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Turntable stereo imaging issue

Wharfedale Diamond 11 Series

rajis141

Member
Joined
Jun 9, 2012
Messages
97
Points
18
Location
hyderabad
Hi members,
I have purchased a vintage AKAI Ap307 turntable and have peculiar issues with this turntable as follows:

The stereo imaging is lacking in this turntable and the speakers appear to be playing separately.
There is a slight audible channel imbalance, the sound is more towards the left.
The quartz lock decreases the speed instead of keeping it steady at 331/3 rpm
I have done the following already:
Swapping R and L channel - Right speaker sounds louder.
Replacing the TT RCA inter connect - Done and is better than the older cables.
Turntable is leveled OK.
Tonearm balance and cartridge alignment - Perfect
FM channel and other inputs to the amp sound great with superb stereo imaging.
Azimuth - Tried to modify the tracking force and using shim to cartridge - No improvement.
Other turntables sound perfect with this stereo setup.
Tried 4 different cartridges and headshells - No improvement.

I seek Help from the knowledgeable members of this forum to identify the problem , since this is a great turntable but feel that there is some minor tweak required which I am missing out and unable to understand.

Regards
 

jls001

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Joined
Feb 9, 2010
Messages
6,195
Points
113
Location
Mumbai
Do cross-check once more cartridge pin connections: red wire goes to right + pin, green to right - pin, white to left + pin, and blue to left - pin. When one swaps any of these, the imaging and bass sounds very weird.
 

rajis141

Member
Joined
Jun 9, 2012
Messages
97
Points
18
Location
hyderabad
Do cross-check once more cartridge pin connections: red wire goes to right + pin, green to right - pin, white to left + pin, and blue to left - pin. When one swaps any of these, the imaging and bass sounds very weird.
Thanks. Sorry forgot to mention checked the wires of the cart leads. Its perfect.
Also checked the continuity from the tonearm pins to the RCA connector output - No issues there.
I think as per your suggestion will once again check whether the wiring connections on tonearm tally with the cartridge connections.
 

jls001

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Feb 9, 2010
Messages
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Points
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Location
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Yes, shine a strong light from a torch and ensure that red, green, white and blue go to the correct pins. I have made this mistake in the past and now know exactly how it sounds:D
 

kbhuvi

Active Member
Joined
May 17, 2018
Messages
236
Points
43
Location
New Delhi
My suspicion is on the sme connector.The spring loaded pins may not be making adequate contact or maybe covered with oxidation. The soldering of the sme pins to the tonearm wires may also have issues.

For speed issues look towards cleaning the switch and the pitch control with some contact cleaner.
 

rajis141

Member
Joined
Jun 9, 2012
Messages
97
Points
18
Location
hyderabad
My suspicion is on the sme connector.The spring loaded pins may not be making adequate contact or maybe covered with oxidation. The soldering of the sme pins to the tonearm wires may also have issues.

For speed issues look towards cleaning the switch and the pitch control with some contact cleaner.
Thanks. I did clean all the switches for the speed regulator. The TT spins at correct speed without the quartz lock. The moment the switch is depressed the speed decreases. Tried adjusting the VR switches but speed increases drastically. This is the set point at the moment. About 30 rpm with the quartz lock depressed. With the quartz lock released it is 331/3.

For the SME tone arm I have cleaned the contact points with Isopropyl alcohol swab. There is no problem related to connections of pins of the arm since the signal from the pin to the RCA jack is OK.
 

Selvin

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Joined
Jul 15, 2011
Messages
580
Points
63
Location
Bangalore
The following you may try.

1. Place a small piece of mirror on the platter and rest the Tonearm on the mirror. Check the Stylus tip is straight vertical to the plane of platter. You may use a USB microscope or a simple Magnifying lens for this.
2. Left track louder means there is a possibility of insufficient Anti skating force. Recheck once.
3. Check with a Mono record where you are getting image (middle or not)
4. If you have a test record, then connect a 47K resistor across each RCA pins and play 1kHz test track. Measure the output voltage across the resistor. If both channel are equal in magnitude and magnitude is close to the Cartridge spec then the Cartridge/TT side is perfect. If not try with different cartridge, check also the contacts/soldering in the loop..
 

kbhuvi

Active Member
Joined
May 17, 2018
Messages
236
Points
43
Location
New Delhi
Thanks. I did clean all the switches for the speed regulator. The TT spins at correct speed without the quartz lock. The moment the switch is depressed the speed decreases. Tried adjusting the VR switches but speed increases drastically. This is the set point at the moment. About 30 rpm with the quartz lock depressed. With the quartz lock released it is 331/3.

