[OMF]

Hello!

I have just received my NoH preamp, which is very very good. Thanks John!

I have the opportunity to adjust level both on my DAC and my power amplifier, so my question is how to adjust it.

I would think that it best to get as high signal as possible into the NoH, or....?

I also would think that it would be best to have as high amplification as possible at the power amp, then I would need fewer windings, less cable, purer signal path, or what do you think John..?

Best regards
OMF

[zybar]

When you say adjust level do you mean gain?

Assuming that is what you mean, I am about to run a test here with my Rowland 201's.  There is an internal switch to change the gain from 26 to 32.

I will let you know if it sounds better, worse, same with my NOH preamp.

Here is what I was told by Rowland:

The 32dB gain sonics should be about the same, but I wouldn't change to 32dB unless and until you absolutely need to do it.

George

[John Chapman]

Hello!

Glad it travelled well! Two part answer:

1- If you can adjust the output of the source then a nice high level is good - up to a point. The large core of the tx102 can handle very high levels (10V to 15V is just fine even higher might be o.k.). If it gets so high that you are normally listenning in the bottom fe steps then i would say that it too far. Ideally you would want to be down from top setting but have plenty of room above and below your normal listenning level to allow some range for volume adjustments.

2- The power amp. If you can adjust the gain most likely it is just a pot in the circuit at some point (not like the Rowland - which sounds like it maybe changes the signal path for the different gain settings). If it is a pot then all the way up is the way to go - otherwise you introduce a series resistance in the path and that can't help things.


Please let us know where you end at!

Thansk!

John

[OMF]

Hello!

For the power amplifier its a dip-switch, so i think what I am doing is changing some kind of resistor in the circuit changing the level of gain. Its not a potmeter.

So I think my power amp plays equally good at all three settings. So should i settle for a low, medium or high output from the NoH....?

Regards
OMF

[John Chapman]

Hello!

If there is no sonic difference then I would set it so the level control of the NOH is about midway when you get your average listenning level. That will allow for some room for adjustment both above and below that average setting.

Thansk!

John

[OMF]

Hello!

I have now match the level, so that the inputlevel is much higher. I feel that this really improved microdynamics and bottom line definiton and punch.

On the remote there is a button in the middle (marked with a mute icon), it also lit a blue light on the NoH. Is this a phase switch or...? If so, whats the correct position?

Regards
OMF

[John Chapman]

Hello!

Glad the levels are working out. Kinda fun having that to play with - not too many power amps have that kind of thing.

The Middle (mute) button is not wired to do anything. It can be wired to be phase BUT it adds a relay to the signal path so unless folks really want phase reversal I do not wire it that way.  It could also be used to activate a tape output.  To date I have not wired any as phase or tape out but I put it in the system to fill up the led spot on the front panel.....

Thanks!

John

[OMF]

Hello again John!

I just wondered what is the input impedance of the NoH, and the output impendance (how much do it vary?)?

Regards
OMF

[John Chapman]

Hello!

Sorry for the delay in replying - was away for a bit. The input impedance and output impedance is 'transformed' by the transformer so it can not be stated as a single number. This is one of the benifits of a transformer based tx - it lowers the output impedance as you lower the volume level.

There is a chart at the S&B web page here:


http://www.stevens-billington.co.uk/page102.htm

It is about 3/4 the way down the page. This chart shows impedances for a kind of worse case situation of a 1K ohm sourde impedance and a 10K ohm amp impedance. It shows how the output impedance lowers as the level is turned down.

If you need more specific details please let me know.

Thansk!

John