Al, would you mind a brief phone chat with me?
Thank you!
Mark
305-775-3020
Thank you!
Mark
305-775-3020
Phono stage gain setting to match preamp and power amp capabilities
Hello All, I have a Whest PS .30R phono stage, with adjustable gain settings. My Audio Research LS-25 preamplifier also has adjustable gain settings (high 18db, medium 12db, low 6db; I have been using high at all times as I believe this is the best sound quality & "native" setting). The Whest gain options are 43, 50, 55, 60, 65, 72. It also has adjustable load settings of 100, 220, 470, 1k6, 15k, 47k.
The cartridge is Lyra Delos (Output voltage: 0.6mV@5cm/sec.) The power amp is an Audio Research VT100 (100wpc). The speakers are Rockport Mira Monitors ( somewhat low sensitivity at 85 dB SPL/2.83 v)
The reason I am looking for advice here has to do with how much I have to turn up the volume control on the preamp up to get to the loud volume that I like to listen at when I am in my loud listening moods. In order to get to the point of a dramatic concert style experience in my living room, when playing vinyl, I have to turn the preamp volume to the 3 o'clock position. Once I get the volume control this high, the noise floor (am I using the term correctly?) or background hiss increases audibly. I do not get loud volume without that hiss. Of course, when the music is full, you cannot hear it. But when the music is lean, the hiss is there.
For the past year or so, I had the Whest set to 60db and 220 ohms. I arrived at 60 because I didn't want to over amplify the signal in the phono stage and get more hiss. But then I had to crank up the preamp volume. Now I just set the Whest to 65, and as expected, the volume control on the LS-25 can be backed down a little. I haven't had the chance to really listen critically or for long enough time to determine if the hiss has diminished. But I will log the listening time soon.
Can you give me any advice on the proper way to set these options? Should I go to full gain on the Whest and back down on the LS-25 volume control even further? Or is a lower gain on the Whest a better way to go? Also, can you help me understand the nature and source of the hiss I hear? What is it, why is it there, and how do I get it to be 'inky black' as some reviewers like to say?
Thanks!
Mark
The cartridge is Lyra Delos (Output voltage: 0.6mV@5cm/sec.) The power amp is an Audio Research VT100 (100wpc). The speakers are Rockport Mira Monitors ( somewhat low sensitivity at 85 dB SPL/2.83 v)
The reason I am looking for advice here has to do with how much I have to turn up the volume control on the preamp up to get to the loud volume that I like to listen at when I am in my loud listening moods. In order to get to the point of a dramatic concert style experience in my living room, when playing vinyl, I have to turn the preamp volume to the 3 o'clock position. Once I get the volume control this high, the noise floor (am I using the term correctly?) or background hiss increases audibly. I do not get loud volume without that hiss. Of course, when the music is full, you cannot hear it. But when the music is lean, the hiss is there.
For the past year or so, I had the Whest set to 60db and 220 ohms. I arrived at 60 because I didn't want to over amplify the signal in the phono stage and get more hiss. But then I had to crank up the preamp volume. Now I just set the Whest to 65, and as expected, the volume control on the LS-25 can be backed down a little. I haven't had the chance to really listen critically or for long enough time to determine if the hiss has diminished. But I will log the listening time soon.
Can you give me any advice on the proper way to set these options? Should I go to full gain on the Whest and back down on the LS-25 volume control even further? Or is a lower gain on the Whest a better way to go? Also, can you help me understand the nature and source of the hiss I hear? What is it, why is it there, and how do I get it to be 'inky black' as some reviewers like to say?
Thanks!
Mark
Showing 6 responses by marktomaras
Is there a way to listen and measure the noise properly? As in, can I turn the volume up, have the input selector on phono, and just listen with nothing playing? Or is that not a way to isolate and listen to noise only? If I could do something in that ballpark, I think it would be easier to hear the changes that you all are suggesting. Either that, or perhaps play a track on the turntable that is extremely sparse and allows one to hear the background noise. Suggestions? |
To recap, some say lower the phono stage gain, and some say raise the phono stage gain. Does anyone want to back up their argument with some supporting evidence? Almarg, As for amplifier interference, I take it you saw my system photo. Is there anyplace on the rack where the amp would not interfere? I ask this because the speaker cables are not long enough to have the amp anywhere other than in the center position. The only option would be to put the amp on top of the rack, next to the turntable, or, reconfigure the shelf heights and put the amp on the bottom, with the preamps on the raised up center section. If you think this is not adequate, then unfortunately, I don't have much of an option. Of course, if I am looking for the source of the hiss, and that is it, I can put the amp on the floor in the middle of the room as I have some longer interconnect, but I think I will save that for the last test. As for the ground loop, just so I understand properly, I disconnect my power conditioner from the wall outlet, plug in the cheater plug, and replug into the wall, and listen for a hiss change/reduction? Is there any danger to my equipment for this test? Thanks! |
No problem Al, thank you very much for your valuable input so far! I have completely rearranged the rack, components, and cables to move the phono stage as far from any other power supply as possible, and I am being particularly careful to route cables smartly. I'll report what I find when done. Thanks Oscar, I think I will do that eventually as well, start at high gain and work downward. ill report my findings soon. |
So, I moved the entire rack around. Hours of fun! You can see what I did here https://systems.audiogon.com/systems/5421 if you look at the 1st and 2nd photos, you'll see the changes. It doesn't look as pretty as it did before, but perhaps I can refine it a bit. I was super careful to keep the signal cables away from power cables, and I was successful to a very large degree. There is not a single signal cable that touches a single power cable. They get close only once or twice, and even then it is an intersection that does not touch, nothing parallel. I noticed the hum get completely eliminated, probably by separating the phono stage from the amplifiers, thank you Almarg for this suggestion. The hiss is still there, but I do have an older tube preamp, is this just the way it is? Besides, I can no longer hear it at listening position. Is there a way to quiet down the LS-25 a bit more? I am still investigating the right gain setting on the phono stage, I think I will go to maximum, listen, minimum, and listen to define the boundaries, and then find the right point in between. The other bonus to this process was that I think the system is more well defined. Generally better in the detail than it was before. Maybe the phono stage was getting more interference than I thought from the location near the power amp? Maybe I had some power cables messing with the signal cables, either way, it is sounding really good. Now to figure out those gain settings... |