Alpair 7.3 FAST / WAW

xam

Member
2013-02-02 3:40 pm
Hey guys,
I just built a TQWT with the MA Alpair 7.3 and i'm really happy with the sound, the Alpair is just great.

Cause of this positive feeling i thought of building a second pair with the 10.2 or a passive FAST with a equivalent driver. I couldnt find any plans for a passive FAST, has anyone did it before? I need a passive crossover because i will use my stereo amp and no dsp with additional amps.

Any idea?

Thx
xam
 
Hey guys,
I just built a TQWT with the MA Alpair 7.3 and i'm really happy with the sound, the Alpair is just great.

Cause of this positive feeling i thought of building a second pair with the 10.2 or a passive FAST with a equivalent driver. I couldnt find any plans for a passive FAST, has anyone did it before? I need a passive crossover because i will use my stereo amp and no dsp with additional amps.

Any idea?

Thx
xam

Since you asked, :D I'll start the bidding with a few disjointed, personal thoughts .

FAST's can be implement a variety of ways - your desire to use only a passive XO would suggest that you'd like a single enclosure per side?

Having heard more than a couple of enclosure designs using the 7.3 and 10.2, I'd recommend the 7.3 for any system in which bass augmentation is planned.

While the 10.2 unquestionably excels at heavy lifting that strains the smaller driver, if you like the 7.3 now, wait 'til you hear it relieved of the heavy lifting.

At the XO frequencies at which I've personally found FAST type systems to be most enjoyable ( 330Hz and below), the component values and cost of parts for passive XO can get up there.

While a bit trickier to implement , series XO have a lot of advantages. A recent project that worked quite well used 2 Mark Audio EL166 / Woofer 6s and Fostex FF85K and relatively simple series network.
 

xam

Member
2013-02-02 3:40 pm
@silverhairbp
Month? I wish you said days, patience isn't my specialty... ;)

@chrisb
Interesting, this is exactly what i thought of.
I have a few ideas on my list, the FAST with the 7.3 was one of it.
An easier test would be a 2.1 or 2.2 setup, one or two subwoofers in an external box powered by an a amp modul and a highpass for the 7.3.

The 10.2 instead of the 7.3 in TQWT could be the satisfaction i'm searching for, the 7 is just a bit to small to handle my needs.
 
@silverhairbp
Month? I wish you said days, patience isn't my specialty... ;)

@chrisb
Interesting, this is exactly what i thought of.
I have a few ideas on my list, the FAST with the 7.3 was one of it.
An easier test would be a 2.1 or 2.2 setup, one or two subwoofers in an external box powered by an a amp modul and a highpass for the 7.3.

I would have tried a trail of breadcrumbs to that destination, but you'd indicated the desire to go passive and avoid extra electronics. ;)
I've been quite happy using the line level input on my single powered woofer - Foster OEM plate amp, but there are dozens of choices in the under $200 each range - even the Parts Express APA150 outboard (great value piece)

Dayton Audio APA150 150W Power Amplifier 300-812

I'd still suggest HP to the 7.3s - if the existing amp with which you're planning on driving them lacks a pre-main loop, implementing a passive line level XO gets a bit more complicated, but still well worth the effort. This is where current generation of budget HT receivers offer a ton of flexibility and great bang for buck, albeit at the sacrifice of sound quality compared to other solutions. (i.e. higher priced / separates - particularly dedicated 2 channel audio only with far less signal processing required for multichannel audio and video switching, etc)

The 10.2 instead of the 7.3 in TQWT could be the satisfaction i'm searching for, the 7 is just a bit to small to handle my needs.
As I noted earlier, I've heard the 10.2 in a range of enclosures - they work quite well in a simple floorstandiong MLTL - Pensil or Brines' M10-A10, and at the sacrifice of a little extension / slam, but with more finesse , the stand mounted MarKen.

I just happen to prefer the 7.3, or for that matter the 12P to the current 10.2s (not that I'm aware of any pending revisions to same, but Mark has clearly demonstrated a trend to upgrade )
 
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xam

Member
2013-02-02 3:40 pm
Thanks for your help, i bought a stereo amp last year which i don't want to replace so fast. (Denon PMA 710AE with the DCD 710 CD Player)
Otherwise i would test the minidsp with 2 simple amps...
At the moment i dont have any possibilitys to filter with this system.

