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View Full Version : Bi-wire, bi-amp connection problems



zhangyu.H
27-04-2009, 07:22 AM
Dear Alan:
As far as i'm concerned,after the coming of 30 anniversary model,C7 3 & M40.1 have changed their connecting way,from bi-wiring to single terminal,what' the reason for that?
Waiting for your reply.
Thanks
Zhangyu

A.S.
27-04-2009, 08:07 AM
I've covered this issue many times here before - for example here (http://www.harbeth.co.uk/usergroup/showthread.php?t=373) and here (http://www.harbeth.co.uk/usergroup/showthread.php?t=313). The answer is twofold:

a) Simplification. Bi-wire has confused some customers and led others down the path of fiddling about with different types of bi-wire links when they use the speaker in non-biwire (standard) mode. We don't believe that changing the standard expensively UK-made* gold plated brass links (supplied with the speakers) for any other connector will improve the sound.

b) I have freely admitted here many times that we ourselves never use bi-wire connection, neither during the design nor at public exhibitions nor listening for pleasure. It was added for purely marketing reasons i.e. consumer choice.

However, looking back over the twenty years or so since we applied bi-wiring terminals, it is seemingly a feature used by a very few customers that all customers must pay for. So speakers from the C7ES3 (that is, C7ES3, M40.1 and soon P3ESR) have reverted to the standard wiring pair. Any change in sound quality? None.

* You cannot believe how expensive these brass links are to make here. The are punched one by one, de-burred by hand, cleaned by hand then sent to London to a jewellers who specialises in gold plating. So expensive is the gold plating process that the jeweller insists on immediate payment and even a small quantity of these links will involve us paying $1000. Despite all of this attention to detail, it's still not good enough for some users ...

zhangyu.H
27-04-2009, 10:15 AM
Alan
Thanks for your detailed explaination.

zhangyu.H
28-04-2009, 02:17 PM
Dear Alan:

A friend of mine meets a problem--he has just bought a pair of Harbeths, HL Compact. During the period of enjoyment,he found that when he connected the speakers in bi-wiring way with 2 amps,not only the tweeters but also the woofers sounded so tiny that he almost could not hear.When he only connected the woofers with one amps,the circumstances didn't change any more,souned but tiny.He can be sure the amps are in all right.

Were there any cases like this before?Because the speakers are second-handed ones,so he wants to know what the problem is,whether the speakers has been "editted" or it is the characteristic feature of design for the "old" HL Compact?
Beg your instructions.
Thanks

A.S.
28-04-2009, 05:48 PM
Ah. I wondered if there was some problem underlying your original posting! OK. let's take this step by step. I'm thousands of miles away, and relying only on your posting I'm trying to imagine the situation that has befallen ni de pengyou.

1. You say "HL Compact". You mean, the very original HL Compact with the black baffle, foam grille and bass unit with the long protruding plastic phase plug in the middle? That unit ended production about 15 years ago. So what has been the history of your friend's speaker these past years? How many people have owned and perhaps modified them inside? Or damaged them? If you email me with the serial number, I can look up our Log Books and find out when they were made.

2. We do not recommend bi-amping. As I've said before, there are many things that can go wrong with bi-amping and it is possible that you can damage the amps and/or the speakers.

Also, if your concept is to drive the woofer from one amp and the tweeter from another amp, how can you be sure that the gain of the amp is the same? You absolutely cannot be sure about the amp/speaker match unless you have electronic test equipment to measure the gain and the frequency response and the phase of the amp. Nobody has that equipment at home so we say, don't play with bi-amping.

