Amplifier selection for your Harbeths (general, not specific Harbeth models)

[macolive]

I am actively shopping for amps and was highly recommended to BAT (Balanced Audio Technology) Amps and Preamps. Has anyone heard BAT electronics matched with Harbeths and if so, how would you describe the sound characteristics? I own the Monitor 30 speakers. Many thanks for your advice.

I am planning to order the SHL5 to mate with my VK-75. I borrowed my friend's Compact 7 and drove them with the VK-75 and they sounded great!!! So much so that I've placed an order with my dealer for the SHL5 right away.

The VK-75 is warm sounding so be careful. Everything else upstream of the VK-75 in my systems is very neutral.

If your front end is warm sounding then you may want to try the VK-75SE as I believe this has a more neutral sound. One more caveat with BAT, I am told that you must use a fully balanced pre-amp to extract the full potential of the amp.

[compozor]

I have Compact 7s in a 2500 cu.ft room, and I listen in the nearfield (approx 7 feet).

I have been using Cary 300B LX-20 single-ended triodes (rated at 20W) and they clip only rarely - and very gracefully. For my listening tastes (classical, often period-instrument recordings) the trade-off of power for sound quality has been well worth it. The purity, timbral truthfulness, dynamics and soundstaging are simply remarkable in my system - and confirmed by other listeners. And I get satisfying in-room levels (85dB) without even opening up the preamp all the way.

I would encourage others with similar listening tastes - if you're looking for ultimate sound quality more than unrestricted power - not to shy away from lower-powered amps.

Frank
http://www.franklarocca.com

[Hu]

Hi Hu,
I am using Plinius 9200 integrated with AH!njoe Tjoen tube CDP+ C7 ES2. Do you speakers make some hissing/buzzing noise from the tweeters and the midwoofers regardless of volume when put your ears close(about 10 inch). And some merchanic hum from the amp itself. Just want to know if this is normal. Thanks.

Hi wlmdx,

My Plinius SA 102 arrived, now I heard some hissing/buzzing noise from the tweeters and midwoofers, especially when I put in its class A mode, with A/B mode just very slight noise, nearly cannot hear. Now I just mailed dealer, have you ever contact to the dealer? Those noises are quite big. I did not hear merchanic hum from the amp itself, just from the speakers.
Thanks!
Hu

[kevint]

Hi wlmdx,

My Plinius SA 102 arrived, now I heard some hissing/buzzing noise from the tweeters and midwoofers, especially when I put in its class A mode, with A/B mode just very slight noise, nearly cannot hear. Now I just mailed dealer, have you ever contact to the dealer? Those noises are quite big. I did not hear merchanic hum from the amp itself, just from the speakers.
Thanks!
Hu

Hu,
Did you try to follow the procedure here?
http://www.pliniusaudio.com/questions/index.asp#09

First disconnect all powercords and interconnects and then reconnect back one by one start from poweramp, it will help to you identify which part of your system causing hum.

Good luck!

Rdgs,
Kevin

[Hu]

Hu,
Did you try to follow the procedure here?
http://www.pliniusaudio.com/questions/index.asp#09

First disconnect all powercords and interconnects and then reconnect back one by one start from poweramp, it will help to you identify which part of your system causing hum.

Good luck!

Rdgs,
Kevin

Thanks, Kevint!

I will try that to find out. Yesterday the dealers brought different source, pre amp and interconnects to try with Plinius SA 102 and Harbeth M30, they found the noise, later when I connect my own source, pre amp and so on, the noise is still the same.

Regards,

Hu

[A.S.]

...they found the noise, later when I connect my own source, pre amp and so on, the noise is still the same.

I think you need to be absolutely clear about the source of this problem: is the hum noise generated in the electronic circuit of the amp (or CD or whatever) or is actually an artifact of the mains supply wiring in your room?

