The story of these speakers starts, a sunny February morning back in 1991, when Polk employee of the year Mollie Jones (Rumours says that she also built the space shuttle) lays the finishing touches of Polks finest the the 1.2TL's. Crafted to perfection the speakers were destined for Riyadh, Saudi Arabia where they would be bought by a young and handsome Swede (Now unfortunately fat and middle aged). 12081 miles after they left the factory he and his beloved speakes end up in Shanghai where they continue to amaze people with their stunning sound.
Designed by Matthew and built by Mollie
Chapter 1. The Awakening
In 2007, cruising the web, me and my unmodded 1.2TL's ended up in this forum. Starting with an XO upgrade and new tweeters I realized what I had missed out during the years. This upgrade was covered here http://www.polkaudio.com/forums/showthread.php?t=53970
Now with all components in place and in the right position.
Chapter 2. The Dynamating
Having ordered by far too much Dynamat and a wannabe girlfriend on hand, the mids and PR's were covered.
Yes I still have more available.
Chapter 3. The Inductors
The Inductors were not touched when I did the initial XO upgrade and there seems to be two camps on CP when it comes to inductor upgrades. What convinced me to try was Mathew Polks words
"However, because of the DC resistance of the inductor, the system isn't perfect. I don't recall the DC resistance of these coils but it was high, at least several ohms depending on the model. This means that the SDA drivers will continue to produce some SDA signal even at very low frequencies. Decreasing the DC resistance will definitely improve the bass response of the system both qualitatively and quantitatively. However, before you rush out to buy those Hi-Q replacement inductors be aware of some concerns.
We chose the higher DC air core coils for a couple of good reasons. First, we were always on the edge of acceptability with the impedance of the SDA's. The DCR of these coils kept the minimum impedance high enough for the amps available in those days. Depending on the model, reducing the DC resistance of these coils may take the minimum impedance down to around 2 ohms. If your amp doesn't mind, you shouldn't either."
Two new 16 mH air core inductors were ordered from North Creek Music Systems. http://www.northcreekmusic.com/COILS.html I bought the largest ones they could manufacture in their winding machine with AWG 14 wires. The DCR was dropped from 3.5 Ohm stock to 1.5 Ohm with the new inductor. This is a big chunk of copper (2.7 kg) so it would not fit on the XO plate.
Instead I mounted it on an existing reinforcement bar with some cable straps.
The old coil was left in place as I was too lazy to make a new holder for the circuit board.
I was prepared to switch to the 2 Ohm setting on the amp as MP mentioned that the minimum impedance would be lowered, but thought I give it a try first with the existing 4 Ohm setting. I left the left channel with the existing inductor to get a direct comparison. The result was a much punchier bass from the new inductor. Visably the speaker movement is also larger. Standing in front of the stock speaker it sounds like the loudness is turned on while the upgraded has a clear and distinct bass. I pushed them up to clipping but no signs of the amp giving up so I kept the 4 ohm setting. I guess my McIntosh amps does not mind......
Chapter 4. The WBT's
The stock connectors were replaced with WBT's Topline. They look good with their WBT Germany gold plate. PE screwed up the delivery with some missing parts but "did me a favor!" by sending the parts instead of refunding me. Thank You PE for this exceptional treatment! 5 connectors would have been useless!
Chapter 5. The Rings and Sealing caulk
Having stressed TOOLFORLIFEFAN Larry with the delivery of the rings, they ended up staying in the box for a couple of months (Chapter 6-347). Due to the high humidity in Shanghai I sent them in for black chrome. This is an electrolytic process used for corrosion protection. The drill rings were left unprotected in the box and already show signs of surface corrosion.
The only thing I needed to add for the installation was some washers for the PR's as the holes were too big.
Sealing caulk was purchased from PE http://www.parts-express.com/pe/show...number=269-300
Chapter 6-347. The Wet Sanding
I have never liked the oak look of the speakers and is more of a dark wood or piano black guy. So decision was taken to replace the grill cloth and give them a new appearance. Hawkeye Gordon had an idea of replacing the side board with aluminium so in order to complicate things I opted for piano black with an aluminium inlay. I decided to go for a 20x5 mm bar. Cutting the slot was a breeze with my new router. After some trial cutting I even managed to get the slot in the middle.
New Mellotone Premium Black Speaker Grill Cloth was ordered from PE http://www.parts-express.com/pe/show...number=260-332 I ordered 4 yards and have probably 1 yard left. I could not find a normal stapler to drive through the board so I bought a carpet stapler and used a hammer.
When I removed the front cloth from the right channel I discovered a "spot"........ Two male suspects were quickly rounded up.
Confronted with the evidence they both admitted to the crime. Eventhough none of them could be considered a first time offender I let them off with a slap on the paw. We have all been puppies ........
This was the easy part of the outside appearance upgrade........
Not being a painter I consulted the internet for some advice on piano black. Well, it did not seem so complicated only a few layers of black and clear coat with some wet sanding between......... To make a long story short. This took me 6 weeks to finish. I dont know how many layers of paint I have applied. I probably emptied the store on 2000 grit sand paper. If you want piano black. Find a healthy painter who likes to do it. Pay him whatever he asks for and give him a tip. I am happy when I see the result and I guess it was worth it. But I will NEVER NEVER again try to do piano black myself.
Chapter 348. The Total Damage
SRS-SDA 1.2TL 2797.02 USD
RDO 198 384.00 USD Shipping 125.00 USD
WBT connectors 326.00 USD Shipping 32.47 USD
XO components 722.60 USD Shipping 33.92 USD
16 mH Inductors 228.00 USD Shipping 240.13 USD
Dynamat 201.75 USD Shipping 219.70 USD
Rings 126.96 USD Shipping 145.00 USD
Corrosion protection 29.63 USD
Grill cloth & Sealing caulk 116.75 USD Shipping 62.46 USD
Aluminium bar 5.93 USD
Speaker 2797.02 USD
Material 2111.99 USD
Shipping 858.68 USD (No I don't get Christmas cards from the courier companies)
Total 5767.68 USD
To all the fantastic CP members for ideas, support and parts!
Special Thank You to Bosch for this little tool.