TU8500 + TU8600 - volume position

Wansmith

Member
2017-02-01 4:38 am
Hi there


Apologies if this question has been covered before.


I use a TU8500 pre and TU8600 power.


Should I put the TU8600 volume knob to maximum, and use the TU8500 to control volume, or should I put the TU8500 volume knob to max and use the TU8600 to control volume?


Thank you
 
Hi,

I do not have the schematics but I assume that the volume control in the TU-8500 is before the gain stage, and in TU-8600 it is connected to the input so that all amplification stages are after the pot.

If that is the case then you get lower total distortion but higher noise if you use the volume control on the TU-8500.

The standard output voltage of a CD player and most DACs is 2V RMS, which may overdrive the TU-8500 output stage if volume is set to maximum. It may not cause clipping but the distortion is certainly higher.
 

Hmavv

Member
2018-08-12 11:50 pm
I got the same setup as you, I just finished building my TU-8500 the other night.

So I'm using my TU-8500 primarily as a phono pre-amp. Using a test record with a 1khz test track and a technics SH-8055, I set the pre-amp volume to the same DB output I had on my Pro- ject tube box s2 set with a 43Db gain. Which is about 2/3 from max volume dial, with the 3x volume gain depressed.

I still use my TU-8600 volume pot to control volume.

Hope this helps!
 
The problem here is that potmeters are arguably the least reliable passive components and their use should be restricted to the minimum necessary.

They have the least impact on sound when they are set to maximum.

I don't see the point in buying an amp kit especially with output transformer upgrade and premium tubes then using two pots in the audio signal path to control the volume, one of which (or both) costs maybe $6. (That small Alps is quite good though.)

If I wanted to use TU-8500 with TU-8200/8600 exclusively then I would bypass both the volume control and the driver stage and use the output buffer only.

Both power amps are sensitive enough to be driven directly from the source unless you use a very low output MC cartridge.

I suspect that the driver stage in the 8500 inverts signal polarity anyway, which in theory requires compensation. Doing that is easy with speakers, but is more complicated with headphones.