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New member Username: CheezePost Number: 1 Registered: Dec-05 | Hello! I have a problem with a sony PS-LX340 table that I'm trying to set up. For some reason, I have to turn the reciever way up to hear what's on the record. I have true phono inputs on the reciever (sansui "blackstack"). The sound from the record is clear, with good highs but a bit lacking on the lows. I have to turn the reciever up high enough that if it was getting a signal from another device the cops would be at my door in minutes. I tried the turntable in phono 1 and phono 2, but still no good. I tried it connected to another reciever, still nothing. The cartridge seems to be ok since I can hear the music at the cartridge with my ear near it. Any ideas what the problem might be? I don't know the history of this turntable and have no manual. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 6933 Registered: May-04 | It still sounds as if the phono input lacks a (working) pre amplifier section. There would appear to be no RIAA eq or gain applied to the signal from your description of the sound. I would try a phono pre amp in line with the auxilary inputs of the system and you will probably have the signal strength you desire. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 6934 Registered: May-04 | If you know a technician who still has a reverse RIAA eq generator on the bench, you could check the function of the pre amp with this device. |
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New member Username: CheezePost Number: 2 Registered: Dec-05 | Thanks for the input. I should add that one of the recievers I tried it with is known to have good, working phono input. Another thing I just noticed is that while the record is playing, I can tap lightly on the dust cover or table and hear a loud bass thump every time I tap it. Something is picking up the tap I give it, and amplifying it, but it's not amplifying the music on the record. I can't figure out what the heck... |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 6940 Registered: May-04 | If the phono pre amp is known to be in good condition, then I would next suspect you have broken the stylus off the cantilever of your cartridge. The thump is probably normal feedback from a poorly or non existent suspended subchasis. Is the table a solid plinth, non suspended table or does it have a suspension of any type? |
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New member Username: CheezePost Number: 3 Registered: Dec-05 | It doesn't seem to be suspended in any way. It feels like the tip of the stylus is there, but maybe feeling it isn't the way to tell? I can feel a tiny point or sharp bump on the end that grabs my fingerprint when I drag my fingertip across it. Does it sound like it could still be broken off? |
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New member Username: CheezePost Number: 4 Registered: Dec-05 | I just looked at the stylus, and it looks like there is a tiny pin maybe 15 thousandths of an inch long sticking up off the end of the cantilever. Would this indicate an intact stylus? |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 6943 Registered: May-04 | No, not necessarily. You could be feeling the bonding agent that mounted the actual stylus to the cantilever. Using a magnifying device is the best way to ensure the stylus is intact and in good working order. Without any suspension to the table it will be quite susceptible to feedback from both mechanical and air borne vibration. Read through some of the threads on this portion of the forum to get ideas about how to treat the location and mounting of the table to minimize the effects of this problem. With a non suspended table it is often best to remove the dust cover while playing a disc and replace the cover only to keep the table dust free while not being used. |
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New member Username: CheezePost Number: 5 Registered: Dec-05 | Ok, I looked at the stylus with a jeweler's loupe. I can see a cone shaped piece on the end of the cantilever. It has a sharp point at the end, whch I would assume is the stylus? |
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Gold Member Username: Frank_abelaBerkshire UK Post Number: 1090 Registered: Sep-04 | Yes Chuck, that's the stylus. It shouldn't be too sharp since that would indicate wear. It should be conical. As I think about it, I think there's nothing wrong with your setup. Here's why: Phono stages usually have less gain than a typical line input device such as a CD player or tuner. Say for example you play your CD player and to achieve a certain volume, you need to play it at 10 o'clock on the volume dial. Well, typically, you'd have to turn up the turntable input to almost 12 o'clock to achieve the same volume. 12 o'clock with the CD player would be LOUD since volume controls aren't linear usually. This is perfectly normal behaviour in most cases. The reason for the lower volume is signal to noise ratio. It's difficult to make a phono stage that is absolutely quiet and yet can pick up the miniscule signal of a cartridge. Or rather, it's difficult to designa phono stage that can pick up the delicate signal of the cartridge without swamping it with electrical noise (buzzes, hum and radio frequency interference) from the phono stage's own electric circuit. As you noted, tapping on the lid makes a loud bump noise through the system. This tells me the electrical situation is OK. The impulse of your finger generates feedback through the cartridge - the deck acts as a sound board, so you get a solid thump from the system. The cartridge is designed to generate a signal from the tiny oscillations in the grooves of the record. So when your skyscraper of a finger comes around bashing the whole planet (relatively speaking), the cartridge receives one almighty signal which it reproduces faithfully through the system. Ambient noise, be it electrical or mechanical, is a real problem when you're talking of signals in the millivolts so it's easier to make as clean a phono stage as possible while maintaining a half-decent S/N ratio, and let the main amplifier take care of the extra volume. It's a trade off. I think there's nothing wrong with your system, just that you needed this explanation. Incidentally, I found a website with styli for Sony decks. You may want to check it out - http://www.styli.co.nz/sony-players.html Click on your player to get to the stylus. Compare that photo with what you've got as a starter. Regards, Frank. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 6961 Registered: May-04 | If the situation is merely a matter of degrees and not a virtual lack of sound from the table, I would say Frank is correct. It is not at all uncommon for a phono section to need the volume advanced to a slightly higher setting than when using the high level inputs such as CD or tuner. When you say there is a lack of bass, is this just a relative thing or is there simply no bass what so ever? |
