Rogers LS6 speaker crossover wiring help please.

[brainhertz]

Hiya, could do with some help, I have acquired a pair of roger
speakers, that are working but sound a bit too harsh, had a look inside one today and someone as rewired them with some thin white wires and maybe removed one or maybe two resistors from the crossover circuit boards. I don't know the value of these resistors as it just states R1 & R2 on the board, also I am not sure if the units are wired correctly, so does anyone have a wiring diagram for them or better still a photo of the fitted crossovers in there own speakers. I will upload a few photos of the first speaker, at this moment I will assume that the other one is the same, but keep you updated when I get to the inside of the other speaker. any help much appreciated Many thanks Mark!!!

[brainhertz]

Hiya again I have spotted a pair of Roger LS6 crossovers on a selling site but they look different to the ones in mine so may be they are earlier or later versions not sure, two inductors three caps & one resistor and the wires look more standard a lot heavier in White/Brown/Green/Red, so not sure what to think. Cheers Mark !!!

[Boater Sam]

Thin wires have no place in a speaker, if you can't find any info, replace with decent thick wire, it will sound better.

[Ted Kendall]

This looks as if The Phantom has made a botched attempt at bi-wiring - I'd guess that R1 was meant to balance the tweeter output against the woofer, and if the two sets of terminals are bridged without it, the treble will be over-bright.

[Radio Wrangler]

It looks rather got-at.

Amongst many weird beliefs floating around in the audio world is one that says that thin wires are better for carrying treble (or sometimes bass) 'information'. As Sam says there is no scientific or engineering support for this in loudspeakers, though the increased resistance of too-thin wire is a real disadvantage (pun not intended). 18 gauge should be fine and stuff that would start your car will give no significant improvement

This belief got going in the world of esoteric speaker cables. Not satisfied with super expensive audiophile cables, someone had the idea that by splitting the input to the crossover, two sets of speaker cables could be run from the amplifier to each speaker. This would allow the owner to choose different special cables for their high frequency and low frequency 'sound'. Loudspeaker manufacturers cashed in on this by providing separate input terminals feeding the high frequency and low frequency sections of the crossover, and adding a profitable increment to the price.

Your speaker seems to have been DIY modded in this way. The upper pair of terminals aren't labelled by Rogers, only the lower pair with the single word "Input". If they had been original there would have been wording saying which pair was which.

They call this "bi-wiring". Engineers find it hilarious and poke fun. Engineers also point out the inconsistency of magic wires between amplifier and speaker, but not inside either. So the audiophiles started sticking magic wires inside, well at least at the bits they could get at. The wire of speaker voice coils and crossover chokes remaining unmagical.

Crossovers often contain resistors which are used to reduce the drive to tweeters to reduce their output to match that of the bass driver. They also get used to damp the Q of resonances. If they are removed the speaker will sound too bright and exhibit a rising step in its frequency response at the crossover frequency.

More worrying is that there doesn't seem to be the expected damping material inside the cabinet. Maybe some magazine article accused the stuff of making the sound 'wooly' or perhaps the perpetrator's religion allowed him to use only single-ended triode amplification of low power, and that the resistors and perhaps the damping went away in an attempt to make the speaker more sensitive given a lack of drive power?

I've not seen inside that model before, but Rogers went along with the Dudley Harwood/BBC style and I would expect there to be something more in that void, though I could be wrong.

You really do need to find someone with an unmutilated speaker to find how to restore yours, I'm afraid.

David

[Ted Kendall]

You see this all the time on certain forums - "I've got this and I'm happy with it - now what can I fiddle with and it up?"

[Radio Wrangler]

I try to avoid those fora, they only make me cry.

It would be too much to hope that someone else on such a site was about to ruin a pair of LS6 and Mark could get the resistors and damping stuff for recycling.

David

[brainhertz]

Thanks for the replies, as boater Sam said the wires need changing as a must, the damping sponge is all intact I have removed it for the photos but it is there, I will be putting the resistors back in and was thinking of 5 watt ceramic type, the circuit board as R1 & R2 etched on it put not sure where to make connections, plus I think the connections for the speakers could have been moved, am I right in thinking that they should be 180 out of phase with each other as in tweeter positive to woofer negative and vise versa. Please can anyone guide me in the right direction, as I don't want to blow a speaker coil as at the moment they all work ok apart from as mentioned being over bright by a long way. Many thanks Mark !!!!