For example: I have been playing with different power amps at home in my tiny 3 x 4m listening room recently. I noticed that there was a small hum on the left channel of one amp (right channel was clean, just the usual tiny hiss). I could live with that hum, no problem. On the next amp, there was a hum on both channels. Actually, it was not a hum, it was a buzz; I could live with this since it was only audible when I put my ear about 3cms from the bass unit. On the third amp, there was a strong hum on both channels.

It turns out that there were several problems and I had to tease them apart. First point to resolve was that the amp was plugged into a mains wall socket that was on the other side of the room. You may think (as I did) "so what? It must be served by the same electrical ring-main, and what is a distance of only about 5m between wall socket A (powering the CD, and preamp) and wall socket B, (powering the power amp)". Both the preamp and power amp were mains grounded.

But you and I would be wrong. There is a microscopic difference in the potential of the earth pins in wall sockets A and B due to the finite resistance of the bonding earth cable between them. To put this into perspective, that small a voltage is about the same as the voltage from your TV aerial that reaches your TV receiver: very difficult to measure but obviously there! So, the potential difference between socket A and B may only be millionths of a volt - surely insignificant - but it confuses the amplifier which will amplify the difference and then delivered to the speakers as a low-level hum or buzz.

I decided that I'd bundle up all three amps and send them back to their manufacturer's excellent service dept. (total cost ?400 to repair, check and calibrate). I then brought all the equipment mains to ONE point; this killed the ground (hum) loop.

Moral of the story:

1. As I have said here before, amps do age. The big smoothing caps (made with a wet paste) do dry out, and they let mains hum through onto the speakers. Only solution: replace them periodically - say every 10-15 years or so.

2. Always - always - connect all your audio equipment to ONE wall socket (or a pair of sockets if they are together on the same moulding).

3. Never, ever, remove or tamper with safety earths as a way of breaking ground loops. This could be FATAL. If the equipment is double insulated and does not have an earth connection that's fine, but if the equipment has an earth pin it needs one to ensure that the case is safe sould there be a mains leakage inside.

[airdavid]

Very interesting, Alan...
thank you !
Anyway, have you read my email about Monitor 30 birth year?
bye

David

[Hu]

I think you need to be absolutely clear about the source of this problem: is the hum noise generated in the electronic circuit of the amp (or CD or whatever) or is actually an artifact of the mains supply wiring in your room?

Thanks Alan,

I tried to disconnect the interconnects between power amp and pre amp, only switch the power amp on, still heard the hissing/buzzing noise from M30s, with Class A mode more, with A/B mode less.

The dealer tried in his shop, the same noise from his West Lake speakers. I am not sure if he connected all his audio equipment (probably Goldmund preamp) to ONE wall socket, I did at home.

Hu

[A.S.]

I tried to disconnect the interconnects between power amp and pre amp, only switch the power amp on, still heard the hissing/buzzing noise

Ok, noted. It's very important that you use just one mains socket to power everything as I explained.

Now, I am not trying to make excuses for any equipment, but as I have some experience designing active speakers which include power amps I am aware of how difficult it is to totally eliminate all and every hiss, hum and buzz. Because the circuitry is in the same case as the mains transfomer there will always be some interference between the magnetic field generated by the mains transformer and the circuits. This is inevitable. There will also be some hiss generated by the circuits. This is also inevitable and to a large or complete extent, predictable by a mathematical analysis of semiconductor (or tube) electron flows - far, far, far beyond my pathetic maths ability. There will also be a buzz associated with grounding inside the case and outside due to the connection to other equipment.

These unwelcome and unwanted noises are exceedingly difficult to eliminate during design and construction of an amp (which is why really good amp designers are so rare) and in the case of the M40 it has amazed me that every single active amp unit has its own very subtly different sonic signature - some have a tiny little hiss: some are absolutely silent etc. etc.. Why? I don't know. The circuit is the same: the layout is the same: the case is the same and yet there are these tiny differences in hiss, hum and buzz if you put your ear on the tweeter.

