Polk 7A's... are they worth fixing?
Comments
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For this upgrade I wanted to keep costs as low as possible since these are going to be garage monitors. Jantzen had the exact value caps, and Mundorf resistors fit the bill. Also replaced the internal speaker wire and fuses.
They are breaking in now.
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Yes. Fix 'em. Use them in the garage or pass them along to someone in need.Main Family Room: Sony 46 LCD, Sony Blue Ray, Sony DVD/VCR combo,Onkyo TXNR 708, Parasound 5250,
Polk SDS-SRS with mods, CSI 5 center + Klipsch SC2, Polk RT2000P rears, Klipsch KG 1.5's sides, Polk Micro Pro 1000, Polk Micro Pro 2000, Polk SW505, Belkin PF60, Signal Cable Classics,Monster IC's, 2 15 amp circuits & 1 20 amp circuit.
Living Room: Belkin PF60, Parasound HCA2200, MIT ProlineEXP balanced IC's,Emotiva XDA-1 DAC/Pre,Emotiva ERC2 transport,MIT AVT2, Polk LSI 9's. -
Eric,
Looking great man! Hope they sound even better than before. Offer on 6500 mid still applies if you need it let me know.
Travis2-ch System: Parasound P/LD 2000 pre, Parasound HCA-1000 amp, Parasound T/DQ Tuner, Phase Technology PC-100 Tower speakers, Technics SL-1600 Turntable, Denon 2910 SACD/CD player, Peachtree DAC iT and X1asynchorus USB converter, HSU VTF-3 subwoofer. -
"Yes. Fix 'em. Use them in the garage or pass them along to someone in need."
Wowzer, thats profound. -
Conradicles, I have a question for you. On your caps 33uf it says 400v on TrashyTrucker post for his cap are 200 vdc can you tell me what the difference is?
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Oldfatdogs wrote: »Conradicles, I have a question for you. On your caps 33uf it says 400v on TrashyTrucker post for his cap are 200 vdc can you tell me what the difference is?
"What does the Voltage Rating on a Capacitor Mean?
The voltage rating on a capacitor is the maximum amount of voltage that a capacitor can safely store.
Remember that capacitors are storage devices. The main thing you need to know about capacitors is that they store X charge at X voltage; meaning, they hold a certain size charge (1?F, 100?F, 1000?F, etc.) at a certain voltage (10V, 25V, 50V, etc.). So when choosing a capacitor you just need to know what size charge you want and at which voltage.
Why does a capacitor come in different voltage ratings? Because you may need different voltages for a circuit depending on what circuit you're dealing with. Remember, capacitors supply voltage to a circuit just like a battery does. The only difference is a capacitor discharges its voltage much quicker than a battery, but it's the same concept in how they both supply voltage to a circuit. A circuit designer wouldn't just use any voltage for a circuit but a specific voltage which is needed for the circuit. For one circuit, 12 volts may be needed. A capacitor with a 12V rating or higher would be used in this case. In another, 50 volts may be needed. A capacitor with a 50V rating or higher would be used. This is why capacitors come in different voltage ratings, so that they can supply circuits with different voltages, fitting the power (voltage) needs of the circuit.
Take note that a capacitor's voltage rating is not the voltage that the capacitor will charge up to, but only the maximum amount of voltage that a capacitor should be exposed to and can store safely. For the capacitor to charge up to the desired voltage, the circuit designer must design the circuit specificially for the capacitor to charge up to that voltage. A capacitor may have a 50-volt rating but it will not charge up to 50 volts unless it is fed 50 volts from a DC power source. The voltage rating is only the maximum voltage that a capacitor should be exposed to, not the voltage that the capacitor will charge up to. A capacitor will only charge to a specific voltage level if fed that level of voltage from a DC power source.
