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julesd68
13-02-2014, 13:41
For some time I have been unhappy with the balance of the sound from my system - there was always more bass coming from the right channel. I thought this was maybe to do with speaker positioning as it is slightly more tucked in a corner by necessity. Today, I swapped over the interconnect channels from the phono stage to the amp, so it goes positive to negative etc and bingo - problem solved - the sound was much more focused in the centre of the soundstage, the bass feels even from both speakers and it just feels right ...

So I am trying to work out what is causing the phase inversion and this is what I have checked -

- the cartridge is wired correctly
- the tonearm interconnect is wired correctly to phono stage
- the CJ phono stage is phase correct, according to the literature
- the speakers are both wired correctly
- I checked a different interconnect and this behaved in the same way

I am pleased to have improved the sound, but would really like to know what is causing the phase inversion, if that is what the issue is??

Rothchild
13-02-2014, 14:13
If reversing the polarity from the Phono stage to the amp does it then it can only be something 'upstream' of that.

Try returning that connection to normal and plugging the deck inverted to the phono stage, if that doesn't have the same effect it would indicate that the phono stage is inverting, if it does then it's something further 'up' that than (cart wiring).

Edit, that said absolute phase seems an unlikely candidate for causing unbalanced presentation?

Reffc
13-02-2014, 14:29
It's not unheard of Jules to have the speaker 4 pin connectors wrongly wired for the Tannoys which can cause phase inversion. Easy test to rule that out is to connect a 1.5V battery to the crossover input terminals and the woofer should move inwards when you touch the wire to the battery (if wired correctly) . However as it's happening by swapping IC's across, it's channel inversion by the sounds of it and not absolute phase inversion as Marc points out. Try removing the ICs completely and trying another pair in their place to rule out an IC termination fault. If the results are the same, then it can only be a wiring issue with the preamp input or phonostage.

julesd68
13-02-2014, 14:35
So following Marc's suggestion, I now have the phono stage to amp wired 'correctly', inverted deck to phono stage and it sounds correct.

This means the issue is to do with the deck somewhere I guess but don't understand it - I have double checked the colour coding on the cart. I've already tried a different pair of IC's so I can rule that one out ...

I wonder if it's something to do with the tonearm - I am unable to connect the tonearm earth cable into the phono stage without causing hum but maybe that's a seperate issue!

julesd68
13-02-2014, 14:37
One other thing - it's not an amp issue as it presents the same problem on both amps I am using at the moment ...

Rothchild
13-02-2014, 14:42
Also, through my cold fuddled brain, just to clarify; swapping rca cables red/black is not inverting phase it's just swapping L/R channels. To invert the phase you'd have to swap tip/ring connections.

Do you have another source to rule in/out the deck as the source of the issue?

julesd68
13-02-2014, 14:55
Just tried the cd player - swapping around the channels doesn't seem to have the same effect so 99% sure the deck is the culprit ...

julesd68
13-02-2014, 15:06
I have just played a track on vinyl and compared the same track on youtube through the pc speakers, and listening to the stereo effects the channels are reversed.
So with my vinyl, I seem to have a more focused soundstage and balanced bass, but the channels aren't correct!
Now I am totally confused. :scratch:

Reffc
13-02-2014, 15:15
Your tomearm wiring to the cart is mixed up then Jules or the lead out wires have been soldered out og phase...it's all it can be. The tonearm could be earthed to the chassis earth for your TT if you have one (ie taken back to a ground in the mains plug)

Mr Kipling
13-02-2014, 19:26
Turn the amp right down. Remove the conectors from the cartridge. Turn the amp up a little and touch the right hot (red). You should get a buzz and the same with the left hot (white). If you do, it would appear your cartridge isn't wired correctly.

julesd68
13-02-2014, 21:12
Turn the amp right down. Remove the conectors from the cartridge. Turn the amp up a little and touch the right hot (red). You should get a buzz and the same with the left hot (white). If you do, it would appear your cartridge isn't wired correctly.

Thanks for that Stephen - I've done this little experiment and you are quite right, I get a buzz with both channels ...

I wonder if the cart can be fixed - hope so, as there is plenty of life left in the stylus.

Mr Kipling
13-02-2014, 23:49
Try reversing the lead back you changed and check cartridge leads again.

Looking at a photo of the interior of your preamp the input/output sockets are mounted to the circuit board so incorrect wiring doesn't seem possible. Do you not have another cartridge to try?
11567

julesd68
14-02-2014, 00:11
I changed back the toneram lead to correct wiring to phono stage and pulled out the two cart leads again - still get the buzzing when touching each lead ...