Maybe i should wait for updates. ;)
 
Hi Xam,

I've been inspired by/interested in this idea for a while. For me it's an appealing concept. At mo, I have an A12 in open U-frame with a passive XO woofer and a super tweeter that I'm working on/playing around with. Its a passive F.A.S.T idea I guess. I'm pretty happy with it. I have an amp to drive it. Other than it is a pretty large speaker for the room I have.

I started with an A10 then got an A12. An A7 might be next.


Making the low pass active solves a lot of issues, but I certainly relate to 'all passive' design ideal.

Having spent some time grappling with this concept, my suggestions would be:

be very clear/specific about the design concept:

Is it a multi way or is it full range with a woofer? If XOing > 200 say it starts becoming a multi way. The execution of the XO becomes critical to success. The complexity of the project is much trickier. If it's a full range with a woofer and you're XOing <200 say, it's more straight forward IMO. More likely to sound 'properly' good IMO.

There are plenty of over > 85-86db woofers to choose from

For me an A7 would lend itself to a more complex, 2-way idea XO > 200.

If you have the resources to do a good passive XO between 250 – 400Hz, then this would be an appealing, possibly very popular speaker project. Unfortunately I don't. Also I think you will need a well damped/high current amp to drive through a large low pass filter and support a low impedance. Unless this can be avoided somehow with a series XO - which I don't know the technicalities of exactly. I think it's kind of 'inverted' XO. Expansion on series crossovers could be an educational topic…

Making the low pass 'active' solves a heck lot of issues, but I can relate to an 'all passive' design ideal myself

I'd define:

The design concept - is it F.A.S.T or a 2-way?

how much $$ I want to spend on a woofer, invest in the project

how loud I like to/can listen

the type of amp I have/plan to use .

This will would steer me to the choice of drivers, general viability of the project.

If I was doing an inverted passive 2-way XO > 200 - 400 or so I'd go a sealed A7 plus a sexy 6-7inch woofer in a vented box. A very luvable idea IMO

If I was doing a F.A.S.T XO < 200 or so - I'd go an A12 or A10. With an ACTIVE sealed woofer. Either with plate amps or a separate amp to drive the woofers.

I have a bit of an itch to work on/try an A7 passive 2-way for myself one day, but I'm baulking at the XO, risk/complexity of it overall. It's outside my DIY scope at mo. So I'm looking on with interest.
 

xam

Member
2013-02-02 3:40 pm
Hey TiMBoz,

I will try to answer your questions bit by bit.
The F.A.S.T. Idea comes with my desire to keep the broadband nature and improve it by an woofer like an afterburner. :cool:
XOing<200Hz

I don't want to spend much more than 300€ for this project - there was a german concept called SevenUp, with the old AP 7 + TB W6-1721.
SevenUp Grau Bausatz - Lautsprechershop von blue planet acoustic
I'm searching for an equivalent project with the new Alpair gen.

For now i'm wondering if i shoud buy/build me a cheap subwoofer to relieve the 7s and look how this works. There are two used MA 10.2 on german ebay, too. :rolleyes:
 
Hey TiMBoz,

I will try to answer your questions bit by bit.
The F.A.S.T. Idea comes with my desire to keep the broadband nature and improve it by an woofer like an afterburner. :cool:
XOing<200Hz

I don't want to spend much more than 300€ for this project - there was a german concept called SevenUp, with the old AP 7 + TB W6-1721.
SevenUp Grau Bausatz - Lautsprechershop von blue planet acoustic
I'm searching for an equivalent project with the new Alpair gen.

For now i'm wondering if i shoud buy/build me a cheap subwoofer to relieve the 7s and look how this works. There are two used MA 10.2 on german ebay, too. :rolleyes:

I can't see any reason why a project such as the SevenUp wouldn't work just as well with the 7.3, with whichever bass driver you consider suitable. We acquired a fair number of CSS SDX7s a couple of years ago, and have just about depleted that stock. It's been particularly fun to work with this driver as it can be used in pretty tiny boxes - greatly simplifying enclosure design.


There are presently quite a few candidates in the 6-8" mid bass driver range from which to choose - on this side of the pond Silver Flute and Peerless are near the top of our dance card - and since this is the Mark Audio forum, I'll vote yet again for a replacement / update to the great little EL166 / Woofer 6 :D
 
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Ok, there you go! the Seven Up project. Someone has already had a crack at it.

