5” Mid-woofer help

[verona]

Hello, I am looking for a mid-woofer for a ported enclosure of about 11 litres net volume and have shortlisted the following 2 drivers:

(a) Scanspeak 15W/8531K00
(b) Hiquphon OW1

I have selected the 8531 (uncoated) version, over the 8530 (coated) one for two reasons:

1. I believe its lower Vas and higher Qt make it more suited to this small enclosure.
2. The response plot seems a bit smoother up to the rise that both exhibit between 1-2 kHz.

Having read lots of posts on here, the 8530 unit seems to be very highly regarded, although there seems to be much less written about the 8531 one. I also saw that the Carrera from Meniscus Audio uses the 8530 and OW1 combination but in a 15 litre cabinet.

Does anyone think the slightly earlier rise preceding breakup of the 8531 is the reason for it seemingly being less popular than the 8530?

If so, I see lots similar units from other manufacturers that go much higher before breakup. For example, the response plot for the SB Acoustics SB15MFC30-8 is level to almost 4 kHz although not quite as smooth as either of the Scanspeaks.

I also note that many of the other units cost a fraction of the Scanspeak ones!

Therefore, I would like to ask:

• Are these Scanspeak mid-woofers really “better” than their rangier competitors?
• If anyone thinks that my choice of the 8531 over the 8530 is flawed for this application.

Any help would be appreciated.
Many thanks.

PS I am very keen, have read quite widely and think I have grasped some basic theory, however, I have very little actual experience!

https://www.scan-speak.dk/datasheet/pdf/15w-8531k00.pdf
https://www.scan-speak.dk/datasheet/pdf/15w-8530k00.pdf
https://www.sbacoustics.com/index.php/products/midwoofers/mfc/5-sb15mfc30-8"

 

[montana1]

Hi verona,
("If so, I see lots similar units from other manufacturers that go much higher before breakup. For example, the response plot for the SB Acoustics SB15MFC30-8 is level to almost 4 kHz although not quite as smooth as either of the Scanspeaks.")
Have a look at measurements done by @gornir on his website audioexcite.com. The SS Revelator in his test is the 4 ohm version but it gives you an idea of the smooth response attribute. I like his driver tests because they are performed using an enclosure rather then an IEC baffle used by the manufacturer.
("Therefore, I would like to ask:

• Are these Scanspeak mid-woofers really “better” than their rangier competitors?
• If anyone thinks that my choice of the 8531 over the 8530 is flawed for this application.")
I have not used this driver myself (although considered it). What turns me off this driver somewhat is the low sensitivity (85.5 db @2.83v.). For a driver costing over $200.00, that seems a little pedestrian to me. YMMV If it were my coin, the Satori line from SB Acoustics would float my boat.

Best,
Rich

 

[verona]

Hello Rich and many thanks.

I have looked at the tests on audioexcite.com as you suggested and they are most interesting.

Certainly, the response curve for the Scanspeak unit tested is much smoother and higher reaching than the manufacturers figures I was looking at.

Would it be correct to assume a similar smoothing and extension of the curve for the 8 ohm versions I mentioned? Many of the 5" Scanspeak graphs show a similar range, lift at 1 kHz and breakup.

I take on board your comment about the low sensitivity. I had opted for an 8 ohm bass unit simply to "match" the 8 ohm OW1 tweeter.

If there is no problem with a 4 ohm bass and an 8 ohm tweeter, the sensitivity of the 4531 bass at 87dB matches the sensitivity of the OW1 tweeter exactly.

I will take a closer look at the Satori line, I see audioexcite have tested quite a few SB products.

I discounted lots of base units because the manufacturers response curves looked rough towards the highend, perhaps I need to re-visit them.

Thanks again, V.

 

[montana1]

Hi verona,
("Would it be correct to assume a similar smoothing and extension of the curve for the 8 ohm versions I mentioned? Many of the 5" Scanspeak graphs show a similar range, lift at 1 kHz and breakup.")
I would say that both versions should offer very similar frequency response curves.
("If there is no problem with a 4 ohm bass and an 8 ohm tweeter, the sensitivity of the 4531 bass at 87dB matches the sensitivity of the OW1 tweeter exactly.")
[The only real benefit to the 4 ohm version would be some 2 db. or so overall system sensitivity increase. Once baffle step is accounted for, you will probably have a 81-82.5 db speakers for 8 ohm version and 83-84.5 db for the 4 ohm version. I would probably lean toward the 8 ohm version as intended by the designer for the Carrera's.

