Haffler set up

After seeing 7_V mention the Haffler set up (or is that hafler setup) in the "HiFi+ goes digital and multichannel!" thread.
I thought I'd like to give it a try for movies.

I'd obviously want to have some kind of level control and to be able to turn off the extra speakers when listening to music.

I have a Cambridge Audio integrated and a pair of Gale speakers sitting around doing nothing at present.

The integrated can be plugged into my pre amp output.
Great, that means I only use one volume control and I can turn the Cambridge off when I listen to music.

The thing I want to know is: how do I hook up the speakers to this amp?

I know that the speakers are somehow connected together and then they are connected to the positive terminals.
After a quick Google the best explanation I could find was from Stereophile.
They said:
"Simply hook two surround speakers with their terminals wired positive-negative-negative-positive across the amp's two positive loudspeaker terminals."

Does this mean that the L+ from the Cambridge goes to the + on the left speaker, the R+ from the Cambridge goes to the + on the right speaker and then the negative from one speaker connects to the negative of the other?

 

Yes! In effect the two rear speakers are out of phase, leading to a broader rear stage, but the same Hafler effect can be had from one speaker but wiring across the two positive amp (or speaker) terminals. In this case it is easier to see that you are getting a L-R difference signal into the Hafler surround.

 

Thanks Steve.

I'll try with one speaker and with two just to see the difference.

I wasn't sure if I had it right.
I initially thought that the rear speakers would be wired in phase and across the positive terminals. Then I found the Stereophile explanation and they say the speakers are out of phase.

I'll guess I'll be doing some playing around tonight.

 

I think you've got the picture but here's one. People apparently sell simple boxes for this kind of thing, which you might find with a bit more googledigging (record for # of 'g's?)

Edited:
Even better pictures here

 

Thanks for the links!

I want to try B in this link.

 

Since the other posts I have seen warnings that one should check that one's amp is OK into this configuration - in effect it is bridged. I think a phone call to your amp maker would be best, to be on the safe side.

 

Hmmm, that's something to think about.
I don't want to waste an amp just for the sake of an experiment.
I'm going to be giving the Cambridge and Gales to a mate for Christmas.

Presumably there is less chance of damaging the amp if the two speakers are wired in series due to the higher impedance.

 

At this stage I think I should bow out of the discussion and see if one of the electronics guys comes up with something

 

Didn't Brian Eno suggest this on the back of one of his albums years ago ?

 

Hafler effect???

I think what you are referring to actually is the HAAS effect.

David Hafler died fairly lately, and invented the ultralinear ouput stage in a valve amp, whereby a portion of the output is fed back into the ouput stage screen grid of the valve, it gives a more triode characteristic, than a pentode or tetrode valve.


Hafler make studio stuff, and according to my John linsley hood book, Erno Borbely designed for them, and Michell Alectos are strangely, uncannily like a borbely design, listed therein, tho both tom evans and graham fowler claim they are their designs, so who is telling the truth? hmmm....I suspect fowler got the design from borbely, and evans had a little look in too.

 

B]Hafler effect???

I think what you are referring to actually is the HAAS effect.

David Hafler died fairly lately, and invented the ultralinear ouput stage in a valve amp, whereby a portion of the output is fed back into the ouput stage screen grid of the valve, it gives a more triode characteristic, than a pentode or tetrode valve.
[/B][/QUOTE]

Nope Hafler popularised extra "side" information with a pair of extra speakers back in the 70s as a sensible alternative to the quad format wars.
Actually 'M-S stereo" is ancient and was well analysed by A. Blumlein in the 1930s and FR Heegard in the 1950s

David Hafler, as you quite rightly mention was an amp pioneer:

Here is a nice resume

cheers

 

Is this a good time to mention the dynavector superstereo?

Its a real shame this isnt in every hifi store, along with subwoofers and supertweeters its one of those products that just... really work sometimes.

perhaps its the effect of adding a second pair of speakers to a stereo signal taken to the nth degree.

RIP mr D, nice amp.

 

No, I wasn't, thanks. I am allowed to use the words 'Hafler' and 'effect' together without meaning a new thing by it, meaning in this case the effect of having rear speakers wired in a Hafler configuration.

 

I recall reading articles about this in hifi mags in the 70's. I remember that a 25 ohm linear wire-wound potentiometer was used in line with the rear speaker to provide a level control

 

Yes, you're right. Mind you, the last time I set up a rear speaker in Hafler mode I didn't have the potentiometer and the rear volume was too high so I threw a blanket over the speaker. It worked fine even though the absorption properties of the blanket were inconsistent with frequency.

Note, that if you use a potentiometer, it must be in line and not to earth, otherwise the rear speakers are less in Hafler and more in parallel with the main speakers.

 

Or you could buy a no longer made Naim AV1 'processor', and guess how that works.......

Bob

 

:newbie:

:ffrc:

 

No wait, I can explain everything :justification mode:

I didn't have a pot to hand and I wanted to try out a Hafler rear.

Actually, the blanket approach worked quite well - pure wool, organically raised sheep and all that. With the level of the rear speaker so that you could only just detect when it was in circuit, it did add a rather nice ambience effect, brought the sound more into the room.

Keep this to yourself technobear but that's how I manage to do my Nonsuch 4s without crossovers. Just added a blanket.

 

well I never, hafler configuration you learn something new every day...

 

Careful if you do try it... Years ago I used to drive a pair of KEF 104/2s as front, with a pair of Gale 301s in a Hafler configuration using a Leak stereo 30+. Worked a treat. But when I decided the Leak must be crap cos it was old and brought in a Rotel RC930RB930 combo to do the same it blew the power amp..
Worked fine with a Musical Fidelity B200 mind so who knows.
And by the way, using a 2x300 Marshall into 2x15" EVs thru a 50Hz low-pass filter as a sub-woofer with the same set-up was awesome, but you really could hear where the bass was coming from despite having 2 volume controls.
And it was still not as cleanly deep as my current Dittons.. (sorry to veer into another thread..