[Chops]

So here's the idea. I've been reading about the slot loaded open baffle design that Nelson Pass has been tinkering with. I find this design quite interesting, so much so that I went and ordered twelve Peerless India W8-12T 12P woofers the other night to do this build. Come to find out via email with Mr Pass, he also bought some of these same drivers, 200 of them in fact!

I don't know for a fact yet, but I'm assuming with the Peerless India drivers slot loaded (which effectively raises the Qts and lowers the Fs of the drivers), I should get decent usable output down into the mid-30's at least, maybe lower. And with six of them per channel, I'm probably looking at an efficiency of around 100dB @ 1w/1m. 

At any rate, I am now looking at "top end" drivers to finish these off. I want to run them between 100-200Hz on up (the lower the better) and something from 6" to 10", maybe 12" if the price is right. The smaller drivers would be fullrange and the 10" and 12" models would be coaxial. My goal is to have them passive with the least amount of components in the crossover and hopefully no need for any EQ.

So far, I've looked at the Dayton PS220 8" fullrange, but read that it needs a LOT of help to make it sound good. I've taken a gander at the TB 1772 8", but it's a bit more than I want to possibly spend. I've considered the Hawthorne Silver Iris. Both the 10" and 15" are the same low-ish price and have read that they sound great, but others have said they aren't refined as other offerings.

As it sits right now, I'm leaning towards the Silver Iris drivers, either the 10's or 15's. They're at a reasonable price of $160 each, which includes the crossovers.

Danny, it would be interesting to know how these drivers stack up against your P-Audio drivers used in the V-2 and Super-V, if those drivers are available for sale separately from the kits, and if so, how much they run. Considering the raving reviews your V series has received makes me really interested in those coaxial drivers you use.

[S Clark]

They're cheap enough, but I've haven't been able to find a Freq/Response curve or an impedance curve for the Peerless India W8-12T.  Without measurements, how do you plan to design a crossover?  Do you have a calibrated measuring system?  Have you measured and built speakers before?
Scott

[Chops]

They're cheap enough, but I've haven't been able to find a Freq/Response curve or an impedance curve for the Peerless India W8-12T.  Without measurements, how do you plan to design a crossover?  Do you have a calibrated measuring system?  Have you measured and built speakers before?
Scott

Well I'm certainly not new to designing or building if that's what you mean. Through future emails with Mr Pass, I'm sure I'll get measurements on these drivers, which in turn will help with the crossover for them. PE has their full T/S parameters at least.

To answer your last question, I have in fact built many speakers over the years, with a great bit of success I might add. I have no way of measuring the drivers themselves, but I do have a calibration mic and SynRTA as well as TrueRTA.

[S Clark]

Well, good luck to you.  I suspect that the project can be pulled off successfully.  Have you used Jeff Bagby's simulator tools.  Maybe they can be of use. 
http://audio.claub.net/software/jbabgy/jbagby.html

[mcgsxr]

I have followed various builds by chops for years, since way back with the 4x15 inch Goldwoods (or were they Pyle's?)! 

I ran Visaton b200 8's on OB for years, and liked what they did.

I have read lots about, but never heard, the Hawthorne drivers.

I have read with much interest about Danny's modified OB speakers, and some day aspire to own those!

[S Clark]

Honestly, I'm baffled as to how I would use the T/S parameters.  Normally, these would be used to design a test box, then take measurements to see what tweeters would work well with the woofers.  I could measure one of your woofers for you on an open baffle, but I'm not sure what good it would do you.  It seems like, you are simply going to have to build the thing out, measure the output of the woofers, and then look at the P-Audio curves to get an idea where to start combining them.  I've overseen probably 50+ speaker builds, but this one is beyond my abilities.  Hopefully, Danny will add his 2 cents. If the P-Audio drivers are for sale separately, Danny will have measurements for them.  Perhaps Mr. Pass could take a look and offer suggestions. 

Scott

[Chops]

I have followed various builds by chops for years, since way back with the 4x15 inch Goldwoods (or were they Pyle's?)! 

