[Luigi]

Hi All

Long time since last posting.

I guess that plenty of the more adventurous types have now tried the B200/Alpha 15 combination in OB setting, and since so many have commented favourably I thought I would give it a whirl as well.

As it happens, the prospect of adding two Alphas, two pretty cheap drivers, looked seriously expensive a couple of years back. This is because I live in NZ and the freight was about x2-x3 the cost of each driver, IIRC. Latey, freight seems less expensive. Wonder why?

Anyhow, current OB set up is with B200s, tamed by a BSC filter to remove the shrillness. It works okay.

I plan to just make up a new baffle for each of the Alphas and the B200s, but would like some advice on how to minimise baffle size - I dont really care about low bass because I already have this covered with a kind of OB U-shaped subwoofer, driven separately.

Not fussed whether I have wings or not this time around; many dont seem to nowadays. 

Therefore, once baffle size is minimised I then need to know how best to position the drivers.

I guess the best is to mount the Alphas as low as possible but not entirely sure where B200s should best be sited in relation to the Alphas and to ear level.

Next, I wish to run both sides off of one stereo amp (an AKSA Nirvana Plus).

And here is where Im most confused; do I continue to run the B200 with the BSC filter in, or should I run this full range on its own (so the drivers are better matched for SPLs) with a crossover on the Alphas to cut them off at around 500Hz?

Also, I just cannot seem to get a handle on what is the best crossover design, or more accurately, values of inductors and caps, to mate the B200s to the Alphas.

If anyone can give a reasonably good answer to this, preferably with a link to a crossover schematic, I would be ever so grateful.

I know lots has already been written about this kind of set up but getting consensus seems tricky.

If someone has already gone through this and come out the other side smiling it would undoubtedly make my life a lot less painful since Im sure otherwise to order the wrong inductors and caps from Parts Express and will likely have to go through the whole process again, plus freight of the same amount repeated!

Thanks in advance for any help (or indeed direction to a link) someone experienced in B200/Alpha mating can give me.

Luigi

[JohnR]

Hi Luigi - I'm just wondering if you have considered an active setup - it would save a lot of messing around with large-value caps and inductors.

BTW: nice avatar, is it your bike?

[Luigi]

Hi John
Nope, hadn't considered active, other than the plate amp I already use for my OB subwoofer.
What are most people using in this situation? Would that mean I keep the B200s as they are, and have another feed from the preamp going to an amp with an active crossover?

In my other life, I test new cars and bikes. That shot was taken at Phillip Island, Australia, turn 5 (Siberia) at the launch of the Ducati 1098R, and the 848 a few years back. I've been there a couple of times with Ducati (even got a few laps on the only Desmosedici down under one time!) and most recently with BMW for the launch of the S 1000 RR, which was a hell of a blast. Pity these bikes don't always translate to brilliant on-road bikes but...

Cheers
Luigi

[Mr Ed]

Luigi,
Here is thread with ton of info, and the B200 seems to be the driver of choice, so it very relivant.
Warning it is 108 pages long...happy reading. There are good tips in there about crossover values.

http://www.audiophiletalk.com/cgi-bin/yabb2/YaBB.pl?num=1176778579

Cheers
Ed

[Luigi]

Thanks Mr Ed
Will peruse this site, which I had not realised even existed, when I get the time.
It will be interesting to see what others have done, not just in terms of component values, but also regarding use of active versus passive solutions.

Cheers

Luigi

[audiotone]

Thanks Mr Ed
Will peruse this site, which I had not realised even existed, when I get the time.
It will be interesting to see what others have done, not just in terms of component values, but also regarding use of active versus passive solutions.

Cheers

Luigi

hi Luigi,

I built the NoBox with B200 and Eminence 15 alpha.
I use the bsc for the B200 and use it full range.
The alphas I connected to a Reckhorn...http://www.reckhorn.com/index.php?ln=en&prod=a403

I also use a spruce phase plug...http://picasaweb.google.be/tony.de.lobelle/20080526VisatonB200SpruceBaffle#5300906780233854994

Nothing left to be desired...(for the last 3 years or so...but never say never...)

success...

[gainphile2]

Hi Luigi

Do you live in Melbourne? If so we can GTG and compare notes. Guys with an OB and motorbike I can relate with 

[Luigi]

Thanks for the input guys.

