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

[nikkoluvr]

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

rpb, by "rigid fiberglass" ; are you using the fiberglass ceiling tiles, or something else?
thanks,
nikkoluvr

[rpb]

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

Yes a 2 liter box does give a little boost below Fc for a 300 hz crossover that may help compensate for a little bit of baffle step.

There's no need to be concerned about getting enough output at 300 hz with most midbasses. The x-over filter will need to reduce the output about -6 dB there anyway, If the mid is 90 dB for example, the baffle may add a little output around 500 hz. The highpass filter will be tweaked to reduce it back to 90 dB. By 350 hz or so, the combination of the filter, and driver response should reduce output (at 350 hz) to 84 dB. I prefer a large midrange chamber that is lined with rigid fiberglass.

[lorenmjones]

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

Yes a 2 liter box does give a little boost below Fc for a 300 hz crossover that may help compensate for a little bit of baffle step.

On a 14" baffle, and crossed at 300hz in a high Q sealed chamber I don't think any BSC will be required. Sim it in 2 liters sealed and also a very leaky box. Watch what happens to the impedance peak to determine your high pass point from the woofer. The rising impedance would make even sims very difficult for the LP to the tweeter. I would confirm whatever PCD sims with a measurement there for sure simply because its smack dab right in the middle of the most sensitive range of hearing. That's the make or break of this project.

[lorenmjones]

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

According to my simulation from BDS a mid placed 34.5" from the floor and 4.5" from the side of the cabinet on a 15" by 42" baffle would be down 1.5db at 300 hz. The woofer does have some rising response that will be exacerbated by the baffle diffraction above baffle loss that would need to be addressed in the filter but I agree it does look like minimal BSC would be needed here.

Here is a pic of the BDS sim

On a 14" baffle, and crossed at 300hz in a high Q sealed chamber I don't think any BSC will be required. Sim it in 2 liters sealed and also a very leaky box. Watch what happens to the impedance peak to determine your high pass point from the woofer. The rising impedance would make even sims very difficult for the LP to the tweeter. I would confirm whatever PCD sims with a measurement there for sure simply because its smack dab right in the middle of the most sensitive range of hearing. That's the make or break of this project.

[Mayhem13]

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

On a 14" baffle, and crossed at 300hz in a high Q sealed chamber I don't think any BSC will be required. Sim it in 2 liters sealed and also a very leaky box. Watch what happens to the impedance peak to determine your high pass point from the woofer. The rising impedance would make even sims very difficult for the LP to the tweeter. I would confirm whatever PCD sims with a measurement there for sure simply because its smack dab right in the middle of the most sensitive range of hearing. That's the make or break of this project.

[lorenmjones]

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

Oops, I need to read more carefully. Distortion measurement was at 94db at 1 meter but the mic was at 10 cm thus the levels would be about 20 db higher at the mic position than at 1 meter. Still the distortion performance is solid and his measurements confirm the on axis and off axis FR from the MFR is accurate. The Klippel data looks quite good although larger excursion obviously won't be an issue for us with this driver.

I guess another advantage of the Faital is the option to cross over to the woofer a little lower if it sounds better that way. On the downside he got the sensitivity at 88.5 but that will probably still be OK.

Well if the actual level was 110 db and higher as the scale on the graph shows, then yes that is pretty darn good. Agreed that 2.5k would be a good target crossover frequency. Also agreed that either tweeter seems able to handle that. Would you think third order electrical on the tweeter?

[lorenmjones]

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

Well if the actual level was 110 db and higher as the scale on the graph shows, then yes that is pretty darn good. Agreed that 2.5k would be a good target crossover frequency. Also agreed that either tweeter seems able to handle that. Would you think third order electrical on the tweeter?

The distortion levels are pretty good given the level of the test and the cost of the driver. CSD shows some energy storage around 2khz. The off axis response starts to droop badly above 2khz which indicates to me for an even power response, a crossover point no higher than 2.5khz. Both the SB26 and DX25 can handle that with steeper slopes.

[Mayhem13]

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

The distortion levels are pretty good given the level of the test and the cost of the driver. CSD shows some energy storage around 2khz. The off axis response starts to droop badly above 2khz which indicates to me for an even power response, a crossover point no higher than 2.5khz. Both the SB26 and DX25 can handle that with steeper slopes.

[lorenmjones]

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

Here is a Vance Dickason test of the Faital 6Fe100.

It looks pretty competent. Distortion performance seems average, not great, with some spikes in the 700 to 1100 range. The 3rd order distortion is not much lower than second order distortion. If the ScanSpeak has better distortion performance would that indicate that it would provide a more clear and detailed midrange? Can the differences in distortion performance be reliably described in any particular way regarding what subjective difference they make on how a driver sounds?

Let me know if you can't see the pdf.

Faital Test Bench VoiceCoil_12_2008.pdf

[lorenmjones]

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

Yeah the Faital is the choice that makes rational sense I'm thinking. I have some irrational desire to use the ScanSpeak but I should probably just find some other project to use that on in the future.

I saw that off axis null acting like a mirror image of the breakup. I was just fiddling around in BDS and it seems possible to get a baffle position that will put a small diffraction null at 3.2k or whatever frequency that breakup is at.

Depends on the low pass point to the tweeter. Anything above 2khz, and you'll need to notch it. But look at the off axis....it's a null at the same freq?......never seen that behavior before. If that's accurate, a slight offset of the mid on the baffle might be exactly a perfect solution.

I wouldn't worry about countersinking that frame. Could go towards aligning the acoustic centers and allow for a classic LR2 crossover. My $$$ would be on the Faital.

[lorenmjones]

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

DX25 would be fine too no doubt. I was anxious to use the SB26 due to it's recent positive attention, and the DX25 is out of stock right now at PE.

Either one would get the job done just fine for sure. Heck, it probably might not require more than a few component changes to swap in one for the other.

It should be back in stock in 2 wks though.

I must have missed something. It looked like the tweet was going to be the DX25, but then it went SB26 somewhere between post #354 and post #359 from the looks of it. No biggie I guess, just have a pair of the DX's sitting here.
thanks,
nikkoluvr

[nikkoluvr]

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

I must have missed something. It looked like the tweet was going to be the DX25, but then it went SB26 somewhere between post #354 and post #359 from the looks of it. No biggie I guess, just have a pair of the DX's sitting here.
thanks,
nikkoluvr

[Mayhem13]

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

Depends on the low pass point to the tweeter. Anything above 2khz, and you'll need to notch it. But look at the off axis....it's a null at the same freq?......never seen that behavior before. If that's accurate, a slight offset of the mid on the baffle might be exactly a perfect solution.

I wouldn't worry about countersinking that frame. Could go towards aligning the acoustic centers and allow for a classic LR2 crossover. My $$$ would be on the Faital.

[lorenmjones]

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

All right. So I think the woofer and tweeter are settled in my mind with ST305 and SB26STCN.

My debate on the mid settles between the ScanSpeak 15M4624G and the Faital 6Fe100

http://www.madisoundspeakerstore.com...5.25-midrange/
The Scan has admirably smooth response, good sensitivity and powerhandling, measured response and distortion that look very good as verified by forum members. On the con side is the price and I guess the 4 ohm impedance could be a con in some ways.

http://www.parts-express.com/faitalp...-ohm--294-1150
The Faital also has a nice smooth response in the required passband, good sensitivity and powerhandling, lower price and it is 8 ohms. Cons include lack of independent measurements, octagonal frame and the mild breakup peak that may need a notch filter.

Any thoughts to help with the decision? I have some irrational desire to use the ScanSpeak, but I think the Faital may be the more logical choice.

Please chime in. Perhaps I'll put a poll up for this as well.

[lorenmjones]

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

I don't know how I was missing that re: the 4 ohm impedance and the 92.5db being 2.83v. Well it should still have adequate sensitivity.

What context did you use it in?

Edit: Oops, I see that you used it in the Nova Forte.

The SS 15M is 90db 1w, it's a 4 ohm driver for sure. The 93db rating is at 2.83v. It's very smooth and extended all the way out to 10khz, very much an optimized mid. I never tested above 100db when I used it but it handled that level just fine crossed at 500hz.