Is there interest in a large three way "monkey coffin" collaboration?

[andy19191]

Re: Is there interest in a large three way "monkey coffin" collaboration?

Well if you can't trust ScanSpeak specs who can you trust? Their FR plot suppports the 92.5db number.

There have been one or two threads on which manufacturers have reasonably accurate published specs and which do not. You might be surprised. In this case the consistency between the 4 measured drivers looked fine and the author speculated that the specification had been changed. Whether it had changed to what he had measured or from what he measured I do not know. Scan-Speak have a link to the Voice Coil article from their online shop which doesn't exactly clarify things.

[lorenmjones]

Re: Is there interest in a large three way "monkey coffin" collaboration?

All you say about box size and output availability favoring ST305 are clearly true.

I don't know if using the DC380 but paired with what are likely a better midrange and tweeter would result in an inferior design.

My initial thought was that even using the 6Fe100 made it enough different than the "Rockin it Old School" to be worthwhile. The 8" mid crossed at 3.1khz just seems like enough of a compromise in the design that switching only the mid would make it significantly different.

Yeah the PRV Audio mid should do fine and at less than half the cost of the Scan Speak. Soon here I'm going to need to make a decision one way or the other.

Because the change is not made because of a better design, but just to be different from an existing design (Rocking It Old School) and we end up with a lesser design.

Because the DC380 is an inferior driver compared to the ST305.

Because in 100 liters sealed, the f3 of the DC380 is + 45 Hz, less than impressive!

Because it takes 130 Liters for the DC380 to achieve an f3 of + 32 Hz in a vented enclosure, while the ST305 is able to achieve that same f3 in 100 Liters and is capable of + 4-5 dB higher output in this enclosure.

Because the 100 Liter enclosure can be relatively easily modified to satisfy the short monkey coffin (large monitor) aficionados. The 130 Liter enclosure is simply too large for this.

Because I like the Dayton DX25 tweeter and have some on the shelf. That said, I do like the SB26STCN also and wouldn't mind going with those.

Because the "Rocking It Old School" design uses a too large mid in my opinion.

Because if we use the PRV Audio 6MB200 mid which is easier to rebate than the FaitalPRO 6FE100 and is cheaper and we build a tall monkey coffin, the design is sufficiently different from the other design to stand on it's own. Especially if we decide to go with the SB tweeter.

http://www.parts-express.com/prv-aud...-ohm--294-2700

[andy19191]

Re: Is there interest in a large three way "monkey coffin" collaboration?

Is there much wrong with the Dayton PK165-8 midrange (apart from not being able to find it in Europe)?

[Juhazi]

Re: Is there interest in a large three way "monkey coffin" collaboration?

The larger surface area of the cone compliments the change from 4pi to 2pi space as it naturally has better directivity lower in frequency.......something you can't overcome with excursion.

I see this said often, but this is not true! The difference in directivity is way out of the passband of a large woofer of a 3-way speaker. Look at this Edge-simulation - 45¤ horizontally off-axis, even the 18" starts beaming at 500Hz!

[andy19191]

Re: Is there interest in a large three way "monkey coffin" collaboration?

Yeah the PRV Audio mid should do fine and at less than half the cost of the Scan Speak. Soon here I'm going to need to make a decision one way or the other.

What does the frequency response look like? Not so much the wiggles but whether it is flat or starts out low and steadily rises.

[thekorvers]

Re: Is there interest in a large three way "monkey coffin" collaboration?

All you say about box size and output availability favoring ST305 are clearly true.

I don't know if using the DC380 but paired with what are likely a better midrange and tweeter would result in an inferior design.

My initial thought was that even using the 6Fe100 made it enough different than the "Rockin it Old School" to be worthwhile. The 8" mid crossed at 3.1khz just seems like enough of a compromise in the design that switching only the mid would make it significantly different.

Yeah the PRV Audio mid should do fine and at less than half the cost of the Scan Speak. Soon here I'm going to need to make a decision one way or the other.

Inferior at least as far as the woofer is concerned and needing an enclosure 30% larger to achieve the same f3 and with lower output capability.

As far as pro's and con's of the DC380 vs. the ST305 are concerned, the only pro I can think of when using the DC380 is that some people favor the looks of a 15" woofer over a 12" woofer in a monkey coffin. Everything else is a con. Not worth it to me.

For me, the ideal combination would be the ST305, the PRV Audio 6MB200 mid with either the DX25 or SB26. I think that would be the most economical and flexible design and the greatest "Bang For The Buck".

[thekorvers]

Re: Is there interest in a large three way "monkey coffin" collaboration?

Is there much wrong with the Dayton PK165-8 midrange (apart from not being able to find it in Europe)?

It is usable, but seems a little more ragged in the FR than the PRV (don't know how much smoothing is applied to the PRV).

[lorenmjones]

Re: Is there interest in a large three way "monkey coffin" collaboration?

It actually has a rise around 1khz and then drops off above that in a shelf sort of fashion before rolling off above 4.5k

What does the frequency response look like? Not so much the wiggles but whether it is flat or starts out low and steadily rises.

[lorenmjones]

Re: Is there interest in a large three way "monkey coffin" collaboration?