Thanks for the speedy replies, as BOATER SAM says the wires need changing and I need too look at the resistors R1 & R2 that are missing. I have all the damping material I just removed it to take the photos. I was thinking of using ceramic type resistors of 5 watts put not sure where to make the connections, and will disregard the top two banana plugs that radio wrangler pointed out should not be there and have been added by the numpty who fiddled with them before. If any body could take a photo of the connections in one of there speaker crossovers or has a wiring diagram it would be a great help. The connections to both the tweeter and woofer have been soldered and surely these would be normal spade connectors originally. For the moment I will strip the speakers down and wait to see if anyone can help with the resistor connections R1 & R2 as I don't want to make a wrong connection and blow a speaker coil as they all work at the moment apart from being as pointed out over bright, Many thanks Mark hope someone as got a diagram or photo of these speakers !!!!!

[brainhertz]

I seem to have posted two replies I thought I had lost the firs one when me coat was ringing ****** mobile phones. Cheers anyway and I will keep my fingers crossed on the diagram or photo needed Thanks Mark !!!!

[brainhertz]

Here is a better photo of one crossover cheers Mark!!!

[brainhertz]

Sorry its upside down, not too good with technology I perhaps could have rotated it before posting !!!

[Edward Huggins]

All those ALCAPS look newish, probably OK - but not in the SOLON class.

[brainhertz]

Thanks Edward, the caps are all ok, but some previous owner as made a mess of the wiring inside the speakers and removed a resistor or maybe two and I don't know now the value or were they were placed in the circuit and need help with this. The rest of the speakers all function but the sound is as stated by fellow members over bright and I don't want to make any mistakes and blow any speaker coils. Really what is needed is a wiring diagram of the crossovers for these speakers or a photo of a standard crossover to enable me to put them back to there original state. Many thanks Mark!!!

[PJL]

The example on ebay has a similar HF network and is using 3.3ohms 2W for R1. This will temper the brightness. If its still too bright then increase the resistance value.

Alternatively, you could start from scratch and research crossover design!

[mhennessy]

Hang about - I'm pretty sure those aren't the original tweeters!

If so, then all bets are off. Returning the crossover to the original design might not actually help.

The replacement tweeter will have a different sensitivity and quite possibly a different frequency response curve. You need to measure the output and see what's what.

Oh - and do bear in mind that Rogers used the same PCB across more than one model, and populated them accordingly. So, just because some components are marked on the silkscreen, it doesn't necessarily mean they were fitted originally.

[PJL]

Look identical to the others on google images. Even if they have been changed, setting the preferred HF gain by ear using a resistor seems the only practical way to go. Changing the crossover design or frequency would require a suitable test environment and specialist equipment.

[mhennessy]

All the tweeters I can find via a Google Image Search for "Rogers LS6a" have 3 mounting screws, and show what appears to be a SEAS 19TAF metal-dome tweeter. The OP's tweeter is secured by 4 screws, and looks like a soft dome.

In which case, he has the LS6 - not the later LS6a. I'd suggest that a moderator changes the thread title to save confusion.

Measuring loudspeakers does not require a specialist environment, and the test equipment to do it need not be expensive. I'm forever posting details about how to do it on here, and it baffles me that so few of us actually do it - it would save a lot of subjectivity.

In the absence of measurements, a subjective comparison with a reference (via an instantaneous changeover box with level-matching ability) can tell you a lot. But trying to do it subjectively with no reference is a rabbit hole that really is best-avoided

[m0cemdave]

Oh dear, what a can or worms...

If anything is missing, it is R1.

-----

The pad between R2 and C6 has never been used, so they were most likely only fitted to another system's crossover that used the same PC board.

There is 500 uF of DC blocking capacitance followed by a 2nd order filter, for the woofer.

The added pair of bi-wire terminals feeds a 3rd order filter, for the tweeter.

"R1" was either a resistor or a wire link to connect the HF filter to the original + input terminal.

-----

As this has been messed about with, nobody can be sure if it's an original crossover board, or how many components have been replaced in the past.

Sight of either an original crossover board or a known genuine circuit diagram will enable restoration of the crossover to original specification.

But if the tweeter has been changed, the original crossover will be wrong anyway.

-----

Best thing to do, Mark, is keep asking on likely forums until you find somebody with an un-modified pair of speakers, and get them to post pictures of the crossovers.

[Radio Wrangler]

Out of doors for the environment. A sound card to source and measure the signal, a power amp, and a microphone with preamp ought to do quite well. Ought to keep the neighbours entertained

David

[brainhertz]

Hiya again I am sorry but as pointed out by Mark Hennessy I made a mistake when posting initially my speakers are in fact LS6s and not LS6as so thanks Mark, I had a look on your web page earlier but at to go out so saved it to have a look at tonight so will have a good read, do you have any clues has to the value of R1 Mark or anybody else for that matter, or do you think I could try different values until I am happy with the results, as m0cemdave as quoted if anything is missing it is R1, I'm not in any rush so at the moment I will keep my fingers crossed and hope something turns up, I do have a lot of test gear including Oscilloscopes but up until now have been more of a collector than user of all the gear I own but maybe I should be putting it to work now. Many thanks Mark !!!!!