New Project: What Would You Do?

[jocko_nc]

I have a new project in house...

I brought home a pair of "old" two-way monitors last weekend. They are 80's-vintage studio monitors "ROR Audio Research, Flushing NY". Real nice cabinets, finished in piano black. I think these were high-end back in the day, but they are shot now.

Here is what I have:

6 1/2 x 1 two ways. foam surround woofer. dome tweeter.
ported cabinet, standard .50 cu ft layout. port tube.
looks like originally a first-order crossover
filled with fiberglass. no kidding, actual fiberglass.

What would you guys rebuild these with? Which drivers? Crossover? Recommendations? I am thinking the ar.com kit w/o cabinets might be good. What about a first-order crossover? I am a Vandersteen fan, they seem to prefer that route.

I will probably replace (if they come out nice) my son's Partsexpress BR-1 kits with these. Regardless, I will compare the two.

Regards,

jocko

[Feanor]

...

Here is what I have:

6 1/2 x 1 two ways. foam surround woofer. dome tweeter.
ported cabinet, standard .50 cu ft layout. port tube.
looks like originally a first-order crossover
filled with fiberglass. no kidding, actual fiberglass.

What would you guys rebuild these with? Which drivers? Crossover? Recommendations? I am thinking the ar.com kit w/o cabinets might be good. What about a first-order crossover? I am a Vandersteen fan, they seem to prefer that route.

...

There a plenty of possibilities for a .5 cu ft box. Do you want to stick with the current cut-outs or would be willing/able to replace existing front baffle? If the former, you'll be more resticted but likely still have quite a few options. Likely you will have to recalculate the required port length and replace the tube based on the driver you select.

First-order cross-overs have various problems as I understand, (though I'm not an expert). For one thing, the drivers have to be physically placed so that they are in-phase around the crossover frequency. In the case of Vandersteens you will see that the drivers are phyisical on different planes which is necessary for that reason. A standard box baffle does not accommodate this requirement. Also, a first-order demands speaker that have reasonably flat response and freedom from resonances for at least two octaves either side of the cross-over point -- this seriously limits your choice of drivers since many, otherwise very fine drivers don't meet these criteria.

In short, I'd avoid a first-order crossover like the plague!

[jocko_nc]

o.k. Here is the plan, per advice from Madisound folks:

Peerless 6.5 HDS mid-bass
Seas 27*** high

The enclosure and port are smallish as far as calculations would show. ???. I'll probably use a lot of damping material and may stuff the port a bit. I guess that makes it more like an enclosed cabinet. That is fine, I may try these as a center channel (have been in phantom with Vandersteen 2Ce mains) or perhaps satellites with a subwoofer. In either, the Peerless driver should be well suited. I am shooting for mid and mid-bass anyway.

The crossover is still in question, that driver has a wide response into the mids. There are several designs out there, I guess I'll just choose one. I would like to try a less-steep transition. ???.

jocko

[PAT.P]

Jocko This thread belongs in Tweaks ,Mods, DIY

[Feanor]

o.k. Here is the plan, per advice from Madisound folks:

Peerless 6.5 HDS mid-bass
Seas 27*** high

The enclosure and port are smallish as far as calculations would show. ???. I'll probably use a lot of damping material and may stuff the port a bit. I guess that makes it more like an enclosed cabinet. That is fine, I may try these as a center channel (have been in phantom with Vandersteen 2Ce mains) or perhaps satellites with a subwoofer. In either, the Peerless driver should be well suited. I am shooting for mid and mid-bass anyway.

The crossover is still in question, that driver has a wide response into the mids. There are several designs out there, I guess I'll just choose one. I would like to try a less-steep transition. ???.

jocko

Madisound's advice sounds reasonable. More damping material will reduce the required box size.

I would avoid a 1st order crossover for sure. A 2nd order crossover has the next less-steep transition and the next fewest components. For a 2nd order crossover, you ought to reverse the polarity of one of the drivers to keep them in phase with each other. In any case, don't forget that you will need a "Zobel" impedance equalizing filter for the woofer and, most likely, an L-pad to reduce the output level of the tweeter.

[Timn8ter]

I'm not necessarily opposed to first order crossovers (I use them in my designs) but first order crossovers are very difficult to get correct. The biggest challenge is the large range of frequencies that can be produced by both drivers. Having two sources producing the same tones can result in IM distortion, creating harmonics not present in the original signal. While any multi-driver system can have this problem, 1st order crossovers increase the potential. One way to avoid this is to combine the first order (electrical) crossover with the natural roll-off of the driver which can result in a second order (or higher) acoustical roll off. Getting assistance from someone for the crossover design (like the good folks at Madisound) would be a good way to go.

[jocko_nc]

Sorry I missed the DIY section...

I bought parts for a crossover recommended by one of the guys at Madisound. It was tweaked for a similar project, identical mid-bass and a high-end tweeter. It's a hydrid circuit, I don't know enough to describe. One of "Roman's" designs.

