Harbeth HL-P3ES2 specific

[A.S.]

John: I would if I actually knew anything about the subject of comparative amplifier topography. As a speaker designer my entire experience is on, as you say, the demand/load side so others are far better qualified than me to comment on supply side (amp) matters.

I just make sure that our speakers will work with just about any general purpose (voltage gain, low output impedance) hifi amplifiers.

[SaifulAJ]

Dear All,

I'm in the midst of identifying the right electronics i.e. cd player and amplification around my recently acquired used HLP3. In the dealer's room, the P3 really play music beautifully with Quad 66 cd player, 34 preamp and 606 power amp.

Good the 66 is, I prefer a new CD player like Quad 99 CDP-2 which can be connected directly to a power amp and I've been offerred a Quad 306 and 405mk2 quite cheaply.

My questions are, would a 306 or the bigger 405mk2 suffice to drive the P3? Would I lose much of 606's grunt, soundstage, transparency and rhytm? and what interconnect and speaker cables should I use for this system?

Please help me on this one. Thank you.

[A.S.]

That's a very good question and has arrived one day after I have been conducting some technical measurements on my own 405 and 606 in the deadroom! Good timing!

Even the 306 has enough power to fully drive the P3 but it will leave you with no reserve. I think the problem with the 306 is not so much the amp but the fact that the 34 preamp seems to clip with a CD input when the volume is at about 13 so if it is true that the 66 can drive the 306 (with a remote volume control?) that that's probably a good idea. But what about the excellently useful tilt control of the 34? You'll lose that functionality.

I noted yesterday that the 606 is definitely less concerned by the speakers frequency dependent electrical loading than the 405, which means that it must be a better design all round. It is also extremely powerful although I must say from my own experience, less reliable. Both the 405 and 606 have loads of power, far more than you'll even really need, but nice to have though when used with care.

Knowing what I now know, I'd select the 606 every time assuming that it sounds OK compared with the 405/306. I'm sure that it does, especially in the bass. You may also want to think about the limiter option if you use the 405 with the P3 (also the 606?).

Hope that helps.

Oh - don't forget: amplifiers age (this has been covered here in depth) and you may wish to have QUAD service whatever one of these classic amps you buy. Put your ear to the speaker (take care!) and with no music playing you should hear nothing but the tiniest hiss. If you hear a buzz ..... QUAD need to service it. My 606 was expensive to service recently because it seems that they replace the entire PSU where as they change individual components in the 306/405.

[Hu]

Oh - don't forget: amplifiers age (this has been covered here in depth) and you may wish to have QUAD service whatever one of these classic amps you buy. Put your ear to the speaker (take care!) and with no music playing you should hear nothing but the tiniest hiss. If you hear a buzz ..... QUAD need to service it. My 606 was expensive to service recently because it seems that they replace the entire PSU where as they change individual components in the 306/405.

My former Quad 909 never gave any hiss or buzz to the speakers, but my totally new Plinius SA102 gives in Class A with no music playing.

[A.S.]

My former Quad 909 never gave any hiss or buzz ...

In that case it was working perfectly.

The point I was making was that if your (old) QUAD does have a feint buzz, than it definitely needs servicing by someone who knows them very well - such as QUAD UK or their agents. They are extrely durable and as long as the capacitors are replaced every 15 or so years then it should give really good sound forever.

[SaifulAJ]

Thanks for the very useful info, Alan. The said CD player is the current Quad CDP-2 which can also control the volume via its remote control.

Now my dealer offers me a Quad 67 Cd player which also sounds nice and way cheaper but here, I have to use a preamplifier like the Quad 34. However, your findings on the 34 clipping issue when the volume hits 13 worries me a bit as I like to listen to my music loud.

I hate electronics, I find it much easier to choose which Harbeths I like because all of them sounds good :-)

[Hu]

Thanks for the very useful info, Alan. The said CD player is the current Quad CDP-2 which can also control the volume via its remote control.