Keep in mind that a good rule for choosing the voltage ratings for capacitors is not to choose the exact voltage rating that the power supply will supply it. It is normally recommended to give a good amount of room when choosing the voltage rating of a capacitor. Meaning, if you want a capacitor to hold 25 volts, don't choose exactly a 25 volt-rated capacitor. Leave some room for a safety margin just in case the power supply voltage ever increased due to any reasons. If you measured the voltage of a 9V battery supply, you would notice that it reads above 9 volts when it's new and has full life. If you used an exact 9-volt rated capacitor, it would be exposed to a higher voltage than the maximum specified voltage (the voltage rating). Usually, in a case such as this, it shouldn't be a problem, but nevertheless, it's a good safety margin and engineering practice to do this. You can't really go wrong choosing a higher voltage-rated capacitor than the voltage that the power supply will supply it, but you can definitely go wrong choosing a lower voltage-rated capacitor than the voltage that it will be exposed to. If you charge up a capacitor with a lower voltage rating than the voltage that the power supply will supply it, you risk the chance of the capacitor exploding and becoming defective and unusable. So don't expose a capacitor to a higher voltage than its voltage rating. The voltage rating is the maximum voltage that a capacitor is meant to be exposed to and can store. Some say a good engineering practice is to choose a capacitor that has double the voltage rating than the power supply voltage you will use to charge it. So if a capacitor is going to be exposed to 25 volts, to be on the safe side, it's best to use a 50 volt-rated capacitor." -
Thank you sir.
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These things sound soooooo much better with the crossover upgrade. They mate very well with the NAD components. I moved them out a bit further than they were in the pictures. Amazing speakers.:cool:
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awesome set up man. My father had his 1.2TL xovers done with Jantenz caps, Im sure there are better but they sound very nice so far...
Not a bad garage set up at all. -
Glad you got them upgraded. Now you need to get a set of 10's 2-ch System: Parasound P/LD 2000 pre, Parasound HCA-1000 amp, Parasound T/DQ Tuner, Phase Technology PC-100 Tower speakers, Technics SL-1600 Turntable, Denon 2910 SACD/CD player, Peachtree DAC iT and X1asynchorus USB converter, HSU VTF-3 subwoofer.
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LOL... May be the only garage rig I've ever seen with acoustic treatments...chandler9a wrote: »Not a bad garage set up at all.More later,
Tour...
Vox Copuli
Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb
"Death doesn't come with a Uhaul." - Dennis Gardner
"It's easy to get lost in price vs performance vs ego vs illusion." - doro
"There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD -
LOL... May be the only garage rig I've ever seen with acoustic treatments...
I actually put up egg crate style foam (I get it free from work) all over the whole garage. It looks like a huge anechoic chamber.:eek: -
... and it looks like a great place to sip a cool one on a warm, Spring afternoon... with an egg-salad sandwich... :cheesygrin:More later,
Tour...
Vox Copuli
Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb
"Death doesn't come with a Uhaul." - Dennis Gardner
"It's easy to get lost in price vs performance vs ego vs illusion." - doro
"There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD -
So I too have a pair of 7A's that I purchased new, right here in Baltimore where they (used to be) made. I haven't had them in service for a while, as my SIL worked there in the early 2000's and I got a Friends and Family deal on some RT200i's.
My younger son expressed an interest, so I came (back) here to see what would make sense and found this thread.
Seeing as how people are recommending the original drivers, as opposed to sourcing new replacements from Polk, I decided to open one of mine up and take a look.
http://i1222.photobucket.com/albums/dd497/reedg01/Mobile Uploads/20160523_201316_zps263ph4u4.jpg
I now see the insulation I have been reading about, I thought it would be wide open so the Mid could pump the Passive Radiator, but that's obviously not the case.
Here's a shot of the front beforehand:
http://i1222.photobucket.com/albums/dd497/reedg01/Mobile Uploads/20160523_200817_zpskkc9uyty.jpg
and here's the back of the MW -
http://i1222.photobucket.com/albums/dd497/reedg01/Mobile Uploads/20160523_201346_zpspi11ky3o.jpg
Obviously, the gasket material between the Mid driver basket and the speaker body itself has gone bye bye, so I will need to replace that. (With what? Sourced where? This inquiring mind wants to know!)
The Mid moves freely and the surrounding portion that returns the driver to its starting position seems to still be doing it's job.
Recommendations from the collective?
Thanks in Advance.
Glenn -
Not sure if you mean this = You can go to HDepot & buy Armaflex Armacell in a roll & cut strips. Mark where your screw holes are & poke thru before you put screws in-so it doesnt twist up...
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While your at it - if you havent already done this.... Buy a tube of Loctite Power Grab (usually 3.00 a tube) apply a bead around EACH side of the magnet on each woofer. This will help protect the magnet from shifting. The old glue on the magnets are sure to be fragile & easily ready to shift at any time..
