Threshold S/550e & SA/4e balanced inputs: a doubt

Basbass · 2nd January 2012, 08:04 PM

Hello

Yesterday I changed the connections between Stereoknight Enigma preamplifier and my Threshold SA/4e S/550e that I use in bi-amping system with B&W 802D through a connection of unbalanced RCA to balanced XLR.
The balanced cables are pro Extron Electronic with Neutrik connectors while the unbalanced cables are more complex DIY cables (I don't know the specs) homemade by a friend.
I have noticed some changes in the perceived sound:

1 - The sound is slightly drier and lost a bit 'of body and thick, it all seems a little' thinner.

2 - The bass is less clear, with less impact and the attacks of the low notes are less precise and less fast.

What can cause this problem? How can it be solved?
In a few days I'll have to keep away from the amplifiers pre-amp so I will need about 6 meters of cable which should be, necessarily, balanced type.
A friend of mine who owns a s/550e told me that he found the same problem, but fortunately he does not need to use long balanced cables...
So I need an explanation to this problem and possibly a solution. It may be helpful to change the unbalanced input of the amplifier circuit (if I remember correctly the final threshold do not have a truly balanced circuitry)? If you can how?
Thanks in advance

Giovanni

wayne · 3rd January 2012, 10:44 PM

The input on balanced was a true 600 Ohms on these if I remember correctly. This can be tough to drive and alter the sound some. It could be increased though.

Speedskater · 3rd January 2012, 11:26 PM

Gee, we had some S/500's at Telarc, I didn't realize that they had 600 Ohm inputs.

Basbass · 3rd January 2012, 11:51 PM

Quote:

Originally Posted by Speedskater

Gee, we had some S/500's at Telarc, I didn't realize that they had 600 Ohm inputs.

Hi

If I remember S/500 has only unbalanced inputs, S/550e and SA/4e are different from S/500, they have balanced inputs too. With unbalanced inputs the sound is OK!
Thanks

Giovanni

Basbass · 4th January 2012, 12:05 AM

Quote:

Originally Posted by wayne

The input on balanced was a true 600 Ohms on these if I remember correctly. This can be tough to drive and alter the sound some. It could be increased though.

How can I increase the input impedance? Where can I find the service manuals of those Amplifiers?
Thanks

Giovanni

wayne · 4th January 2012, 08:47 PM

I will see what I can find on Threshold. Didn't think to take much when I left.

Basbass · 4th January 2012, 09:06 PM

Quote:

Originally Posted by wayne

I will see what I can find on Threshold. Didn't think to take much when I left.

Many many thanks...

wayne · 6th January 2012, 08:38 PM

You can check input impedance with an Ohm meter on this and verify.
It can be increased by changing R1 on the rear panel board and R2 on the front end board.

Basbass · 6th January 2012, 09:16 PM

Quote:

Originally Posted by wayne

You can check input impedance with an Ohm meter on this and verify.
It can be increased by changing R1 on the rear panel board and R2 on the front end board.

Many thanks again!!!

2nd January 2012, 08:04 PM	#1
Basbass diyAudio Member Join Date: Jan 2012 Location: Carignano, near Turin	Threshold S/550e & SA/4e balanced inputs: a doubt Hello Yesterday I changed the connections between Stereoknight Enigma preamplifier and my Threshold SA/4e S/550e that I use in bi-amping system with B&W 802D through a connection of unbalanced RCA to balanced XLR. The balanced cables are pro Extron Electronic with Neutrik connectors while the unbalanced cables are more complex DIY cables (I don't know the specs) homemade by a friend. I have noticed some changes in the perceived sound: 1 - The sound is slightly drier and lost a bit 'of body and thick, it all seems a little' thinner. 2 - The bass is less clear, with less impact and the attacks of the low notes are less precise and less fast. What can cause this problem? How can it be solved? In a few days I'll have to keep away from the amplifiers pre-amp so I will need about 6 meters of cable which should be, necessarily, balanced type. A friend of mine who owns a s/550e told me that he found the same problem, but fortunately he does not need to use long balanced cables... So I need an explanation to this problem and possibly a solution. It may be helpful to change the unbalanced input of the amplifier circuit (if I remember correctly the final threshold do not have a truly balanced circuitry)? If you can how? Thanks in advance Giovanni

3rd January 2012, 11:26 PM	#3
Speedskater diyAudio Member Join Date: Sep 2002 Location: Lakewood, Ohio	Gee, we had some S/500's at Telarc, I didn't realize that they had 600 Ohm inputs. __________________ Kevin

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3rd January 2012, 10:44 PM	#2
wayne diyAudio Member Join Date: Jan 2002 Location: Northern California	The input on balanced was a true 600 Ohms on these if I remember correctly. This can be tough to drive and alter the sound some. It could be increased though.

4th January 2012, 08:47 PM	#6
wayne diyAudio Member Join Date: Jan 2002 Location: Northern California	I will see what I can find on Threshold. Didn't think to take much when I left.

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