Author Topic: Preamp to power amp connection?  (Read 1006 times)

Offline sgp512

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Preamp to power amp connection?
« on: August 10, 2020, 20:41 »
Hi,
My preamp has 2CH stereo outputs with output impedance of 600 ohm. I have a 5CH power amp which I only utilizing 2CH for now. The input impedance is 47k ohm.
I plan to bi-amp my speakers by utilizing 4 CH from the power amp. Is it safe to connect a pair of 1-to-2 RCA splitters at my Preamp output to feed to 4 CH of my power amp? Do we expect any negetive effect on the sound quality? Pls advise. Thx  :)

Offline pcking

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Re: Preamp to power amp connection?
« Reply #1 on: August 10, 2020, 22:51 »
You can do so without any issue.
You can also use a 1 Female to 2 rca Male adaptor if your rca inputs spacing on your power amp allows that.
"The worse of the two is he who, when abused, retaliates. One who does not retaliate wins a battle hard to win."

Offline sgp512

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Re: Preamp to power amp connection?
« Reply #2 on: August 10, 2020, 23:32 »
Roger that. Thx for your quick reply  :D

Offline Doggie Howser

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Preamp to power amp connection?
« Reply #3 on: August 11, 2020, 06:53 »
You can do so without any issue.
You can also use a 1 Female to 2 rca Male adaptor if your rca inputs spacing on your power amp allows that.
Doesn’t that halve the input impedance?

600ohms is a pretty high output impedance for a preamp. I’m guessing the 47kOhm input impedance on the power amp was already cutting it pretty close.
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Offline sgp512

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Re: Preamp to power amp connection?
« Reply #4 on: August 11, 2020, 20:35 »
I did some online search yesterday and read from a foreign forum that the basic rule of thumb is to have next stage input impedance at least 10x higher than the output impedance of the previous stage. Not sure if that's a good guideline but that's what I could find before buying 1-2 RCA splitters as per bro pcking's confirmation.

Offline pcking

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Re: Preamp to power amp connection?
« Reply #5 on: August 11, 2020, 22:07 »
You are right that the input impedance will be halved to 23.5kohms but it's still about 40 times higher than the output impedance of 600ohms.
Although it's not an ideal way to use splitter, the benefits of Bi amping should outweigh the cons.

Quote from: Doggie Howser
link=topic=298199.msg1348628#msg1348628 date=1597099989
Doesn’t that halve the input impedance?

600ohms is a pretty high output impedance for a preamp. I’m guessing the 47kOhm input impedance on the power amp was already cutting it pretty close.
"The worse of the two is he who, when abused, retaliates. One who does not retaliate wins a battle hard to win."

Offline Doggie Howser

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Preamp to power amp connection?
« Reply #6 on: August 12, 2020, 17:18 »
I encountered no end of noise with my Ayon CD5S as a preamp and that had an output impedance of 300 ohms. That was hooked up to a power amp with 47kOhms input impedance and it was incredibly noisy.

Ayon didn’t implement global negative feedback and they said it was to be expected.

The matching preamp for that power amp had an output impedance of 100ohms - for reference.
« Last Edit: August 12, 2020, 17:19 by Doggie Howser »
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Offline pcking

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Re: Preamp to power amp connection?
« Reply #7 on: August 12, 2020, 17:28 »
Having a higher output impedance to a power amp has nothing to do with noise.
The mismatch of output and input impedances will only cause roll offs.
The noise you have encountered is most likely due to your preamp having tubes.

I encountered no end of noise with my Ayon CD5S as a preamp and that had an output impedance of 300 ohms. That was hooked up to a power amp with 47kOhms input impedance and it was incredibly noisy.

Ayon didn’t implement global negative feedback and they said it was to be expected.

The matching preamp for that power amp had an output impedance of 100ohms - for reference.
"The worse of the two is he who, when abused, retaliates. One who does not retaliate wins a battle hard to win."

Offline Doggie Howser

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Preamp to power amp connection?
« Reply #8 on: August 13, 2020, 06:53 »
Most tube preamps have higher output impedance. Wonder what the OP’s has

When I used the Jadis amp with 100kOhm input impedance for power, it was dead quiet.
« Last Edit: August 13, 2020, 06:55 by Doggie Howser »
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Offline sgp512

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Re: Preamp to power amp connection?
« Reply #9 on: August 13, 2020, 12:53 »
I am using a DIY 5670 based preamp in cathode follower config. Power amp is emotiva upa-500.
Tested 1CH with 1-2 RCA splitter yesterday, dead quiet background noise.
Will buy better quality 1-2 RCA splitters. Thanks bro pcking again for his confirmation  :)

 

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