For the SME tone arm I have cleaned the contact points with Isopropyl alcohol swab. There is no problem related to connections of pins of the arm since the signal from the pin to the RCA jack is OK.

If you have already done then
1. Check for leaky capacitors on the mother board
2. Direct drives have variable resistors (VR) for Quartz Lock adjustment. Either they are dirty or have not been adjusted properly. However, the output needs to be monitored while adjusting the VR. The ICs may also have drifted in value.

The connections may show continuity but the current generated by the cartridge is very small and it may not effectively cross the problem area resulting in suppressed sound.

I would suggest to have the some experienced tech look at it. Also consider a rewire of the tonearm to eliminate future issues.

Sorry, cant be of further help. Please do post the reasons when you get the problems sorted out.
 

rajis141

Member
Joined
Jun 9, 2012
Messages
97
Points
18
Location
hyderabad
The following you may try.

1. Place a small piece of mirror on the platter and rest the Tonearm on the mirror. Check the Stylus tip is straight vertical to the plane of platter. You may use a USB microscope or a simple Magnifying lens for this.
>>>Checked. Also checked 4 different cartridges and 4 different headshell.
2. Left track louder means there is a possibility of insufficient Anti skating force. Recheck once.
>>>> Checked and played around with antiskate lower or higher.
3. Check with a Mono record where you are getting image (middle or not)
>>> Need to check
4. If you have a test record, then connect a 47K resistor across each RCA pins and play 1kHz test track. Measure the output voltage across the resistor. If both channel are equal in magnitude and magnitude is close to the Cartridge spec then the Cartridge/TT side is perfect. If not try with different cartridge, check also the contacts/soldering in the loop..
>>> Sorry no test record and cannot do electronic manipulations since i am unaware:confused:
 

rajis141

Member
Joined
Jun 9, 2012
Messages
97
Points
18
Location
hyderabad
If you have already done then
1. Check for leaky capacitors on the mother board
2. Direct drives have variable resistors (VR) for Quartz Lock adjustment. Either they are dirty or have not been adjusted properly. However, the output needs to be monitored while adjusting the VR. The ICs may also have drifted in value.

The connections may show continuity but the current generated by the cartridge is very small and it may not effectively cross the problem area resulting in suppressed sound.

I would suggest to have the some experienced tech look at it. Also consider a rewire of the tonearm to eliminate future issues.

Sorry, cant be of further help. Please do post the reasons when you get the problems sorted out.

Thanks a lot. If the tweaks don not work I will have to seek professional help.
 

kuruvilajacob

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Jul 11, 2011
Messages
1,230
Points
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Location
Kottayam
It may be due to some problem with the cart. Why don't you try another cart and see if you are getting soundstage
 

JayaRaa

Active Member
Joined
Apr 14, 2015
Messages
835
Points
43
Location
India
Thanks a lot. Have seen it.

Great. What phono stage are you using? Is it the same used for all carts tested? Asking as most of the common issues have been dealt with, hence what else could be contributing to this peculiar problem?
 

Gerry_the_Merry

Well-Known Member
Joined
Apr 27, 2010
Messages
668
Points
63
Location
Mumbai
Hi members,
I have purchased a vintage AKAI Ap307 turntable and have peculiar issues with this turntable as follows:

The stereo imaging is lacking in this turntable and the speakers appear to be playing separately.
There is a slight audible channel imbalance, the sound is more towards the left.
The quartz lock decreases the speed instead of keeping it steady at 331/3 rpm
I have done the following already:
Swapping R and L channel - Right speaker sounds louder.
Replacing the TT RCA inter connect - Done and is better than the older cables.
Turntable is leveled OK.
Tonearm balance and cartridge alignment - Perfect
FM channel and other inputs to the amp sound great with superb stereo imaging.
Azimuth - Tried to modify the tracking force and using shim to cartridge - No improvement.
Other turntables sound perfect with this stereo setup.
Tried 4 different cartridges and headshells - No improvement.

I seek Help from the knowledgeable members of this forum to identify the problem , since this is a great turntable but feel that there is some minor tweak required which I am missing out and unable to understand.

Regards
why did you try to modify tracking force for changing Azimuth?
 

rajis141

Member
Joined
Jun 9, 2012
Messages
97
Points
18
Location
hyderabad
Great. What phono stage are you using? Is it the same used for all carts tested? Asking as most of the common issues have been dealt with, hence what else could be contributing to this peculiar problem?
Here again I have used 3 different phono stage: 1) CNC diy 2) Schiit Mani 3) Sedco
 
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