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Post by rcheliguy on Mar 7, 2015 11:48:09 GMT -5
I'm using an OPPO 105D as the preamplifier and I know it uses the 32bit DAC to adjust the volume.
As a result a volume of 1 on a scale of 0-100 sometimes seems a tiny bit too loud first thing in the morning if I just want a little something in the background.
I've noticed that for some music that I have a night and day response change at about 40% power on my XPA-2. It varies depending on how compressed the music is, but seems to have to do with an overall volume level. I'll say between 35%-50% depending on the dynamic range of what I'm listening to.
In this example I have a volume of 35,36,37,38, 39, and boom at 40% I suddenly hear a lot more detail.
I'm trying to understand this better. I know a bunch of people are now using an Oppo 105D a a preamp with balanced outputs to drive various amplifiers and it is enjoying wide acclaim.
I'm also curious if the way an A/B amplifer handles dynamic load is different from how a Class A handles dynamic load ?
In other words does an A/B amplifier require a certain volume to get into a sweet zone of operation where it is more sensitive to dynamic content.
I had a friend over who has been into audio for 3 decades come over and he liked how my system sounded but said it didn't sound as articulate at lower volumes which actually matched what I was hearing.
My speakers have a 200W amp supplying bass at a 380Hz cross over, but the detail I'm referring to is all in the higher ranges. I've heard many Martin Logan's over the years, but I don't remember ever hearing this behavior. I've done a lot of experimentation and finally figured it was worth asking about this.
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DYohn
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Post by DYohn on Mar 7, 2015 12:05:43 GMT -5
IN GENERAL: digital volume controls reduce bits to reduce volume. You are almost always better off leaving a digital volume control at 100% and using an actual analog volume control in a preamp to adjust the signal to the amp. Preamps are good things.
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Post by Gary Cook on Mar 7, 2015 16:33:42 GMT -5
In the thread disussing the differences between the XDA-1 and the XDA-2 Keith pointed out.......
In a UMC-200 discussion thread, Keith also mentioned.......
My experience also indicates that there is no real substitute for a decent pre amp.
Cheers
Gary
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Post by plm on Mar 7, 2015 16:47:26 GMT -5
Remember that the Oppo implements its volume control in the digital domain, in 32-bit. This means that you have to attentuate by 96dB before you actually start to lose any resolution whatsoever from the source material if it is 16-bit.
So, unless you're attenuating below these levels then it's not going to be the fact that it's a digital volume control causing a problem.
It could be that the Oppo isn't particularly linear in its output at low levels (not very likely), but it could also be that the Martin Logan's have some nonlinearity that you're hearing, and they have a sweet spot that is higher up the power band.
Also, you have a bass driver which is most definitely not going to be completely linear. We tend to think about nonlinearities of cone drivers when they are reaching xmax or the limits of the coil gap, but they do also have to overcome the rigidity of the suspension to move from rest as well, so there are all number of reasons why cone drivers can sound different at different levels.
Finally, there's our hearing, which is most definitely nonlinear with volume.
One thing you could try, if you find you're using the Oppo well down it's attenuation range all the time is to get some line level attenuators and use them on the inputs to your amps. I do this routinely on mine with -6dB attenuators so I'm always pushing my preamps a little harder. Since mine all have analogue volume controls it helps keep them in their most linear part of the sweep for channel balance.
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Post by Kent on Mar 7, 2015 17:39:59 GMT -5
I agree there is no substitute for a pre amp in the chain. I don't generally use my Oppo 105 for CDs but was curious one day so I decided to hook it directly into my amps. The sound collapsed. Very thin and lacking any realistic quality. I have also heard other systems where a source has gone direct and the same thing happened until a pre amp was added.
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Post by garbulky on Mar 7, 2015 18:21:10 GMT -5
Well yes. I have tried an XSP-1 with the oppo and the oppo was obviously at full output and the sound was REALLY good. I would recomend it as an upgrade. It provides the source electronics to the best setup I have heard!
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Post by pedrocols on Mar 7, 2015 23:58:30 GMT -5
I would also consider a passive preamp between the oppo and the amps. That way you can keep the volume on the oppo at 100% and control the volume with the passive preamp (AKA Volume Control). However, it is important to now some specs to find out if the passive preamp can be a suitable option. I currently using a passive preamp and I am considering selling my $4,000 preamp because the passive preamp does an excellent job as a preamp between my DAC and Amps.
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Post by rcheliguy on Mar 8, 2015 16:11:53 GMT -5
I think I'll just leave it alone. I specifically purchased the 105D because it could be both the preamp with XLR balanced outputs and my digital media center.