What I suggest is this: forget about bi-amping and bi-wiring. Ref-fit the bi-wire links between the tweeter (+) and bass (+) and tweeter (-) and bass (-) terminals on the back of the speakers and return the speakers to the original ex-factory condition. Then, find a standard, conventional hi-fi stereo amplifier and connect it to the 'normalised' speakers. Test and let me know what you find out. There must be a simple explanation for this. But we have to apply some Sherlock Holmes detective work to discover the real problem.

zhangyu.H
29-04-2009, 01:09 AM
Alan
A lot of thanks again,
I like the sound of Harbeth so much that I post 2 threads named "I love Harbeth" at a Chinese Hi-Fi forum,so a lot of Harbeth lovers take me as a professional,as you see,because of the language barrier,many of them can't communicate with you directly,so when they have some questions ,they come to me ,I just want to try my best to help them.

I hope we can build up a available way between the fans of Harbeth who can't speak to you in person and you, I do this without any economic benefits but want more and more people to know more about Harbeth.
In addition, your Chinese is good,O(∩_∩)O~。
张雨

zhangyu.H
29-04-2009, 06:31 AM
Alan,my friend's speakers' serial number is 3177,besides the certain parameters,he wants to know whether there are any differences in the design of frequency divider.

zhangyu.H
29-04-2009, 06:42 AM
Here is his speakers(they have been renovated on the surface and the screws).

garmtz
29-04-2009, 07:07 AM
As far as I can see, their is only one binding post. If you connect two amplifiers to this one binding post, you will short out both amplifiers, and possibly break them both. It would be wise if you would adhere to the advice Alan has given above.

zhangyu.H
29-04-2009, 07:26 AM
As far as I can see, their is only one binding post. If you connect two amplifiers to this one binding post, you will short out both amplifiers, and possibly break them both. It would be wise if you would adhere to the advice Alan has given above.

Thanks for your reminding,but I'm sure they are biwiring speakers.

A.S.
29-04-2009, 07:50 AM
OK, you have answered one question - these are indeed the original HL Compact (my first speaker design as the new owner of Harbeth company). They sold extremely well, especially in Japan and really created the foundation for the modern Harbeth company. I'm delighted that they are looking so fresh.

Back to the technical issues:

Yes, these are indeed bi-wireable (or bi-ampable). The top red/black terminals are wired to the tweeter crossover and the bottom two to the woofer crossover - see attached picture. To maximise my help you please need to follow the clear instructions I made in my previous posting, which I repeat again here:

"What I suggest is this: forget about bi-amping and bi-wiring. Ref-fit the bi-wire links between the tweeter (+) and bass (+) and tweeter (-) and bass (-) terminals on the back of the speakers and return the speakers to the original ex-factory condition. Then, find a standard, conventional hi-fi stereo amplifier and connect it to the 'normalised' speakers. Test and let me know what you find out...."

Please respond as I have requested. Problem solving by "remote control" at such great distance and across two languages must be conducted in a strictly logical way - please. Remember: many people are watching this thread and if we proceed in a logical way it may be of help to someone else in the future. That is the entire purpose of this Harbeth User Group - to build a knowledge archive for the future.

-----------------------------

P.S. I looked up the Log Book production records for these speakers. Your friends original HL Compact s/n 3177A-B were made on 31 Aug. 1990 and shipped to Hong Kong on 25 Sept. 1990. They are walnut. So, they are nearly 19 years old, and as we know, Harbeth speakers are built to last.

>

zhangyu.H
29-04-2009, 01:18 PM
Alan
We are so lucky to make such a wise choice to choose Harbeth, not only for the reason of the fantastic sound, but also for the great technical backup from you.

My friend's HL Compact works well when connect it in the normal way. But when he took the wire jumpers away, linked the tweeters' terminals with one stereo amp, and the woofers' with another one, the problem that I mentioned before appears--both the tweeters and woofers sounds so tiny that he almost couldn't hear the music. And we don't know what the problem is.

A.S.
29-04-2009, 01:51 PM
Pleased to try and be of service. I have very many friends in PRC and Hong Kong so I really would like to try and help you resolve this problem.

This is very interesting. First two basic tests ...

TEST No. 1
=========

Remove the bi-wire links and using the regular amplifier connect the speaker cable to only the top two (red/black) terminals. Can you hear a normal tweeter-only sound? You will not hear bass/middle, only high frequencies, but does it sound normal for listening with only the tweeter connected?

