Quiet 12v Power supply?

[Deleted]

I tried some power supplies with a Total Airhead today and found that the dynamic range increases quite dramatically.

The problem is that all my supplies make it hum nicely. Does anyone know of a quiet supply that's easily available with 12 or even 15v DC with the centre pin positive that's likely to be quiet and not cost a bomb? The plug size is the same as the Aune. (whatever that is??)

The best that I tried was the Aune supply. So it looks like I need something similar that could be even quieter.

Ian

[Deleted]

Have you tried a 12v Laptop/LCD style PSU?

Like this ?

Or much cheaper here.

May be worth a shot, seems to be the same kind of thing Aune use.

[Deleted]

I tried some power supplies with a Total Airhead today

Is MERTON in the U.K. for a holiday ? ;D

[Deleted]

May 25, 2011 22:22:00 GMT @sandyk said:

I tried some power supplies with a Total Airhead today

Is MERTON in the U.K. for a holiday ? ;D

;D ;D I/m going to get myself in trouble if I say anything but I can't look at the amp now without laughing. Trouble is, the amp makes just as much unwanted noise. ;D ;D

Thanks Chris, I'll have a look. Everything I have seems to start hum off and I don't really want to spend big money 'cos it's only a Merton, sorry Airhead.

All the power supplies I have put a healthy mains hum into it and it changes with the proximity of your hand to the unit as well. It lowers slightly with batteries inserted and goes down a bit more when connected to an Ipod but it never goes.

Is there such a thing as a 'quiet' power supply?

Ian

[jonclancy]

Oi, you lot!! Stop taking the rise out of M.

Right, that said, both supplies liked to are switchers. Noisy and 'orrible. Though might be better than the current ones you have, Ian. There are many choices for a quiet or really quiet power supply. The correct DC plug can be got from Maplin. What is the supply current requirement?

Choices are:

Linear 3-pin reg based PSU (78XX or LM317 etc)
The above plus a Ripple Eater
The linear reg as a pre-reg for a super reg*
* a Walt Jung based design. perhaps?

Some respected regs are: ALW Super Reg, Teddy Reg, Super Teddy Reg, Avondale TPX, Paul Hynes etc etc

Or how about a battery? Sealed Lead acid, gel, LiFoPO4 (JKeny might have a view on this...).

So, bottom line is: what is your current requirement? Then work from there.

Alex has identified 3-pin fixed regs that are good for 3A. That's quite a lot of juice...

HTH

Jon

[jonclancy]

Sorry, forgot to add that if all your supplies are hummmmmming, you might want to experiment with the grounding side of things. Try tying your source and amp chassis together, maybe?

[Deleted]

Hi Jon,

Sorry about my awful humour.......

The Total Airhead is a little portable amp that's powered by 4 aaa batteries. Not bad sounding and Headroom does sell a power supply for it. They're a little secretive about what it actually is but I have found from Headfi that it is a positive centre and will take up to 15v.

I looked around to see what I had and found that the Aune supply gives 12v and had the right sized plug as well. The Total Airhead really improved with 12v but that hum .......

The chassis is rubber!! Probably, the one from Headroom hums just as much so I'm loathe to buy anything expensive for a portable amp.

The Aune power supply is less noisy than any others I have though.

Ian

[Deleted]

Ian,

I was looking at the Headroom site and seems you are not alone with your noise problem.
www.headphone.com/headphone-amps/amplifiers/headroom-total-airhead.php hit "Customer reveiws"

Maybe there is a QC problem somewhere?

If it's new, wack it back to 'em.

If outside Gtee maybe send it up to Mike for once over. Like Jon said it could well be a grounding issue, especially as it still hums on batteries!

[Deleted]

Thanks Chris. I don't like asking on there because they all get so funny about 'Google is your friend'. Bloody painful. I just think if they don't want to talk, then go away!!!

The amp doesn't hum on batteries, it's mains borne. It goes down when I connect the Ipod and goes down a bit more if I insert the batteries as well as have it plugged in.

I just assumed the power supplies are noisy. Can't earth the chassis 'cos its rubber.

Maybe it's just a crappy amp. It sounds ok though.

