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LP/Vinyl bass vs digital bass

post #1 of 42
Thread Starter 

Last night and today, I examined the difference between the two, driver vibration wise. I have some Polk Audio Monitor 10s and I was playing some digital beats. The drivers come out and back to one set place (about even with the cabinet, like when they are resting/off). In vinyl bass, the drivers were coming out of the cabinet, and back into the cabinet, to different points each time. Is this because the two midbass drivers are trying to hit the 20hz and below freq range (no active subwoofer just radiators mind you), or is this just the way vinyl bass should be? Is this bad? Today I wanted to crank up some America (Album Alibi, big baby head cover), and I almost blew the speakers by letting them go back and forth (wasn't very loud music, but the drivers all of a sudden started spazzing out and squeaking). It seems like I hit the needle (turntable above my head and receiver down below, shook the shelf?) but it they did it until I could reach the mute button, and no visible scratches on the record. It seems like with loud vinyl that contains some fairly serious lows it sends the drivers out of control. Why is this? P.S. There was some fuzz on the stylus that I just blew off with a light breath before the listening session.

post #2 of 42

 

Record warp is famous for causing woofers in ported enclosures to go crazy.

 

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post #3 of 42
Thread Starter 

It only looked a tiny bit warped, not perfect but it didn't look severe. And the enclosure is not ported.

 

http://www.polkaudio.com/homeaudio/products/recent/monitor10/
 

Quote:
Originally Posted by Steve Eddy View Post

 

Record warp is famous for causing woofers in ported enclosures to go crazy.

 

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post #4 of 42

 

Is the woofer in the Monitor 10 have its own sub-enclosure inside the cabinet? Or are the two midbass/mids in their own sub-enclosures?

 

And the record doesn't have to have a severe amount of warp.

 

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post #5 of 42
Thread Starter 

I've looked inside and everything is in the same one big cabinet. I've played records that are warped so bad that the needle moved up and down close to an inch (approximately) and this didn't happen, but that amp seems to have been clipping off the low end cause this amp is more vintage (came with the speakers as a gift) and much better. Could that be it? I've actually seen inside because I took out the bottom 10 inch woofer to test it to find that it was a radiator. I decided to use this amp that came with it to see if it improved the bass and it did greatly. Since I changed, I have noticed this effect with the vinyl I play.

post #6 of 42

 

Ah, ok. So what's going crazy? The 10" passive radiator or the other drivers?

 

By the way, a passive radiator behaves just like a ported speaker. In both cases, the drivers will unload below the tuning frequency.

 

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post #7 of 42
Thread Starter 

All three. The radiator is driven off of the vibrations and changes in air pressure inside the cabinet from the top two midbass drivers (look to be 4-5inch), so all are moving to at least some extent (doesnt have to be noticeable) or none are moving. I thought maybe the midbass drivers, since they are the only actives, were trying to hit 20hz or below since thats about what it looked like they were vibrating at. Don't ask what the tweeter was doing, because I believe that I was too distracted by the drivers to say, sorry. I think it was fine, but im not sure on anything. The drivers were flexing a ton but almost no actual sound was being made (under listening volumes, and then the squeaking/buzzing of what i think was the voice coil). I believe this is called the drivers being unloaded, am I wrong? Scary sight...

post #8 of 42
Thread Starter 

The only way I could blow the bottom subwoofer though is by ripping the rubber though since it is not active, so it was probably fine throughout this "event".

post #9 of 42

 

Yes, that's drivers unloading alright. So clearly you're getting some very low frequency output coming from your analogue source. Phono stages sometimes include a subsonic filter to prevent just this sort of thing.

 

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post #10 of 42
Thread Starter 

OK no wonder this didn't happen on the other amp. It had virtually no low end (i assume clipping). Would you recommend staying vintage with my JVC R-X500 receiver (couldn't find a manual online, good luck if you wanna google it LOL), or go with a new amp?

