peerless 850122 efficiency

[michael]

Hi i am designing some new front speakers and i want ti use the peerless 850122 woofers in an MTM configuration. But i am concered about what TS parameters to use, on the peerless site they say the efficiency is 86.5 whilst a peerless brochure distributed by wes has it as almost 89db(88.6).
Which info do i look at seriously?
because if it is the higher then i will use a higher efficiency tweeter to keep up.

[GM]

Can't comment on the discrepency beyond the fact that historically, Peerless isn't known for publishing very accurate specs. Possibly they 'updated' the driver and rather than change their website, just sent out a bulletin with revised specs to distributors.

FWIW, here's some averaged measured specs from a well broken in pair:

Fs = 56.8Hz

Vas = 15.5L

Qms = 3.55

Qes = 0.495

Qts = 0.434425

Re = 6.1

Sd = 143cm^2

Calculated from these:

Eff = 89.44dB/W/m

BL = 8.08 N/A

Cms = 5.2808e-04 mm/N

Mms = 14.86 g

Obviously though, for getting max performance/best correlation to the sim you'll have to break in/measure yours.

GM

[qwad]

I for one would go with the peerless specs as the other is supplied by STONES AUDIO.... that is an unknown factor and too much of a difference between the two efficiency is an average across the f/r spectrum taken at 500hZ/ 1K, 1.5K, ETC , etc and if you check out the peerless responses there is no smoothing applied whereas mr r storey of stones does use max smoothing so much so that it is difficult to correlate to peerless's freq response curves cheers TC

[kelticwizard]

Originally posted by GM

Fs = 56.8Hz

Vas = 15.5L

Qms = 3.55

Qes = 0.495

Qts = 0.434425

Re = 6.1

Sd = 143cm^2

Calculated from these:

Eff = 89.44dB/W/m

BL = 8.08 N/A

Cms = 5.2808e-04 mm/N

Mms = 14.86 g

Obviously though, for getting max performance/best correlation to the sim you'll have to break in/measure yours.

GM

See, this is what bothers me. I checked the published and measured, (by Stones audio) specs and see that for Stones Audio specs to be accurate, the Bl product has to be over 8.

The published Bl spec is 7.

Now, I can see that spiders, surrounds and a lot of other things need breaking in and can play tricks on the numbers and on the Qts. But Bl product is the result of the magnet-which should not change-and the number of windings on the voice coil-which also should not change. So even though there is variation unit to unit in terms of Vas, Fs, Qts, etc, the Bl product should not change.

But here, it does. For both GM's and Stones Audio's measurements, the Bl product is 8, not 7 like Peerless says.

I would go with the specs Wes components gives you. They are close to GM's measurements, which I think gives them the nod over Peerless' specs. I think Peerless changed the magnet assembly and never got around to changing the published specs. Because Bl product should not change if you use the same components in the magnet assembly.

For what it is worth, I think that the old spec of 86.5 db@ 1W/1M is a little low for a lot of systems, which tend to average around 88 dB. So I think Peerless changed the magnet assembly to yield a higher sensitivity and never got around to changing the published specs.

[qwad]

i agree with you it is more than likely an oversight by one of the overworked development engineers at peerless.... cheers TC

[michael]

I had already decided to go HDS woofers instead as they have a higher efficiency, but if the stones specs are right then the CSX would have higher.... id much rather spend $25 less per woofer and get the CSX if they are higher efficiency. i know that both specs model almost the same so the box wont be changed much but the XO will have to change if i have an extra 2db of efficiency. if this is the case it should almost match the HDS tweeters 93db.
so what do i do. HDS or CSX? if the csx is too suspicious and the real sensitivity cannot be found then id rather use the HDS but the CSX has a much nicer price especially when i am buying 4 of them.

[kelticwizard]

I do believe that one member said that there was additional difference between the HDS series and the CSX series other than the fact that the HDS is cast basket and CSX is stamped steel. Something about different spider and less distortion.

That being said, the CSX, (850122), and HDS, (850439), do have remarkably similar Thiele-Small specs and remarkably similar response curves as well. This seems to hold pretty true throughout the CSX and HDS lines.

For a cost conscious DIYer, my choice would be the CSX. first, both Stones Audio and GM measured the sensitivity as being in the range you want.

Second, click on the frequency response chart for both the peerless 850122 and the HDS 164. Are these two response charts almost identical, or what?

Third, notice that on Peerless' own respnse chart for the CSX, the speaker is playing at 88 dB throughout the midrange, even rising to 90 dB on the higher ranges. Apparently Peerless put the right response chart on the website, but didn't change the Thiele-Small numbers.

Fourth, please notice that the Bl product for the HDS is 8.9, yet it has very close specs to the CSX as measured by Stones Audio. Considering that the Bl product is where the speaker gets the driving force from, can someone explain to me how the CSX as measured by Stones Audio and GM can give the same response as the HDS as measured by Peerless when the CSX only has a Bl product of 7 and the HDS has a Bl product of 8.9?

It can't. Peerless had to upgrade the magnet structure and just forgot to upgrade the specs.

I would go with the CSX and save myself $100.

[michael]

Okay this is fantastic, i get to save money and get a good efficiency at the same time.
Now if someone could help me workout a XO to use with the HDS tweeter (aus only) i can order them and be on my way to audio bliss
the HDS/XLS tweeter is found here

[PeteMcK]

If you got the figures from the WES catalogue,
I think there are a fair number of typos and mix ups;
better to go for the (Unreliable?) data from the Peerless web site I think

Pete McK

[catapult]

Now if someone could help me workout a XO

Michael, we've had this conversation before. The XO is the most important part of the speaker and you can't just "workout" a design on paper, using factory numbers and expect decent results.

If you want a custom design, start by purchasing measuring gear and XO design software. Build the box, install the drivers and measure the response of the drivers in your box. Then plug all that into the design software and start simulating different XOs. When you find one that looks promising, build it and listen/measure the actual results. Repeat as needed. This can take weeks or months.

If you aren't up to all that, just build a proven design where all the hard work has been done. You were provided with a number of links to good designs last time you asked about this.