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Tape outs or rca y cables?

manogeorge

manogeorge

Active Member
I'm new to preamp/amps, I've always used receivers but recently picked up a Hafler 220, Soundcraftsmen PCR800 and a Soundcraftsmen model three preamp. Using only two of the outputs on the preamp I need to run both amps. I currently have them going through my HK intergrated amp and out of the tape outs 1 and 2. I figure there's no benefit from this, but is it any different then just using y cables? The y cables would eliminate about 3 feet of cable so that should be something.
 
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Well, the answer is yes and no.

Yes having two amplifiers plugged into 1 preamp output will reduce the signal to both amps.

If your preamp has an output impedance of 2k ohms (I am estimating on the high side), and both of your amps input impedance is 50k ohms, then you can factor the loss.

The loss of preamp output voltage when connected to 1 50k ohm amplifier would be:

Say the output voltage open load is 2.000 V.
The current through the loads is
2(V)/(2k +50k ohms)= 40uA

The preamp's output voltage is reduced by 40(uA)*2k (ohms) = 80mV, so the output voltage, now that it's plugged into 1 amp is 2.000(V)-.08(mV) = 1.92V
The loss, in dB, is: .354 (dB)

If you plug it into 2 50k ohm amplifiers, the loss is .668 dB

The difference, in dB, between the preamp's output level is .314 dB.

Yes, there's a difference, but not in practical terms.
 
manogeorge said:
I'm new to preamp/amps, I've always used receivers but recently picked up a Hafler 220, Soundcraftsmen PCR800 and a Soundcraftsmen model three preamp. Using only two of the outputs on the preamp I need to run both amps. I currently have them going through my HK intergrated amp and out of the tape outs 1 and 2. I figure there's no benefit from this, but is it any different then just using y cables? The y cables would eliminate about 3 feet of cable so that should be something.
Click to expand...

Jon_Logan said:
You want to "Y" the preamp outputs.

The REC/TAPE Out jacks aren't volume controlled.
Click to expand...

If if you notice what manogeorge posted, it appears that he is using the preamp output to drive the second amplifier (HK) on which he is using the two sets of tape outputs.

If this is the case, then output level of the tape outputs is controlled by the varying output level of the pre-amplifer.

manogeorge, is this the configuration that you have?

If it is, then you are going through a lot of additional electronics, that would not be needed using the "Y" cable. Might actually sound better with the "Y" cables.

Jon_Logan's post re the hard numbers indicates that there would only be a small change in the over all signal that would be supplied to both amplifiers.

As long as the change in level is consistent over the full frequency range, the sound quality should not suffer.

Now. if for some reason this connection scheme should cause a non-linear change in the frequency response, narrow band differences of less than 1dB have been shown to be audible on pink noise sources. This might indicate that a non-linear change of 1 dB or less might be audible when listening to music.

There are other changes that may take place.

These changes are not perceived as changes in loudness, rather they are perceived as changes in timber, clarity, air and other terms. This is one of the difficult parts, since our perception of audio quality is quite subjective.

What is true for one is not necessarily true for another.

You will received a number of opinions, both pro and con on the use of "Y" cables and even on the quality of the "Y" cables.

Give the "Y" cable scheme a try. Spend some time doing some critical listening to music that your a familiar with. Then decide if the sound quality that you have is acceptable.

Remember it is all about the :music::music::music:
 
Thanks. You're right, I didn't read it carefully.

If the external integrated amp is being used as a 'Y' connector, I think chances are it's equivalent to an actual 'Y' adapter.

Most integrated amp or receiver designs I remember passively routed record out signals directly from the input selector, though. If it's one of these designs, I think the integrated amp and the 'Y' connector are equal.
 
Ok, so it doesn't make a difference, that's kind of what I was thinking would be the answer. I switched to the y cables because I found a decent set that I didn't even know I had and it also cut down on several feet of cable going to the HK amp. I'm happy with it. Thanks for the input.
 
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