Help.. warm/cold balance problems (again)

[Marc B]

I posted a while back with a problem I had with a Dussun V8i amp. The amp would slowly change from being so bright and thin it hurts your ears, to really warm and over powering sound. I put this down to my mains voltage averaging on 255v and the amp being a 220v model.

We travel on a few more months and I now have a completely different hifi system but the same problem is still present.

So far to try and rid the problem I have...

* Replaced every bit of my gear (twice)

* Called the electricity board out to lower my mains voltage. I now hit around 242-249v.

* Bought shitloads of acoustic bass trap panels

* Bought one of those Tacima RF shield mutli plug things

* Swapped out all my phono cables for balanced XLRs

* Tried 5 different plug sockets in my room

* Put my power amp on its own plug socket (with ferrites on the lead)

* re-arranged the room countless times.

I am at a loss of what to do next ?

Amps usually sound fine when I first get them but then start drifting to a bright sound.
I play around trying to solve it and after another week/month the sound returns to normal for a few days and then starts off on its merry way again.
It's a really slow cycle and I have to counter balance it by shifting my speakers forward/backwards about 18".

My thoughts are now it's either some weird RFI/EMI or the bias on the amp is unstable (though the amp repair guy made a point to say to me that the bias was spot on perfect when he fixed it just before xmas)

Also, you notice the effect more with larger power amps over smaller ones. Thinking back , I didn't notice it with my old Arcam Alpha 8 but did with the Kora , Primare, Dussun and now the Classé.

I do live in an old house which has been converted into flats, the electrics seem pretty new and the electric board have confirmed that there isn't a problem with my mains impedance or anything.

someone help please, I'm going bonkers with this

[anthonyTD]

hi marc,
how is your room temperature? is it constant or does it fluctate widely, if so this could be playing a big part as speakers react very diffrently to temp changes, ie; warm room full sounding with plenty of bass etc, cold room thin sounding brittle etc.
also just noticed your amps are 220v models, the over voltage [255v] could also be playing a big part too.
hope this help.
regards,anthony,TD...

[Marc B]

Hi

As far as I'm aware the room temps don't make any difference to the sound. I've had it sound both great and terrible in both hot and cold rooms.

Also , the 220v amp was sold and my current amp is UK spec. I have checked my mains monitor and the sounds cycle doesn't seem to have anything to do with the voltage I'm getting in the mains.

To be a bit clearer, what I have gathered is that the sound starts warm and full , this quickly (over the period of a day or 2) changes to cold , bright and edgy. The bass, which on good days, hits you in the chest goes and I'm left with a thin, almost distorted sound.
The sound then takes a few weeks to slowly get back to normal and as soon as I get happy with it , it starts all over again.

I've tried different sources, preamps , cables etc.

One thing I have noticed is that my playstation 3 audio is also distorted when I wear headphones via the TV set. Whatever it is might also be having an effect on that too.

I'd love to get my mits on one of the room EQ software/mic kits as I'm certain it's like somoene slowly adjusting a tone control.

[DSJR]

As above..

Can I please respectfully add that mood and physical condition has a lot to do with it too. I have off days with stuffy, blocked ears where the BC2's laid back upper mid/lower treble becomes a bit too much and I have to leave it until my ears "feel" better. A day or two later and they sound superb. The temperature in our house is pretty constant during the day time, so in my case this isn't the case..

The fact that you have this difficulty with all the gear you have does seem to indicate either room temperature or just "off days" with your ears.

Hope you can find a solution soon. Active ATC monitors (ignore the passive ones PLEASE) are a bit mains sensitive, so be warned in advance.......

[The Vinyl Adventure]

Whybuynew.com are selling behringer deq2496 b stock for £149 (they are £250 new) although I would have thought you would end up going round in circles trying to eq a forever changing sound.
are you perhaps experiencing a prolonged break in period?
If one unit takes a time to settle in and then that is followed by a another unit going through some break in teething issues perhaps that could cause some problems?

[Marc B]

yeah it's quite possible (if break in really exists)

All cables are pretty new and so are the rest of the bits.

Would be funny if it was my ears blocked though, I'd have wasted about £6k trying to sort it.

I've just got me some ear cleaner oil stuff so shall soon find out

[John]

Might also be getting one of those rfi noise sniffers and see if you can isolate any issues
This is the kind of stuff that drives people bonkers hope you sort it out soon

[Haselsh1]

This is going to sound bloody bonkers but are you close to a military installation...? A few years back I was using an SE valve amp and had a problem. I solved the problem by fitting ferrite rings to my interconnects. RAF Fylingdales radar installation is three miles up the road.

[Marc B]

funny you should say that..