Doesn't this suggest the issue is with the tonearm wiring, not the cart?

Not sure what I did with my old MP-10 so don't have another cart to hand just now.

YNWaN
14-02-2014, 05:18
Part of the problem with diagnosing this problem relates to a point made by earlier contributor. When Julian states that he has located a phase problem because he has swapped interconnect connections and the sound is better, he is not describing what he has done accurately. Unless he has got out a soldering iron and physically modified the interconnect in question, all that has actually been done is swap the left channel for the right - in itself this has nothing to do with phase.

Depending on how a recording has been made/mixed, there will be more base on one channel than the other. Having one speaker more tucked in to a corner will significantly alter the bass response of that speaker compared to the other. I would like to see a picture of exactly how the speakers are positioned.

The turntable earth lead hum is an unrelated issue and the interconnects will make a hum sound if you touch a fingertip to the centre pin of each connector (neither are related). I have to say, nothing I have so far read suggests there is a phase or wiring fault.

Oldpinkman
14-02-2014, 06:30
Part of the problem with diagnosing this problem relates to a point made by earlier contributor. When Julian states that he has located a phase problem because he has swapped interconnect connections and the sound is better, he is not describing what he has done accurately. Unless he has got out a soldering iron and physically modified the interconnect in question, all that has actually been done is swap the left channel for the right - in itself this has nothing to do with phase.

Depending on how a recording has been made/mixed, there will be more base on one channel than the other. Having one speaker more tucked in to a corner will significantly alter the bass response of that speaker compared to the other. I would like to see a picture of exactly how the speakers are positioned.

The turntable earth lead hum is an unrelated issue and the interconnects will make a hum sound if you touch a fingertip to the centre pin of each connector (neither are related). I have to say, nothing I have so far read suggests there is a phase or wiring fault.

+1

Get a test record to confirm phase. Or bring both speakers really close to other facing each other and see if the bass is less or more. Less bass=out of phase.
But the only way interconnects could affect phase is if they are wired wrong and swapping them won't change that. It will just perhaps change which speaker you hear it from.

Mr Kipling
14-02-2014, 08:24
When you said in your opening that you swapped interconnects and it now going positive to negative what exactly did you do? I was thinking your system was using XLR connectors and you had reversed the connection on one, which would invert the phase.

If the arm connections were at fault either the red or white would be grounded and you would not get a buzz, just a bit of a tick.

julesd68
14-02-2014, 10:07
Thanks for your input chaps. Of course when I started this thread I didn't really know the difference between phase and polarity issues. So I have done some reading up and I now understand that swapping around interconnects clearly doesn't invert phase.

As a final experiment I put the RCA interconnects back to normal and properly inverted phase at the cartridge, using the following guide I found on Audiogon -

Left Channel
blue to white
white to blue

Right Channel
green to red
red to green

Didn't get a chance to play any lp's as it gave me a pronounced buzz in the right channel. Does that tell me that the cart / toneram is correctly wired?

What I'm still confused about is how much better the system sounds when I swap around the polarity of the interconnects. The soundstage feels fuller, better focused and the bass appears perfectly positioned in the middle of the soundstage, instead of having this preference for the right channel. This I wouldn't have expected. I tested this on a couple of records. Swapping around the interconnects via cd didn't seem to have the same pronounced effect.

Here are pics of the speakers. Please, before anyone goes to town on my speaker positioning, I do not have any choice at all where to position them - it's not how I would like them to be, but it's where they have to go in this room ... The right speaker is close to side and rear walls and has a sofa in front of it, whils the left speaker has a little more space behind it due to recessed window but has a storage chest next to it.

https://farm6.staticflickr.com/5507/12517548183_878fd0f224_n.jpg (http://www.flickr.com/photos/34449145@N05/12517548183/)

https://farm8.staticflickr.com/7322/12517544863_584bd1bdd0_n.jpg (http://www.flickr.com/photos/34449145@N05/12517544863/)

Oldpinkman
14-02-2014, 10:45
I can see this getting ever more confusing

Changing RCA interconnects will not offer the chance to change phase or polarity. You could change both with the speaker leads or the cartridge leads, but neither with a conventional rca (unless you take a soldering iron to it)

Your changes to the cartridge effectively reverse polarity. ignoring a few esoterics (like OOPs and I think Glen Croft's amps) this will have no effect you will hear. But it must be better to have correct polarity so put blue to blue, green to green etc. The terminology can get a bit muddled but from my point of view when I talk about "phase" I mean "different phase". either one channel having different phase to another, or one driver having different phase to another.

