Question for Demeter VTBP-201S

[dimi_did]

Hello, I bought the preamp Demeter VTBP-201S.
In documentation on this préampli I read that: "Internal Volume Trimmer: This control is designed to match the output volume of the Tube Bass Preamplifier with the input sensitivity of any power amplifier."
Could you say to me about which volume that speaks:

this one

or that one?

Thank you.

 

[Jonathan Starr]

Some power amps require more signal to drive them to full output than others.

If you need more drive from the preamp to pucsh the power amp, then turn the pot up a bit.

If you can overdrive the power amp easily, then turn it down.

Perhaps someone else can answer this more scientifically.

Aloha,

Jonathan

 

[Reefer]

He's referring to the internal volume trim pot that's in your 1st picture.

 

[dimi_did]

If you need more drive from the preamp to pucsh the power amp, then turn the pot up a bit.
If you can overdrive the power amp easily, then turn it down.

Thank you for your answer. You speak about the this small blue trick inside the preamp or about volume general?

 

[metron]

The factory setting for the internal trim pot in my Demeter (the one in the first picture) was set straight up and down which is very close to where you have yours set. I found this level more than sufficient to drive my power amp to full output.

Basically, if you crank the volume knob on the preamp and its to much signal for your power amp then turn the internal pot clockwise. If you need more volume then counter-clockwise.

 

[Joe Beets]

Are you using the line out jack to your power amp or the XLR? The line out should have plenty of poop, but if you use the XLR it will be real weak.

 

[metron]

Are you using the line out jack to your power amp or the XLR? The line out should have plenty of poop, but if you use the XLR it will be real weak.

Definitely should be using the line out. The XLR flat output is low but more then enough signal to send to any mixing board. There is also a post XLR output which is very hot like the line out.

 

[dimi_did]

Ok thank you very much the guy for this information!

 

[Reefer]

Basically, if you crank the volume knob on the preamp and its to much signal for your power amp then turn the internal pot clockwise. If you need more volume then counter-clockwise.

Huh?? I think you have this backwards. Clockwise is more output, counterclockwise is less.

 

[metron]

Huh?? I think you have this backwards. Clockwise is more output, counterclockwise is less.

Crap I might! I popped the top off once and I remembered it as the opposite of this but my mind fails me these days. Sorry people.

 

[DLM]

Basically, if you crank the volume knob on the preamp and its too much signal for your power amp then turn the internal pot clockwise. If you need more volume then counter-clockwise.

Two questions: 1) Are you saying that the external volume knob and the internal pot are linked together so if you adjust one it affects the other? 2) How do you know when it's "too much signal?" Is it by hearing distortion at moderate poweramp levels? If someone wanted slight distortion and they cranked their external volume knob all the way but still got a clean sound, would they then be able to increase the internal pot and then adjust the external volume knob to whatever degree of distortion they want?

 

[marc40a]

I'd stick w/ the factory setting. My volume knob @ 12-1 o'clock has always been more than enough to drive a power amp into clippping.

 

[John D Harris]

I did a little experimenting with mine for 1st time (hadn't been able to locate the trim pot before -- doh! -- thanks for the pic).

I ran my PLX1602 into a pair of pretty good Sennheiser headphones.
I couldn't tell much difference at all between pretty low and all the way up other than the output volume.
It's difficult to try matching levels while tweaking without a db or electrical meter.
Seems like there might have been a little bit of HF reduction at lower levels, but I could say for sure without knowing that the output levels were matched between the two.

I ended up increasing it to max and then backing off about 5 or 10 degrees.
Since PLX's are a bit less sensitive than some other amps, I thought I would try this for awhile and see how it does.

 

[metron]

Two questions: 1) Are you saying that the external volume knob and the internal pot are linked together so if you adjust one it affects the other? 2) How do you know when it's "too much signal?" Is it by hearing distortion at moderate poweramp levels? If someone wanted slight distortion and they cranked their external volume knob all the way but still got a clean sound, would they then be able to increase the internal pot and then adjust the external volume knob to whatever degree of distortion they want?

Yeah the pot inside effects the range of the volume knob. I didnt mess with it much. If you can drive your power amp into full output with the volume knob at 12 or less then its probably set too high. Thats all I meant by too much signal. As far as distortion goes you wont get much out of this preamp. When I get it to the point where it starts to break up it seems like it breaks up really fast and gives a non pleasant buzz instead of the nice musical type of distortion you might get with another preamp. This preamp is for clean sounds only IMO.

 

[John D Harris]

I did a little experimenting with mine for 1st time (hadn't been able to locate the trim pot before -- doh! -- thanks for the pic).

I ran my PLX1602 into a pair of pretty good Sennheiser headphones.
I couldn't tell much difference at all between pretty low and all the way up other than the output volume.
It's difficult to try matching levels while tweaking without a db or electrical meter.
Seems like there might have been a little bit of HF reduction at lower levels, but I could say for sure without knowing that the output levels were matched between the two.

I ended up increasing it to max and then backing off about 5 or 10 degrees.
Since PLX's are a bit less sensitive than some other amps, I thought I would try this for awhile and see how it does.

I practiced with a different band today and I got the definite impression that my sound was punchier with a bit more clarity.
I made some tone settings changes, so I'm not sure if the increase in punch & clarity was because of my gain tweaking or tone tweaking.

It made me wish I had a stacked pair of Schroeder 410.
With my current settings and arrangment of tubes, kneeing down in front of the 410, the sound is really incredibly awesome.

 

[DLM]

...If you can drive your power amp into full output with the volume knob at 12 or less then its probably set too high. Thats all I meant by too much signal...

How does one know when there's "too much signal?" There's no preamp clip light on the Demeter. However, there's a clip light on my poweramp. Would this be an indicator or are you saying my ears will be able to tell when there's too much signal?

 

[metron]

How does one know when there's "too much signal?" There's no preamp clip light on the Demeter. However, there's a clip light on my poweramp. Would this be an indicator or are you saying my ears will be able to tell when there's too much signal?

Use the clip light and your ears. I like to be able to turn my volume up to about 2 max. Its still very clean at this level. Honestly that didnt require any messing with the knob as the factory setting was just about right. I would only use the trim knob if you dont have enough output which isnt likely with this preamp.

 

[John D Harris]

How does one know when there's "too much signal?" There's no preamp clip light on the Demeter. However, there's a clip light on my poweramp. Would this be an indicator or are you saying my ears will be able to tell when there's too much signal?

Depends to a certain degree on the power available and the cabs you use.
Some cabs will stress (and audibly let you know) before any clipping occurs.

Bad (non-tube originated) clipping amp will usually be plainly audible.

If your power amp is clipping and there's no audible indications, you're probably underpowering your cabs.