New Monitor 7 owner: intro and questions
Horseshoe
Posts: 11
Hello all. I have been lurking here for a couple months after picking up a pair of Monitor 7Cs a couple months back. I am powering these through a Marantz 2245 (unrestored, but fully functional) to primarily play vinyl through a restored Denon DP 755. The idea here is to build a vintage hi-fi system such as I wanted as a teen and I am pretty happy with this so far.
To date I have made the tweeter upgrade to the O194s and am happy I did. With most music, the speakers sound fantastic. Straight up magical with outlaw country like Willie and Waylon, and perfectly respectable with almost anything else I have thrown at it from classic rock, funk, 80s new wave, acoustic singer songwriter, etc
Where I am running into trouble is in the bass with more aggressive music. Playing moderately loud (11-12:00ish) I get what I would describe as a "kick drum" sound. Bop bop bop bop bop that is hardly musical at my listening position, approximately ten feet away, tweeters slightly above ear level. The sound is less pronounced outside of this position and does not occur when A/Bd against either headphones or a pair of bookshelves (currently using the bookshelves as stands for the monitors as a temporary means to elevate them). Speakers are roughly 20 inches from the back wall, with one speaker roughly three feet from the corner, and the other on open wall. My listening position is a fabric couch with a brick wall behind me, canvas artwork on the wall.
My question: is this bass mess a function of the old capacitors (a recap is forthcoming)? Can I expect this to go away? Or am I missing something else? I haven't pulled the mids to see if a magnet has shifted, but I assume not as they sound wonderful under most circumstances. I assume this isn't the amp clipping because 1) it's at less than half volume, and 2) it sounds fine through headphones and other speakers.
My follow up question is, I can handle this recap, right? I have no soldering experience but I a moderately handy.
Thanks for any input you guys may have. I look forward to getting the most out of these speakers!
To date I have made the tweeter upgrade to the O194s and am happy I did. With most music, the speakers sound fantastic. Straight up magical with outlaw country like Willie and Waylon, and perfectly respectable with almost anything else I have thrown at it from classic rock, funk, 80s new wave, acoustic singer songwriter, etc
Where I am running into trouble is in the bass with more aggressive music. Playing moderately loud (11-12:00ish) I get what I would describe as a "kick drum" sound. Bop bop bop bop bop that is hardly musical at my listening position, approximately ten feet away, tweeters slightly above ear level. The sound is less pronounced outside of this position and does not occur when A/Bd against either headphones or a pair of bookshelves (currently using the bookshelves as stands for the monitors as a temporary means to elevate them). Speakers are roughly 20 inches from the back wall, with one speaker roughly three feet from the corner, and the other on open wall. My listening position is a fabric couch with a brick wall behind me, canvas artwork on the wall.
My question: is this bass mess a function of the old capacitors (a recap is forthcoming)? Can I expect this to go away? Or am I missing something else? I haven't pulled the mids to see if a magnet has shifted, but I assume not as they sound wonderful under most circumstances. I assume this isn't the amp clipping because 1) it's at less than half volume, and 2) it sounds fine through headphones and other speakers.
My follow up question is, I can handle this recap, right? I have no soldering experience but I a moderately handy.
Thanks for any input you guys may have. I look forward to getting the most out of these speakers!
Comments
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Check for air leaks by pushing and holding the passive radiator in while watching the mid-driver, which should pop out then slowly recede over 3 seconds or more.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 -
Aha! So one driver makes consider noise as if air is escaping and recedes much faster than the other. Would I then look to replace that rubber surround?
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I'd be pretty suspicious of an "unrestored" 2245, too. There are a ton (or a tonne, if you're Canadian) of electrolytics (many in or parallel to the signal path) in there that the decades will not have been kind to.
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Oh yeah that 2245 will go in for service soon as I understand that it needs it. But I don't see how it can be the culprit if it isn't happening in the other speakers.
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Aha! So one driver makes consider noise as if air is escaping and recedes much faster than the other. Would I then look to replace that rubber surround?
There is no suitable replacement surround. Try to figure out where the air is escaping from. If the surround is cut/cracked then your best bet is to find a replacement on eBay, etc. If the surround has become unglued at the edge, reglue it.
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 -
Got it thanks. Visually it looks perfect so I will see if I can find an area that came unglued.
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It's also possible that the spider has become unglued from the cone. You'll have to remove the driver to inspect that.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 -
Never mind.
- SDA 2BTL · Sonicaps · Mills resistors · RDO-198s · New gaskets · H-nuts · Erse inductors · BH5 · Dynamat
- Crossover upgrades by westmassguy
- Marantz 1504 AVR (front speaker pre-outs to Adcom 555)
- Adcom GFA-555 amp · Upgrades & speaker protection added by OldmanSRS
- Pioneer DV-610AV DVD/CD player
- SDA CRS+ · Hidden away in the closet
- SDA 2BTL · Sonicaps · Mills resistors · RDO-198s · New gaskets · H-nuts · Erse inductors · BH5 · Dynamat
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Huh. I pulled the mids out to see if I could find any visible issues and was surprised to see both have 1989 dates. The cabinets are pristine on the outside so I assumed that they had been babied but looks like someone had a bit too much fun along the way. On the upside, the magnets have been glued so I don’t need to worry about that!
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I don't think I'd assume that because the magnets are glued that it means none of the voice coils are scraping. Who knows what someone else might do? You should very carefully push in with 4 fingers equally spaced at the joint between the cone and the dust cap and listen/feel for any rough sounds like scraping.
Also, a cracked spider can be VERY difficult to spot sometimes. You may need to have very good light and a magnifier or good eyes anyway and push out evenly with both hands on opposite sides of the cone from the inside while looking for any cracks that might open up. Look through all 4 of the openings because you never know where it will be. Probably will be right near or right at the glue joint between the cone and the spider.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
I have, and I don’t feel anything that doesn’t feel smooth. I don’t understand the term spider though. Is this the rubber surround or something else? Thank you for your help.
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It's the woven corrugated circle towards the rear.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 -
For reference
Home Theater/2 Channel:
Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer
dhsspeakerservice.com/ -
Got it. Thanks!