I have spent tens of hours playing with wires, tracks, grounds and so on and driven myself nearly (or more) mad to understand this. But - reality check - 'can you hear it at 50cms away or more'? Answer: no. All these noises are masked by the aircon system, the traffic noise, the TV next door and of course, the music itself. So why chase a standard of perfection down at the noise floor? It's just not necessary - or is it?

In my humble opinion, having recently become much more aware of the gurgles, groans, heart beat and spurious quasi-tones from inside my own body (and ears) when meditating in a quiet room just before sleeping, it seems to me that this sets the threshold of a worthwhile signal to noise ratio in the electronics. I should add that comparatively speaking, the problems with speakers - even good ones - are so gross and so ghastly that all this amp stuff pales into relative insignificance. And I'm not proud of that.

Lastly: it is not fair to judge an amp (pre or power) when the input is 'open circuit' because the input will pick-up and amplify aircraft, taxi, mobile phone, TV, computer and other rubbish noise.

To be fair to the amp you need to short circuit the INPUT i.e. connect the INPUT plug's hot pin to the input plug's ground or connect it to a preamp that is turned off.

[Don Leman]

. So why chase a standard of perfection down at the noise floor? It's just not necessary - or is it?

Thank you Alan for your very considered reply.

One other point which I have thought about from time to time is the relationship of these noises to speaker sensitivity. e.g. If the noise source is in the amp then switching to more sensitive speakers would make the hum/buzz more obvious.

Seems logical but is it?

[wlmdx]

Hi wlmdx,

My Plinius SA 102 arrived, now I heard some hissing/buzzing noise from the tweeters and midwoofers, especially when I put in its class A mode, with A/B mode just very slight noise, nearly cannot hear. Now I just mailed dealer, have you ever contact to the dealer? Those noises are quite big. I did not hear merchanic hum from the amp itself, just from the speakers.
Thanks!
Hu

Hi Hu,
I contacted the US distributor and spoke to Mr.Scot Markwell. He advised me to try several things to rule out that I don't have a noisy amp. No matter how I tried the noise is still there. The only thing that changes the noise is the MUTE botton. If the unit on MUTE,I have the hiss/buzz. If the unit is on operation, the noise is lowered. Check the link:
http://www.audioasylum.com/forums/am...ges/39053.html

I have the similar problem. If your amp was produced in the 2004, you might fit into that category. He is currently waiting for a respond from Gary (Plinius factory) to see what's the fix. I am pressing for a new amp. Hope this help.

[Hu]

Hi Hu,

I have the similar problem. If your amp was produced in the 2004, you might fit into that category. He is currently waiting for a respond from Gary (Plinius factory) to see what's the fix. I am pressing for a new amp. Hope this help.

Hi wlmdx,

Thanks! My amp was produced now, in March. I hope the distributor will contact to Plinius to see what the problem is.

Hu

[A.S.]

You're absolutely right Don. I did notice that Lao Hu mentioned a brand of speakers which, right or wrong, I associate with high efficiency and big drivers. This would definitely enhance the noise. If, for example, the other speakers were 6dB more sensitive than a typical Harbeth - say around 91/92dB - that would equate to a doubling of the spl of the noise just due to the speaker's higher efficiency. That definitely would be noticeable even on a casual listen.

There is another factor here: the subjective quality of the noise. Is it hard and harsh with a definite tonal character to it? Soft like a gentle wind? Random and spluttering? Bass heavy? Top heavy? All these characteristics can give a clue to the precise noise source.

I strongly believe that a gentle, warm, soft hiss can actually subjectively enhance music. Truly. It gives the ear a reference point around which to pivot the ear's Automatic Gain Control action. Strip away the noise so that the background is deathly quiet and the ear has to work much harder, constantly tightening and relaxing the muscles in the ear itself.