Ian

[elysion]

www.rockgrotto.proboards.com/index.cgi?board=m&action=display&thread=6465

Have a look at the bottom (last two posts) of this thread. Those MINWA/ELV psu's should do they job as long as you don't need more than 12VDC. They are linear regulated (with big heavy transformator...), but you can also select from a few output voltages. They are dirt cheap if you order from ELV (don't know if they send to UK though). The size of the plug and the polarity are no problem since you can change both.

Perhaps you should also look on the MINWA website. They have also other linear regulated psu's (some with fixed output voltage).

BTW: How much amperage do you need?

[jonclancy]

May 26, 2011 13:21:56 GMT @iancraig10 said:

Hi Jon,

Sorry about my awful humour.......

The Total Airhead is a little portable amp that's powered by 4 aaa batteries. Not bad sounding and Headroom does sell a power supply for it. They're a little secretive about what it actually is but I have found from Headfi that it is a positive centre and will take up to 15v.

I looked around to see what I had and found that the Aune supply gives 12v and had the right sized plug as well. The Total Airhead really improved with 12v but that hum .......

The chassis is rubber!! Probably, the one from Headroom hums just as much so I'm loathe to buy anything expensive for a portable amp.

The Aune power supply is less noisy than any others I have though.

Ian

Ah, it starts to make sense now. A 6VDC battery supply. We can work out a rough current draw by asking how long it lasts on a set of batteries (and which type - 2500mAH rechargeables for instance). That'll mean we can specify the psu. I reckon only a few hundred mA. Then look a the amp and work out if it needs a separate ground mod to stop mains borne earth hum (are the other supplies people using noisy switchers??). But with 12V, what about the LiFePO4 batteries?

Cheers

Jon

EDIT: All these questions are answered in the manual...

1. approximately 40 hours on 4 AAA batteries.
2. anywhere from 5 to 12 VDC with a current rating greater than or equal to 200mA. The center tip is positive and the tip size is a 5.5mm outer diameter and 2.1mm inner diameter.

[Deleted]

Thanks Jon. I have plenty of power supplies that supply the correct voltage and have plenty of current. It's just that they introduce a hum. Apparently, the components can go as far as 15v.

The hum reduces when connected to an Ipod but still there so it's an earth problem.

The battery option seems a bit ott for a crappy little portable amp. Maybe I need an 'earthed' supply?

If I buy one from Headroom I suspect the very same hum will exist.

Thanks Christian as well. They are kind of similar to what I've been trying.

I wonder whether it would be better if I used an 'earthed' power supply. I noticed that the Aune supply has a three pin plug, but the earth is plastic so there isn't one.

The Airhead does become quite dynamic sounding once it has a few more volts going through it.

Ian

[jonclancy]

Hi Ian,

Have you tried looping the power cable through a ferrite?

The Aune supply is double insulated. I would try experimenting with a small trafo, and 7812 3-pin reg and try different earthing strategies.

I would try earthing your source and amp, though.

Cheers

Jon

[Deleted]

I think I'll have a look for an 'earthed' power supply. The Aune isn't connected to earth but the amp becomes quieter when connected to the ipod so it myst be an earthing thing.

So annoying because the Airhead is a lot better plugged in with more dynamics but the hum starts.

If I could lose that, it's would be quite an acceptable sound with higher impedance headphones as well.

It's only a cheapie so no big deal but after reading about it, I was curious.

Ian

[elysion]

Maybe it's worth to try a different mains connector. Maybe other devices connected to the same mains connector interfere with your wallwart. If your wallwart is a SMPS, then it's not really a suprise.

I've had a similar issue with my Cambridge Audio Sonata CD30 V2 CD-player. It was connected to a powerbar shared with a lot of other devices. For a long time, I didn't even notice the hum the SMPS was producing. After connecting the CD30 to a mains connector which no other devices connected, the hum disappeared instantly.

Of course, I now know also the biggest problem with the Sonata CD30 V2: It's the SMPS. The V1 had also a (less efficient) SMPS. It's not a real problem as long as you know about it and if you do the right steps afterwards. But it's annoying.

If (and I'm not so sure with that) I need another CD-player in the next few years, I'd probably go for a more expensive CD-player with a toroid.