I reckon it's a very nifty idea. At least in aesthetic/static appeal. Part of the fun is combining the A7 with a ones own woofer preference: for myself perhaps with a 'metal' cone. Wouldn't be hard to come up with a nicer looking box for it either. Pity there weren't more details for the XO etc.

Also there are a couple of other very professional looking projects around with the A7 combined with active subs. Suggest have a look over those, and decide how you want to proceed. I don't think you'll be stuck for suggestions on possible woofers to use etc.:D
 
Hi All

Having built a set of 7.2 pensils I'm keen to explore as FAST option to fill in the bottom. I've also completed a set of ESLs that bottom out just below 40Hz, and I am amazed how much better the bass is compared to my olf KEFs that bottomed out at 50 Hz. So I've been looking for a 8-10" driver that will have f3 in a closed box (for good group delay) below 40 Hz. So far I have only found one, the Scanspeak 23W4557, which looks very good but is horrifically expensive.

Q1: does anyone know of other smallish woofers with f3 below 40 Hz? I've searched online T&S databases and the Scanspeak driver is a standout.

Q2: Has anyone tried adding mass to a woofer cone, e.g. by adding a metal ring or epoxy near the dustcap. This would lower the fs and enable operation to lower frequencies in closed box. The cost is higher Q of the driver - bigger cabinet volume, and a loss in sensitivity. By my reckoning, adding about 30% extra mass to one of the Dayton 8" drivers would have the desired effect.
 
Hi All

Q2: Has anyone tried adding mass to a woofer cone, e.g. by adding a metal ring or epoxy near the dustcap. This would lower the fs and enable operation to lower frequencies in closed box. The cost is higher Q of the driver - bigger cabinet volume, and a loss in sensitivity. By my reckoning, adding about 30% extra mass to one of the Dayton 8" drivers would have the desired effect.

Hi G, Guys,
I'd strongly urge not adding 30% additional mass to a small woof (or any small driver). I'm certain no driver designer will factor-in additional loads of this magnitude into the driver's suspensions. There's a real risk of taking the unit's power-train out of operational alignment, coil rub leading to circuit failure is a possibility. I'm certain most all makers will their void warranties against such modifications.

For further discussion on modifications of this magnitude, please use a forum section like the lounge:

The Lounge - diyAudio

Thanks
Mark.
 

Einric

Member
Paid Member
2011-02-26 2:12 am
Bozeman, MT
AP6.2 Gold x Dual DA175 Passive FAST

Here is just a simulation but it looks kinda promising, Parts would cost about $200 +S&H.
4 DA175's should provide plenty of bottom end.
The A6.2MA will be in the Madisound 1.7l chamber and the DA175's would be in 1.8-2cuft shared tuned to 31-33hz.
 

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Hey guys, sorry to go off topic but what's that software your using for sims Einric?

A friend just gave me 500 bucks and asked me to build her! a set of towers. I'm set on the A7.3 and possibly the SLS 830669. Thinking slim cab with the SLS mounted on the sides.

I am limited to about 150 per driver and local availability for drivers in Melbourne, Aus.

Has/could anybody sim the SLS with the A7.3?

Cheers for any advice.
Dean
 
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Still looking at a FAST system with the A7.3, but finding an appropriate woofer is a bit of a pain... with my various requirements of low f3, ~60L sealed box size etc. the two best fits I've found so far are the Scan Speak 26W/8534G00 and 26W/8861T00. the latter being near 4x the price of the former...

Looking forward to getting this built, but it's turning into a long term project including amps and DPS :)
 
What's pictured, is that four per enclosure? With multiple smaller woofers would I need a vented enclosure to get a lower frequency response. Or would I be able to stay sealed and utilise active DSP/PEQ to cut & boost my way there... within reason.

Am looking at peak SPL of 80~85dB, so most of the drivers mentioned will hit well over 90dB with 4~8 Watts.
 
What's pictured, is that four per enclosure?

4 Peerless 830870 4" bass drivers. We had to get Scott to design an ML-V to get the bass enclosure tall enuff to support the co-laterally mounted mid-tweeter to be at a reasonable height. PLLXO 1st order at 240 Hz.

The ML-TL for these bass drivers is used with a pair as a woofT for the uFonkenSET (same XO).

uFonkenSET-matched-woofT.jpg


These woofers like lots of volume but do dig low in the quarter-wave boxes. When working on our stand-mount MTM i 1st looked at these, but they needed 30 litre BR to match the extention of the 2 Silver Flutes W14 (in 10 litre) we finally settled on.

dave