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New member Username: CheezePost Number: 6 Registered: Dec-05 | It's more drastic than Franks impression. I can turn the volume all the way up and not hear the music over a vacuum cleaner. Can't hear it very well in the next room even. With the reciever getting a signal from the tuner, it would shake the dishes out of the cabinets at that volume. (actually, it would trip the overload in the reciever). I can't even get an acceptable listening volume. I'm wondering about this pre-amp thing. Could it be that the last turntable that was connected to my reciever had a "built-in" pre-amp, and that is why things worked fine before and not now (if this deck doesn't have a pre amp built in)? The reciever is a Sansui AU-710. I thought this reciever was set up on the phono inputs for the low signal strength that is typical with turntables. As far as the bass issue, I believe it will be resolved at the same time I get my signal strength back where it should be. Thank you folks for taking the time to help me figure this out! Hopefully we'll figure out the problem. |
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Gold Member Username: Frank_abelaBerkshire UK Post Number: 1098 Registered: Sep-04 | Hey, where's Tim (Timn8ter)? He's got an AU-710 according to his website. I'd imagine that the AU-710 has a phono stage built into it. I'd be surprised if it didn't. Then again, the description you've just given us indicates that there isn't a phono stage in the amp. Another way of checking is to plug in the CD player or tuner to the phono input and turn it up to normal volume levelk. If it sounds fine then there's no phono stage in there. If it sounds distorted you're overloading the input because it's expecting a much smaller signal. It should not hurt the amplifier if you do this for under a minute or two. The lack of bass is easily explained too. A phono stage is not just an extra gain stage. It also follows the RIAA curve (typically) which boosts bass more than treble. In order to get a bass signal to fit into a vinyl groove, the bass waveform has to be reduced a lot more than higher frequencies (since they're smaller wavelengths). Therefore, on the way back, you have to expand the bass waveforms a lot more than the midrange and treble waveforms to make them right. Regards, Frank. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 6968 Registered: May-04 | If we are talking about a Sansui AU-710 integrated amp that was made back in the late 1970's, then it has a phono section built in. That doesn't mean the phono pre amp is still in working order and gets us back to my earlier response. How long has it been since you had a table plugged into this amplifier? Has the amp ben in storage since that time? Also, we may be making an assumption that we should not expect to be true. What type of cartridge is mounted on the Sony table? |
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New member Username: CheezePost Number: 7 Registered: Dec-05 | That's the right amp...70's or early 80's. I never had a table plugged into this amp, although the previous owner did. The other amp I have does the same thing with this table, but worked fine with a different table (technics). The Technics table is gone now. I've never used the sony table I have now, and I acquired it secondhand. I've never heard it work. The cartridge on it is a sony VL-45G. The stylus is a sony ND-145G. The "other" amp that I tried this table on is a sony STR-D790. The results were the same, which leads me to believe the problem lies with the table rather than the reciever, unless BOTH recievers require pre-amps on the phono inputs. Oh, the phono 2 jacks on back of the reciever have dummy caps plugged into them. They have a tag that warns not to use them in any other jacks than the phono jacks. I don't know if this is of any significance in determining anything, but when I unplug them I get a loud hum from the speakers, and a good pop when the connection is made when I plug them back in. Come to think of it, that should mean the reciever is made to take the low voltage input from a turntable, or it wouldn't matter if the dummy plugs were plugged into the phono jacks or any other, right? I opened up the table, and there is no amp inside the table at all. The wires from the cartridge run through the tone arm, a junction board, and straight out the back in the RCA plugs and ground wire. I checked the connections in the junction with an ohmmeter and they were fine. I could find no problem, so I put it back together and got the same results. Seems like it should be so simple?!?! I took the cartridge out and pulled the coil assembly out of it and check the coils for continuity...both coils are good and get a similar resistance reading and no short to the case, so the cartridge seems to be good. Frank, I'll try a stronger device plugged into the phono jack for a second and see what I get. |
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Gold Member Username: Frank_abelaBerkshire UK Post Number: 1106 Registered: Sep-04 | Chuck, From your first comments in your last note, this indicates a problem in the turntable. Perhaps something's wrong with the cartridge. It may have had it. regards, Frank. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 6984 Registered: May-04 | "I took the cartridge out and pulled the coil assembly out of it ... " This does not compute. You pulled the coil assembly out of the cartridge? As you can see, there is nothing in the turntable that should impair the level the cartridge outputs. It is possible the cartridge has become demagnetized and therefore is not capable of putting out a higher voltage than you are hearing. And, at this point, if the table is consistently low in level when used with different amplifiers after these same amps have tested OK with another table/cartridge, the only conclusion that seems to make sense would be to declare the cartridge defective. If you feel confident you have eliminated all other possibilities, then that would be my next move. Try a different cartridge and that should give you the answer you need. You don't even have to attach the new cartridge to the arm to find out whether this will solve the problem. Just attach the tonearm wires to the cartridge pins and lightly touch the cantilever when it is pluuged into your amplifier. If the level doesn't increase, I will be surprised and, most likely, stumped. |
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New member Username: CheezePost Number: 8 Registered: Dec-05 | Thanks! I'll give it a try. I'll have to order a cartridge from somewhere, so it may be awhile before I post with results. (radio shack doesn't still carry them do they?) What I meant by taking the coils out of the cartridge is that the cartridge is enclosed in a plastic housing. I popped the plastic off to view the coils and the coil connections. That's where I checked the connections. I hope this solves the problem, and thank you both for your valuable help. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 7008 Registered: May-04 | Radio Shack doesn't stock cartridges but if you have a shop in your area that caters to DJ's, they would probably have a cartridge to try. |