If you want to affect the phase, as defined, you would need to reverse one channels cartridge wires and not the others. So green to red and red to green, but blue to blue and white to white should put the system out of phase.

If you don't have a test record, the best way to confirm out of phase is to place the speakers facing each other about a foot apart. If they are out of phase the bass will reduce noticeably (assuming the speakers are not wired incorrectly internally - Owen told me of Andrew Jones of TAD visiting a customer who had taken delivery of another manufacturers $100,000 speakers, where one of the drivers was wired out of phase - he tested with a battery as his only available tool to confirm what he could hear. If you put a battery across a speaker the cone should move out one way (plus to plus) and in the other way (minus to plus) all drive units need to move the same way when the same polarity is applied).

So "the system sounds so much better when I swap the polarity of the interconnects". Do you really mean you change them so that the signal is on the outer connector and the ground is on the pin, or do you mean you swap left to right channel and right to left channel? Again - to get it right, get a reputable symphony recording and check the first violins are on the left and the Double basses on the right (a test record is not big bucks and really handy for this sort of thing)

If you are listening to classical, where, broadly, more of the bass is to the right of the sound stage, then if you have the channels reversed, and the bass coming out of the left channel this will sound different from the bass coming from the right channel. With your right speaker in a corner, it should emphasise bass more than the left channel speaker which only has a rear reflective surface (plus floor!) and the radiator moves some of it a wee bit clear of the wall.

Before I waffle more, can we be rock solid clear what you are doing that you call "reversing the polarity". Do you mean "reversing the channels" - left to right and right to left? "Reversing the polarity" would involve a soldering iron or some custom built interconnects. If you were doing that the same for both channels it shouldn't really affect the sound.

julesd68
14-02-2014, 11:40
OK Richard, sorry am still using wrong terminology. :doh: To be clear - the system sounds best to my ears when left and right interconnects are swapped over from tonearm into phono stage. It's really not subtle, but that was only on a couple of my old favourite rock lps.

Having done your classical record test the issue isn't so clear. I wired the tonearm lead into the phono stage 'correctly' and found an excellent test record - Rach symphony 2 with Andre Previn - you get very deep double basses on the right channel at the start of the disc, and then the violins come in on the left ... I listened to excerpts from three or four other classical records and found the sound very satisfying, and nicely balanced, if not exhibiting quite as extreme stereo effects. Perhaps the issue then lies with the way some of these old rock lp's are recorded?

Oldpinkman
14-02-2014, 12:53
Julian

This is making a bit more sense. We don't appear to have a phase problem. The issue is right channel / left channel swapping. I suggest you set everything "normal" first

Then test a CD to make sure violins on the left double-bass on the right. Then set the record player to be the same.

So your problem is old rock LP's? With the system "right" for classical is it "right" now for those LP's or "wrong" (ie would you want to be switching wires around, whatever label we give that switching)? If its a question of preferring some rock LP's more one way round than the other, it probably relates to the way they are mixed and the fact that your system probably emphasises right channel bass because of having one speaker in the corner.

Can you, as a temporary experiment, rather than a permanent room change, bring that right speaker away from the right hand wall by the width of the speaker cabinet, and maybe forward by the same amount as the left speaker is away from its wall, and listen then? Does that change things?

julesd68
14-02-2014, 15:06
Thanks Richard - I don't have much room at all to play with in the right corner but I can try shifting the sofa away a bit and I think I do have a bit of room to move it away from the wall but probably not the width of the cab ...
Not sure it's going to go down well with the mrs but needs must ... :lol: Will try to have a go this weekend.

I'll do the cd test but pretty sure it will be correct. I certainly don't want to be swapping wires around for individual lp's - would much prefer to hear them as them as they were designed but with a more balanced bass image. I guess I need to test a few more of my old rock lp's and see whether they all have the bass strong right channel - the Rush lp's certainly seem to! Seems like if there's a bit more bass 'reinforcement' on the right speaker, certain lp's are exaggerating this but still a bit strange why the soundstage just felt more lively and 'correct' with the channels reversed ...

BTW I did a 'proper' cartridge phase inversion as you suggested, but that didn't improve things ...

YNWaN
14-02-2014, 19:13
Yes, you are experiencing more bass reinforcement from one speaker than the other - it's as simple as that. Everything else is unrelated ephemera.

Mr Kipling
14-02-2014, 20:34
Have you not tried playing a mono recording, if you have one? You should get a central image depending upon how your speakers are positioned. If you don't have anything in mono (and have no mono switch), connect a wire between the r & l centre pins of the phono plugs and position your speakers to get a central image.

julesd68
16-02-2014, 13:33
Well I've moved the right speaker away from the wall and the bass certainly feels a bit less 'bloated', and the bass balance between the two speakers feels right, but from doing a bit more experimenting I am starting to think there might be a different issue.