I ran Visaton b200 8's on OB for years, and liked what they did.

I have read lots about, but never heard, the Hawthorne drivers.

I have read with much interest about Danny's modified OB speakers, and some day aspire to own those!

Yes, those were the Pyle PPA15's. You know I still have those drivers sitting at my father's house too. Maybe one day I'll build a couple of ripole subs with them. If they played flat to 16Hz in those huge H-frames, they'll definitely dig deep in the ripoles and be a lot more compact. Man, I really miss the sound of those H-frames. I have yet to hear anything that compares to them, and I've had and/or heard a lot since then.

BTW, this pic was taken back in May of 2003!



I keep forgetting about the B200's. I'm just concerned how they cope with the treble and beaming. I like detailed, crisp treble, and the B200 doesn't have a whizzer cone or a phase plug, though Dave (planet10) does offer a phase plug for them.

I've heard a lot of good things about the Hawthorne drivers as well, but there's also been a bit of talk about their midrange quality and the issues around the crossover point to the tweeter. With the P-Audio drivers that Danny uses, they seem to be perfection from what everyone says about their overall sound. I'm not sure if the drivers Danny uses are stock or modified. Plus the fact that Danny is a genius when it comes to crossover design, it could simply be his crossovers that really make the P-Audio drivers since to perfection.

The main concern however is that I want the entire system to be passive and use no EQ'ing to correct things. And I want to run everything off of one amp, my Monarchy Audio SM-70 Pro. I think it would be the perfect amp for this type of speaker system. Low powered Class A amp with high efficiency open baffle speakers... What more can one want? 

With that in mind, I have thrown around the idea of using a couple of those small 25 watt subwoofer plate amps that PE sells for the woofer section and use the SM-70 Pro for the fullrange/coaxial drivers. I could use the crossover in the plate amps for the woofer section and build an inline passive crossover for the SM-70 Pro.

[roscoeiii]

With the bass being taken care of by the Peerless drivers, I'd go with a smaller cone for your wide band driver. Less issues with distortion introduced by larger cones running wide range of frequencies that way.

I have some unused  Fostex 206Es if you are interested. Been meaning to list them. Shoot me a PM if interested. A fairly popular choice for full range designs.

[Chops]

With the bass being taken care of by the Peerless drivers, I'd go with a smaller cone for your wide band driver. Less issues with distortion introduced by larger cones running wide range of frequencies that way.

I have some unused  Fostex 206Es if you are interested. Been meaning to list them. Shoot me a PM if interested. A fairly popular choice for full range designs.

This is true to a point and the 206's are fine drivers, but I want to weigh all my options before pulling the trigger on any one driver yet. I have a pair of FE103E's that have several thousand hours of break-in on them and in their current setup, they sound excellent.

With that said, with the reading I've been doing lately, the consensus seems to be that the larger the fullrange/coaxial driver, the bigger and better the sound stage and imaging. This is one of the great benefits of open baffle designs, and if it means possibly going with a larger driver to get there, then that's what I want.

[roscoeiii]

Consensus? No such thing in the audio world in my experience. Maybe you have found a group of folks in certain threads who sing the praises of larger drivers. But many will disagree and point to the strengths of smaller drivers, especially if your bass is taken care of.   

In particular, for a larger driver driven full range or over a wide band of frequencies break up modes and the distortion that they cause become a real concern. I read a great post about this distortion and the issue of dostortion in loundspeakers in general, but can't seem to find it right now.

[Chops]

Consensus? No such thing in the audio world in my experience. Maybe you have found a group of folks in certain threads who sing the praises of larger drivers. But many will disagree and point to the strengths of smaller drivers, especially if your bass is taken care of.   

In particular, for a larger driver driven full range or over a wide band of frequencies break up modes and the distortion that they cause become a real concern. I read a great post about this distortion and the issue of dostortion in loundspeakers in general, but can't seem to find it right now.

Well like I said, that's just what I've read.

