Bass and phase issue with NS1000Ms

[drSM]

I ve been using my NS1000 s for the last 3 to 4 years, to my huge delight.
I got them used of course and i think the previous owner brought them in from Japan.
Recently i ve noticed, using two integrated amps in good condition, that bass is better when the balance knob is turned fully one way or the other.
ie when only one speaker is receiving signal the bass is better than when the balance knob is in the 'middle'.

I checked the wiring - polarity correct, apparently 'in phase'.

I reversed the polarity to the RT speaker.
Bass clearly became stronger, and overall the sound was quite pleasant.

I pulled out HFS 75 and confirmed that in this state my system was out of phase.
This has me puzzled.

Could the bass unit of one speaker be wired out of phase?

Must add that I have generally been happy with the overall bass performance of my NS1000 s ( normally wired)
but this accentuation of bass when the polarity to one speaker is reversed putting the system out of phase does not make sense to me.
Surely the bass should be worse overall

What could be going on ?

[Macca]

Quite possible one bass driver is wired wrongly, thee things happen. Only way to be sure is to get inside and take a look.

Otherwise it could be an issue with a component on the crossover.

[drSM]

Thanks Martin
It is odd what i have found here
It doesnt make sense - something must be wrongly wired.

[Ali Tait]

Easy to check with an AA battery and some wire. Put some short pieces of wire on the terminals, dab them onto the battery positive onto the positive terminal and negative likewise. Note whether the driver goes in or out. Repeat for the other speaker. If they both go the same way they are wired the same.

[Macca]

It isn't unknown for speakers to leave the factory with the positive connection marked negative, and the negative as positive. Makes setting up speakers so much more interesting.

Try Ali's tip, will require a methodical process but you should locate where the error is at some point along it.

[walpurgis]

If you try the battery trick with Tannoy 'pepperpot' dual concentrics, the bass cone moves backwards with the + of the battery connected to the + of the speaker, not forwards as you'd expect.

[drSM]

Easy to check with an AA battery and some wire. Put some short pieces of wire on the terminals, dab them onto the battery positive onto the positive terminal and negative likewise. Note whether the driver goes in or out. Repeat for the other speaker. If they both go the same way they are wired the same.

Thanks Ali
No way 1.5V dc will damage speaker drive units?

U guys agree with me that reversing the polarity on one speaker should not accentuate bass ( assuming all correct wiring inside spkr and with source, interconnects and amp) ?
ie in this out of phase situation bass should diminish and stereo imagery is lost.

[Ali Tait]

Will be fine if you just dab it on momentarily. Hold the neg on the battery terminal and just dab the pos on while looking at the driver.

[Firebottle]

U guys agree with me that reversing the polarity on one speaker should not accentuate bass ( assuming all correct wiring inside spkr and with source, interconnects and amp) ?
ie in this out of phase situation bass should diminish and stereo imagery is lost.

Absolutely correct Shahrin. Without a doubt one woofer is wired incorrectly.

Another easy check is to position the speakers very close to one another and facing each other. Play some music and if one is out of phase then there will be virtually no bass, as one speaker output cancels the other.

:cool:

[karma67]

I have a Yamaha wiring diagram for the ns1000, I will sent it too you to check later if you like

[drSM]

I have a Yamaha wiring diagram for the ns1000, I will sent it too you to check later if you like

Please Jamie, Ta
I will be busy tonight w AA battery at first but may venture 'inside'.
If indeed one woofer is wrongly wired i have to find which it is .

bloody weird cause generally i ve been happy with the overall bass performance of these babies.
very odd ....:scratch:

[drSM]

Test with 1.5V AAA battery showed that with +ve terminal of battery to +ve terminal of speaker both woofers moved Forwards.
Checked and double checked
So i was mistaken about this phase thing.
I could not remember what source i played that nite other than internet radio thru my SBT.
But good vinyl last night confirmed that all was well - I am in phase .... and happy.
I learnt a few things and thank you all for help.
shamefully yours,
Shahrin

[Ali Tait]

Good the speakers are ok. Happy listening.

[Qwin]

The +/- terminals are clearly marked on the bass driver casting.

The wiring schematic is on my website.

The wiring tags on the crossover board are also marked, the bass does not go through the L-Pads so tracing the connections is straight forward.

Does your balance control design give a volume lift to one channel when hard over?

As you turn the balance one way, the control decreases the volume to one speaker but raises the level to the other, quite often, increasing volume makes bass more prominent, hence our tendency to crank it up.

Maybe you are just hearing the more prominent bass, due to overall level increase and as it is happening which ever way you turn the control, ie, to both speakers, I think this might be the case.

I have lived without a balance control for a while now, but experienced a similar thing when I tried an old amp that did have this control, so you may not have a problem.

[drSM]

Thanks Ken - you are no doubt one of the Ns1000 experts on this forum.
I am OK now.
No issues - i did not want to go beavering inside the speaker :)