I really don't want anything else in the chain. If this isn't a characteristic of the XPA-2 than I'm leaving it alone.
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KeithL
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Post by KeithL on Mar 9, 2015 11:27:10 GMT -5
As digital volume controls go, the one in the Oppo is quite good (the Oppo 105 uses the volume control in the Sabre DAC chip as far as I know). Don't confuse linearity, distortion, and step size. Just as, with an analog potentiometer, the manufacturer can choose the taper, with a digital volume control the manufacturer can choose the difference in gain between each step on the control. This is always going to be a compromise between using tiny steps that offer a lot of precise control, the number of steps that you want to have, and how long it takes to turn the volume up or down. (Internally, a 32 bit digital volume control could theoretically use billions of steps; but you wouldn't want to wait for the volume to change; so, externally, a certain number of adjustment steps is decided upon.) The usual practice is to assume that you're going to be using the control near the top of its range; and so to have smaller steps near the top, where they'll be most audible, and then use larger steps down lower where less precise control is needed. As far as this goes, it's simply a matter of whether you happen to like the steps chosen by a particular vendor or not. There is no specific "right" - although most vendors use some sort of "modified audio taper" - which means that, as you turn the volume up or down, it moves approximately the same distance IN DB for each turn of the knob or for each second you hold the button - which means that the actual gain associated with each step varies logarithmically. (Basically, someone decides how many steps there will be, then picks a 32 bit number for the gain on each step.) Often some sort of "acceleration" is also used - so the steps move proportionally faster as you hold the button longer or spin the knob faster. Note that none of this specifically has anything to do with how the device sounds (or performs) at any specific setting. For example, a unit with smaller steps - or larger ones - isn't going to necessarily sound different when set at one particular step. And the fact that the difference in gain between steps may not be linear in no way suggests that the audio transfer function isn't linear (which would be what affects distortion). (If you have a 16 bit digital volume control, then the issue is that, whenever the volume control is set to less than full output, you are forced to represent the actual audio data using less bits - aka "less resolution" - and so the audio quality is reduced. This isn't a problem with the Sabre because it has a 32 bit volume control, and isn't a problem with any of our current products because we actually control the volume in the analog domain - using a digitally controlled analog ladder network. Note that, with the Sabre DAC, you don't actually get 96 dB of attenuation with no loss of quality, because the DAC itself doesn't have 32 dB of resolution, but you do get plenty of headroom that you aren't going to hear any loss of resolution at any reasonable listening level.) I think I'll just leave it alone. I specifically purchased the 105D because it could be both the preamp with XLR balanced outputs and my digital media center. I really don't want anything else in the chain. If this isn't a characteristic of the XPA-2 than I'm leaving it alone. |
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Post by lionear on Mar 9, 2015 20:52:23 GMT -5
It might not have anything to do with the Oppo. Some speakers need a certain minimum amount of energy in order to come alive. Room acoustics will also vary with volume level. Congratulations! You might have found the "magic volume level" for your system and your speaker, in your room.
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Post by rcheliguy on Mar 10, 2015 8:33:51 GMT -5
It might not have anything to do with the Oppo. Some speakers need a certain minimum amount of energy in order to come alive. Room acoustics will also vary with volume level. Congratulations! You might have found the "magic volume level" for your system and your speaker, in your room. If that's the case I wish it was a bit lower in volume. My den is definitely not acoustically ideal. With all the variables involved I have it about as optimized as I believe I can get it without closing off the corner of the room which is a traffic area that sees a lot of use. As it is I had to toe out my right speaker because there is no corner behind it and dipole speakers don't handle that very well. Toeing it out allowed me to center my sound stage, but is definitely not optimum placement. My speakers would like to be pulled out into the room more but that exacerbates the right rear firing wave disappearing. My speakers are both supposed to be toed in slightly and adjusted away from the back wall such that the rear firing wave creates a nice ambiance. In addition the speakers have a front and bottom firing woofer which definitely depends on the room. So I've had to turn down the left woofer about -2dB and boost the right woofer by about 4 dB to get the bass to sound right. The left side could get overpowering comparatively speaking. Given everything involved, electrostatic speakers were not an ideal choice for this room, however I've wanted a set of Martin Logan speakers since I was in college so I've got them. |
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bootman
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Post by bootman on Mar 10, 2015 8:55:04 GMT -5
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Post by plm on Mar 10, 2015 10:32:27 GMT -5
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bootman
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Post by bootman on Mar 10, 2015 10:38:01 GMT -5
Yes, that would be the one to try. Same price for the XLR version.  |
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Post by rcheliguy on Mar 10, 2015 11:13:46 GMT -5