Anyway, I'm going to build two pcs. Parts are on the way. I may try one as a center. I may give them to my kid. I may save them for outdoor use at the new house, under the screened porch. I will certainly give them to my friends to try out, leave them scratching their heads as to what they are. I am curious their opinions.

The cutout is 1/4" more than what I have and I have to make allowance for the Seas leads. No problem, MDF surgury is next weekend. I am certainly going to stuff the box well, it is probably undersized and not tuned for a lot of bass reinforcement anyway. I will go for something between ported and enclosed. That was what the original design attempted. I have a feeling these will sound real nice, though will be lacking in the low end. Say, this is fun!

Of course, the next issue is a subwoofer, since I may have a great satellite on my hands... The Lady may even be rid of the dreaded Vandersteens someday. ???.

jocko

[Feanor]

...I bought parts for a crossover recommended by one of the guys at Madisound. It was tweaked for a similar project, identical mid-bass and a high-end tweeter. It's a hydrid circuit, I don't know enough to describe. One of "Roman's" designs.

...

Good luck with your project. You seem to have things well in-hand.

[jocko_nc]

Got these put together this weekend, between football games.

First observations:

I think I was pretty close to the intended results. Very bright sound, though not really harsh. I am a Vandersteen guy, it sounds as though I am listening to the speaker, not the recording, though the sound is great. The Seas is a heck of a tweeter. I got the textile dome, the metal dome would have probably been too much. The mids and high are very pronounced, much more than I am used to. Detail is excellent. These would make a great satellite, the low end is indeed a little lacking, though what is there is very accurate and clean. The cabinets are basically black holes. I am going to take them over to a buddies house to try with a sub. These would probably make a great monitor.

I compared these to my son's Parts Express BR-1 and it was a joke. A sick joke, really. Not that that his speakers are so crappy, these are just a world apart better. The BR-1 sound like a cheesy 12-inch 3-way paper cone job circa 1980. Boomy. Muddy. Sloppy. (I did not recall they were so bad...) Versus the Vandersteens, the two are completely opposite in character, though probably equal. The low end of Vandys is no contest. However, the mids and highs from the project speakers are stunning, they really kick you in the face. If one is into that sound. They will crank, too.

Good job on the driver recommendation and crossover, Madisound. Those guys know their stuff. $200.00 total, I already had the cabinets. Nice quality, 80's-hip black piano finish, very retro. Recycled most of the hardware.

I'll post some pics in the DIY sometime.

A brother of a friend of mine has a boutique AV store in town. I am not sure what lines he carries, but I will try to bring my project in and hook up in the store. That would make for an interesting demo.

jocko

[Feanor]

Got these put together this weekend, between football games.

First observations:

I think I was pretty close to the intended results. Very bright sound, though not really harsh. I am a Vandersteen guy, it sounds as though I am listening to the speaker, not the recording, though the sound is great.
...I'll post some pics in the DIY sometime.

A brother of a friend of mine has a boutique AV store in town. I am not sure what lines he carries, but I will try to bring my project in and hook up in the store. That would make for an interesting demo.

jocko

The sound may mellow a bit with a few dozens of hours of burn-in.

We'll look forward to the pics and further listening impressions.

[jocko_nc]

Update:

I am pleasantly astunded with the detail these things are putting out.

I have been working with Roman at Madisound, taking his advise on the modeling of this design. My existing cabinets were close to ideal dimensions for a two-way monitor. Damping is spot-on. I guess the original designer knew this. I do have a hump in the output at around 1 kHz that I would like to get rid of. This is where some recordings sound a bit off, I presume. (Not that they are bad, they are close to great, just need some more work.) I am going to build a different crossover (per Roman) that is more flat. I will then add series resistors and evaluate overall output of the tweeter. At 1k, the tweeter is not the culprit. I think we are close to a killer sound.

These are definitely monitors. It is easy enough to overtravel the woofer, they are "mid-bass" anyways. They do have a detailed output, however. Peerless is right on calling them 'high definition sound".

Modifications will be next weekend. Stay tuned, if interested...

jocko

[jocko_nc]

o.k. Here we go...

I got the revised crossovers in today. Per Roman, these are more like 1.5 dB flat, the rise at 1 kHz is gone. Big difference, the sound is much better balanced now. I would guess his calculations were right on. The software uses an amazingly accurate model.

If anyone wants to build a detailed satellite or monitor, I would recommend giving this design a try. The drivers are excellent and the crossover seems to be spot-on.

Not sure what I am going to do with these. I need subwoofer now.

Here are some pics:

[jocko_nc]

For those of you interested... Here is the Speaker Workshop sheet Roman came up with for the project: His calculations were amazingly accurate.

jocko

[poneal]

RomanB is a very knowledgeable fellow. He has helped me on numerous occasions while learning Speaker Workshop. My 3 way is based on his Daedalus design. Needless to say I am anxious to finish them up so I can listen to them. I'm sure they sound great. Regards, Paul.