[stingfan]

Received my P-9 over the weekend, as the second of two upgrades for my system.  First was the 9.02 to 9 SE's, which was outstanding.  See my other post on that subject.  I wish I had as much success with the P-9.  So far I've made the following observations:

1.  After correctly connecting and powering up the P-9, it initializes, then hangs with a message on the Control display saying:  "Load Settings" - it took 30 minutes of guess work to realize that not only must a source be connected to the P-9, but it has to be powered up in order for the P-9 to complete it's boot up.  Odd.  No documentation about this in the manual.  There should be something on this, unless my unit is faulty, and this is incorrect behavior for the unit.

2. The volume control.  Brilliant idea separating POTS from the signal path, not so good execution, not so good user interface.  The ALPS potentiometer in the analog section is totally out of sync with the digital step volume controlled on the remote and the Control unit's digital dial.  Step 1 is too lound, and steps 2-10 are huge leaps in volume/decibel.  At 12'oclock on the ALPS dial, the digital read out shows just 13/100, and the sound output is much louder than 13% of volume.  Its not linear.  As you go from 12 to 9 oclock on the ALPS the digital steps are much smaller.  I can't get the volume where I want it at lower volumes because the steps are too big in between.  Only way is to get up and adjust the ALPS dial by hand every time.


3.  The remote control.  Very cool looking. Think light saber from star wars.  However it is buggy.  Sends a murky signal to the control unit that gets the display oscillating back and forth from volume levels. For example, its easy to get the system to flicker back and forth from Volume level 1 and 2. Erratic behavior for a $3k pre amp.

4. Volume 0.  When using the remote to trigger the alps motor to drive the volume down to 0, the pre-amp lets out a nice static-buzzing sound in the left channel EVERY time, when it motors from any volume down to 0. 

5. Perhaps most elusive was a soft but noticeable (read: annoying) buzzing sound coming from the left speaker.  After about 3-4 hours debugging this last night...uggh, thinking it was power or interference related, it turns out to be P-9 pre-amp related.  I simply switched my XLR outputs to the amps, putting right channel to left and left to right.  Surprise, the buzzing jumped over to the right speaker (when plugged into the P-9's left XLR output), at idle, when the pre-amp is on, but no music playing.  I thought it was perhaps power coming to the P-9, so I used a variety of clean circuits and wall sockets, to no avail.  I even put my P-8 back in to listen for any buzzing.  dead quiet with the P-8 and 9 SE's. 

6.  LCD display.  A personal preference here, but I was surprised that Nuforce went with a backlit display versus using white LEDs on the black screen like the gorgeous display used on the squeezebox, which i don't even own, but have seen at a friend's place.  In a bright sunlit room it is very hard to read the Nuforce display from a distance, and its display is not very high resolution pixels, and the contrast is not optimal.  The fonts of the text on display look a bit old school.  I would have thought these details would be as polished as the pre-amp system design itself.

What happens when you combine the issue in 6 above with item 2 above, you get stuck in a volume guessing game:

When turning down the volume with the remote, you can't tell what setting it is on so a natural reaction is to watch the ALPS dial move.  However the digital volume values move much faster than the ALPS motor, so I've found myself lowering voluming too far, or to zero, then back up too high, then back down, largely due to the huge steps in the lower 0-13 volume values on the display.

Now all of this really got in the way of some serious music listening.  Today I  spent the morning confirming my debugging efforts and then listened to some great tunes.  Initial impressions on pure audio are impressive, and the unit really is most revealing.  That is the best word to use to describe the P-9.  It really gets out of the way of the music, which I believe achieves the objective Nuforce was aiming for.  I am sure it will get even better with more than an hour or two of demo'ing that I've done thus far.  Unfortunately, I am not sure I am going to keep the P-9 in my system, due to these problems that plague me above.   It's too early to call it, let's see how Nuforce addresses these issues.  If I don't keep it, I'll likely revert back to my trusty P-8, for the time being. 

In summary, the P-9 performing pretty darn well out of the box, but feels like a "beta" product to me.  Many little details must be worked out, as the rest of the players in this price level and performance level won't skimp in these areas at all, such as controls, interface, usability, and of course performance.  The ModWright team comes to mind in terms of product quality, and as a formidable alternative, despite its very different (tube) offering in their SWLP 9.0SE.  Also, the underdog - CIAudio PLC-1 passive line controller comes to mind as a solid, and well executed product in this arena at a very competitive price. 

I'm a big Nuforce fan, and am hopeful/optimistic that these items will be resolved for a product at this level.  Nuforce is a very responsive company. Stay tuned!

[Karsten]

Stingfan,

You should not have any buzzing in left channel. Unless it is ground loop related my guess is that you might have been unlucky and gotten a defective P9.

I agree with some of your critics but knowing NuForce's excellent customer support I'm quite sure that any problem will be addressed as soon as possible.

My major concern in testing this unit has been sound quality, as good as it is with the P9 I can live with a few small issues until NuForce comes up with a fix. The P8 also had some issues in the beginning, but these were all addressed quickly and with no expense to customer, my guess is that we will see same story with the P9.

