RCA y-cable or input selector switch?

z-adamson

Addicted Member
CD player (teac) to two different preamps.

Should I use a y-cable or a switch?

Which is preferable and why?

I understand the advantage of being able to use both preamps simultaneously with the y-cable. This may come in handy one day, but at the moment it is a non issue.
 
On another thread, someone made mention of a preamp/receiver design detail that is used on some units. They apparently short unused inputs to ground to reduce noise, in addition to just not connecting them on through to the amp. If one of your inputs is grounded when unused, then using a Y-cable splitter would allow that to impact the other system's input. Plus, your CD player's output would be driving a dead short. While it is more than likely protected with a series resistor, it still is a 'non-optimal' situation. Using a switch would effectively isolate un-used branches of the circuit.

All that said, I've never run across this situation, as I use Y-cables to split outputs so I can use them in two places at once -- both inputs active and selected. A quick test will tell you.

If one of the systems you're feeding is some distance away, there may be ground or interference issues that come up that may lead you to choosing a transformer-isolated solution or using a distribution amp of some type. Depends on your system architecture...

But hey, at least you're not using the Y-cable to combine two signals! :)

Chip
 
Two things, one for practicality and the other for sound quality.

A good Y cable with built in resistors will cost as much as a good CD or DVD player at the GW, so just buy another CDP.

When putting a system together, just because you can link/connect 500 pieces of gear together with RCA cables doesn't mean you should.
A simple system with the shortest rout a signal has to travel will sound better.
The less Power Cords and IC you have in your system, the less points of entry you have for noise, RFI and ground loops.
 
My suggestion is to start out simple with the Y. If it doesn't do what you want you can escalate to the next level.
 
I use a Realistic Tape Control Center, which will set you back about $20 based on a google search. It is admittedly more than what you need, but would allow for expansion in the future if you wanted.
 
If going the switch way, It's preferable that the both signal and ground switched instead of having the ground common.
 
Explain your system. We are guessing. A possibility: Connect 2 preamps together. TapeRec (out) to Aux (in). Connect CD player to first preamp.
 
Almost all preamps will short out other unused inputs, so using a Y to the line inputs will not work. However, if both preamps have a tape input, you use a Y cable to them and then press the tape monitor in for the one you want to listen to.
 
If you care about sound quality, avoid using a Y adapter as it will sum the metrics of both cables at either end.

What's your scenario for using two preamps?
 
If you care about sound quality, avoid using a Y adapter as it will sum the metrics of both cables at either end.

What's your scenario for using two preamps?
hk725 > citation 16a
hk725 > hafler 220

At the moment I have 1 CD player for the two systems. If there is a viable means of running both systems with 1 cdp, great.
 
FYI, and I probably should have mentioned this before, I am currently using a cheap switch. Seems to be working ok at the moment, but I would like a better long term solution.
 
At the moment I have 1 CD player for the two systems. If there is a viable means of running both systems with 1 cdp, great.
I would vote for connecting the CDP to the first preamp and source the second via the tape outputs from the first which is essentially a buffered unity gain circuit.
 
I would vote for connecting the CDP to the first preamp and source the second via the tape outputs from the first which is essentially a buffered unity gain circuit.
I will give this a go.

If I want to use preamp #2 and not preamp #1 (the preamp with the cdp connected to it) does preamp #1 need to be turned on?
 
If I want to use preamp #2 and not preamp #1 (the preamp with the cdp connected to it) does preamp #1 need to be turned on?
Yes.

That's the only way to get the active buffer to reduce the cumulative challenges of the y-adapter scheme.
 
Yes.

That's the only way to get the active buffer to reduce the cumulative challenges of the y-adapter scheme.
Just rewired things this way....cdp > first hk725 aux in > first hk725 tape out > aux in of second hk725.

hk725 = harman kardon preamp

I can listen to the cdp through the second hk725 with the first hk725 turned off or on.

Are you saying it will work with the first hk725 off, but I loose the active buffer? In other words, it works either way, but it is preferrable to have both preamps on when listening to only the second preamp?
 
I can listen to the cdp through the second hk725 with the first hk725 turned off or on.

Are you saying it will work with the first hk725 off, but I loose the active buffer? In other words, it works either way, but it is preferrable to have both preamps on when listening to only the second preamp?
Experiment for yourself. Buffering can be a good thing depending upon the impedance values of your components.
 
E-Stat: Actively buffered tape outputs are pretty rare on regular stereo pre-amps, integrated amps and receivers, even more so on the more classic designs - in fact most tape-outs just sport a little decopuling via a resistor in series per channel. And the hk725 belongs to that majority that doesn't sport actively buffered tape-outs.

So other than the extra 1k resistors (in this case) in the path to the tape outs, there's little technical difference between a parallel y-connection from the line-outs of the CD player and a connection through one hk725 via tape-outs to the other. However, there's a big difference in functionality, 'cause in the latter case the second(ary) hk725 couldn't be fed by the CD player independently of which source is selected on the first hk725 anymore.

And for the record, Wayner's claim above, that "almost all preamps will short out other unused inputs", to my experience also is anything but realistic.


z-a: Spec says 23 kOhm input impedance for the line inputs - so even driving two hk725s in parallel should be aboslutely no problem for a typical CD player. Especially in case the distances from the CD player to the two hk725s wouldn't be all that short (read: more than some 3 metres max. to each side), you should make sure that the y-cable-solution is made of a reasonably low capacity cable type, though.


Greetings from Munich!

Manfred / lini
 
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