LOL! Sorry guys. I'm not giving up my remote control What I do in the early AM is typically watch TV with my breakfast and I just run the Audio out of the TV. No biggie. I don't think this would help me in any way other than with .very low volumes. |
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bootman
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Post by bootman on Mar 10, 2015 12:39:25 GMT -5
LOL! Sorry guys. I'm not giving up my remote control What I do in the early AM is typically watch TV with my breakfast and I just run the Audio out of the TV. No biggie. I don't think this would help me in any way other than with .very low volumes. I get it. |
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Post by lionear on Mar 10, 2015 13:00:43 GMT -5
It might not have anything to do with the Oppo. Some speakers need a certain minimum amount of energy in order to come alive. Room acoustics will also vary with volume level. Congratulations! You might have found the "magic volume level" for your system and your speaker, in your room. If that's the case I wish it was a bit lower in volume. My den is definitely not acoustically ideal. With all the variables involved I have it about as optimized as I believe I can get it without closing off the corner of the room which is a traffic area that sees a lot of use. As it is I had to toe out my right speaker because there is no corner behind it and dipole speakers don't handle that very well. Toeing it out allowed me to center my sound stage, but is definitely not optimum placement. My speakers would like to be pulled out into the room more but that exacerbates the right rear firing wave disappearing. My speakers are both supposed to be toed in slightly and adjusted away from the back wall such that the rear firing wave creates a nice ambiance. In addition the speakers have a front and bottom firing woofer which definitely depends on the room. So I've had to turn down the left woofer about -2dB and boost the right woofer by about 4 dB to get the bass to sound right. The left side could get overpowering comparatively speaking. Given everything involved, electrostatic speakers were not an ideal choice for this room, however I've wanted a set of Martin Logan speakers since I was in college so I've got them. I have dipole-type speakers, too, and my room is also asymmetric - there's a wall on the right side, and the left side opens out into the dining area. It's completely open. I have my speakers about 1 m off the front wall and they have the same amount of toe-in. This would make the Right speaker a lot louder than the Left speaker. I took care of this by using the Balance control on my preamp to attenuate the Right speaker - it's about the 10 o'clock position. I absolutely hated the idea of using the Balance control. It was something I really had to get over. But the results are great. I get very good soundstage - certainly equal to what I had in previous homes (where I had three walls to work off), and equal if not better than set-ups at my friends' homes, and so I don't feel I'm missing anything. If you don't have a preamp, then you might need to get something like a Control Freak (assuming it allows you to set Left and Right volume independently). I also have to agree with other posters that, at least to my ears, it's better to have a preamp, rather than to drive the power amps directly. Using a preamp may allow the Oppo to perform at its best, and give you additional options like having a Balance control. (I also like to use the "Reverse Polarity" switch on my preamp for some jazz recordings.) As for the volume level being too high: If you mean that the sound is harsh and compressed (especially female vocals) then this may be an indication that the speakers need to be placed further out into the room. There's a "happy place" where the sound wave that is sent backwards will reflect off the wall, and join up nicely with the sound wave that's sent forwards. |
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Post by jmilton on Mar 10, 2015 13:49:25 GMT -5
There's a "happy place" where the sound wave that is sent backwards will reflect off the wall, and join up nicely with the sound wave that's sent forwards. So, the sound reflects and travels faster than sound to catch up to the forward wave of sound?   |
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Post by rcheliguy on Mar 10, 2015 13:53:23 GMT -5
Lionear,
That made a lot of sense and is directly applicable to my situation.
I went ahead and ordered a balanced control freak. I'm going to put it inline on only the left side to adjust the attenuation to see if I can even everything out with my right speaker toed in as suggested. I'll verify phasing when I'm done, but don't expect any problems.
I suspect that having the speakers setup properly will have a noticeable impact on the sound quality.
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Post by rcheliguy on Mar 10, 2015 14:15:22 GMT -5
There's a "happy place" where the sound wave that is sent backwards will reflect off the wall, and join up nicely with the sound wave that's sent forwards. So, the sound reflects and travels faster than sound to catch up the the forward wave of sound? You did know about the special air behind a panel which makes the sound waves propagate faster... Anyway, with conventional cones you have sound waves coming off of a speaker reaching to you at different times because of how the music is going up, down, left and right and then bouncing before reaching you. So you have the side walls floor and ceiling all playing a part. With ML's there is a 30 degree arc and the music is primarily projecting forward and backwards, but not nearly as much up and down. so it mostly interacts with the rear and side walls and less with the floor and ceiling. You move the speaker until the sound is clear and the sound off the back wall is pleasing. I'm looking forward to seeing what happens when I attenuate the left channel in my setup. |
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