TEST No. 2
=========

Do not refit the bi-wire links. Now remove the speaker wires from the top two red/black terminals and connect to the bottom two only. You should hear bass/mid sounds only, no high frequencies. Does that sound normal for listening with only the bass unit connected?

We may have to work through some more steps but I'd appreciate your reply to this.

A.S.
29-04-2009, 02:23 PM
Whilst eating my lunch, mulling over your problem, I just realised that there is something strange about your photo of the terminals.

Can you confirm that the red terminals are on the left (as shown in your picture) or on the right side?

garmtz
29-04-2009, 08:59 PM
Thanks for your reminding,but I'm sure they are biwiring speakers.

Sorry, couldn't see it from the earlier picture, my bad...! :)

zhangyu.H
30-04-2009, 02:28 AM
Sorry, couldn't see it from the earlier picture, my bad...! :)
Thanks for your warm reply,it's my fault to put up such a misleading picture.O(∩_∩)O~

zhangyu.H
30-04-2009, 02:49 AM
Whilst eating my lunch, mulling over your problem, I just realised that there is something strange about your photo of the terminals.

Can you confirm that the red terminals are on the left (as shown in your picture) or on the right side?

Thanks,Alan,we're sorry to take your personal spare time to think about our problems.
The more we communicate,the more confident we'll be.I think we're closer to the answer.
I'm going to talk to my friend to make sure the basic issues.Then I will feed it back to you.

A.S.
30-04-2009, 07:54 AM
"Personal spare time" - what is that?! Life is so short that I don't divide my day into 'work time' or 'leisure time'. There is just available time - and I feel responsible for HL Compact, my first speaker-child now 19 years old.

Actually, our youngest son David had his 21st birthday last Sunday, so we are especially aware of how the years are slipping past us all ...

keithwwk
30-04-2009, 12:57 PM
Dear Alan,

Sorry to interupt this thread with my questions.

Your speaker terminal question had inspired me to have questions need your help.

I wonder what is the real meaning by labeling a speaker with (+) and (-) beside to avoid mis-polarity connection. Do you think there are any differences in sound if the follow assumptions are true?

1. If both L and R of speakers side and amplifier side are connected correctly (red to red, black to black), when the 1st musical note is playing, the woofer is out-going movement.

2. If both L and R of speakers side are connected correctly (red to red, black to black), but in amplifier side both L and R are connected reversed (Red to Black, Black the Red). when the same 1st musical note is playing, the woofer is in-going movement.

A.S.
30-04-2009, 01:43 PM
I would not expect any difference in sound quality. How can you be absolutely sure that right through the recording process, then through the CD player, then amplifier then speakers that there has not been a phase reversal at one or more stages? You can't. You absolutely cannot guarantee "phase coherence" with the original wave as it pushed onto the microphone's diaphragm because the recording, mixing, editing and mastering process passes the signal through so many people and so much equipment. But you can at least be sure that the relative inter-channel phase between L & R is correct as it arrives at your ear (otherwise you suffer the so called 'out of phase' situation).

So, the answer to your questions 1 and 2 entirely depends upon the phase situation of all the preceding stages of the recording chain as I mentioned above. If the phase of the recording chain up to the speakers is coherent with the original sound wave at the microphone then you are correct that (1) will give an outgoing wave from the speaker and (2) an ingoing one*. But if there is phase reversal at any prior point in the chain (and you cannot know this and even with test equipment and studying the music waveform you may not be able to say for sure) then the reverse condition may apply i.e. in (1) the cone moves inwards and in (2) the cone moves out.

Does this help?

* I'm reminded that traditionally QUAD pre and power amplifiers were both intentionally phase inverting. Now if you use the QUAD pre with the QUAD power amp, you have phase inverted the phase inversion, so you are back to in-phase again. But if you use the QUAD power amp on its own with another non-QUAD preamp which is not phase inverting, then condition (2) will apply.

keithwwk
30-04-2009, 02:49 PM
Thanks Alan for the prompt reply. I will try it on my setup to see if I can hear any differences.