Does anyone know whether, with the appropriate passive filter to the Alphas, a single 50wpc power amp, like the AKSA Nirvana Plus I have, will be able to drive both the B200s and the Alphas as if it is a single full range OB speaker?

Im not chasing huge volumes, just regular lounge-type listening levels with palpable midrange, articulate bass and clean imaging and staging. With a decent preamp I find there is plenty enough high end information coming from the B200s.

I'd rather shoot for a simple system than go biamping. I have tried to biamp several times before and had trouble integrating everything.

Will look into the No Box solution.

Gainphile2, near Melbourne, but separated by 2500km of Tasman sea!

Current actual owned bike is an Aprilia Falco. in the shop at moment awaiting a new sprag bearing for starter motor. Cost of Aprilia replacement? $1862. Cost of same bit out of US? 50 bucks. I simply do not know how they seriously think they can charge this sort of money and get away with it!

[Badwater]

You have plenty.  I have successfully used a modified Dynaco ST70 (35 watts per channel) to drive a similar set up to ear splitting levels.

[lowtech]

I assume you're aware that you will have a 6db increase in level with the addition of a 2nd woofer.  Not a problem if you're going to drive them actively - just reduce the gain accordingly.  Nobody mentioned it, so I thought I would...

[Luigi]

It has been some times since I purchased an amp that includes an active crossover; mine was a Kiega 250 bought almost a decade ago.

Have things moved ahead much? What active set ups are folk using these days to drive the Alphas?

[-Richard-]

Hi Luigi ~

I am currently using a re-designed Heathkit amplifier (circa 1950) using EL-84 tubes in Triode configuration... 8 potent watts (it has the pre-amplifier built in) with treble and bass controls... bless Sam Kim... to drive the B200's and Alpha 15's joined together with a simple cheap copper coil inductor with a value of .80 for the Alpha's... the B200's run full-range. Believe me... it quite enough to release all of the musical potential those 2 drivers can deliver. Potent 3-D, holographic, room-filling, dynamic, musically alive sound.

I even was able to run these speakers with a 2.5 watt 45 SET amplifier with a "passive" preamp... and the sound was quite satisfying... modest levels to be sure... but sublime where it played.

I will probably be unpopular if I say that the right tube amplifier... preferably triode-based (not necessarily Single Ended... this one is not) will bring out the full potential of this driver combination. At least that is my experience... and the subjective factor of audio must be considered... simply because it recontextualizes everything brought into play in the service of the music.

The steep rise in the B200's, noted by many intelligent sensitive listeners who write their insights on Audiocircle, does not appear in my system. Cheap, "universal" CD player, cheap wire, cheap crossover... simple... the music is glorious.

But... and here everything becomes a bit strange, admittedly... one needs a synergistically sympathetic amplifier... preferably tubes... to realize the full potential of this driver combination in OB's.

Please let us know how things unfold for you, Luigi. Thanks for sharing your insights.

With Warmest Regards ~ Richard

[SteveRB]

My set up is similar to Richard's -- i use an old Eico HF-81 and passive crossover. I am still waiting for my second pair of Alpha's to contour the low end a bit further.

[Luigi]

Okay, I have made some decisions, now that the Alpha15s have arrived.

I'm going to give the passive crossover route a spin, and drive the B200s (with BSC filter in place; no going back there) and the Alphas together with my AKSA amp.

Im still not much closer really to knowing how to put the Alpha15 filter together though.

As it happens I have a few inductors hanging around from old projects. And given so many people seem to be using different values, I thought I'd ask which might work best of the ones I have.

One pair is 2.3mH, the other pair 0.8mH. Im guessing the 2.3mH inductors will be nearest to being about right but really have no clues here at all.

Could anyone help by telling me : should the (whatever value seems best) inductor go across the terminals or in line with the positive?

Im also unsure whether or not I need to use a cap for this crossover? Some don't seem to be using a cap, others do.

If so, is this in line with the positive lead or across the terminals?

The frustrating thing about this is that I have seen the information somewhere in the past but just cannot seem to be able to google my way back to where it was...

And some of these threads are now 200-odd pages long...

And all I need are a couple of cap/inductor values...

Cheers

Luigi
(sounding like a stuck record)

[guest4954]

The 2.3 mH will do best when choosing between the options you have.
In my passive set-up I use 4.1 (B200 full range - Alpha 15 with a low pass filter)
There are people running both the drivers "full-range", i.e. no filters, just the drivers parallel.