 

If new, how's this:

 

http://www.stereophile.com/solidpoweramps/678/ Adcom GFA-555

http://www.canuckaudiomart.com/view_images.php?cat=Preamplifiers&catnick=preamplifiers&cfid=64036&image_id=361870 (Some Adcom preamp)

That one was recommended by a fellow Head-Fi'er.

 

How's a Marantz PM-5004 for an integrated? According to Stereophile it has a good phono stage.

post #11 of 42


 

Quote:
Originally Posted by Steve Eddy View Post

 

Yes, that's drivers unloading alright. So clearly you're getting some very low frequency output coming from your analogue source. Phono stages sometimes include a subsonic filter to prevent just this sort of thing.

 

se

This is very true. However, based from experience, I think you vinyl is either warped and/or dirty or your cart is misaligned or might need a new stylus.

 

I have done hundreds of vinyl transfers and have never once engaged the subsonic filter on my any of my preamps or phono stages.

 

Another culprit, although rare, is very low level hum (below the usual 50Hz or 60Hz). This is probably due to something in your analogue front end not having proper grounding. You can find solutions to these problems on google and I would highly recommend you look into eliminating each possible problem one by one.
 

 

post #12 of 42
Quote:
Originally Posted by jtaylor991 View Post

OK no wonder this didn't happen on the other amp. It had virtually no low end (i assume clipping). Would you recommend staying vintage with my JVC R-X500 receiver (couldn't find a manual online, good luck if you wanna google it LOL), or go with a new amp?

 

Wait a minute. What other amp didn't it happen on? Sorry if you'd already mentioned it. But trying to squeeze posts in between work. biggrin.gif

 

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post #13 of 42
Quote:
Originally Posted by LFF View Post

This is very true. However, based from experience, I think you vinyl is either warped and/or dirty or your cart is misaligned or might need a new stylus.

 

I have done hundreds of vinyl transfers and have never once engaged the subsonic filter on my any of my preamps or phono stages.


Yes, that's what I meant, record warp. Didn't mean to say it was on the source material itself.

 

 

Quote:
Another culprit, although rare, is very low level hum (below the usual 50Hz or 60Hz). This is probably due to something in your analogue front end not having proper grounding. You can find solutions to these problems on google and I would highly recommend you look into eliminating each possible problem one by one.

 

If it's below 50 or 60 Hz, I'd say it'd more likely be motorboating.

 

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post #14 of 42
Thread Starter 

I don't know the model number off the top of my head but some 15yr old sony receiver. And I'm sure a new stylus is necessary. I got this setup from the neighbors family when they passed away. They didn't know what to do with it. That was quite a bit before I was a Head-Fi'er and now that I know what I have, I'm gonna take good care of it, and who knows how that stylus has been treated. Recently, I was listening to Americas Alibi album and on the side labeled "Our Side" (they did Our Side and Their Side instead of side one and side two, nice touch lol), there is a number and/or some writing carved into the end part that tells the turntable that the record is over. I put the needle towards the end and muted the speakers to make sure this wouldnt give me any surprises like this event today, and sure enough the needle flew across the paper label for some reason and kept going. I thought maybe I hit it when I was watching closely and jumped at the sight, and it did it again. It jumped the second time too (might have been me reaching to pick the needle up so I didnt damage the stylus). Another time the needle fell off the outer edge when I was starting it on The Beatles' Revolver album, so i barely touched it with my finger and that little push combined with the grooves pushing the needle towards the start of the record at the beginning sent it flying across the record. Both of these times were just accidents that I learned from, and luckily without any damage to the records as much as I've noticed. I have the arm at 1.75 grams weight I think, or maybe 1.5g, and that's all I know how to set. It was at 2g which seemed too high and I read somewhere about 1.5g being good, so I decided it had been fine so I met in the middle. So those two things have most likely given the stylus some grief, and I wont be letting these happen again by my fault, which was really just the Revolver one, and I learned from it. If only this turntable could position itself on the end of the record like my dad's probably damaging Audio Technica ATH-something $80 turntable. About the phono stage, wouldnt there be one built into the receiver? I thought it was required for a turntable to play.

post #15 of 42
Thread Starter 

And whats a vinyl transfer?

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