Quite honestly, I'd much rather go with a larger single driver unit myself, such as the 206. It would make for an extremely easy build with the least amount of passive circuitry in the signal.

I might just take you up on that offer for your 206's. Then I'd get those two 25 watt plate amps from PE for the 12 woofers and speak to whomever to help be design a passive inline crossover to go to my Monarchy amp for the 206's. That would mean absolutely no passive circuitry between the amps and drivers... The way it should be.

BTW, that Pass Aleph 30 you have would be a great companion for my project, but probably out of my reach at this point. Though I am in the midst of selling off some gear as well.

[Danny Richie]

Danny, it would be interesting to know how these drivers stack up against your P-Audio drivers used in the V-2 and Super-V, if those drivers are available for sale separately from the kits, and if so, how much they run. Considering the raving reviews your V series has received makes me really interested in those coaxial drivers you use.

I have measurements of the Silver Iris 10 with Hawthorne crossover. The response was pretty rough, and I wound up designing a new crossover for it to fix the response and phase issues. It was not bad, but not in the same league as the P-Audio drivers.

And yes, I will be glad to sell you the P-Audio drivers. I can even make it real easy for you and sell you the drivers with crossovers. All you have to do then is replicate the front baffle size. It sounds like the upper section of a V-2 would work out great for your experiment.

[roscoeiii]

Chops,

THe Aleph has come and gone. It  could be very good, but I might go for a First Watt amp instead if you are looking at Pass designs. I've heard most of the line and all are great. I think the 6moons reviews nail their differences.

Just lemme know if you are interested in the 206s. I also have an extra  MiniWatt amp (long story) that would work great with that speakers. Love those little things.  PM if that'd interest you. I actually preferred the Miniwatts to the Aleph 30 with full range drivers.

[Danny Richie]

Another thing to keep in mind is that you could use our SA-1 plate amp for the lower frequency drivers. It has a transform circuit built into it so it will give you a much more linear output in an open baffle.

Also, while many of those drivers are sold as full range drivers does not mean that they do not require passive components. And most of the ones that I have tested and measured still needed corrective passive components to correct for rising response or break up modes.

[Chops]

Another thing to keep in mind is that you could use our SA-1 plate amp for the lower frequency drivers. It has a transform circuit built into it so it will give you a much more linear output in an open baffle.

Also, while many of those drivers are sold as full range drivers does not mean that they do not require passive components. And most of the ones that I have tested and measured still needed corrective passive components to correct for rising response or break up modes.

Hi Danny,

I forgot about that little SA-1 amp of yours. I just might give those a go. Looks like a couple of my items are selling this weekend and I should be getting some decent cash in hand for them. So you never know, I might be hitting you up soon for a couple of those amps.

As for passive components on the fullrange drivers, I realize there's gotta be some kind of correction circuit involved, but it wouldn't be as bad as having correction circuits along with a passive 2-way crossover in the mix.

On that note, wouldn't it be better to build a passive crossover circuit for line level use BEFORE the amp running the fullrange, maybe even the rising response and break up modes? That way, there's nothing between the amp and voice coil.

[Danny Richie]

As for passive components on the fullrange drivers, I realize there's gotta be some kind of correction circuit involved, but it wouldn't be as bad as having correction circuits along with a passive 2-way crossover in the mix.

It's not any different at all. In fact a well designed two way circuit will maintain a smoother impedance response and be a more consistent load to the amplifier than a single full range driver with a compensation circuit. You just trade off the rising amplitude for the rising impedance.

On that note, wouldn't it be better to build a passive crossover circuit for line level use BEFORE the amp running the fullrange, maybe even the rising response and break up modes?

What you are really talking about is just actively attenuating a peaked area. That is just turning the volume down where it is ringing. The problem is that you don't stop the ringing that way. The break up is still there and the stored energy is still a time smear easily seen in the spectral decay.

There is no free lunch.

And the driver and crossover combo used in the V-2 makes it free of any of those problems. It is a very inexpensive solution for an open baffle design that really sounds great. I highly recommend it.