Best,
Rich











Best,
Rich

 

[wolf_teeth]

Just buy the Carrera kit , designed by Paul Carmody. It uses those drivers.
Wolf

 

[ernperkins]

If you're outside the US and shipping is too expensive you can find the full Carrera writeup including the crossover HERE. I've heard them and they are great speakers - you'd be hard pressed to beat Paul's design.

 

[dtaylo3]

Quite true. The SS driver and Hiq tweeter are used in a number of well respected DIY and commercial designs. Anyone who build's or listens to the Carrera extols its virtues. I would be more worried about the quality of your amplifier than the capabilities of the Carrera. The SS will deliver bass in spades, at pretty much astounding levels for a 5.5 inch driver, but at the expense of some efficiency. You can pump a lot of power into it if you desire. Make sure they are quality watts.

 

[verona]

Hello all and thanks for the feedback.

Its good to hear your views on the Carrera and if I could use a 0.5 cu.ft. cabinet I would probably just buy the kit. Unfortunately, I am limited to 0.38 cu.ft.

So, do you think the same Carrera SS 15W8530K00 (and presumably crossover) will work in my smaller cabinet or would it be better to use another SS 15W variant and possibly a modified crossover?

Thanks, V.

 

[verona]

@Montana1
Hello Rich, I have been looking at the audioexcite tests again, particularly the SS 15W4531G00.
It seems there is a huge difference between the manufacturers data (Vas, Qt etc) and the same data measured in practice.
So, my original concern about the early break up of the SS 15W units turns out not to be a worry after all, but the manufacturers data I have been using could be miles off!
Wow, this is harder than I thought!
I am too far down the road of building my own cabinets at about 0.38 cu.ft to change the size now. Also, I now realise I am not experienced enough to choose a completely new bass unit.
Therefore, I think I will stick with a unit from the SS 15W range that you experts have used in a similar sized cabinet with good results. As I am keen to use the Hiquphon OW1 tweeter, the Carrera feels like a good starting point. I see that Troels Gravesen has used the similar base units in quite small cabinets which is encouraging.
So, all I need to do is sort out the crossover and port - which are the parts I have been dreading all along!
ATB, V.

 

[wolf_teeth]

I think the smaller box will be fine, as long as the baffle is the same width and height. The baffle size is important for xover application due to BSC and its effects. The Carrera is also meant for stand-mount, and not to be used against a wall; if that matters. All of this in tow, the smaller box will likely be okay, you'll just likely have to run it sealed due to the volume reduction.

Later,
Wolf

 

[verona]

Hello Wolf,
OK, thanks for making the point about the baffle. My baffle size is frozen unfortunately and I was unaware of the Carrera at the time so it will be pure chance if it is similar! I will check. How close would it have to be? Mine is rectangular with rounded vertical edges.
Rather than go sealed, I think I would prefer to find another driver in the SS range suitable for a small ported box, but I note your suggestion.
Thank again, V.

 

[Gracol]

Hi Verona,

I have the Satori MW13P in an 8 litre ported enclosure, and it works really nice! Really clear and spacious sound and good bass performance too from such a small driver. I have mine paired with the SS 9500 tweeter.
Sorry, don't have any experience with the SS woofer so can't compare.

G

 

[verona]

Hi Verona,

I have the Satori MW13P in an 8 litre ported enclosure, and it works really nice! Really clear and spacious sound and good bass performance too from such a small driver. I have mine paired with the SS 9500 tweeter.
Sorry, don't have any experience with the SS woofer so can't compare.

G

Hello Gracol,
Thanks, someone suggested I should look at Satori units yesterday. Lots of people seem to like them, nice tweeters as well.
However, I would be out of my depth just now specifying a complete new speaker system. The more I look into it the more I realise its not an exact science, more like a black art.
Since the cabinet was my main area of interest, I think I will try to base my units etc on a well regarded existing design.
All being well, I will feel more adventurous next time.
V.

 

[montana1]

Hi verona,
Something else to consider is getting your hands on the crossover schematic with whatever direction you go. Otherwise, you will need to perform your own design through measurements or simulations. Either way, the complexity level goes way up. My suggestion would be to keep looking at proven designs were the designer has made everything available including the crossover. I don't know of a proven design (free) using the OW1 tweeter that you desire to utilize. Maybe someone else can chime in. If you are willing to consider other drivers the field just opened up for more options. I will do some research today and post any designs that look promising.

Best,
Rich

 

[verona]

Hi verona,
Something else to consider is getting your hands on the crossover schematic with whatever direction you go. Otherwise, you will need to perform your own design through measurements or simulations. Either way, the complexity level goes way up. My suggestion would be to keep looking at proven designs were the designer has made everything available including the crossover. I don't know of a proven design (free) using the OW1 tweeter that you desire to utilize. Maybe someone else can chime in. If you are willing to consider other drivers the field just opened up for more options. I will do some research today and post any designs that look promising.

