Question about volume, detail and a Class A/B amplifier

[garbulky]

Well..if you are looking for improved audio quality the XSP-1 would be my first bet with the oppo 105.

[rcheliguy]

Mar 10, 2015 14:21:51 GMT -5 garbulky said:

Well..if you are looking for improved audio quality the XSP-1 would be my first bet with the oppo 105.

Absolutely!  My  goal is to have as much redundancy as possible!

[rcheliguy]

This is disheartening. It appears that the OPPO 105D prefers an amplifier with an input impedance of 47K ohm or better. The XPA-2 is not the greatest match for it even with the balanced inputs with 33kohm impedance.

[bootman]

Jump on this and do it right.

emotivalounge.proboards.com/thread/41500/xsp-gen-550-shipping-obo


...I have no relationship to the seller.
But this is a great deal.

[rcheliguy]

I don't have room for another component. I'd be much more likely to dump the XPA-2 and get something with a higher input impedance.

Sadly I'm a week past the 30 day return policy.  I could have gotten a pair of XPA-1L's with 50k ohm input impedance and there would have been a good match.

Spilt milk.

[bootman]

Mar 10, 2015 16:30:46 GMT -5 rcheliguy said:

I don't have room for another component. I'd be much more likely to dump the XPA-2 and get something with a higher input impedance.

Sadly I'm a week past the 30 day return policy.  I could have gotten a pair of XPA-1L's with 50k ohm input impedance and there would have been a good match.

Spilt milk.

Are you 100% sure this is what the root cause of your problem is?

[rcheliguy]

I'm waiting to hear back from OPPO tech support but I've been reading a lot more information about this and it appears that the sound quality suffers and it is not recommended to use an amp with lower than 47k ohms.

The problem is that I don't have room for mono blocks and even the XPA-1L's get warm.

I think I may be better off going to something like a Wyred4Sound amp that runs cool and has a 97k ohm input stage. Then I have no problem with the amp heat in the enclosure space I have.

Obviously I'm going through buyers remorse and various knee jerk reactions at this point. I'll get my facts together and cool off.

The XPA-2 was an experiment to see if I could get by with something this inexpensive.  I'm just kicking myself for not doing my homework better before taking the plunge.

[garbulky]

It's not about redunandancy.
There is always a pre-amp in the chain. Depends on which one is doing a better job.
The pre-amp doesn't dissapear if the oppo is told to do preamp duties.

Turning off the oppo volume control by making it output maximum volume with the XSP-1 shifts the prea-mp duty to the better analog stage of the XSP-1. The plain answer is that with an XPA-2, the XSP-1 simply sounds better.

[rcheliguy]

Here is the response from OPPO.

"As long as the input impedance is 10 to 47KOhm, then it will work. You may just need to increase the volume more to get the same amount of amplification power from your amplifier."

I'm going to try out attenuating my left speaker and seeing if I can keep the sound stage centered with both speakers toed in before I do anything else.

I'm not adding a preamp to this system, period. The OPPO is the only source for everything I listen to. Far too many people with extremely expensive systems have the 105D working beautifully as a pre-amp.

Also keep in mind that if something were to change that the XPA-2 is the easiest component to replace.  The OPPO has a huge amount of functionality and is a phenomenal value to me. The speakers are something I have drooled over for years. They look gorgeous and can sound amazing. Unfortunately the amplifier is hidden from view and while an important workhorse is nothing I am emotionally or functionally attached to. 

For now I will hope that adjusting the power levels between the speakers allows me to place the speakers better and improves the room synergy in a noticeable way.

[plm]

I think there is a risk that you may be disappointed even if you change the amplifier. I've never heard of anyone having great success with the Oppo using it directly to drive power amps. There doesn't seem to be any good reason why, because I'm sure everyone isn't driving amps with low input impedances, but this does seem to be a recurring theme.

[rcheliguy]

Mar 11, 2015 11:39:12 GMT -5 plm said:

I think there is a risk that you may be disappointed even if you change the amplifier. I've never heard of anyone having great success with the Oppo using it directly to drive power amps. There doesn't seem to be any good reason why, because I'm sure everyone isn't driving amps with low input impedances, but this does seem to be a recurring theme.

That's interesting because I know of  few people with systems in the 20-30K range who are floored with the results using the OPPO 105 or 105D as their preamp.

They all only have  a OPPO 105(D),  1 amp or 2 mono blocks and Speakers.  Please note that I'm not talking about any OPPO other than the 105.  I wouldn't consider doing this with my OPPO 83, or 93 or even a 103.

However if you read what I am planning to do, I'm taking this one step at a time. First I'm going to balance the speakers and see if I can get them situated better.

The speaker placement / room interaction is likely to have a very noticeable impact on the sound quality.  

Remember I've got them closer to the back wall than I want them because of the right speaker disappearing into the opening on the right side.
And I've got the right speaker toed out which is the opposite of all recommendations for speaker placement.

If I can attenuate the left speaker such that I can pull them both away from the wall properly and toe the right speaker in like it should be pointed it should make a larger difference than anything else I'm looking at doing.

I'm still going to hope that will get me where I want to be without changing anything else.

[rcheliguy]

OK, I just need to shut up for a while.

After more tinkering with the speaker placement something major happened. I'm going to take precise measurements of where I finally ended up. The sound stage is spectacular! I'm completely floored. This is what these speakers sounded like when I auditioned them!!!!

These are definitely very picky speakers to get just right, but OMG I think I've finally got them just right!

I've had a lot of knee jerk reactions lately so I'm going to set on this for a while, but at least for this moment in time color me very happy!

