Cheapie build - Peerless 5 driver 2.5 way MTMMM

[Dave Bullet]

So scouring Madisound for cheap drivers (pity the shipping is more than the driver cost - sigh), I found these and put them together in a 2.5 way MTMMM design (last 2 M being the 0.5 way woofers).

I need to box mount these and tweak for baffle placement / diffraction, but here is my first attempt.

Goals:
>= 91dB sensitivity - limits cheap tweeter choices and forces a higher than desired crossover frequency.
Cheap drivers (all 10 drivers < USD$200).
>= 4 ohm load
Router not required - can surface mount if needed
Standard square box.

I've got no idea what the HD profiles look like on these cheap peerless drivers.

Results:
~ 92dB sensitivity
Minimum impedance 4.6 ohms @ 3,600 Hz.
LR4 acoustic target. Crossover point high (~2,600Hz), but in order to protect the tweeter. Went as steep as I could without going fancy.
Box options:
- Vented = 104L. F3 = 48 Hz, Tuning = 52 Hz
- Closed = 49L. F3 = 91 Hz. Q = 0.71

Given the flange of the woofer, you could get away with surface mounting these so no need for a router if you can't do recessed holes.

Drivers:
Woofer - Peerless BC18EK05-08 6.5" = USD $15.50 (on sale)
Peerless BC18WK05-08 6.5" Paper Cone Woofer

Tweeter - Peerless DX25TG59-04 1" = USD $20.71
Vifa DX25TG59-04 1" Fabric Dome Tweeter

According to Zaph (John Krutke): "Smooth and extended response at both ends with mild 3dB depression in the whole top octave. Low Fs for a tweeter with no rear chamber. Good CSD. Excellent 2nd order HD above 1.8kHz, very bad 2nd order HD below 1Khz. Cross over 1.8kHz LR4 or 2.5kHz LR2. Very efficient with high power handling"

See the distortion plot for yourself:

http://zaphaudio.com/tweetermishmash/compare.html

Caveat - this tweeter has been revised since Zaph's original test in 2005.

Total cost for drivers USD $165.42

[Alaric]

I'm in. The ease of box construction is my hook. I can buy the wood and have it cut at Home Depot. If there's no routing necessary, the rest is within my skill set. I'm following this with much interest. The soft dome tweeter is a bonus. Evr since my old A/D/S L1530s I've been a huge fan of soft dome mids and tweets. :T I'm looking forward to your build and results.

[Dave Bullet]

The WinISD plots show vented can be as low as 50L with only a 1dB peak. I know Curt Campbell has mentioned on his site the benefits of a smaller than optimal vented box with lower tuning (minimizes the negatives).

I've searched for other drivers that hit - sensitivity + low price + flush mounting and there aren't any.

In anycase - my real problem is the shipping cost to little old New Zealand ~ USD $200!!! (drivers alone, let alone crossover).

I'm not giving up however... still to come
1. construction modeling (3D and BDS). I'm likely to offset the tweeter on the vertical axis as having distances to the edge that are not equidistant / golden ratio / acoustic ratio lends to a smoother baffle ripple (plus reduces C-C spacing of the MtM)
2. Excursion modeling and max SPL (I want to see whether woofers or tweeter will give out first)
3. box alignments
4. Crossover tweaking based on the above
5. Crossover BOM / parts cost estimate

[Dave Bullet]

I'm in. The ease of box construction is my hook. I can buy the wood and have it cut at Home Depot. If there's no routing necessary, the rest is within my skill set. I'm following this with much interest. The soft dome tweeter is a bonus. Evr since my old A/D/S L1530s I've been a huge fan of soft dome mids and tweets. :T I'm looking forward to your build and results.

I agree. I haven't had much experience with metal domes, but I did do a comparison between Seas 27TBGFC/G (metal) and its identical sibling (apart from dome material) - 27TDFC/G (fabric) and the metal dome had a certain harshness on certain tracks (identical crossover).

I hope to be able to build these... however I have another pair I've been building for..... 11 years lol. Crossover components arrive tomorrow hopefully!

So don't get your hopes too high :-) I also need financial approval to spend a vast sum on shipping cost.

[Alaric]

I have no measuring equipment, nor skills, with which to bet the BOM cost on. Otherwise I'd be tempted to spread it over a couple months and build the darn things, tweaking them after if need be.