Best,
Rich

Hello Rich,
Yes, agreed, I have come round to thinking along the same lines now. I certainly don't want to get into crossover design and simulation.
I have seen crossover schematics on the internet for a couple of OW1 designs, the Carrera and one by Troels Gravesen. Does that mean anyone can use them?
I was sort of hoping that the tweeter part would not be affected much by the cabinet size, but that the bass unit choice and crossover would be.
But I see the SS 15W8530K00 has been used in very small cabinets so I was homing in on these for my 0.38 cu.ft cabinet. Basically a small Carrera!
Anyway, thanks for your trouble. If you do find anything promising I would be very grateful.
ATB, V.

 

[montana1]

Hi verona,
Take a look through audioexcite.com on loudspeakers drop down option. There are several builds in the Revelation series using the SS 15W/4531G in anywhere from 11-14 liters. I would say the 8 ohm version would work as well in a .38 cu.ft. cabinet (not 100% positive though). As for schematics made available online, I would say you could make use of them.

Happy hunting,
Rich

 

[ernperkins]

What is your baffle width? Paul's design uses an 8" W X 14" H baffle. If your width is close to 8" it should be OK.

Going from 0.5 ft3 to 0.38 ft3 doesn't make a lot of difference if you can handle a longer port. I used the 15W8530K00 T/S parameters from zaphaudio and used WinISD for modeling. I first modeled the 0.5 ft3 cab (red trace) which matched Paul's results (43 Hz tuning, 2" X 7" port) almost exactly. I then modeled a 0.38 ft3 cab (blue trace) with the same tuning of 43 Hz. The only real drawback is the port length increases to 10.5" which may be hard to fit in the cabinet.

One possible option is to use a 1.75" diameter port which reduces the port length from 10.5" to 8". This will increase the port velocity which may cause audible "chuffing". For a 100 dB output WinISD gives a max port speed of 27 m/sec for the 0.5 ft3 cab using a 2" port. For the 0.38 ft3 cab it gives a max speed of 23 m/sec for a 2" port and 30 m/sec for a 1.75" port. These are all pretty high values, but so is the 100 dB output.

 

[montana1]

Hi verona,
I just noticed Paul Carmody has the Carrera build on his website (nice!). I would still be inclined to buy the kit from Meniscus Audio in the spirit of DIY and supporting the efforts made by individuals like Paul who make these designs available with little financial gain as motivation.

Best,
Rich

 

[verona]

Hi verona,
Take a look through audioexcite.com on loudspeakers drop down option. There are several builds in the Revelation series using the SS 15W/4531G in anywhere from 11-14 liters. I would say the 8 ohm version would work as well in a .38 cu.ft. cabinet (not 100% positive though). As for schematics made available online, I would say you could make use of them.

Happy hunting,
Rich

Thanks Rich, will do.
V.

 

[verona]

What is your baffle width? Paul's design uses an 8" W X 14" H baffle. If your width is close to 8" it should be OK.

Going from 0.5 ft3 to 0.38 ft3 doesn't make a lot of difference if you can handle a longer port. I used the 15W8530K00 T/S parameters from zaphaudio and used WinISD for modeling. I first modeled the 0.5 ft3 cab (red trace) which matched Paul's results (43 Hz tuning, 2" X 7" port) almost exactly. I then modeled a 0.38 ft3 cab (blue trace) with the same tuning of 43 Hz. The only real drawback is the port length increases to 10.5" which may be hard to fit in the cabinet.

One possible option is to use a 1.75" diameter port which reduces the port length from 10.5" to 8". This will increase the port velocity which may cause audible "chuffing". For a 100 dB output WinISD gives a max port speed of 27 m/sec for the 0.5 ft3 cab using a 2" port. For the 0.38 ft3 cab it gives a max speed of 23 m/sec for a 2" port and 30 m/sec for a 1.75" port. These are all pretty high values, but so is the 100 dB output.

Hello,
This is helpful info, many thanks.

My front panel is 6" flat then about 1" radii each edge, so it is about 8" wide in all.

Ill try to confirm the modelling as you did, but I'm encouraged by what you have said so far.

I can't get a 10.5" straight port in (front to back) but could if it was curved upwards. I see companies doing ports and 90° elbows. Do these work as well as straight ones?

I could probably make my own port with a constant radius bend if not.

Thanks again, V.