I have a police station 200 yards away , the areas main hospital about half mile away , the local radio station about 1 mile away and army barracks at the end of my road.
There is an air force base around someplace too , near blackpool I think ?

hmmm

[REM]

Hi Marc

Just to increase your paranoia, you also have BAe to the east of you at Samlesbury and to the west at Warton both with their own aerodromes.
That air force base you are on about is an old cold war 'listening post' run by, I think, the Navy tracking nuclear subs in the Irish Sea (cleverly disguised as a golf course, fiendishly clever these MoD types!) so you never know what nasties are hiding in the ether.
Don't forget, you have that massive nuclear plant at Cottam/Lea to think about as well, blimey I'd just move if I were you:lol:.

Hope this, er, helps.

Cheers

[Ali Tait]

Maybe try a balanced mains transformer.This should get rid of any RF nasties in your mains.

[Spectral Morn]

There's also an entire Dalek Battle group several miles below you, waiting to come forth and reek havoc ;)....:doh: shouldn't have shared that bit of info. Want to catch UNIT with their trousers down. Those high energy matter transmitters screw sound up quite a bit....:eyebrows::lol::lol::lol::lol::lol:.

Seriously mains could be at fault, but I am not sure it is that. Classe` is not a warm sounding product imho. What kind of sound are you after ? What is your full system set up? Components do change a wee bit during run in, but the general character stays intact..usually. Exceptions are the MF KW500 integrated, warm to start with (very nice) then growing forward and brighter after being run in (not so nice imho). Its always been the other way round in my experience so far with most makes of components.

The interference sources mentioned so far could have an effect. Is there a regular pattern to this problem? Days, hours etc.

Odd problem.


Regards D S D L

[Themis]

Yes, odd problem indeed. :( Looking for a pattern could be helpful.

[Marc B]

Strange as it is , the bass returned a couple of hours ago?

It's still a bit sharp in the top end but now sounds full and not like frequencies are missing.

Another thing that it does is goes phasey in the midrange. I usually have a rock solid centre image , this seems to smear a bit when the bass fades.

As for a pattern , the last time I had bass was 2 weeks ago , it started going thin just after the weekend (I know this as it was my weekend off and I work every other weekend)

Going to try one of these, do you think it will be able to cope with an amp that draws 1200 watts ?

http://www.airlinktransformers.com/transformer/bps2000-balanced-power-supply.asp

Even if it doesn't fix it I'm sure it will come in handy in the future/

[Barry]

Marc,

If you are really surrounded by all these 'dodgy' installations, the use of a balanced mains power transformer (as you have cited) ought to help. If it doesn't, try fitting ferrite clamps on the speaker leads?

I suspect that it might be an RFI problem. The mains unit will prevent common-mode interference getting into the amp from the mains. Fitting ferrites to the speaker leads may help prevent the very same RFI from getting into the amp via the speaker terminals and causing mischief.

Give it a go.

Regards

[John]

Strange as it is , the bass returned a couple of hours ago?

It's still a bit sharp in the top end but now sounds full and not like frequencies are missing.

Another thing that it does is goes phasey in the midrange. I usually have a rock solid centre image , this seems to smear a bit when the bass fades.

As for a pattern , the last time I had bass was 2 weeks ago , it started going thin just after the weekend (I know this as it was my weekend off and I work every other weekend)

Going to try one of these, do you think it will be able to cope with an amp that draws 1200 watts ?

http://www.airlinktransformers.com/transformer/bps2000-balanced-power-supply.asp

Even if it doesn't fix it I'm sure it will come in handy in the future/
I go for the 3kva or 5KVA just to be sure it cope with the amp

[DSJR]

I've used ferrites on my mains leads for years now. They either don't make a difference or it's the bass that *slightly* seems to improve and become more tuneful and even.

I hadn't considered the airborne RF possibility, but a good friend of mine used to live not far from a US "listening" base in Bedfordshire (now de-commissioned I believe) and he had rf problems.

[Marc B]

coincidence or not ???

I've just thrown my Tacima RFI 6 way thing on the telly/pc/ps3/cable box/network stuff and everything has popped into perfect balance.

I don't know if the PC was throwing shit down the mains or not, or its something else, but it now sounds quite nifty again (I know the moment I post this, sods law will say the balance will start to wander again)

[Dave Hewitt]

Hi Marc
I once had a Korsun that did exactly what you describe,some days great with good bass,next day thin and quite harsh.Never found out what caused it but at weekends when the nearby woodworking factory was not in use the amp usually sounded ok.I have also found that having switch mode supplies on same sockets as hifi makes for a crap sound.I will be interested in the outcome of the transformer you propose using seems like a good idea.
Regards Dave.

[Marc B]

hi

I'm not up on what items would have a switch mode power supply ?

Do you mean the wall wart type things ?

[Stratmangler]

All of this stuff will have SMPS - telly/pc/ps3/cable box/network stuff

[Dave Hewitt]

Hi
Pretty much all the gear you mention ,pc, telly,ps3 etc will have a sm power supply,usually if the wallwart feels like its an emtpty box its switch mode.
Dave.

[Marc B]

Thanks for that. hopefully it wasn't a coincidence with the Tacima on the TV/PC plug and that's my problem then.

It's only took over 2 years to work this out :)