IMHO your starting point is better then without inductor. The bigger the value of this inductor in this setup the lower the cut-off frequency of the alpha.

In your case + from amplifier to both one side of the inductor as well as the the plus of the B200. The - of the amplifier to both the minuses of the two drivers.
Connect the other side of the inductor to the plus of the alpha.

My 2cts.

Michiel

[SteveRB]

I am no expert at all, but this site really does help keep the simple stuff straight: http://www.bcae1.com/passxovr.htm

[Luigi]

Damn I hate losing everything before posting.

To recap briefly. Thanks for the help guys; Michiel et al. Managed to sneak the new drivers in under the radar, whipped the old 15s out of a couple of U frames, and inserted the Alphas right into the vacant spaces, same screw holes and all.

Cobbled up the 2.3mH inductors and all was up and running within an evening. Aint OB just the best?

Well, except for the bass.

Just kidding; this is a blast compared with the B200s; dramatic improvement. Much more body, better defined midbass. Easier imaging. All good, and I expect this will be better in a hundred or so hours.

I will continue to use 15 inch sonosub OB bass for subwoofing; this kicks just so well and integrates nicely, and will mean I wont have to go to dual Alphas; couldn't stand the final speaker being even bigger than it already is.

At present the U boxes sit alongside the existing baffle so this weekend will get the skill saw out and chop the existing baffles below the B200 cutout so they can sit atop the U baffles. That way I can get a grip on how to ............design the final solution baffle for the B200 and Alpha.


Will probably just do it simple, in a large isoceles triangle (had to google that one!) about 10 inches at the top and maybe 18 inches at the bottom. With maybe a couple of wings to support the whole thing.

Just a few queries here.

Should I mount the B200 symmetrically in the baffle or site it more towards the outer edge?

How close should the B200 be to the Alpha for best integration?

And how far should the alpha15 be off the floor.

Thanks for help y'all.

And thanks Eminence for this simple cost effective inspired design. Im an alpha believer.

[dgator]

Hi Luigi ~

I am currently using a re-designed Heathkit amplifier (circa 1950) using EL-84 tubes in Triode configuration... 8 potent watts (it has the pre-amplifier built in) with treble and bass controls... bless Sam Kim... to drive the B200's and Alpha 15's joined together with a simple cheap copper coil inductor with a value of .80 for the Alpha's... the B200's run full-range. Believe me... it quite enough to release all of the musical potential those 2 drivers can deliver. Potent 3-D, holographic, room-filling, dynamic, musically alive sound.

I even was able to run these speakers with a 2.5 watt 45 SET amplifier with a "passive" preamp... and the sound was quite satisfying... modest levels to be sure... but sublime where it played.

I will probably be unpopular if I say that the right tube amplifier... preferably triode-based (not necessarily Single Ended... this one is not) will bring out the full potential of this driver combination. At least that is my experience... and the subjective factor of audio must be considered... simply because it recontextualizes everything brought into play in the service of the music.

The steep rise in the B200's, noted by many intelligent sensitive listeners who write their insights on Audiocircle, does not appear in my system. Cheap, "universal" CD player, cheap wire, cheap crossover... simple... the music is glorious.

But... and here everything becomes a bit strange, admittedly... one needs a synergistically sympathetic amplifier... preferably tubes... to realize the full potential of this driver combination in OB's.

Please let us know how things unfold for you, Luigi. Thanks for sharing your insights.

With Warmest Regards ~ Richard

Richard, are you running one or two Alpha 15s per speaker? Also, what is the effect of the .8mh coil? is that a low pass? thanks

[opnly bafld]

Richard, are you running one or two Alpha 15s per speaker? Also, what is the effect of the .8mh coil? is that a low pass? thanks

I believe he is using one Alpha per baffle.
The .8 mH inductor (low pass) should start rolling the 15 out at @ 1500 hz, but a quick glance at the graph on this page will tell you otherwise.
http://www.parts-express.com/pdf/290-407s.pdf

Lin

[dgator]

I believe he is using one Alpha per baffle.
The .8 mH inductor (low pass) should start rolling the 15 out at @ 1500 hz, but a quick glance at the graph on this page will tell you otherwise.
http://www.parts-express.com/pdf/290-407s.pdf

Lin

Yeah, I was stumped when I saw .8mH. Why not low pass the 15A at 200-300hz?