I've steered away from the early 70's rock lp's as a lot of them seem to favour quite strong stereo panning where you get more guitar on the left and drums/bass on the right. So using some later material as a reference where the sound is more 'centred' I am left with the feeling that it feels like a balance issue. The right speaker just seems a tiny bit more dominant than the left. So I swapped over to the Sony amp which has balance controls, and just favoured the left channel a little, and the sound certainly felt more 'balanced' and even.

My question is what could be causing the perception or actuality of imbalance? It's not the amps, as it's the same issue with both of them. I am ruling out the speakers and the room arrangement, as listening on cd, I felt the sound was perfectly balanced in the middle of the soundstage. So I guess it means something to do with phono stage or cart - if so, how could one measure if there is an imbalance in which either is ouputting? One option would be to try a different cart of course - am a bit loathe to do this having got it set up just right ...

Oldpinkman
16-02-2014, 17:02
Well I've moved the right speaker away from the wall and the bass certainly feels a bit less 'bloated', and the bass balance between the two speakers feels right, but from doing a bit more experimenting I am starting to think there might be a different issue.

I've steered away from the early 70's rock lp's as a lot of them seem to favour quite strong stereo panning where you get more guitar on the left and drums/bass on the right. So using some later material as a reference where the sound is more 'centred' I am left with the feeling that it feels like a balance issue. The right speaker just seems a tiny bit more dominant than the left. So I swapped over to the Sony amp which has balance controls, and just favoured the left channel a little, and the sound certainly felt more 'balanced' and even.

My question is what could be causing the perception or actuality of imbalance? It's not the amps, as it's the same issue with both of them. I am ruling out the speakers and the room arrangement, as listening on cd, I felt the sound was perfectly balanced in the middle of the soundstage. So I guess it means something to do with phono stage or cart - if so, how could one measure if there is an imbalance in which either is ouputting? One option would be to try a different cart of course - am a bit loathe to do this having got it set up just right ...

Hmm
I am bidding for a balance control on a custom Pip for that very reason. I personally think my hearing may be better in my left ear. That said, a great deal of material is recorded with instruments spread from side to side rather than centered and a lot has vocals very much on one channel, which if you want everything coming out of the middle is a bit disconcerting. Mind - it shouldn't apply to records and not CD's - should apply to both. Easiest solution is to get a test record. If you want to know for sure you need a silly scope as well. But if there is a strongly defined central image on the phase test when the lady says so, then there's nothing wrong with your kit, in the limits of your hearing.

Come to think of it, having run the test, there's nothing wrong with my right ear. Conclusion - a lot of material has a left of centre bias for the vocals and lead. Bloody record producers...:doh:

I think your issue will be unbalanced room set up. Try listening on headphones and see if the problem is apparant. Also - do you have a new lp with the "free" inclusive CD? That would be a good test for whether it is a phono only problem. Truth is though - if you are not noticing it on classical LP's then its more likely to be the recording mix coupled with your speaker placement in the room. But if you really think its the cartridge and phono stage try a test record.

Or if your pouring decent whisky... ;)

Mr Kipling
16-02-2014, 17:58
You could try swapping over the valves from R to L in your phono stage.

julesd68
16-02-2014, 18:08
You could try swapping over the valves from R to L in your phono stage.

Yes I had been considering that earlier - the phono stage has 2 x 12AX7, 1 x 12AU7 and 1 x 5751.

I will try swapping the 12AX7 round and if that is inconclusive, will also put back the stock 5751 that I changed a month or so ago, just in case there is an issue with the NOS replacement.

If none of that works, sounds like I need to get one of the test records that Richard suggests - not cheap at £25 but should be useful in the future aswell for cart set up ...

Kember
16-02-2014, 22:07
Yes I had been considering that earlier - the phono stage has 2 x 12AX7, 1 x 12AU7 and 1 x 5751.

I will try swapping the 12AX7 round and if that is inconclusive, will also put back the stock 5751 that I changed a month or so ago, just in case there is an issue with the NOS replacement.

If none of that works, sounds like I need to get one of the test records that Richard suggests - not cheap at £25 but should be useful in the future aswell for cart set up ...

Julian

I have a couple of test LPs you can borrow. Just pm me and I'll drop them by with the hospital trafos I promised you could try out.

Best

Peter

PaulStewart
16-02-2014, 22:32
PM sent