[plm]

Mar 11, 2015 14:25:35 GMT -5 rcheliguy said:

Mar 11, 2015 11:39:12 GMT -5 plm said:

I think there is a risk that you may be disappointed even if you change the amplifier. I've never heard of anyone having great success with the Oppo using it directly to drive power amps. There doesn't seem to be any good reason why, because I'm sure everyone isn't driving amps with low input impedances, but this does seem to be a recurring theme.

That's interesting because I know of  few people with systems in the 20-30K range who are floored with the results using the OPPO 105 or 105D as their preamp

I'm actually going to get a chance pretty imminently to try a 105 in a friend's second system, directly driving a pair of Aragon Palladium monos and B&W Nautilus 801s, so it'll be great to get firsthand experience of how well it works directly.

It sounds like you're approaching things the right way, but one other thing to caution you on is that if the Oppo has a relatively high output impedance (irrespective of what the manufacturer may quote) then a) that would explain why it's fussy about the input impedance on amps, but b) you'll be effectively increasing the output impedance on the channel you're using the Control Freak on. So if you can position your speakers so you don't need to use the Control Freak then you will potentially be better off. It looks like you're on top of that though.

[rcheliguy]

I'm not afraid to say that I got lucky.

In anticipation of getting the control freak I toed them both in and pulled them way out into the room and closer together to a place I would never keep them. Then I experimented some more and at one point they started to sound right. So just for grins I started to move them backwards a little at a time. I still had to boost the bass on the right speaker by about 6dB, but I got them far enough back so there would be no WAF issues and the sound actually improved. They are still further away from the back wall than I originally had them but they are closer together.

I'm guessing I must have had some kind of cancellation going on before that required a certain volume to "power through", because I'm hearing plenty of detail at much lower listening levels now.

I spent over 3 hours just listening to music that I know marveling at the instrument placement on the sound stage, how singers seem pop out sounding like they are right there. There was definitely a vertical, horizontal and fore/aft placement.

It is scary how sensitive these speakers are to placement at least in this room.

I don't have any prejudice against my XPA-2. The reason I singled it out was that I knew people with Martin Logan's who used the OPPO 105 as a preamp with great results, and I've heard the spectacular imaging and detail at low listening levels from many Martin Logan speakers over the years. As you may expect, one of them has a Wyrd4Sound amplifier. Since there are only 3 components in this system and I thought I had exhausted my speaker placement options I made a poor assumption. So this all falls back on me, but that's fine since I finally got it where I wanted it.

FYI, I've got my OPPO set up to default to powering up at a volume of 10 rather than the last volume before power off.

[bootman]

^^^^^

I know the amp was the easiest to replace but as you yourself found out, speakers and the room make the biggest difference by far.
So much so that if you would have not moved the speakers and swapped just the amp, not much difference would have occurred.
I would also say that even the preamp (sound wise) in your case would have been minimal.

Good job getting these setup right in your room.

[rcheliguy]

FWIW, The OPPO 105D is truely an amazing piece of equipment.

So far I've played BD's, CD's, SACD, HDCD, streamed music by WiFi, asynchronous USB, and USB fob.
It also natively runs Pandora, Netflix and others.

My RC Helicopter flight simulator computer, now has another function and is running FooBar2000 and streaming music by Asynchronous USB
My daughter was playing iheartradio.com "SpinCycle" through the same Async USB connection.

It has one heck of a nice headphone amplifier as well.

The fact that it has a balanced XLR preamplifier outputs on the back is icing on the cake.

The only issues I've seen are:
1. Sometimes when you change input sources you hear a tiny bit of noise like low level static but it only lasts for a couple seconds and then stays clean.
2. If you have the WiFi enabled and are using WiFi browsing or the USB Fob it will sometimes get stuck and require rebooting to get working well again.
3. Minor: the volume difference between 0 and 1 is a bit more of a jump than I expected.

[rcheliguy]

Mar 12, 2015 6:44:41 GMT -5 bootman said:

^^^^^

I know the amp was the easiest to replace but as you yourself found out, speakers and the room make the biggest difference by far.
So much so that if you would have not moved the speakers and swapped just the amp, not much difference would have occurred.
I would also say that even the preamp (sound wise) in your case would have been minimal.

Good job getting these setup right in your room.

I just wish the sweet spot was wider than 2' where I sit, but I suspect that is as good as it will get in this room. It sounds great in the vast majority of the room, but the sound stage  drifts to the side you are closest too when you are off center.

[rcheliguy]

I'm loving FooBar2000 and organizing my music and listening from there nearly exclusively by asynchronous USB to the 105D

FooBar2000 also has a volume control on it so I can drop the volume at very low levels when my OPPO is registering a 1.

The OPPO has .5dB increments from 0 - 100 which means 25dB of control over the volume. If the amplifier has 29dB of range that probably means that it starts 4 dB, hence my issue with low volumes.

[plm]

You don't want to be attenuating in FooBar really, as this is going to be reducing bit-depth in the 24-bit domain prior to sending it to the Oppo. When you attenuate in the Oppo at least you're doing it in the 32-bit domain.

As soon as you're past 48dB overall attenuation you'd be losing bits on 16-bit material with FooBar.

Since you have the ControlFreak, why not run both channels of the Oppo through it, dial in sufficient attenuation that you can run FooBar at 0dB and have a nice, usable volume range on the Oppo? That way you'd be maximizing the bit depth available to you, and not going through two sets of digital mathematics to reduce the volume.

[rcheliguy]

The Control Freak is sitting in its box and will probably never be used. I don't want anything in the analog music stream if I can help it.

Once again, I'm only talking about when my OPPO is at 1 on a 0-100 scale that I'm using this. First thing in the morning before my wife is up.

I guarantee that I'm not hearing any artifacts at these extremely low volumes.

The rest of the time the OPPO volume is perfectly fine and I think having that inline would be a deficit.