Page 3 of 5
Re: Using Power Amps without a Pre Amp
Posted: Sun May 16, 2021 4:19 pm
by Geoff.R.G
Bill hart wrote: ↑Sun May 16, 2021 1:56 pm
Thanks everyone, very interesting and helpful. Excellent group.
I guess where I am coming from is, with a limited budget and a dac that can provide a level of control, am I better off spending money on power amps and a pre or power amps and upgraded cables? The consensus seems to be that you don’t need the pre.
Geoff.R.G, interesting what you say about output levels and sensitivity. My current system is using the RME dac into a Croft Micro pre amp with a pair of Quad II power amps which I had modified in the early 1990s by Doug Dunlop of Concordant fame. Sounds excellent but I have the RME output set to about 50% and the Croft volume set to around 33%.
There are suggestions that restoring the Quad II to original has sonic benefits. The Concordant mods raise the HT voltage which is, apparently not a good idea. Have a look here
http://www.keith-snook.info/quad-ii-concordant.html. However if you are planning to buy NVA mono-blocks I wouldn't bother with doing anything with the Quads.
Re: Using Power Amps without a Pre Amp
Posted: Sun May 16, 2021 4:40 pm
by savvypaul
My P90sa is almost always set to around 11 o' clock (the volume that I usually listen at with vinyl sources), then with digital I use the fine adjustment (and remote control) of the RME DAC. I don't detect any change in sound quality when reducing the volume using the RME compared to setting the RME a +-0db and then adjusting with the preamp. That was not the case with the Squeezebox that I used to use, though, which sounded noticeably better when fixed to maximum...as so often, it depends on the quality of the implementation and what the designer is trying to achieve. Experiment and find your own answer.
Re: Using Power Amps without a Pre Amp
Posted: Sun May 16, 2021 7:07 pm
by CN211276
My P90 SA is usually set at 11 o'clock which is best for the tv. Being a metal fan I think turning it up to 12 would cause me a lot of grief if I did not live in a detached house.
Re: Using Power Amps without a Pre Amp
Posted: Sun May 16, 2021 7:20 pm
by Daniel Quinn
You lot must not be using low Output moving coils , mine is set at 25 past.
Re: Using Power Amps without a Pre Amp
Posted: Sun May 16, 2021 8:35 pm
by Geoff.R.G
savvypaul wrote: ↑Sun May 16, 2021 4:40 pm
My P90sa is almost always set to around 11 o' clock (the volume that I usually listen at with vinyl sources), then with digital I use the fine adjustment (and remote control) of the RME DAC. I don't detect any change in sound quality when reducing the volume using the RME compared to setting the RME a +-0db and then adjusting with the preamp. That was not the case with the Squeezebox that I used to use, though, which sounded noticeably better when fixed to maximum...as so often, it depends on the quality of the implementation and what the designer is trying to achieve. Experiment and find your own answer.
My inclination would be to set the volume on the pre-amp and then use the volume controls on other sources such that the overall volume remains unchanged between sources.
Re: Using Power Amps without a Pre Amp
Posted: Mon May 17, 2021 12:02 am
by Ithilstone
Daniel Quinn wrote: ↑Sun May 16, 2021 7:20 pm
You lot must not be using low Output moving coils , mine is set at 25 past.
Old blue SA had 24 steps
new ones have 23.
Past 25 means you must have use something else... therefore it is hard to tell actual volume
Re: Using Power Amps without a Pre Amp
Posted: Mon May 17, 2021 8:49 am
by Daniel Quinn
25 past is the time on the dial (roughly) I havnt counted the steps
Re: Using Power Amps without a Pre Amp
Posted: Mon May 17, 2021 9:55 am
by Fretless
RD was always worried about directly driving NVA power-amps from a digital source. There is the possibility that a DAC (for example) will have its output reset to max at startup and damage both amps and speakers as soon as music starts playing.
The passive preamp inbetween also then acts as a safeguard, the volume being set to a level high enough for further control via the source component but low enough to protect poweramp and drivers.
Re: Using Power Amps without a Pre Amp
Posted: Mon May 17, 2021 10:05 am
by savvypaul
Daniel Quinn wrote: ↑Sun May 16, 2021 7:20 pm
You lot must not be using low Output moving coils , mine is set at 25 past.
Low output MC (SPU)...high efficiency speakers.
Re: Using Power Amps without a Pre Amp
Posted: Mon May 17, 2021 10:35 am
by Geoff.R.G
I know this may sound silly but, giving the volume control setting as a clock position is only valid if the pot, or stepped attenuator, has its datum at 6:00, meaning that zero is around 7:00 (potentiometers have a dead space between 5:00 and 7:00 with the datum at 6:00). I can't tell you where my volume control is set because my pre-amp displays the volume as a number (quiet at the back I like having a remote control). On my more usual audio devices the control positions are marked in db from -60 to +10.
I am assuming that DQ's 25 past (5:00?) is full volume.