I surely can't be the only person whose ears actually pop (and I can feel the muscles working) when I am listening to music such that I find myself swallowing to equalise the pressure. I guess that this ACG mechanism is an evolutionary protection mechanism: the protection from the damage of a loud sound and the 'gaining-up' of the ears sensitivity to a more useful dynamic range when that twig snaps some 20 feet behind - and life may hang on a thread.

I have long considered that when pople talk of the so called 'hard' digital sound v. the 'soft' analogue sound they are actually commenting on the background hiss level. I dare to suggest that if noise, of a similar spectral character to that associated with analogue recording, was deliberately superimposed onto even the 'hardest' digital recording that it would sound perfectly acceptable.

[Hu]

You're absolutely right Don. I did notice that Lao Hu mentioned a brand of speakers which, right or wrong, I associate with high efficiency and big drivers. This would definitely enhance the noise. If, for example, the other speakers were 6dB more sensitive than a typical Harbeth - say, around 91/92dB, that would equate to a doubling of the spl of the noise just due to the speaker's higher efficiency. That definitely would be noticeable even on a casual listen.

I do not know what sensitivity West Lake have, but I got surprised at the store that noise is much more obvious (I stood about 1M far from the speakers and could hear quite big noise, with my M30 I have to be closer to the speakers. I asked the dealer what the speakers they are broadcasting, they say they are West Lake.

Hu

[A.S.]

Speakers made in USA? Then I think that the efficiency will be much higher than Harbeth. That is the reason that you heard the hiss more distinctly. Plus, of course, the fact that the Harbeth have a flat frequency response.

[danrubin]

The recommendation of powering all components from a single wall socket is interesting and not something I have heard before. Two things come to mind:

Could this be different in England than it is in the US?

Power has become a very big deal with American audiophiles (maybe the rest of the world too). Expensive power cords, power conditioners, and so forth. We don't need to have that conversation, but I want to remark on a couple of things. First, common practice has been tending toward dedicated circuits for one's audio system, and usually more than one such circuit so that you isolate source components from amplifiers, analog from digital, etc, etc. It's all connected back at the breaker box, but nevertheless, this is what people do. I am not aware of this creating ground loop problems for people.

Another practice is to avoid power strips and the like and, if not using a conditioner, plug everything straight into the wall. To do that and to implement your suggestion would require either very few components or a lot of outlets at the one circuit drop. Both are possible.

[Hu]

Speakers made in USA? Then I think that the efficiency will be much higher than Harbeth. That is the reason that you heard the hiss more distinctly. Plus, of course, the fact that the Harbeth have a flat frequency response.

In the case, how could such amps drive USA speakers? I could hear from those speakers very distinctly, not only hiss from tweeters but very annoying hum (somehow like the noise of PC fan) from midrange in its A class mode.

And, if that nearly only makes such hiss/hum when it is in A class mode, in A/B mode you almost cannot hear, does that have something to do with the mains?

Hu

[A.S.]

I'm sorry to say that I can claim no originality for the observation that all grounded hi-fi equipment should be connected to the supply at one point in the room. I should have adhered to this - it is basic electrical engineering and applies the universe over. But convenience and haste made me overlook this.

If the equipment is not grounded i.e. has a two-pin mains plug not three, then the is no issue with ground loops by definition and you can (probably) plug-in to the supply anywhere in your house or your neighbours.

Taking the supply back to the mains inlet board especially in old houses with strange wiring has to be a good idea, but it's a rather extreme option.

I really should have recalled the problems I had eliminating hum from recordings made off my (grounded) amplifier onto the sound card in my (grounded) PC. The PC was in one corner of the same room adjacent to a convenient wall socket ; the amp in the opposite corner adjacent to another socket and I ran a phono to jack screened (hence grounded both ends) lead between them. Eventually, three safe solutions were found to work in breaking the ground loop: an optical connection (no connection to ground at all), high quality 1:1 audio signal isolating transformers (expensive, some small audio quality issues - this has been the standard practice in the BBC for some 70 years) or powering the PC from a mains isolating transformer of the type used on a building site. In avery case, the trick is to prevent a ground loop. (Thought: there is a fourth option: to power the PC from a long mains cable plugged into the amp's mains socket but that was ugly.)