A.S.
30-04-2009, 03:23 PM
I'm confident that under properly controlled conditions (i.e. no break, instantaneous A-B switchover) you will not hear a difference. I say this because let's not forget that music is not like pure tones: it's completely randomised across the orchestra. For example ... (and I'm just proposing this conceptually, I have not checked this as a fact.) if a violin is bowed outwards compared to inwards, does that change the phase of the sound?

zhangyu.H
01-05-2009, 05:54 AM
We have found what the problem is.
The terminals of tweeters and woofers are totally reversed,that is to say the ones above are woofers',and the ones on the bottom are tweeters'.So that's why my friend said,"When I connect the "woofers terminals" only(actually they are the tweeters'),the volume is so tiny.

A.S.
11-05-2009, 09:23 AM
I assume then that this matter is closed. Why this unauthorised change was made to the speaker after production remains a mystery.

codel
19-11-2009, 09:46 AM
I have by-wired my HSL5s and I notice that in low volume the one speaker plays louder than the other. When the volume increases the two speakers sound equally. Any suggestion about the problem?.

harbethpr
19-11-2009, 09:53 AM
This is not the speaker. I suggest that you revert to the std. connection. Sounds like an amplifier volume control tracking problem.

hifi_dave
19-11-2009, 10:03 AM
Codel,
I agree with the above post. Some amplifiers have mismatched volume pots at low volume levels so you get the problem you complain of. What is the amplifier ?

codel
19-11-2009, 11:06 AM
The amps are two Conrad-Johnson MV52 (tubes)and the preamp is a Conrad-Johnson PV 12.

hifi_dave
19-11-2009, 03:49 PM
Mmmmmm, you'd expect expensive gear like that to have well matched volume pots. Is there any adjustment to attenuate the pre inputs or the power-amp input ?

A.S.
19-11-2009, 04:00 PM
To be fair to the amp manufacturer, volume control tracking is considered importand in the middle of the volume control's range, not so much so at the extremes, where people don't listen.

I've covered the issues concerning volume controls here (http://www.harbeth.co.uk/usergroup/showthread.php?p=5783)

codel
19-11-2009, 05:04 PM
Αs my power amps have no volume potentiometers I understand that I will have to check my preamp pot.

Thanks everyone for the assistance.

hifi_dave
19-11-2009, 06:57 PM
I'm not familiar with that CJ pre but sometimes, pre's have an input level control to attenuate the signal into it. That would give the required effect. Alternatively, CJ might suggest attenuation of the pre output.

codel
22-11-2009, 06:16 PM
I wonder if I replace my pre and the two amps with an integrated amp for example an LFD Integrated zero LE mark III, would be a good idea to enjoy the music from my SHL5s.

hifi_dave
22-11-2009, 07:16 PM
Sounds like a good plan to me but you must audition first.

musicquest
23-11-2009, 02:31 AM
Knowing the CJ line fairly well, and the Lfd slightly, you'd surely be going down a step or two.
Not that the LFD wouldn't work nicely with them. If you have the upgrade bug in general, I'd explore further.

Gan CK
23-11-2009, 06:01 AM
I wonder if I replace my pre and the two amps with an integrated amp for example an LFD Integrated zero LE mark III, would be a good idea to enjoy the music from my SHL5s.

Having tried & heard quite a number of amps with the wonderful SHL-5 over the years, I'd say that the LFD LE III is IMHO one of the most musically communicative solid state amps with it. But of course you'll have to listen to this combo to see if its what you are looking for.

codel
12-12-2009, 03:57 PM
I have auditioned my SHL5 with the LFD Integrated zero LE mark III and I can say that it is not what I was realy looking for, compared with the two Coonrad Johnson MV 52 power amps and the CJ PV 12 PRE. I will now audition them with the Sugden A21SE Special Edition Integrated Amplifier.