How to connect two turntables ?

There's really no easy solution. Switch boxes nearly always create hum, and you'd surely get degraded sound if not worse using a Y cable.

Your solutions are:

a.) buy an outboard phono preamp and plug table #2 into a line level input.
- or -
b.) plug the tables one at a time into the amp.
 
You can do that in a pinch, but it is not ideal at all. When you use a Y adapter you are also leaving both turntables running into the amp at the same time. Technically you have them electronically connected to each other and the signal from one cart is running into both the amp and the other cartridge. It is great if you want to play two different records at the same time, which is trippy and maybe fun.

The best solution is a component selector box, like this one:
http://cgi.ebay.com/Vintage-Realist...291?pt=LH_DefaultDomain_0&hash=item5d2c48411b

I have no connection to them, but I have a few of those lying around for just that. Radio Shack used to sell several of these. A lot of vintage receivers only had a couple of inputs, so you can use these things. A lot of video selector boxes are still available, and you can use those as well as you just use the RCA audio jacks for each unit selector.

Good luck!
 
best way is to get a vintage pre or receiver with 2 phono inputs, they arent too hard to find if you look. and if it has room for two phono's your probably getting a higher quality piece of gear.
 
Years ago I used a DJ mixer. In effect you get two phono preamp sections and a mixing / switching circuit to select what to playback.

Might be cheaper than a decent phono preamp but audio quality might be questionable with low end models. And you waste your amp's phono section.

Depending on your budget and taste, you might want to look for a Technics 9070 preamp. It offers three phono inputs - one is MC - of very good quality, as well as 3 tape loops. Looks a bit industrial but might cost you less than a good quality standalone preamp.
 
Switch them at line level and all should be fine. That of course means you'll need two phono preamps but unless you're a purist at least one of them could be something relatively cheap.
 
A DJ mixer is a godo suggestion, but if you never run them at the same time and the carts are both MM (/HOMC) or both MC, a proper set of Y adapters will do just fine, I've even used this in a club once when one of the phono channels (the fader) crapped out on the DJ mixer. I you don't play them togethet at the same time, no problems.
 
I you don't play them togethet at the same time, no problems.

How? The other cartridge is still in the circuit with the Y adapters. It might not make a huge difference but I cant imagine paralleling cartridges is a good thing to do intentionally. I'd choose separate amps and line level switching first, a phono level switcher second and Y cables as a "I've got nothing else to possibly do" choice. It still might sound fine but it's something to be avoided.
 
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No good, those introduce hum when used with turntables.

If they do, then there are only two things which could cause it:
1. Poor shielding of the switch boxes, caused by (for instance) the box being plastic, and the wiring to the switch inside the box being non-shielded.

2. Incorrect earthing - the earth wires of the two turntables should be both connected to the same amplifier earth point. The earthing for the turntables shouldn't be connected to one of the output lead shields, like Rega and some other manufacturers do - that will cause an earth loop. The only solution for that is to rewire the turntable correctly, with a separate earth wire back to the amp.

There's nothing else inside a switch box that should cause hum - it's exactly the same circuit as the input switch on the amp. One of my preamps which I built has two MM inputs and a MC input. The MM input selector is exactly the same as putting a switch box between 2 turntables, and the MM phono input - that's all it does. And no, when I use 2 turntables into those 2 inputs, as I regularly do, it doesn't hum!
 
Thanks all for the input. I forgot I have a AV switcher that will take up to 4 inputs that I can try. If it does not cause any hum I may be in business.
 
Even if you sort out the grounding issues and have no hum, you are still adding more connectors and switches to the circuit. That won't really make much of a difference with a line-level signal, but with the tiny signal that comes off of a cartridge, you might find the sonic degradation to be audible. An AV switcher is made to handle line-level signals, not the weak signal of a TT cartridge, which is quite sensitive to capacitance, etc... of what it flows through. Your AV switcher will "work", but is likely to noticeably reduce sound quality.

Think of it this way: If someone is carrying a load of 100 bricks (=line-level signal) and you lift one off, they may not notice the difference; it's only 1 percent. But if they are only carrying two bricks (weak phono signal) and you remove one brick, it's a 50 percent change in their load, very noticeable! With a small signal, the less there is in the path, the better.

With a Y-adaptor, the other TT's wiring and cartridge are being put into the circuit, even though the other TT is off. Given the TINY signal coming from a TT, it's definitely a less-than-desirable solution.

Between those two options, the switcher might be the lesser of the two evils...

OR you could just plug-and-unplug each time. The risk to that, of course, is that you'll wear out or break the connectors much faster due to all the physical movement. But you'll get the best sound that way.

But the BEST way would be to have two phono preamps, or a preamp with more than one phono input. No losses due to additions to the wires carrying those tiny signals, plus no wear-and-tear from repeated plugging and unplugging, plus convenient flexibility over what you listen to. The only drawback is that it might cost more.
 
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Can I use the Y adapters since my receiver only has one phono input?

No. One cartridge will see the other cartridge as part of the input and it is too low an impedance. I.E. the cartridge impedance might be 100 ohms, magnetic cartridges should be loaded at 47,000 ohms so with a second cartridge in parallel (that is what a Y-Adapter does) both cartridges are loaded with 99.78 ohms. Not right.

I didn't read the other posts so this might be redundant.
 
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The sytem doesn't see a load from the other one if you don't play anything through it..

I do not agree with this... except as I'll state below.

No. One cartridge will see the other cartridge as part of the input and it is too low an impedance. I.E. the cartridge impedance might be 100 ohms, magnetic cartridges should be loaded at 47,000 ohms so with a second cartridge in parallel (that is what a Y-Adapter does) both cartridges are loaded with 99.78 ohms. Not right.

I agree with this.

Now the exception... If both turntables have muting switches a Y cord might work. The problem is I don't know if muting switches typically short the signal wire to ground or if they open the signal wire so there's no connection to the cartridge. If they ground the signal then Y cord won't work at all. If they open the circuit then a Y cord will work just fine. Both TTs have to have non-grounding muting switches.
 
I tried it and... no good

The AV switcher did in fact introduce some hum and cut down on the audio level. It looks like the general consensus is also to avoid the Y adapters. I guess I will be on the lookout for a 2 phono preamp or receiver. Thanks again.
 
I do not agree with this... except as I'll state below.

I agree with this.

Now the exception... If both turntables have muting switches a Y cord might work. The problem is I don't know if muting switches typically short the signal wire to ground or if they open the signal wire so there's no connection to the cartridge. If they ground the signal then Y cord won't work at all. If they open the circuit then a Y cord will work just fine. Both TTs have to have non-grounding muting switches.

I admit to trying this once. The problem I had with the mute switch was that when one muted (A Dual and it shorted hot to common) it shorted the whole phono input, zero ohms paralleled with any impedance is zero ohms.

Is that what you mean by a non grounding mute switch?
 
Switch boxes nearly always create hum.

"Nearly," perhaps, but not always. I've used the one at the link below and noticed no hum or degradation of sound quality. You may have to experiment with ground-wire patterns, but it works wonderfully, is well built, and it's just $37.50.
-Bob

http://www.esotericsound.com/elect.htm
(Scroll about half-way down the page to the Rek-O-Kut Low Noise Stereo Phono/Aux Switch.)
 
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