Finally, powering from extension leads plugged into one mains wall socket: fine; no problem - this is what I do. You can run several of these off one socket, sufficient to power everything but make sure they come from one single or double wall socket and that you don't exceed their rating.

I was discussing studio grounding during an installation of M40 Actives at BBC TV Centre a few weeks ago and the wireman confirmed that the studio had a good, solid 'star' earth point in an equipment rack. All audio signals were of course balanced (hot, cold and ground or live, return and ground) and that although they were distributed around the studio with balanced shielded cable the shields were snipped off at the distant end as one end was bonded together at the star earth point, which was connected to the building's earth strap to ground. Hence, no possibility for ground loops since there is no cable between signal grounds: they are all at the same potential, at the same point in space in the equipment rack.

[danrubin]

I believe that mains power in the US is not balanced as it is in the UK. Hence a market for power conditioners that deliver balanced power (Equi=tech, Balanced Power Technologies). People who use these say they never have ground loop problems.

[A.S.]

I believe that mains power in the US is not balanced as it is in the UK...

Sadly, completely untrue. The situation in the UK - and I would guess the world over - is that the 'neutral' feed is connected to a huge, solid stake buried in the ground at the power station. In your home your 'earth' pin is also connected (or definitely should be connected) to a solid stake driven ito the ground by or in your home with a thick cable: go and look for it: have it routinely checked: know where it is. There is no way at all that this power transmission system can be described as 'balanced'. It is exactly the opposite: it is unbalanced, single-ended from the power supply just as a phono-phono lead is.

So, the 'live' feed is swinging + then - volts relative to the neutral wire 50 times a second (or 60 times a second in the USA etc.) and the neutral wire is at or very close to the same potential as the earth wire.

IT REALLY MATTERS that you know which pin is truly 'live' and which pin is truly 'neutral' on each and every mains socket in your house. In the UK we have a really solid plug (also in Hong Kong and other empire-legacy places) where this can not be confused: the plug can only be inserted one way. But elsewhere, you can often plug in a two-pin (non-earthed) plug either way round and accidentally swap over the neutral and live.

WHY DOES THIS MATTER? Because a shock from the true neutral is not likely to kill you. It is so close to ground potential that it can (almost, but not actually) be considered 'ground'. But if you get a shock from the true 'live' it could/will kill you.

HOW COULD THIS HAPPEN? If your equipment uses a mains switch or a standby circuit that only switches one side of the mains supply - it would be designed to expect to switch the live side. The other side of the supply will flow around the circuit and to the wall socket even when the switch is open and internally the entire equipment will be charged. That's OK if the switch has interrupted the true live feed, because the neutral - almost at ground potential - willl be running around the circuit. But if you inadvertently transpose the live and neutral, then the switch is not protecting you: the entire circuit is live even when the switch is off, and in the case of electrical failure, the case could become live. If there was no proper safetly ground connection then when you touch the case the mains live passes through your body seeking the ground. Fatal.

http://www.cherwell.oxon.sch.uk/prm/efact10.htm

http://www.theanswerbank.co.uk/How_i...tion40795.html

http://www.zen22142.zen.co.uk/Circuits/Power/tps.htm

Conclusion: Check your home wiring for the safetly of your entire family. Be 100% sure it is wired correctly. Know which pin is truly the live pin in each and every socket right through the house (you can buy a simple neon tested for this). Make sure the earth bonding is perfect. Never ignore the earth pin if the equipment expects a saftely earth. Get your wiring checked periodically: unbeknown to you, earth wires do loosen and drop off; one day your life may depend upon its integrity.

PS. Did you know that over a period of many years the 50/60Hz mains cycling causes the screws in plugs and sockets that crimp the wires to actually unscrew? Make sure all connections are tight.