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Thought I'd offer these up for a forum share so others can see if they prefer them over spikes. I removed them from my SDA-converted 8TL's and will not be setting them back up as RTA's.
Chime in if interested and I'll pay to ship US-48. Keep them a few weeks until someone else wants to try them and pass them on.
https://forum.polkaudio.com/discussion/197223/seismic-ball-bearing-isolators?utm_source=community-search&utm_medium=organic-search&utm_term=seismic+ball
Chime in if interested and I'll pay to ship US-48. Keep them a few weeks until someone else wants to try them and pass them on.
https://forum.polkaudio.com/discussion/197223/seismic-ball-bearing-isolators?utm_source=community-search&utm_medium=organic-search&utm_term=seismic+ball
xschop
4 ·
Re: Mid life crisis,Yea or Nay???
If that's a current pic, you took some seriously good care of it!
bcwsrt
2 ·
Re: Monitor 7A Resurrection - Advice Needed
If you are going to go the full baffle replacement route you could go with 1" MDF or maybe even HDF if you know someone who works in a cabinet shop that can get it. You could put a 1/4" chamfer on the outer edge and 1/4" rabbeted construction so that the internal volume remains the same.
I wouldn't worry about chamfering the inside edge of the baffle if you kept the baffle 3/4" and countersunk the drivers. I'd definitely do it with a 1" baffle though.
The SL2500 only came with the M7 Series II which had a different crossover from the 7C. To use the RD0-198 you have to either do the TL mod to the 7C crossover or get the Series II crossover.
PS: It is possible that the passive radiator in the 7C and Series II could have had a different tuning mass compared to the 7B and 7A, because it is based upon the midwoofer it is paired with and the enclosure volume. See if the seller has the passives too.
I wouldn't worry about chamfering the inside edge of the baffle if you kept the baffle 3/4" and countersunk the drivers. I'd definitely do it with a 1" baffle though.
The SL2500 only came with the M7 Series II which had a different crossover from the 7C. To use the RD0-198 you have to either do the TL mod to the 7C crossover or get the Series II crossover.
PS: It is possible that the passive radiator in the 7C and Series II could have had a different tuning mass compared to the 7B and 7A, because it is based upon the midwoofer it is paired with and the enclosure volume. See if the seller has the passives too.
Gardenstater
1 ·
FOR SALE: ATI Amplifier AT3000 3007 7 x 300 Watt
Fully balanced amplifier from ATI made in USA in California. 300 Watts into 8 ohms, 450 Watts into 4ohm. AT3007, SEVEN Channels. Two Toroidal transformers! Heavy duty. Replaced my Emotiva XPA-5 and blew it out of the water. Looking to go in a different direction with Class D and save my back from this 140lb monster.
In good working condition. One binding post is partially broken but workable with banana plugs and bare wire.
ATI is the manufacturer for larger manufacturers such as Outlaw, Mark Levinson, Adcom, Lexicon
ATI's "Pure Balance"® technology introduces a range of models that feature true differential design; balanced from input to output. This design allows the quietest and purest reproduction of the audio signal. Power output is 300 Watts RMS/channel into 8 ohms from 20Hz to 20kHz with no more than 0.03% THD and I.M. distortion.
Remote Trigger:
Activated from 3.3VDC to 24 VDC via a heavy-duty relay.
Protection Circuits:
Optically coupled with full automatic reset.
Toroid Transformers:
40% more efficient than EI type. Separate bi-filar windings for each channel guaranty lower noise and crosstalk.
Circuit Boards:
Double-sided, FR-4 glass-epoxy, computer-grade boards are assembled in-house.
Soft Start Circuitry:
Ultra soft turn on reduces in-rush current to a minimum. Multiple units can be turned on without tripping circuit breakers eliminating the need for sequencing.
Power Transistors:
High-current, bi-polar output transistors with active bias circuits result in effortless operation.
Power Cord:
Detachable, 3-wire cord, 20 amp circuit.
7 Year Warranty:
Parts and labor against defects in parts or workmanship.
Dimensions:
17"w X 8.75"h X 18"d (chassis)
Local Pick up in 92677. ASKING 2300.
In good working condition. One binding post is partially broken but workable with banana plugs and bare wire.
ATI is the manufacturer for larger manufacturers such as Outlaw, Mark Levinson, Adcom, Lexicon
ATI's "Pure Balance"® technology introduces a range of models that feature true differential design; balanced from input to output. This design allows the quietest and purest reproduction of the audio signal. Power output is 300 Watts RMS/channel into 8 ohms from 20Hz to 20kHz with no more than 0.03% THD and I.M. distortion.
