Polk monitor 7b diy repair and upgrade.
hammy1750
Posts: 20
I have a pair of Polk monitor 7B's that I use as my main speakers but there was a surge that fried my amp and in turn my speakers so I have repaired (it was beyond my capabilities so I took it to a shop. Shout out to pro tech repair) and now its time for the speakers and my goal is to repair and upgrade them with solen caps along with milles resistors. I was wondering if I could get any advise past the basic it needs to be done.
Comments
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What's "fried" on your speakers?
For caps, the majority here favor Sonicaps, www.soniccraft.com . They also carry Mills resistors. For a slightly lower cost option, Clarity caps are often suggested.
Other recommendations are to use Loctite Power grab to secure the magnets. The glue can fail with age and a wrong bump. The power grab can also seal any seams in the cabinet as needed.
Replace the wood screws holding the drivers with machine screws and hurricane nuts. (There are also "Larry's Rings" from a member here, but they are currently out of stock for a while. These are more handy for SDA speaker where there are many more drivers and screw holes.)
Some people also dynamat the speaker baskets.
If you are not looking to mod these, you may get more hits in the "Vintage Speaker" section. That is a good section to search. -
Thanks. Should I glue the cones if I am getting new one from Polk. The old ones ripped to shreds from the amp. And the caps are 34 and 12 so I don't know what company would make the best capes for the price (my Bridget is less than 80 for all 4 caps) that the budget just for Thebes's caps the full budget isn't less than 200 and preferably less than 180
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Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Thanks. Should I glue the cones if I am getting new one from Polk. The old ones ripped to shreds from the amp.
Woah. Can you post pictures?
Edit: Unless you mean "ripped to shreds" figuratively and not literally.afterburnt wrote: »They didn't speak a word of English, they were from South Carolina.
Village Idiot of Club Polk -
For one of the cones it was literal also here is a few pics of the speakers taken fully apart. I am curently ordering parts for the repair.
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If any one wants I can't make a video because i some what know what I am doing (that's a very big some what) and other people could watch and if any one decide they want to do the same upgrade/repair they could se what I didn't wrong and do it better. Just like this post or comment if you want a video of the build.
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Man that had to of had some SERIOUS voltage go through it. Are the inductors melted? What does the pcb look like?
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the coils were chard black and the one that blew out was not in one peace (i don`t have any pics of the part its all in the trash) the one that stayed in i think only stayed in because it melted to the cavity it sits in.
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the parts for repair are in the mail so here is a current parts list for the
'budget repair' budget as in 200 for the whole thing (not replacing tweeters they some how survived... i hope) every thing but The speaker cones where ordered on amazon.
2x mills 2.5 ohm 12w resistors
2x mills 4.5 ohm 12w resistors
2x solen 33uF 400v capacitors
2x solen 12uF 400v capacitors
20ft Harmony audio 4 gauge black wire
2x duel fuse holder (cheep Chinese no brand)
2x Parts express wire terminals (2 pairs)
2x Polk speaker cones for the 7-bs
There might be More parts but I can't think of them right this second burn i will update this if I remember (I am as of now not ceiling the cones but I might in the future I am already at the 200$ budget)
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Also with the voltage it looks like it sent 1200 Vdc into the speakers. It's a late 1970's ps audio elite inatagrated 55 watt amp and a house wired in the late 50's to early 60's. a power surge went threw the amp. It blew the fuse on literally all of my equipment except The speakers and the amp. So everything was unharmed exept the speaker said and the amp where booth need to be total the rebuilt. (I really need a surge protector)
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let us know how you like the Solen caps in the high pass. Many have tried and taken them out because of shrill screechy uncomfortable sounds.
Those might be BIG CAPS space will be at a premium. Try to leave the resistors up off the board for better airflow around. -
I have a very warm amp so I'll post how it sounds (I will also record it playing) any segestions on songs to run threw it?
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^^Anything sung by Yoko Ono.The best way to predict the future is to invent it.
It is imperative that we recognize that an opinion is not a fact. -
Also, normally people delete the fuse block. It didn't seem to help you anyway.
H9"Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul! -
I have a very warm amp so I'll post how it sounds (I will also record it playing) any segestions on songs to run threw it?
I think you meant to say you HAD lol so warm it toasted your speakers almost to the point of inferno
just teasing So what will you be driving the speakers with now? -
Same amp I had it full restored (more of a compleate rebuild with every part replaced) but it's all new original parts and I kept it's great sound shout out to pro tech repair in Akron Ohio USA they did a great job
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A complete rebuild with every part replaced and it's still all original? An oxymoron there. No need to post a video.
H9"Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul! -
It's all original parts from the 70's for the amp just the parts have never actually been used.
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welp that just my luck. I get the speakers working and they sounded Amazing not harsh at all and after about 20 min of playing (i was half way threw side A of tubular bells) when the left Chanel of my newly redone amp heavily distorts. so basically it might be a short time until i can get some music pumping threw the new parts.
i do not be leave it was the shops fault it sounds like a dud cap or loose wire. (the distortion sounds like the mid to highs oscillating on and off and the sound is to distorted) but i tested the speakers and there both work great i just don`t have an amp to drive them now. -
Umm and how is that not the shops fault if they did a complete rebuild? Many shops will run the repair for many hours(days) through tuff loads to make sure their work is satisfactory.
Hopefully this amp is still under warranty from said shop. -
my current plan it to (when the amp is fixed) run this list of albums threw the speakers.
Tubular balls by Mike Oldfield
Maynard Ferguson (I don`t know the album name at this second)
wish you where here by Pink Floyd
quadrophenia by The Who
Harder they come by Jimmy Cliff
some random grateful dead songs
this is the list so far there will be more added in a later post -
ya but some times stuff just happens with 30+ old new stock parts
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also to any one attempting a repair or upgrade on a pair of monitor 7b speakers this will help A LOT trust me on this one
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The inductor values for the 7B as follows,
Small - .4mH
Large - 1.55mH
It should also be noted that the leads from the fuse are now severely oxidized on this model and I would suspect all of the vintage Polk speakers with fuses mounted on the binding post cup. This is an issue that should be addressed.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
^^^ The leads on my 1A's were green. I ended up eliminating the fuses.Mojo Audio Illuminati v3>>Quantum Byte w/LMS>>Rpi/PiCoreplayer>> Starlight 7 USB >> Mojo Audio Mystique v2 SE>>ModWright SWL 9.0 SE Signature>>Hafler DH-500 Amp+ (Musical Concepts Fully Modded)>>
SRS 2.3TL (Fully Modded)...Velodyne Optimum 8 subwoofer
1KVA Dreadnought
Marantz SA 8005
Pioneer PLX-1000 Turntable - Shure SC35C/N35X - V15III/VN35HE
Yamaha TX-540 Tuner...Sony BDP-S570
Sony PS4
Separate subpanel with four dedicated 20 amp circuits.
1. Amplification 2. Analog 3. Digital 4. Video
"All THAT IS LOST FROM THE SOURCE IS LOST FOREVER" -
I went with 2 fuses per speaker that are slightly underrated because of my amps problems but for new amps I would agree and eliminate the fuse (the fuses are in cerise)
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I am taking my amp to the shop today so I will be able to get some recordings on the sound quality hopefully soon. I will also record strate into a recording box run after the amp for comparison (it will all be in flak or wave files)
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fuse only protects the tweeter section normally so does the second fuse protect something else?
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7B fuse leads....
Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
From the scamatick the + wire goes strate into a the fuse meaning it protects every thing. Also any one who has a pair of 7b or any pair of 30+ year old speakers I recommend new fuses