there is luxman,gold PH-10 ,
Musical Fidelity LX-LPS that has two inputs for 2 turntable at same time that can be selected phono1 or phono2. |
Almarg, I was in a way responding to the (good) point that you made. To do this properly, you need to isolate the lead carrying the "ground" side of the cartridge output (which as you correctly state is merely the other side of the coil from hot) from both chassis ground and the shield around the phono cable. Chassis and shield leads can be connected to the chassis of the switch box and hence back to the preamp. Then switch BOTH sides of the coils of both cartridges, with no ground reference, using a DPDT. It occurs to me that you would need two DPDT switches, one for each channel, or one 4PDT switch. |
Thanks for all of the replies. Doesn't appear to be a safe and secure way to deal with this. I guess those who have multiple armed tables have to deal with this issue as well.
Seems like the best way to deal with this is to keep the two set of RCAs close and continue to manually swap them. I like the idea of getting a second phono stage, thanks.
BTW, although it doesn't matter much, the two tables are in a different system than the one pictured in my virtual systems.
The two tables I am swapping out are a Basis 2500/Vector/Benz Ruby H and Clearaudio ReferenceTG1/Clearaudio Signature M cartridge the Phono Stage is a Thor TA3000.
Thanks All |
Lew -- Not sure what you mean in your last post. There are presumably two rca plugs (for left and right), plus a turntable ground wire, at the phono amp end of the cable from each turntable. The "ground" (non-"hot") side of the cartridge output for each channel is connected to the outer part of the rca plug which corresponds to that channel through the cable shield.
Regards,
-- Al |
FWIW, with respect to Almarg's comment, you should probably use a DPDT switch, so as to switch both sides of the two cartridges simultaneously. There should be no problem with that. The shield would be separated from the so-called "hot" and "ground" outputs from each cartridge. The cartridge ground should not contact chassis ground at all. |
Why don't you call Joule Electra and ask if they can add a second input? I know they offer this feature for the OPS-2 for a very modest cost. I imagine they could do it for the OPS-1 too. |
There are phono stages that have 2 inputs... |
Just buy a second phono cable & twist tie it/both near the rear of the pre amps phono section.
Works for me.
You still may have to make changes @ the pre amps phono section to match the new load. |
I agree with Sid and Lew that each cartridge must absolutely not be allowed to be loaded by the other cartridge. I don't know if the Dynavector DV20X listed in your system description is the high output or low output version, but in each case you'll notice in its specs that the recommended MINIMUM load impedance is around 6 times greater than the cartridge's dc resistance. And besides that, while inductance appears to be unspecified, it too is likely to be significant and would make the loading presented by one cartridge to the other (if they were connected together) frequency dependent.
I'm not sure that a mechanical switch would work very well either. Each channel of a cartridge output should be thought of as a differential, balanced pair of signals, one side of which should be grounded when and only when it reaches the rca input on the phono preamp. A typical mechanical switch will switch one of the two leads of each channel of each cartridge, but will permanently connect the other lead (the one that is on the shield of the turntable's interconnect cable) to the metal enclosure of the switch (through the rca shell), and to the shields of the leads from the other turntable and the other channel, as well as to the shields of the output cables. Which, considering the low signal levels that are involved, would seem to be an invitation to noise, hum, and ground loop problems.
Regards,
-- Al |
Dear Gjrad: The other issue is that both cartridges will see the same load impedance, if both cartridges performs at its best with the same load impedance that will be fine.
I don't know the Joule facilities about, I mean if you can change the load impedance in an easy way through an external control.
Regards and enjoy the music.
Raul. |
As Sidssp inferred, you COULD use a splitter, if you also used a switch, so that the phono circuit was only "seeing" one of the two cartridges at any one time, or to put the same concept in another way, so that the cartridge you are listening to will not "see" the other cartridge in parallel with the phono input impedance. This probably would require an outboard box containing a switch plus two pairs of phono inputs. If you decide to do that, just hard wire the from the internal leads to the one phono input on your preamp (i.e., I would advise you to avoid using yet another pair of ICs with another set of RCAs to do this). |
No, you cannot use a splitter at the input to a phono stage, not even the AudioQuest splitter. The reason is that cart has very low internal impedance. When you put two carts together in a splitter, they are effectively shorting each other out.
Your best option other than replacing the phone stage is to get a high quality mechanical A/B switch. |
Spliiting that will degrade the sound. Keep in mind the siganl coming from the cartridge is a weak and EMI/RFI vunerable signal. If you must do this for budget reasons till you can aquire a second phono stage. You would be best served by looking at AudioQuest splitter blocks, these can be found at most audio web sites. Audioadvisor.com for example. |