I think your assessments are accurate regarding the woofer. I was mainly trying to cater to what I perceived as people's preferences for a 15" woofer. The 15" Series Two woofer does OK in 100L vented as well, but since it is less efficient it doesn't really give that much greater output. It also costs $35 more.

I am bouncing back and forth way too much here but the ST305 does make a lot of sense.

I am still not sold on the PRV midrange. It probably is a good driver but the lack of anyone using it and giving a good report about it here on the forum is less reassuring. Also, call me shallow, but I don't like the printed logo on the dustcap aesthetically. Some folks here have definitely given good reviews in this thread regarding the Faital mids. Certainly either of those is better bang for the buck than the scan disco.

Inferior at least as far as the woofer is concerned and needing an enclosure 30% larger to achieve the same f3 and with lower output capability.

As far as pro's and con's of the DC380 vs. the ST305 are concerned, the only pro I can think of when using the DC380 is that some people favor the looks of a 15" woofer over a 12" woofer in a monkey coffin. Everything else is a con. Not worth it to me.

For me, the ideal combination would be the ST305, the PRV Audio 6MB200 mid with either the DX25 or SB26. I think that would be the most economical and flexible design and the greatest "Bang For The Buck".

[andy19191]

Re: Is there interest in a large three way "monkey coffin" collaboration?

I was mainly trying to cater to what I perceived as people's preferences for a 15" woofer. The 15" Series Two woofer does OK in 100L vented as well, but since it is less efficient it doesn't really give that much greater output. It also costs $35 more.

The 15" is designed for a bigger box. 125-150 litres with appropriate tuning gives a significantly better bass response for the 15" compared to the 12" in 75-100 litres.

[rpb]

Re: Is there interest in a large three way "monkey coffin" collaboration?

Two of these 4 ohm 5.5" drivers in series will be 90 dB and 8 ohms. Cost for two is $42. Having two mids may help smooth the diffraction ripples.

http://www.madisoundspeakerstore.com/approx-5-woofers/silver-flute-w14rc25-04-ohm-5-1/2-wool-cone/

[lorenmjones]

Re: Is there interest in a large three way "monkey coffin" collaboration?

Welcome back Kim

Those drivers are pretty well regarded from what I understand and would get the job done. Very smooth response for sure. Should be easy for crossover work.

Two of these 4 ohm 5.5" drivers in series will be 90 dB and 8 ohms. Cost for two is $42. Having two mids may help smooth the diffraction ripples.

http://www.madisoundspeakerstore.com...1/2-wool-cone/

[lorenmjones]

Re: Is there interest in a large three way "monkey coffin" collaboration?

That is true. In spite of my earlier mention of the DC380 the ST305 certainly makes the most sense.

So what do we do to make this worth doing as opposed to the "Rockin It Old School". Clearly that isn't a project that gets a lot of mentions or recommendations on the board.

Is just using a smaller mid and a different crossover enough to make this project worth doing as a new contribution to the DIY speaker community?

Would a different tweeter plus a different mid make it worthwhile? SB26STCN?

Would using a more "hifi" marketed mid make it enough different? Scan Disco? A pair of the Silver Flutes? Or just focus on the same basic design ( smaller mid and different crossover) but perhaps executed a little differently in some areas enough different?

The 15" is designed for a bigger box. 125-150 litres with appropriate tuning gives a significantly better bass response for the 15" compared to the 12" in 75-100 litres.

[lorenmjones]

Re: Is there interest in a large three way "monkey coffin" collaboration?

That is true. In spite of my earlier mention of the DC380 the ST305 certainly makes the most sense.

So what do we do to make this worth doing as opposed to the "Rockin It Old School". Clearly that isn't a project that gets a lot of mentions or recommendations on the board.

Is just using a smaller mid and a different crossover enough to make this project worth doing as a new contribution to the DIY speaker community?

Would a different tweeter plus a different mid make it worthwhile? SB26STCN?

Would using a more "hifi" marketed mid make it enough different? Scan Disco? A pair of the Silver Flutes? Or just focus on the same basic design ( smaller mid and different crossover) but perhaps executed a little differently in some areas enough different?

The 15" is designed for a bigger box. 125-150 litres with appropriate tuning gives a significantly better bass response for the 15" compared to the 12" in 75-100 litres.

[Mayhem13]

Re: Is there interest in a large three way "monkey coffin" collaboration?

I see this said often, but this is not true! The difference in directivity is way out of the passband of a large woofer of a 3-way speaker. Look at this Edge-simulation - 45¤ horizontally off-axis, even the 18" starts beaming at 500Hz!

[ATTACH=CONFIG]48342[/ATTACH]

.....and you've missed the point that the larger driver maintains directivity lower in frequency........who care's what happens at 500hz in this design?......a directivity match is already dead much higher with a 5-6" mid. That's not the issue. You can't sim what i proposed and you certainly can't measure it in a closed space where everything we're talking about is in the modal region.

Sometimes it's a good idea to step back from the notions of HiFi and look at what the Pro industry does where output and efficiency are the primary goals. When we're comparing the ST and the DC, we're not looking at sonic perfection.......neither have a respectable BL for that. We're talking extension, power handling, efficiency and affordability. How Loren chooses to prioritize those is up to him.