Bose cube replacement question. - Page 4

What you say that you measured is not possible; you might just as well be claiming that your 901s double as cold fusion reactors.

Bose doesn't like to publish that either because it could confuse customers.

Well, obviously it is possible because that's what I measured. I told you what I measured, exactly how I measured it, and the tools I used. What more do you need?

If I told you I was able to fly, told you how fast I flapped my arms, how I jump and off of what...would you just accept that I am able to fly? I have seen posted freq reponses of the 901, in professional rooms...and FLAT, they are not! bell curve like without much low or high is what they look like...

Yes. You're a hawk.

And how could you possibly know that? What? Do you work for Bose and do customer support, talking to Bose 901 customers all the time, advising them on how to hang their speakers from the ceiling? LOL

It would probably be more productive if the discussion concerning the 901s were moved over to the other thread on this page devoted to the 901s.

Putting that aside, if someone questions the frequency response measurements done by dat56, wouldn't it be more profitable for that person, or someone else on this forum, to do his own measurements and report back?, Then we have a basis for judgment. Otherwise we only have conversation.

What's interesting about dat56's measurements is that they show a real drop-off above 12,500 Hz. In fact they are 5 DB down at that frequency. Doesn't this conform to some of the complaints that people have about the 901s...... that the 4 1/2 inch drivers are not capable of extended high-frequency production? If dat56 was trying to exaggerate things you would think he would have shown a better high-frequency curve, but he does not.

Another interesting thing is the drop of 4 DB at 200 Hz and 5 DB at 250 HZ. 200 HZ happens to be the place where Bose (or his designer) pushed the resonance. That suggests to me that dat56 is measuring something real.

Regarding the "Cube" discussion, I must reiterate that I am no fan of Bose' s home theater satellite systems. They give me a headache.

That might have been a necessity before the advent of loudspeaker design software, but not today. What the 901 can, and cannot, do is a calculation that can be performed in less than one second. The same applies to all speakers, all you need are the driver T/S specs, box dimensions and modeling software. The f3 of the 901, unprocessed, is 80Hz. Response is down -10dB at 60Hz, -16dB at 50Hz, -40dB at 25Hz. No amount of space loading, cabin gain and processing will account for the 25Hz response that the above chart claims. Total fantasy. It's surprising they do that well. The cab impedance at 10kHz is 30 ohms, of which 24 ohms is inductive reactance.
Edited by Bill Fitzmaurice - 2/20/13 at 2:18pm

no wonder they are the no.1 selling speaker in north korea and iran. i had a feeling amar built them for something other than hanging flower planters that commy bas*ard
Edited by smasher50 - 2/20/13 at 3:10pm

Do you really feel that design software can accurately predict the performance of a speaker system which outputs a large amount of reflected sound into a an unpredictable acoustical environment? I'm dubious.

If anybody knows what he's talking about, it's Bill.


http://billfitzmaurice.com/

I think what bill is saying is that this software can predict how low or high a speaker with x driver(s) with x size can possibly go. And the formula, which may not exactly predict how a speaker will sound, can accurate the db at various frequencies, based on the properties of the driver! It appears that the gentleman either did his measurement improperly or is embellishing abit!
The 901 has been measured many times by many people and many of those measurements are posted on line...and not one of them looks flat! Bell-curve esque....
However, I don't doubt that they sound good to some and if so, great! But if we are talking about science and not opinion, let's be accurate!

My point is that if the poster was embellishing he would have embellished the high frequency response, which is not impressive. So you do in a sense have a bell curve if you consider the drop-off at 12,500 hz given that most speakers are measured to 20 khz.. Also the dip near the point of resonance is interesting and suggests that the poster is measuring something predicted by the design of the speaker. Also, we're looking at a speaker that is heavily equalized.

Using predictive models is scientific, but just as frequency response tests can be very inaccurate with respect to omnidirectional and dipole speakers, unless the testing method is adapted, so design software may not accurately predict speaker behavior with a system that has very great room interaction.

I looked for frequency response curves online, but could not find one. If you have some graphs, please post them. But dat56 took the time to measure his speakers, and it's a bit much to infer that he's confabulating without objective proof to the contrary. It would make sense for those who doubt him to counter his measurements with measurements of their own.

If we are to be scientific, then we should also be logical. Argument from Authority is not logical. (This not directed to you, but to the previous poster)
Edited by taichi4 - 2/20/13 at 7:45pm

With a very high degree of accuracy. It gets a bit difficult in the high frequencies, as you need to use a program that allows a lot of data input, like AkAbak. In the low frequencies it's a cakewalk, even with elementary programs like WinISD Alpha Pro or HornResp. And acoustical environments aren't unpredictable, it's simple math. Room modeling programs are just as effective and accurate as speaker modeling programs.
But one doesn't even need to model the response of the 901 driver to know that -5dB at 25Hz is totally off the wall. With an Fs of 86Hz and Qts of 0.36 that notion is just plain silly, and +5dB at 31.5 is ludicrous.
Edited by Bill Fitzmaurice - 2/20/13 at 7:44pm

Even with a big bass boost from the equalizer?

