If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Excessive low-frequency noise for some records (AMI G-120)
I'm re-condition an AMI G-120, and now that I have the mech all
working, I'm working on sound quality issues. I've bypassed the internal original amp, but I'm still using the speakers in the juke. So I can rule out an amplifier issue. I've found that, for some records worse than others, there is an inordinate amount of low-frequency "noise" while the records is playing. When I EQ the bass all the way down, it goes away. When I jack the volume up, I get low-frequency feedback. Could this be due to the fact that the turntable no longer has the fabric ring for insulation between the bottom of the record and the metal? I know I need to replace that anyway, but it would be nice to know if that is a good candidate for the causeso I can go on to other things. Thanks in advance, Cory |
Ads |
#2
|
|||
|
|||
Excessive low-frequency noise for some records (AMI G-120)
On Dec 8, 10:11*am, wrote:
I'm re-condition an AMI G-120, and now that I have the mech all working, I'm working on sound quality issues. I've bypassed the internal original amp, but I'm still using the speakers in the juke. So I can rule out an amplifier issue. I've found that, for some records worse than others, there is an inordinate amount of low-frequency "noise" while the records is playing. When I EQ the bass all the way down, it goes away. When I jack the volume up, I get low-frequency feedback. Could this be due to the fact that the turntable no longer has the fabric ring for insulation between the bottom of the record and the metal? I know I need to replace that anyway, but it would be nice to know if that is a good candidate for the causeso I can go on to other things. Thanks in advance, Cory The original ami cartridge is ceramic while most stereo receivers/amps have a magnetic cart input. Usally when one is used on the other, the differance is very noticable. Do you have the turntable grounded to the amp? |
#3
|
|||
|
|||
Excessive low-frequency noise for some records (AMI G-120)
|
#4
|
|||
|
|||
Excessive low-frequency noise for some records (AMI G-120)
On Dec 8, 8:29*pm, Tony Miklos wrote:
That is such an easy amp to rebuild, may as well do it and see what it sounds like. *Also check what indy-gus posted. *Be sure the cartridge matches the amp you are using. *Sometimes an extra ground to the amp will cause a ground loop (bad), that will give you a 60 cycle hum. Sometimes things work better with an extra ground and sometimes they are worse. I was planning to re-build it anyway, I think I only need to replace a couple of the tubes and probably have to re-cap it, since it was sitting in storage for so long (27 years). I'll check the ground issue. The amp is a 1990s era Pioneer stereo receiver I just had lying around that happened to have a phono input. I'll try an extra ground wire (thanks indy-gus) and see what happens. Right now, the only thing connected to the amp is the speaker wire for one channel and the phono input cable. Is this low freq feedback that starts the whole cabinet shaking? *If so first be sure the mech is floating on springs. *Normally it is bolted down tight for shipping then you loosen those bolts again. *If it's bolted tight find the shipping bolts and loosen them. I already had loosened the shipping bolts, I figured those springs were there for a reason! Next, is the turntable motor mounted to soft grommets? *If they are dried out replace them. *Get the right kind, don't install something found at home depot or lowes, they will be too stiff. I think the motor is, yes. I also don't think that is the problem, since I don't hear the noise until a record is actually being played, or sometimes when the armature/cam/records changer is moving records around. When the turntable is spinning, it is quiet. Thanks for the suggestions! Cory |
#6
|
|||
|
|||
Excessive low-frequency noise for some records (AMI G-120)
On Dec 9, 2:54*pm, John Robertson wrote:
Have you loosened the shipping bolts so the mechanism is floating on the spring suspension? This 'sounds' like acoustic feedback to me... Yep, did that a while back. I made sure they were as well. |
#7
|
|||
|
|||
Excessive low-frequency noise for some records (AMI G-120)
I added an extra ground wire, and that didn't seem to help. It didn't
sound like 60-cycle hum anyway. One thing that did help quite a bit was to put a few pieces of felt between the record and the turntable itself. There is supposedly supposed to be a piece of black velvet on the rim, apparently to dampen vibration, and that was long since worn to nothing. The felt really seemed to help, so I'm going to get a replacement turntable fabric ring. |
#8
|
|||
|
|||
Excessive low-frequency noise for some records (AMI G-120)
mrschmitz wrote:
On Dec 9, 2:54 pm, John Robertson wrote: Have you loosened the shipping bolts so the mechanism is floating on the spring suspension? This 'sounds' like acoustic feedback to me... Yep, did that a while back. I made sure they were as well. Have you confirmed no acoustic feedback by using external speakers only? John :-#)# -- (Please post followups or tech inquiries to the newsgroup) John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
#9
|
|||
|
|||
Excessive low-frequency noise for some records (AMI G-120)
With that pioneer amp hooked up are you trying to run it real loud ?.
Turntables in general will do that if you try to get it loud with to much bass |
#10
|
|||
|
|||
Excessive low-frequency noise for some records (AMI G-120)
On Dec 9, 5:54*pm, John Robertson wrote:
Have you confirmed no acoustic feedback by using external speakers only? Actually, I did, on accident. Before I had the amp removed, I just used an old PA speaker (externally) and it sounded about the same. But I do think there is a little bit of acoustic feedback, since it was worse when I have it running through the internal speakers. I have a feeling I was also trying to pump it too loud with the external amp (as Ken G. said below), since at lower volumes it was hardly noticeable. |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
HUGE LOT 78RPM RECORDS FOR SALE-(1000) RECORDS FOR $250 | duty-honor-country | Juke Boxes | 4 | June 17th 06 02:32 PM |
HUGE LOT 78RPM RECORDS FOR SALE-(1000) RECORDS FOR $250 | DeserTBob=professional asshole=posting to myself | 8 Track Tapes | 4 | June 15th 06 11:31 AM |
HUGE LOT 78RPM RECORDS FOR SALE-(1000) RECORDS FOR $250 | Liberal Destruction | 8 Track Tapes | 0 | June 14th 06 02:15 PM |
1951-D frequency | Alan Williams | Coins | 4 | April 19th 05 01:04 AM |