter" curve. I pointed out that one of your measurements was MLS and the other Sinusoildal, your welcome for my taking the time to find your error, no charge dood. But you cannot admit it and are now using the crossover as an excuse. The amplitude of the difference cannot be explained by the crossover, indeed the NLA even has it shorted out in extended, and if you did measure with and without then your claim of "fixing" the "boom" would be BS. So which time were you BSing Zilch? I'm done, wasted enough time with an internet troll. Don't wave your dumb ass internet finger at me, WTF you think you're the teacher, LOL!

 

[Pete B]

Alternatives to stacked Advents

There is a valid advantage to stacked Advents and that is headroom, and increased efficiency. I can easily bottom single Advents with bass heavy material.

An alternative to the traditional stack would be to wire the second box in such a way as to make the pair a 2.5 system where the second woofer is used for BSC. Only one tweeter would be used. This arrangement is less critical of placement of the second system, still the second woofer should be close to the woofer in the main pair.

I've not done any work on this, but it was something I wanted to discuss before this thread turned into speakers according to zilch.

Pete B.

 

[Zilch]

NLAs never had Masonite woofers, and they never had Rev2 filters, so WTF are you talking about when calling them NLAs? Also, you cannot put a masonite woofer in a NLA box without cutting. As I said I'm (almost) done reading you.

Another easy one. They are LAs, not NLAs. See post #1 of my Advent thread here:

http://audiokarma.org/forums/showthread.php?t=165025

What the boxes are is irrelevant to the issue of BSC. They had stock foam in them, just like the OLAs I compared them to. I took it out of these LAs and put fiberglass in them, as described in the thread. It reduced the boominess. Running them active WITHOUT the stock filter reduced it substantially more, clearly indicating that there is BSC in the Advents, contrary to your belief, enough for them to measure "underdamped" nearfield, 2-Pi, just as Stereophile reported for the Smaller Advents.

I pointed out that there would be differences with and without the woofer XO, and you've latched on to this and used it as an out for your erroneous measurments.

You say there's "Gobs" of BSC, wrong again Zilch, no way there's anywhere near 8 dB to explain the 10 dB peak in your "with filter" curve.

And yet another easy one, Pete: put a 1.6 mH inductor in Spice (you claim to be well familiar with it,) and what does it do? How much BSC does it provide between 100 Hz and 1 kHz?

I pointed out that one of your measurements was MLS and the other Sinusoildal, your welcome for my taking the time to find your error, no charge dood. But you cannot admit it and are now using the crossover as an excuse.

At your urging, I re-measured using MLS, Sinusoidal, and RTA and posted the results @ #79 for you. They are substantially the same, no matter the method. There is no measurement methodology error.

http://audiokarma.org/forums/showthread.php?p=1977297#post1977297

It'd be good if you posted something other than gratuitous blather in support of your claims here. :yes:

The amplitude of the difference cannot be explained by the crossover, indeed the NLA even has it shorted out in extended....

See above. NLA used a different woofer and a different inductor. Presumably, the system low-frequency response is the same, based upon what is written here and elsewhere. I say "presumably," because I don't yet see that anyone have ever measured them. Perhaps YOU can be the first. :thmbsp:

... and if you did measure with and without then your claim of "fixing" the "boom" would be BS.

Again, read the thread. I am "fixing" the Large Advents there. The first thing that went was tweeter. The second thing was the crossover, and the "boom" went with it, all but gone, as I have shown. They are no longer Advents, alas.... ity: