The HiFi and Home Theater thread...what gear are you listening to?

[ilitig8]

Phase cancellation due to cabinet modal emanation could play into it as I'm sure you already realized, however, if your slope is at 2nd order, that is usually 12 db per octave and could be compounding the panel resonance issue. A 24db slope or better is usually best for integration as I have found. 2nd order harmonics/reflections would bring it into the room at the 300hz region you're describing as well.

The impedance of the cabinet tuning may just be adding to the issue. It's a perfect storm.

If you go active, go at least 24db per and cross and corner brace the cab. If you haven't already, don't use MDF. It was only brought into play for convenience and is horrible acoustically. Use plywood or real wood for a 1" thick cab and at least a 1.5 baffle if at a 10" driver or above.

Cabinet resonance isn't much of an issue, certainly not in the pass band. The spectral decay shows some low level modes on the sidewalls directly adjacent to the driver at about 475hz but they only manifest themselves (at any appreciable level) when the woofer is driven full range when run within its passband they are essentially non-existent. The bass cabinet is probably more inert than most anything available commercially. I use my semi-secret 3 piece laminate which is just over 1.75" thick for everything but the baffle, the baffle is a 4 piece laminate just over 2.5" thick. It consists of a 14 ply birth plywood made by Appleply (known for consistency and almost no voids) then a layer of 1/4" VERY low density wood and topped with a 3/4" sheet of MDO, I have a 5x9 foot vacuum bag for veneering so with a proper layer of glue and some time in the vacuum bag it becomes one serious piece of sheet goods, weight for a 4x8 sheet is just under 150 pounds. All the joints are lock mitered using a custom made shaper bit (this stuff laughs at every router even a Porter Cable 7519). The cabinet it fairly well braced inside just due to the transmission line. Long story short cabinet resonance shouldn't be an issue here and the decay waterfall bears that out.

I can't wait to start testing with an active crossover it will let me test just about any topology I like in a couple of minutes compared to spending hours modelling and building each passive one and switching phase takes mere seconds. In the end I am almost sure you are correct and that I need a higher order crossover topology, This is frustrating because the whole project was designed around low parts count low order passive crossovers and the driver I picked was one of the few 8 ohm drivers that modeled well with low order and 200hz Xover point AND kept the impedance above 4ohms to keep the overall system impedance reasonable. Had I planned active bass management from the beginning I could have used drivers that modeled better and were more capable in terms of extension and SPL along with being cheaper.

[wschofield3]

Cabinet resonance isn't much of an issue, certainly not in the pass band. The spectral decay shows some low level modes on the sidewalls directly adjacent to the driver at about 475hz but they only manifest themselves (at any appreciable level) when the woofer is driven full range when run within its passband they are essentially non-existent. The bass cabinet is probably more inert than most anything available commercially. I use my semi-secret 3 piece laminate which is just over 1.75" thick for everything but the baffle, the baffle is a 4 piece laminate just over 2.5" thick. It consists of a 14 ply birth plywood made by Appleply (known for consistency and almost no voids) then a layer of 1/4" VERY low density wood and topped with a 3/4" sheet of MDO, I have a 5x9 foot vacuum bag for veneering so with a proper layer of glue and some time in the vacuum bag it becomes one serious piece of sheet goods, weight for a 4x8 sheet is just under 150 pounds. All the joints are lock mitered using a custom made shaper bit (this stuff laughs at every router even a Porter Cable 7519). The cabinet it fairly well braced inside just due to the transmission line. Long story short cabinet resonance shouldn't be an issue here and the decay waterfall bears that out.

I can't wait to start testing with an active crossover it will let me test just about any topology I like in a couple of minutes compared to spending hours modelling and building each passive one and switching phase takes mere seconds. In the end I am almost sure you are correct and that I need a higher order crossover topology, This is frustrating because the whole project was designed around low parts count low order passive crossovers and the driver I picked was one of the few 8 ohm drivers that modeled well with low order and 200hz Xover point AND kept the impedance above 4ohms to keep the overall system impedance reasonable. Had I planned active bass management from the beginning I could have used drivers that modeled better and were more capable in terms of extension and SPL along with being cheaper.

Sounds like you have it covered with the active research, however, don't dismiss panel resonance by looking at spectral decay only. You'd be surprised to see what a cab looks like with speckled laser interferometer modal analysis and how that resonance, no matter how small, manifests itself in 2nd and 3rd order harmonics and frequencies in the room.

No question that the slope is the primary issue but keep the aforementioned one in mind too. Go get em' and please let me know how it turns out.

[Chicolabronse]

Wrong thread!!

[Rdenney]

My stuff is waaaay too old and pedestrian for the OP.

My stereo for music is:

-Magnavox CDB650 CD player, one of the early greats and still great.
-Spectro Acoustics power amp, 100 watts per channel, linear power supply with about a hundred-pound transformer similar to a vintage Flame Linear
-Onkyo Integra P304 preamp
-Technics SL20 belt-drive turntable (belt drive = good)
-Vintage decent Grado cartridge that still sounds good
-Yamaha cassette deck (an ebay replacement for a deceased TEAC Tascam mix-down deck that I had been using for playback)
-New Advent Loudspeakers, one of the true classics of the acoustic suspension class, from 1979. I've replaced the drivers (the foam surrounds had deteriorated)

The original TEAC open-reel deck finally died so profoundly, and I had so little material left on open reels, that I got rid of it. I had replace those freaking relays several times.

My TV sound system is a Kenwood 7.1 surround-sound amplifier (4.1 actually in use), 100 watts per channel, with a nice remote calibrated microphone for automated EQ and balance. Linn Index Plus loudspeakers (front), Polk Audio bookshelf speakers (rear), Boston Acoustics subwoofer. It's good enough for our system, definitely not state of the art. The Linns are the best aspect of that system, but they lacked the punch of the Advents.

Computer: EMU external sound processor, Carver 75-watt power amplifier, Alesis Monitor One near-field monitors. This system is very, very good for what I spent on it.

I bought everything on this list new except for the Yamaha cassette deck.

Probably all of it (except for the TV stuff) could stand to be recapped, just like the audio section of my Ten-Tec Omni V amateur radio transceiver, another classic of the discrete-component era. I'll get to it eventually.

Rick "who plays orchestral tuba parts along with recordings, so the playback is loud, but only when the wife is not home" Denney

[ilitig8]

Sounds like you have it covered with the active research, however, don't dismiss panel resonance by looking at spectral decay only. You'd be surprised to see what a cab looks like with speckled laser interferometer modal analysis and how that resonance, no matter how small, manifests itself in 2nd and 3rd order harmonics and frequencies in the room.

No question that the slope is the primary issue but keep the aforementioned one in mind too. Go get em' and please let me know how it turns out.

Thanks for the insight.

I will certainly update possibly with a build thread once I have them together and I am happy with them. I fear it is going to be quite a while since my first order of business is getting the home theater built (after the woodworking shop).

[scottjc]

The best studio monitors I ever owned were Richard Allen RA8's but I sold my studio set up long ago and, due to recent difficulties, have yet to rebuild the home system I really want.
One day it will all come together again...
Sent from my Nokia Lumia 1020 using Tapatalk

[Quicksilver]

I can't see the brand on the speakers of the "new" system but it looks great! Are they Klipsch? They look like Paradigm also but when I blow up the pic, it gets fuzzy.


.

They are Paradigms. Actually they are the same Monktor 7's in both pictures but grills on and off. Ale them appear different possibly.
Love the setups in this thread.

[wschofield3]

My stuff is waaaay too old and pedestrian for the OP.

My stereo for music is:

-Magnavox CDB650 CD player, one of the early greats and still great.
-Spectro Acoustics power amp, 100 watts per channel, linear power supply with about a hundred-pound transformer similar to a vintage Flame Linear
-Onkyo Integra P304 preamp
-Technics SL20 belt-drive turntable (belt drive = good)
-Vintage decent Grado cartridge that still sounds good
-Yamaha cassette deck (an ebay replacement for a deceased TEAC Tascam mix-down deck that I had been using for playback)
-New Advent Loudspeakers, one of the true classics of the acoustic suspension class, from 1979. I've replaced the drivers (the foam surrounds had deteriorated)

The original TEAC open-reel deck finally died so profoundly, and I had so little material left on open reels, that I got rid of it. I had replace those freaking relays several times.

My TV sound system is a Kenwood 7.1 surround-sound amplifier (4.1 actually in use), 100 watts per channel, with a nice remote calibrated microphone for automated EQ and balance. Linn Index Plus loudspeakers (front), Polk Audio bookshelf speakers (rear), Boston Acoustics subwoofer. It's good enough for our system, definitely not state of the art. The Linns are the best aspect of that system, but they lacked the punch of the Advents.

Computer: EMU external sound processor, Carver 75-watt power amplifier, Alesis Monitor One near-field monitors. This system is very, very good for what I spent on it.

I bought everything on this list new except for the Yamaha cassette deck.

Probably all of it (except for the TV stuff) could stand to be recapped, just like the audio section of my Ten-Tec Omni V amateur radio transceiver, another classic of the discrete-component era. I'll get to it eventually.

Rick "who plays orchestral tuba parts along with recordings, so the playback is loud, but only when the wife is not home" Denney

Rick, it is definitely not pedestrian at all, as a matter of fact, you have some great sounding components in there, especially the SA power amp which you referred to as similar to the Flames Linear (I saw many a 700B go up in flames, well in smoke anyway). The Magnavox CD player is one of the best sounding units from its day and is still good today. That was one of the first dual DAC's instead of the multiplexed ones prior and they built and designed it like the proverbial brick outhouse.

Sorry you had to put the TEAC RtoR down. Was the TEAC cassette deck the old 224?

So, you play the tuba too? You renaissance guy!

The best studio monitors I ever owned were Richard Allen RA8's but I sold my studio set up long ago and, due to recent difficulties, have yet to rebuild the home system I really want.
One day it will all come together again...
Sent from my Nokia Lumia 1020 using Tapatalk

Not familiar with the Richard Allen's and you'll get it together again, for sure!

They are Paradigms. Actually they are the same Monktor 7's in both pictures but grills on and off. Ale them appear different possibly.
Love the setups in this thread.

I thought they were Paradigm's....great speakers! Yeah, some great setups here! Keep em' coming!

[Rdenney]

I've already repaired the power supply in that SA amp once. With a linear power supply, a shorted diode in the rectifier does bad things. (We used to call them rectum-fryers, but that isn't so decorous these days). The filter caps are going again. I have a 250-watt Samson PA amp that I will probably press into service while pondering the SA. It's not as clean at rated power, but that rated power would damage the structure on my house, so I doubt I will notice. Lack of headroom has caused more bad sound than a little extra harmonic distortion.

Rick "who used to be a country-band roadie back in the day" Denney

[wschofield3]

I've already repaired the power supply in that SA amp once. With a linear power supply, a shorted diode in the rectifier does bad things. (We used to call them rectum-fryers, but that isn't so decorous these days). The filter caps are going again. I have a 250-watt Samson PA amp that I will probably press into service while pondering the SA. It's not as clean at rated power, but that rated power would damage the structure on my house, so I doubt I will notice. Lack of headroom has caused more bad sound than a little extra harmonic distortion.

Rick "who used to be a country-band roadie back in the day" Denney

The difference between a PA amp and a consumer oriented one is usually a matter of TIM or transient intermodulation distortion. TIM is much more noticeable at any volume than THD and translates into harsh, grating sound. I would not recommend it for a home based system. Negative feedback is the culprit.

If you want to get the SA filter storage caps redone, I'd do it again, or, let me find you the deal of a lifetime on a replacement. I know lots of good dealers with pre loved gear that are sonic and financial bargains.