Bi-wiring Unitiqute2

You need to be careful about biwiring as it doubles the parallel capacitance load on the power amp from the speaker cable.  It can be OK, but you need to chose the type of cable carefully.

Personally, I've never found biwiring the be particularly beneficial, I've found the money (i.e. double the cost or close to it) to be better spent on buying better speaker cables with better connectors and keeping to single wiring.

Don't bi-wire,  it really does not not do that much.   The most important parameter with naim amps is inductance & bi-wiring halves that of a single cable run.   Although Chord cables are not a problem for Naim,  they do have less inductance than required per metre & halving that is not going in the right direction.  As a single run they are perfctly OK,  I use Odyssey,  but 5m per side. Chord Clearway is 14AWG (2mm)  & 2.5mm cable should help a little to improve definition.  However my concern with your system is the Unitiqute driving PMC GB1's,  its a bit underpowered to get the best from those speakers.      

Thanks for your quick replies. Perhaps I will try to move to a 4 mm^2 cables in single runs. About driving the PMC's... I am quite surprised with qute's capacity to drive these speakers. With the qute volue at 50... they sound really loud :-) I can not imagine to use a 70 W/channel amp.

...Javi

Driving speakers well isn't a matter of watts, it's a matter of what's referred to as 'grip' - meaning how well an amp can control speakers that are a difficult load that can stress less able power amplifiers so reducing their sound quality.

The power amp in the UQ2 can't possibly hope to compete with a NAP 300 power amp costing five times as much.

The Qute is nowhere near powerful enough to drive the GB1 properly. Something like a Supernait, SuperUniti or NAP 200 is what's needed. 

I don't know about the GB1is, but PMC speakers in general are reputed to work best with amps having high damping factor, like the transmission line speakers of old such as IMF which I understand were their original inspiration. I'm not sure what the damping factors of the Unitiqute or the Rotel you had before, but I've heard somewhere that Naim power amps tend to have relatively low damping factors. If that is true, and if the Rotel had high DF then it could well explain your observed reduction in definition. If you like the sound of the PMCs (other than the deteriorated bass) you might find that a change in amp - or addition of a separate power amp - is necessary, though whether there are any Naim amps with high DF I don't know.   PMC themselves seem to favour Bryston amps.

Damping factor might have an effect,  especially in this case were the amp does not have that much power.  But I don't agree that applies to all Naim amps (all have low damping factor)  I've heard PMC GB1's sound fantastic on a NAP200.

Mike, IB,

I've never understood the thought behind high damping factor in amplifiers.  The relevant measure is the effective circuit damping factor: The ratio of the drive impedance plus the load resistance to the load impedance.  The speakers will usually have several ohms of resistance, for instance, an 8Ω impedance speaker will usually have at least 4Ω of resistance, so the effective damping circuit factor can't exceed 2 anyway.

If the amp has a DF of 18 (anything below 20 is usually regarded as low) the effective DF is 1.8, if the amp has a DF of 50 (very high) the effective DF is 1.92 - so not much difference (and most speakers have more than 50% ratio of resistance to effective impedance, making the difference correspondingly less).

Have I missed something?

Huge, i agree, DF is only meaningful to me with the amp, speaker cable and speaker in circuit...... The damping factor of an amplifier is simply the speaker load impedance divided by the amplifier loudspeaker impedance ... So a speaker impedance of 8 ohms matched with an amp and speaker cable impedance of .1 ohms would have a DF of 10... However what is often missed in such discussions that I see is that DF varies with frequency... So an amp speaker coupling DF might be 100 at 4kHz but drop to 5 at 50Hz.. Giving a forward mid, with a warm loose bass type presentation... Probably not sounding that great..... Hence the importance of matching...

Simon

Simon I get that the output impedance varies with frequency, but the voice coil resistance of a drive unit doesn't.

So taking your example, at 4kHz, the relevant drive unit will be the tweeter, which often has a higher voice coil resistance than bass mid units .  For example, it's 5.7Ω for a Scanspeak D2008 as used in a number of older Naim speakers (and my Spendors), thus the best effective DF you can achieve at 4kHz is 8/5.7 = 1.4, even if the amp is a perfect amplifier with an infinite DF.

Huge & Simon,  I agree,  its a combination of amp, cable, speaker & frequency & even then its far more complex.   I only answered the DP question that was raised by IB (I had doubts about it at the time thinking this DF might end up as another "debate")   IMO DF is a one of those hifi "myths" that has been reduced to a simple set of numbers,  whereas the effect(s) of an amp on speaker & a speaker on amp is far more complex.

Mike, exactly, amplifier DF is a red herring.  The resistance and complex impedance of the speaker dominate.

Furthermore, in power amps, when the transient effects of back EMF interact with feedback loops and combine with phase margins etc ...   .

Huge posted:

Mike, exactly, amplifier DF is a red herring.  The resistance and complex impedance of the speaker dominate.

I would also add the cable ...........  C&L / fs effects,  dare I mention TL's  .................. 

Javi A. posted:

 At the moment I feel my actual setup has no as clear definition as the old Rotel+BW system.

A heavier gauge cable (Chord are 2.5 mm²) will improve the definition?.