My current speakers have metal tweeter domes, and the speakers overall still make me smile. BUT, with the wrong amplification or source, they can go from detailed to fatiguing without much lead time. And as I drift through my mid 50s I have to wonder how much my hearing is playing a part in my perception now. I was only in my early 40s when I bought them, and just replaced the tweeter domes a couple months ago.

[Dave Bullet]

I have no measuring equipment, nor skills, with which to bet the BOM cost on. Otherwise I'd be tempted to spread it over a couple months and build the darn things, tweaking them after if need be.

My current speakers have metal tweeter domes, and the speakers overall still make me smile. BUT, with the wrong amplification or source, they can go from detailed to fatiguing without much lead time. And as I drift through my mid 50s I have to wonder how much my hearing is playing a part in my perception now. I was only in my early 40s when I bought them, and just replaced the tweeter domes a couple months ago.

I am in my late 40s and far less tolerant of bright, sibilant or harsh recordings. I'd be lucky now I think to hear into the 15KHz range (probably less with motorcycling ;-) but that doesn't change the fact that forward / bright speakers in the treble range, especially if you like some 70s and more forward 80s recordings; unbearable to listen to long term (= bad speaker in my book for its intended purpose). Thats why I think environment (hard or soft room) and music type you listen to play a huge part.

I've designed only 2 speakers prior - a 2 way and a 3 way. Both measured very close (within 3%) of their simulations throughout the frequency spectrum, so I am pretty sure my modeling / methodology is accurate.

Caveat above - is the above design is missing BDS and bafflestep effects (e.g. the hump at 100Hz should disappear as the curves are based on IEC baffle measurements and will not compare with the slimline baffle I am proposing which you have yet to see). I need to confirm this - so please don't pull the trigger on ordering any parts! I'd actually recommend not to build anything I post that I haven't actually built and measured to confirm the response and that someone else (other than myself) likes what they hear.

The other benefit with flush mounted woofers, is you could (if you had the capability) recess the tweeter behind - meaning closer C-C spacing of the MtM and therefore reducing lobing effects (nulling) as you move vertically.

The listening height / axis will place the tweeter ~ 823mm from the ground (aligns with my high couch). The actual height can be varied as long as all the drivers have the same spacing apart (either moving them all down the front of the baffle - or making the baffle shorter and cabinet deeper to maintain volume - as long as the baffle width doesn't change).

Sadly - I may never build these due to the high shipping cost from madisound. I can't find these drivers from partsexpress nor wagner online (closer Australian based retailer).

I might re-visit with a slightly more expensive woofer that is available worldwide to enable more DIYers to build. The tweeter will likely remain due to its good distortion profile, high sensitivity, reasonable budget and availability.

[Dave Bullet]

My latest woofer on offer is the Peerless SDS-P830657 6.5".

https://www.madisoundspeakerstore.com/peerless-woofers-6-7/peerless-830657-6.5-sds-woofer/

This is a little more expensive but is available in Aus (AUD$35) and madisound (USD$19) so still viable.

Downside is it is ~ 2dB less efficient than the BC18 above. Upside is it supports a narrower profile so a tower can be narrower for a slimline look.

I'll model some xover tweaks and post here, including box sim as above

[Dave Bullet]

I have the pleasure to announce 2 designs, both using the Peerless 830657 woofer and Vifa DX25TG05-04 (aka Scan speak D2604-830000).

Design "A" - a 4 woofer MTMMM 2.5 way. Min impedance 3.6 ohms between 4KHz and 7Khz
Design "B" - a 6 woofer MMTMMMM 2.5 way. Min impedance 3.0 ohms at 9KHz

Enclosures
A - 80L vented, tuned to 40 Hz, F3 = 54Hz, Max SPL 111dB. System sensitivity ~ 89 dB (including ~ 4 dB baffle step compensation)
B - 120L vented, tuned to 40 Hz, F3 = 54Hz, Max SPL 114dB. System sensitivity ~ 92 dB (including ~ 4 dB baffle step compensation)

The remainder of the images in this post relate to the A design

[Dave Bullet]

Design B

[Alaric]

Silly question, but, can wagner online get them for you if they don't stock them?

[Dave Bullet]

Silly question, but, can wagner online get them for you if they don't stock them?

That's a good question. I don't know. I hope so. I actually found another aus site. Theloudspeakerkit.com. they include a shipping estimator online. I'll get quotes from both Wagner and the loudspeakerkit. Definitely going to pull the trigger on the Biggie.