Now my dealer offers me a Quad 67 Cd player which also sounds nice and way cheaper but here, I have to use a preamplifier like the Quad 34. However, your findings on the 34 clipping issue when the volume hits 13 worries me a bit as I like to listen to my music loud.

I hate electronics, I find it much easier to choose which Harbeths I like because all of them sounds good :-)

I am using Quad CDP-2, yes it controls the volume, but for me with 99 preamp sounds in a better way.

[A.S.]

I know that the later QUAD remote units can control volume, but how about the tilt function. Is that remotely controllable? I assume that the tilt electronics is built into the QUAD preamp, so no peramp, no tilt. Is that correct?

I was surprised at the clipping on the 34, but that's how I find it. Important point to bear in mind about (earlier) QUAD units like 33, 34, 44 preamps and QUAD 306, 405, 606 power amps ... they are designed as matched pairs. The implications of this are ...

1. The preamp is phase inverting; the power amp is phase inverting. That means an inversion of an inversion = back to in phase with the input to the preamp for the signal to the speaker.

2. The power amp's input sensitivity is, to my mind, extremely high. Just 0.5V rms will fully drive the power amplifier to maximum rated output. Anything more on the imput and the amp clips.

3. A typical CD player will produce about 2.0V rms at peak recording level which is all too often the norm these days (four times that needed to clip the QUAD power amp) so it's essential to throttle down the CD signal if driven directly into the power amp. You have to throw away 3/4 (three quarters) of the signal coming from the CD player which implies that the in-line volume control will be operating near the bottom of its range where the inter-channel tracking of (mechanical) volume controls may not be very linear.

It's a mystery why QUAD set the sensitivity so high at the power amps inputs. 1.0V or 2.0V would have been much safer, as indeed is the case with the professional QUAD 520, but that has other issues of load interdependence.

[tinears02]

Hi AS,

I hv been using a passive preamp (oxymoron) made up of a resistive pot as a preamp feeding the 306 followed by the P3. The 'hot' output of the 306 is connected to the 'hot' input of the P3. Can you confirm that I need to swap the connection if I want to maintain absolute phase? And to think I hv been using it all these years (14 and counting) without realising it.....


It is true the preamp is not really needed and the high gain of the 306 is more than adequate. The combo above drives my 16' x 24' room to more than adequate levels. However, my experience is that an active preamp (with gain) sounds better than a passive, resistive one. Solid or hollow state, it did not matter. What was most interesting was when my passive preamp was substituted with a transformer-based attenuator. That sounded very nice. There was just more details, and one could hear the decay of notes and 'soundstage'. Even my non-audiophile wife remarked she noticed a difference.
Hmmm, there is more to it than meets the ear.

YH

[A.S.]

Interesting comments.

Yes, in theory as the Q306 is phase inverting you could swap the hot/cold connections to both speakers but don't bother ... it will not give you the result you seek. Why:

1. Can you be sure the CD player is not phase inverting? No, not without test equipment.

2. Can you be sure that the entire recording chain, all the microphones, the mixing desk etc. etc. is not phase inverting? No.

So - I wouldn't bother to make any changes.

As for you comments that introducing a transformer or an active preamp into the reproduction chain could enhance quality compared with a passive volume control - this is counter intuitive. All and every transformer ever made imparts a tiny bit of its own sonic signature on the signal passing through it, which is why of course, valve amps (which are built around output transformers) have a special tone that solid state amps can't mimic.

[tinears02]

Alan
It is counter intuitive, that is why I found it interesting.

The transformer attenuator in question has less than 0.05% distortion
across the audio band with 2V input. The Quad 34 uses TLE2071 opamps
with 0.02% distortion at 20kHz (Av=10, 2k load), not that far away.
And if one adds the few stages together....
Today's opamps are some 2 orders of magnitude better, cf LM4562.