I would still like to see frequency response tests from other sources. Why not?

Silly isn't a term I'd use in this discussion because it's personal and pejorative. Implausible or impossible are more objective terms, if that's what you mean .

Equalizers don't have 30dB of boost, and if you did boost by 30dB you'd blow the cones right out of the frames. You do realize that 30dB equals 1000 times the power, right? Clearly you don't do what I do for a living. If you did you'd find that using the term 'silly' in this case is being kind.

Yes, I realize the amount of power required for 30 db. It's your assessment that the Bose is 30db down.

Still would like to see some frequency response tests.

It's science, not just his assessment. I can model a sub using Thiele/Small parameters for a sealed box, and I don't even understand most of the physics of it (I don't have an engineering degree). It ain't rocket science to do it, and Bill's a professional speaker designer. This is about like saying you don't trust an MD to know how to take your pulse, respiration, and blood pressure and interpret the readings. LOL

^ This!!!!!!!!

Yes. I don't trust every M.D. You should read up on iatrogenic disease, or just do a search on medical mistakes and malpractice.

I found this from an Australian Publication...of the Series IV, augmented by a "Spatial Control Reciver" (which apparently has the equalizer integrated into it). The article shows a much more respectable graph than a bell curve.

http://www.avhub.com.au/images/stories/australian-hifi/reviews/2012/2012-12/bose_inc_cover.pdf

You're looking at the response of the receiver, not the speakers. Look at the speakers. That freq response is a freaking mess! That is nowhere near flat, it is absolutely horrific!

Absolutely horrific?

Unbelievable.

Yes, horrific. Compare it to this:

http://www.revelspeakers.com/Products/Details/42

http://www.soundandvisionmag.com/article/revels-salon2-super-speaker-model?page=0,1

28 Hz to 20 kHz +/- 1.3 dB.

Those crappy 901's aren't even in the same galaxy.

Yeah. Thanks anyway. I don't need to do that... But you should stop arguing out of ignorance, Did you even read the article you posted? Or do you just look at pictures and guess poorly based on table legends? LOL

Graph 5 is the speaker response after that bell shaped equalization curve in graph 2 has been applied. These graphs support what Bill's been trying to tell you. The EQ looks to have a boost of about 15db for 25hz. Then the actual measured response of the speakers looks to be about 12 to 15db down AFTER EQ. I might be off by just a few db trying to read it, but do the math.

+1

Bill's advice speaks for itself. I do believe that he defecated out more audio knowledge this morning than most people will know in a lifetime.

Since we are not about conjecture, here is the replacement driver that PE sells for the 901. It is, shall we say, unimpressive.

http://www.parts-express.com/pe/showdetl.cfm?partnumber=290-922

Agreed.

A 30 watt, 1 ohm driver, with an F3 of 83hz in a small-ish enclosure is going to require more EQ than +15dB to be flat at 25hz. Even then, there will be little (if any) headroom. So, one MIGHT be able to match the alleged spec at 25hz at....say....80dB...but not any where near real-world program levels. And, as Bill said, it would require a friggin ARC WELDER of a power amplifier to generate that response at 25hz.

I agree with Bill. That spec as provided by dat is a physical (and electrical) impossibility. Simply stated: it's a lie.

Well...

 

When I first glanced at this picture, I thought "that's kind of a small TV screen". Then my brain kicked in.

In fact, with the original 801 (a 901 with eight drivers) pro sound model and the original passive contour network bands went nuts trying to get them loud enough. That's because the typical power amp at that time was only 100 watts, and the passive contour network ate up roughly 6dB of the amp output, so a 100 watt amp became a 25 watt amp. Bose had to come out with their own amp, the 1800, to drive the 801s. It was a 4 space 80 pound monster. I saw one band that had four 801s, which they bought under the false promise that these small easily carried boxes would give them all the output they needed. I saw them in a 200 seat room, and their vocals could barely be heard. This was the '70s, and back then almost no one ran instruments through the PA, so the only thing in those 801s was vocals. And yes, the 801s were easily carried. A lot easier than the 200 pound rack holding the two 1800s they needed to drive them.

Really, your response is funny, given that it is you who are speaking from ignorance. Did You read the article?

Everyone here has been arguing that dat56's frequency measurements were lies or embellishments. No one has advanced their own measurements which contradict them. Instead a theoretical predictive model is used as evidence, which it is not. It is a simulation.

Based on this model it has been suggested that the Bose 901 could not possibly have respectable base, and that it's graph must be a bell curve even after equalization.

Here is what the reviewer says about the Bose (it appears that here he is speaking about the unequalized Bose, but it's not quite clear):

"... The bass was good although sometimes it seemed a little strained. The mid range was superb - incredibly lifelike, in fact - while the high frequencies were generally excellent although occasionally they sounded somewhat less than perfect."

According to the article, after equalization with the receiver, "the response then is generally within about ± 5 dB in various little - after compensating the mic position a little - would any setting of the spatial control."

Overall the reviewer has praise for the Bose 901, at least the version that he was testing. So you might want to adjust your monitor, get some new glasses, or just open your mind. LOL