Remote Trigger:
Activated from 3.3VDC to 24 VDC via a heavy-duty relay.
Protection Circuits:
Optically coupled with full automatic reset.
Toroid Transformers:
40% more efficient than EI type. Separate bi-filar windings for each channel guaranty lower noise and crosstalk.
Circuit Boards:
Double-sided, FR-4 glass-epoxy, computer-grade boards are assembled in-house.
Soft Start Circuitry:
Ultra soft turn on reduces in-rush current to a minimum. Multiple units can be turned on without tripping circuit breakers eliminating the need for sequencing.
Power Transistors:
High-current, bi-polar output transistors with active bias circuits result in effortless operation.
Power Cord:
Detachable, 3-wire cord, 20 amp circuit.
7 Year Warranty:
Parts and labor against defects in parts or workmanship.
Dimensions:
17"w X 8.75"h X 18"d (chassis)
Local Pick up in 92677. ASKING 2300.
aboroth00
1 ·
Re: Strictly Jazz - Suggestions and a discussion about the music.
My favorite Miles Album, Workin’ With:
I know everyone who likes Jazz, knows Miles Davis, but if you haven’t heard this album, you need to.
I know everyone who likes Jazz, knows Miles Davis, but if you haven’t heard this album, you need to.
headrott
2 ·
Re: An "Identify these trees, if you please" post. :)
One tree I never saw when I lived in NH years ago was the Sycamore. Yet a couple states away they're plentiful. I remember thinking they were huge beech trees when I first moved to southern NE.
motorstereo
2 ·
Re: Westmassguy's Idea: Employing Damping to Mitigate Comb Filtering and Lobing
Just for kicks I thought I would list everything I have done to these speakers:
-Replaced binding posts with Cardas posts on black painted aluminum discs.
-Added a layer of dampening material between crossovers and top of cabinet.
-Westmassguy crossover rebuild with Sonicaps/Mills resistors.
-Sonic Barrier as described above.
-Replaced stock internal wiring with Neotech 14 gauge stranded OCC wire.
-Dynamat on woofer/passive radiator baskets, and inside of binding post plate.
-Epoxied driver magnets.
-Added screws to passive radiators where Polk did not install them.
-Replaced driver and passive radiator gaskets.
-Sealed the cabinet with Loctite Power Grab.
-Filled the inside of the crossover coil spools with Mortite to add weight/mass.
-Filled the inside of the 12 inch Polk Stands with sand and epoxied them together.
-Speakers are decoupled from stands with Herbie's Audio Labs "Big Fat Dots".
-Stands decoupled from wood floor with Herbie's Audio Labs "Little Fat Gliders".
-Periodic application of Deoxit Gold to connections, fuses etc.
In order of impact, the greatest gains came from David's crossover rebuild, the damping work described above, replacing the binding posts, using the Herbie's Big Fat Dots, and replacing the internal wiring. The other stuff adds up as well, especially isolating the crossover from vibration noticeably improves resolution. I wish you folks could hear these speakers, Matthew Polk would get a kick out of them for sure.
-Replaced binding posts with Cardas posts on black painted aluminum discs.
-Added a layer of dampening material between crossovers and top of cabinet.
-Westmassguy crossover rebuild with Sonicaps/Mills resistors.
-Sonic Barrier as described above.
-Replaced stock internal wiring with Neotech 14 gauge stranded OCC wire.
-Dynamat on woofer/passive radiator baskets, and inside of binding post plate.
-Epoxied driver magnets.
-Added screws to passive radiators where Polk did not install them.
-Replaced driver and passive radiator gaskets.
-Sealed the cabinet with Loctite Power Grab.
-Filled the inside of the crossover coil spools with Mortite to add weight/mass.
-Filled the inside of the 12 inch Polk Stands with sand and epoxied them together.
-Speakers are decoupled from stands with Herbie's Audio Labs "Big Fat Dots".
-Stands decoupled from wood floor with Herbie's Audio Labs "Little Fat Gliders".
-Periodic application of Deoxit Gold to connections, fuses etc.
In order of impact, the greatest gains came from David's crossover rebuild, the damping work described above, replacing the binding posts, using the Herbie's Big Fat Dots, and replacing the internal wiring. The other stuff adds up as well, especially isolating the crossover from vibration noticeably improves resolution. I wish you folks could hear these speakers, Matthew Polk would get a kick out of them for sure.
Jazzhead
1 ·