 

I'm afraid you need a much more powerfull amp, now it seem as it sound "muffled" and maybe pushed too hard no real definition as with suited speakers

You can do several things, replace the UQ, buy another amp or connect a Naim poweramp, letting the UQ act as preamp, or replace speakers to easier types

Changing speakerwire will provide minor changes and biwire could make things worse

I'm not convinced that damping factor is a red herring, although I wholeheartedly agree there are many factors at play of which DF is only one, and how significant any one factor will be will depend on the others (most definitely including speaker cables, crossover network, and acoustic loading of the speaker driver). I am aware of claims that with an amp DF below about 20 there can start to be audible effects - higher DFs are academic, other than that they may reduce the significance of, for example, the resistance of speaker cables. However, mine is only received wisdom from having read many  reviews of speakers and a few dissertations on DF, but not having made a proper study of the subject, so I bow to those that have.

incidentally, I only recall seeing DFs quoted in the form of 'minimum xx at yyHz, latter typically 40Hz or lower, so the question of false impression given by quoting at a higher trequency I don't think happens generally.

b_lund posted:

I'm afraid you need a much more powerfull amp, now it seem as it sound "muffled" and maybe pushed too hard no real definition as with suited speakers

You can do several things, replace the UQ, buy another amp or connect a Naim poweramp, letting the UQ act as preamp, or replace speakers to easier types

Changing speakerwire will provide minor changes and biwire could make things worse

B-Lind, thaks for you reply!

Do you think that adding, for example, a NAP100 (50W/Ch@8Ohms) will improve the audio quality even lisening the music at the same valume (i mean getting the same dB from speakers)?

...Javi

Anyone who is concerned about amplifier DF should only ever consider 8Ω speakers.  6Ω speakers should be treated with caution and 4Ω speakers should be avoided like the plague.  However there are some 4Ω speakers that work very well, so halving the amplifier's DF clearly hasn't had a particularly detrimental effect!

In short, just don't worry about it.  If an amp designer can't get that simple thing right, the amp will be downright terrible in so many other ways that it won't matter anyway!

Incidentally the reason for specifying DF at 40Hz or thereabout is that very often that's the frequency where the amplifier's DF is at it's maximum.

Javi A.

Do you think that adding, for example, a NAP100 (50W/Ch@8Ohms) will improve the audio quality even lisening the music at the same valume (i mean getting the same dB from speakers)?

Hola Javi,  adding a NAP100 is a possibility,    it gives 50W/8ohms vs 30W/8ohms for the UQ.   It opens up the possibility of bi-amping - Unitiqute powering treble & NAP100 bass,  but I understand that might not be as good as UQ on "no speakers" & NAP100 powering it all.   Therefore it has to be strongly advised to go for a dealer demo FIRST to be sure this gives the right & final result

Thanks!!!

I will think a little bit about all your replies. I also have to test equipment precission for longer time. I bougth it about two months ago and I only used it for a few hours.

Thanks to eveyone... Javi

Dear all...

after reading some post on the net I found quite usual to complement/upgrade the Unitiqute2 with the NAP100. People says that the improvement in sound quality is noticiable (setting speakers-off option on the qute). Some people tried to use the NAP100 to biamp the PMC but always the same. Using the internal amp on the qute degrades the sound quality.

I thinks the best will be to get an NAP100. In a few weeks/months I will update it and I will give my feelings here.

Thanks to all for all your help.

From Spain....Javi

Hold on a moment ... when you say "At the moment I feel my [UnitiQute + PMC GB1i] setup has no as clear definition as the old Rotel+BW system." it appears you are comparing two very different systems and come to the conclusion that the thing you don't like about the new system is down to the cables.  Do you still have either the amplifier or the old B&W speakers (which B&W by the way) to try half old and half new?

At some point did you listen to the UnitiQute and PMC GB1i together and like them?  Could it be you just don't like the combination and preferred the presentation of the previous setup.

My own setup is a UnitiQute as front end to a NAP200 and a pair of PMC Twenty.23 - quite similar to your GB1i.  I found the UnitiQute drove them adequately but there was a definite step up with the NAP200.  Personally I wouldn't add a NAP100 to the UnitiQute, but go for a second hand NAP200 instead.

Eloise,

I had a fire at home and I lost everything including the Rotel RA-04 amp RCD-06 and BW DM602S3! So I can not test different combinations.

I read issues about Naim and speaker cables. The old system was bi-wired with 2.5mm2 cables. The actual system is using Chord Clearway cables. Single run, 2mm2, and screened so that is the resaon why I was thinking about the cables. They are not the closest to the NAIM speaker cables. I will think about the NAP200.

...JAvi

There are a few other things that can reduce the apparent definition of a system.

Electrical interference can get in from the mains or via the Ethernet.

Wired Ethernet also usually sounds better than WiFi (and turn of the WiFi in the UQ, by using the menus).

Are you using Wave (*.wav) files to feed the streamer, using MP3s will definitely cause a loss of definition.

I also agree with Eloise, expecting a €1500 streamer / amplifier to drive €2000 speakers well, is really hoping for a lot.  Yes the UQ2 will drive them without damage, but they are likely to be a tough load for the little UQ2 and it won't be able to give it's best sound into a load like that.  However a NAP200 may need different speaker cables: The Chord Clearway is shielded, and shielding if done properly increases the capacitance of a cable.  The NAP200 is sensitive to cable capacitance, hence the recommendation for NAC A5 (Or Linn K20 if you really need to save money).

Hi. I recently auditioned my UQ2 +nap100 and DNM reson speaker cable with PMC db 1 gold, and they sounded fantastic together. Currently waiting for another dealer to bring in some Revel standmounts, but if those don't impress, I'm getting the PMC s.

Of couse the MP3 is completely out of my list. After ripping to wav the 600 CDs that survive to the fire I discover Tidal (flac of course) and I am really happy with it.

I was reading the user/installation guide for the NAP100 and they say that you can use any cable so the limitation of cables does not apply for it.

I will see this afternoon if I have the wifi on. I will switch it a bluetooth of to see how it sounds.

...JAvi