Real life examples of synergy

[pauln]

La Scalas have a reputation of presenting a little less low end (but very cleanly).

 

Using my modest 45 year old solid state 28W rated integrated amplifier, I have never thought the low end was lacking at all. I attributed this to having listened to Heresys for 30 years before getting the La Scalas... I never really thought the Heresys lacked much, and the La Scalas just sounded absolutely complete.

 

Now, over in another audio forum that has a section that is "Exclusively Sansui", a number of members there restore and refurbish vintage amps and make threads in which they take pictures and walk through the process. In one of those, the fellow was working on the phono pre-amp board of the top of the line of the series (AU-9500) and I was interested because mine is the AU-6500.

He was doing a couple of things, including doing some calculations, circuit simulations, and measurements of the parts of the phono board that are responsible for reversing the RIAA  compensation applied at the time of cutting the record... he found an anomaly. In the AU-9500, the spec is flat but the actual component values on the stock phono board started raising the bass at about 320Hz with a curve that was about +3.5dB upon reaching down to 20Hz.

This apparently undiscovered "mistake" was behind the nearly universal appeal of this amp. I provided the info and asked if he could run the figures for the AU-6500. He did, and these also begin to raise bass about 160Hz but pushes to +3.5dB down at 20Hz. It looks like this whole series of amps enjoys this "mistake" and explains their reputation and characteristic desciption of "warm tube sound".

 

This is not a huge boost; the lowest where the La Scala can use it down around 40Hz the boost is +2dB.

 

So three things of note:

 

- this is a nice match with the La Scalas, not totally recovering a flat response, but helping a little bit

 

- this boost in the phono stage rather than doing it with the tone controls may be a nicer more subtle way of raising the low end, in so far as the main amp may take the preamp signal flat without tone adjustment

 

- specs may be misleading for various reasons

 

 

 

[dtel]

Very cool, I love Sansui, a 8080 was my first good receiver, gave it away to a family friend many years ago...........like a dumbass.