Once you get used to it, it is actually not that hard to operate. It is just a bit confusing at the beginning with the volume delay, now I don't even think about it anymore.

Karsten

[rustydoglim]

It is likely that something got shaken and came loose during shipping. There should not be any buzz. And the remote shouldn't do that to the display either.
We have offered to pay for shipping to retrieve the P-9 for inspection.

[stingfan]

Excellent response time from Nuforce as always.  < 2 hours is pretty great.  Thanks for that.  Though I doubt a loose wire is the cause of all the issues, as some appear to be design related.  Thought it may indeed address the buzzing sound. I'd love to hear more about the ALPS step ratio, and the design intention there.   

Karsten, I agree, and am keepin' the faith here.  However, its less for me about getting used to the analog and digital volume units (which I do think is a brilliant idea in theory), but more about the volume steps and calibration of the interface itself.  I'm a product designer and marketer myself, so I'm used to looking at new interfaces open mindedly.  Volume step 1 needs to be much lower, and the digital values need to sync linearly to accommodate all systems more universally. What I can't get used to is getting the volume just where I want it from the remote.  Level 2 is almost ideal, and Level 3 is much too loud for one particular recording.  The steps are too big.  I don't think it is at all unreasonable to expect volume control steps to be flawless for a pre-amp at any price.  Wouldn't you agree Karsten?  I'm curious Karsten, what value is displayed for volume level when the ALPS is at roughly 12 o'clock?   9 o'clock? do you notice the quasi-logarithmic volume steps across 0-100 as I've described?  Admittedly, I am unaware of ANY pre-amp on the market today that uses anything but a linear 'interface' to the volume.  50% (12 o'clock) ~= 50% of loudness out of the system.  Particularly, I've not seen or experienced anything other than uniform gain/volume.  All other POTs based pre's have just one rotation and they've managed to be quite precise and fine without a logarithmic step function.  Thoughts?


Newly discovered issue #7:

Sometimes when turning the digital dial on the control unit, the ALPS volume goes up, but the digital read-out stays at volume 1, sometimes when I'm at 2/3 volume.  Seems like this happens most often just after using the remote for volume changes.

Yes, the P-9 transparency is amazing.  I've already switched back to my P-8 to notice the difference in performance.  Quite notable.  I'll miss the purity and detail.

If the steps could be changed in software to be more precise,  the buzzing in left channel eliminated,  the clicking in speakers when muting or switch sources could be eliminated, and the remote not causing display flicker, we'd keep her for sure...  Yes my expectations are very high, as they should be for potentially the best pre-amp out there. We'll just have to see how this progresses. 

[rustydoglim]

I am reposting Casey's comment to stingfan here:

The P-9 gain/volume control is set for most common speakers and source device. At volume 1 (display 01), the P-9 output (1V, 1KHz Sine Wave input) is 27.4mV. The output on a Ref 9 with 4 ohm load is 0.3V.  This is very low already. If you have super efficient speaker, we can adjust gain for you. But this will be done on a case by case basis.  More about the volume control design below. 

With P8, the digital volume control is not as 'pure' device as the passive Alps pot, and the primary goal for electronic volume control (as in the P8) is it's very easy to use software to dial-in exactly the volume level, and there are 200 steps available.   

The challenge with P9 is that we have exactly 1 rotation on the Alps pot, as limited by its physical form.   Compare this to the equivalent of "20 turns" (equivalent) on P8 volume. 

One point that I want to make is that human hearing is 'logarithm' in nature, and on P9, we decided to simply divide down the 1 rotation into 100 steps, as the Alps port is logarithm in nature, display=50 not necessary means a 12'o clock position on the analog pot, but rather, the Alps port gain is at the 50% level in dB scale. 
We are tracking the voltages electronically and not memorizing the physical position.

Display issue.  We decided to go with a minimalist display, through trade-offs that we decided to take.  Fancy display needs a fancy control circuit, and the display controller itself could be too complicated, consumes too much power, and required faster clock, all detrimental to audio performance.   The LCD we used is very simple, requires minimal power, and runs without any noise detectable on the analog line.   

We can easily scale the volume level to where you feel is most comfortable, hence, if possible, try to take some note so we know approximately what's the level we should adjust for you.

On the noise issue, can you try flipping Ref9SE from XLR to RCA position?    Just to make sure that the noise is not caused by XLR cabling.   

P9 has 10x more bandwidth then P8 and also means more care is required in setup. You should start with P-9's factory power cord. Check if that helps to eliminate the noise.

[stingfan]

Just got back and setup my 'inspected and adjusted by Nuforce' P-9 today, since some of you asked for an update, I'll post in summary.

Most if not all of my issues originally cited at the start of this post still persist after the inspection.   The most problematic for me is the volume sensitivity of the new digital to analog volume interface.  It still persists as described in both of my postings, making it impossible to electronically (including remote) fine tune the volume low-medium levels.