Even if one eschews the distortion induced by magnetic parts in
transformers and even order harmonics of valve amps,
I find a solid state preamp with resistive
pot also sounds better to my ears than just a
pure passive preamp - I do not know why.

All,
if you have the opportunity, try this out and hear for yourselves.

cheers
YH

[A.S.]

I don't think its fair to compare distortions in such crude terms as total harmonic distortion %. What is the nature of the distortion? Second or third? Perhaps more revealing is the intermodulation and non-linear distortion performance.

Take care not to sidestep the issue: what you may prefer is not necessarily what is technically distortion-free. That's legitimate of course and you are perfectly free to say so, but what you would be saying is 'I like some colourations'. Again, no crime in that but when a technical product that is much more complicated sounds superior to something extremely simple it does raise some serious questions that need to be addressed.

It is, as I said, counter-intuitive and taken to its extreme, the goal in hifi would not be minimalism, but maximisation.

In my experience, there is always an explanation for sound quality differences that are counter-intuitive but they are not obvious and take some detective work. The solution is intellectually satisfying though.

[A.S.]

POST SCRIPT: I am wrong about QUAD 606.
=========

I have just found the sticker on my 606 where I wrote "This amp is Non-inverting".

If that is correct, it is unlike the 405 which I'm sure is inverting. I will double check this and report as soon as possible. It's very curious that QUAD have two opposite stances on this issue.

[tinears02]

I do not disagree with you, Alan. Gross simplifications are necessary in a forum like this, and I am certainly not a fit antagonist to your genius and experience.

YH

[A.S.]

No room for genii here! Experience - yes.

Remember - viewed from 25 or 50 years in the future, these will be seen as the Dark Ages of audio, as the biplane is now compared to the 787. That shouldn't prevent us from discussing and ruminating over our combined experience. My wish is that when our contribution to audio is scrutinised our part is seen as solid, pragmatic, credible and real knowledge-building - i.e. of some use to those who will follow us. What other reason is there for our combined efforts?

[P3ed]

Greetings to all,

I am new to the forum, but have owned several Harbeth loudspeakers over the years, finally settling on the venerable HL-P3 (first gen), because of its marvelous mid-range transparency.

Each pair of Harbeth?s I owned have been driven by solid state amplification of various wattage and brand, but I would like to hear from owners who are using tube equipment to drive theirs, and what brand/model it is.

I am contemplating the purchase of a pair of 50-watt per channel, Quicksilver Audio Mid-Mono?s to use with the HL-P3?s, but don?t want to rush into it if the general consensus is to stay with SS amplification.

Give me your reasons either way, as your opinions are very much welcomed. Thanks in advance to anyone who cares to share theirs.

Regards,

William

[P3ed]

Silly me,

I see that my own question has been answered in one of the threads above. Sorry, I should have navigated the site more thoroughly before posting. Answer at your leisure.

William

[P3ed]

Hi,

The exterior veneer (walnut) on my HL-P3's is becoming somewhat dry. Do you have any recommendations on what I can use to restore the luster and shine to them once again? Should I use wax or sealer/refinisher? What is the best method? Thanks for any input.

Regards,

William

[SaifulAJ]

Just an update to this thread I started.

I finally end up with Quad 67, 34 and 606 for my P3s. What a combination! Thanks to my dealer (Tropical Audio of Malaysia) for giving excellent service and they really know Harbeth and Quad throughout. With dealer like this, I am sure more and more music fans will eventually convert to Harbeth in Malaysia.

Now I'm a very happy man. Maybe happier with 7ES-3 or SHL-5 in place but the P3s are really no slouch. Harbeth enriches my life and I really mean it. Thanks to Alan for such great magic!

[A.S.]

Thanks for the feedback. In my experience, Sam Chan (Tropical Audio, Malaysia) has completely reliable and dependable judgment about what makes great music at home. He has a vast experience to draw on and many satisfied customers. We are all very pleased that you are happy.