Other high-end pre-amp makers have shipped product with the very same problem in their first versions of motorized alps pot based pre-amps, including Modwright's formidable SWL 9.0SE linestage pre.   See the posting here for the same experience customers faced with volume control, they explain it in a way perhaps more clearly for folks with systems similar to mine:

http://www.audiocircle.com/index.php?topic=37705.0

In certain cases the problem can be adjusted by shortening the electronic pulse from the remote.  But in case of P-9 this is not possible, because the electronic controller intercepts the communications/control of the pot itself.  Technically, we would need to see this digital controller (not the remote) shorten its volume pulse  signal that communicates directly to the alps, via the controller cable to the analog section.  Lowering the gain doesn't solve the problem for highly sensitive systems completely because it still doesn't shorten the jumps in volume at the low-mid volume levels. 

But if you can live with these artifacts, or you have a less sensitive system, you may not be as affected.

I'm working on the case with the Nuforce gang.  They are quite helpful and interested to solve this design problem. For now, P-8 is back in my system, maybe waiting for the P-9.5...  More to come...

[nuforce-casey]

Since we are not related with ModWright, from the thread, I speculate that they are using a 100kOhm Alps, so the issue is how much you can move per 'pulse', with a 100kOhm, the resolution/step is greater than 10kOhm.   I gather this from 2 points: (1) the gain is listed as 15dB,  (2) comfortable listening range is 7-10 o'clock.

The fundamental problem with Stingfan's setup is the 101dB sensitivity of his speakers.  At full attenuation of the volume control, fully counter-clockwised, the attenuation is -36db.  After we reduced the gain from 2.3x (7dB) to 1x (3dB), the minimal volume pot setting is -39dB, which is not audible unless using very sensitive speakers.

Since the performance of P9 is 100dB S/N ratio, using 101dB speakers, you can actually hear our noise floor. 

When you use 'Mute' , P-9 deactivates the input and output relays.    So, Volume=00 is -39dB attenuation, but 'Mute' is open circuit.

[stingfan]

The fundamental problem with Stingfan's setup is the 101dB sensitivity of his speakers.  At full attenuation of the volume control, fully counter-clockwised, the attenuation is -36db.  After we reduced the gain from 2.3x (7dB) to 1x (3dB), the minimal volume pot setting is -39dB, which is not audible unless using very sensitive speakers.

I didn't know that owning sensitive speakers is actually a 'problem' in one's audio setup.    Top of the line audio components should always be tested with a full range of components including 3rd party products, before being released.  A pair of 89db speakers is not a sufficient test, as we've discovered.  Many folks have 90-101db sensitive speakers, and we're real people too! 

[rustydoglim]

Our guess is that the extra noise you're experiencing is due to the highly transparent P-9 that allow the noise to pass through, with 101db speaker, even little noise become audible with the ultra performance P-9.  We think you'll need to upgrade your amplifiers to V2, our next generation amplifier board with 20db lower noise floor than current V1 based amps.  You're not too far from office and we can bring a pair of Ref 9V2 SE over to give it a try. We'll be in touch.

[beachbum]

hello jason, my p-9 is on its way to me, should be in town friday, thanks but whats the ref -9 se v2, how about a little info, mike

[rustydoglim]

Make sure you read the P-9 application note (separate copy from the manual). It it is not included, email us.
For V2 questions, see the V2 FAQ and V2 topic.

[beachbum]

Got it thanks Jason

[John Casler]

Got it thanks Jason

Mike,

Just received the e-mail that the P-9 has landed at "your" location.

Guess I know what you will be doing this weekend.

Have fun.

[beachbum]

Hello John yes we have it, but after a long day at jazz fest going to be tough to install into system, Dr. john, Van Morrison, and many others played there butts off today, tommrow its Rod Steward, Johnny Rivers, and to many to see. thanks John

[John Casler]

Hello John yes we have it, but after a long day at jazz fest going to be tough to install into system, Dr. john, Van Morrison, and many others played there butts off today, tommrow its Rod Steward, Johnny Rivers, and to many to see. thanks John

Gotcha,

I guess as good as the P-9 is, when the option is to hear the real thing ya gotta keep your "true reference" at the front of the line.

Enjoy the "FEST"

[KrK]

Was there a solution about the problems with the P9? I have the same here posted in point 5..... \Even the sound is not on the middle of my speakers but is getting to the right. I have a little "gap" on my left speaker.

Now I am playing with my AVP16 and the stereo sound is beautifull: wide, deep, open, voice exactly between the two luidspeakers..

[nuforce-casey]

Was there a solution about the problems with the P9? I have the same here posted in point 5..... \Even the sound is not on the middle of my speakers but is getting to the right. I have a little "gap" on my left speaker.

Now I am playing with my AVP16 and the stereo sound is beautifull: wide, deep, open, voice exactly between the two luidspeakers..

Is better for KrK to file a help ticket with Nuforce support, as cases like this are not necessary straight forward.

I would suggest removing all the input connection from source components, and install one at a time, and listen carefully to each.  The high b/w of P9 would means that one channel may have more high-frequency or low frequency (DC) energy that could saturate the channel.   Try to find out if any particular upstream equipment or interconnect cable could be the cause.

Also, make sure that the 15-pin control/DC cable is not closed to any strong field (power cord, speaker cable, transformer from tube equipment).