[hsnam]

hi all,
glad to know there's a place to continue my latest addiction.

anyway, i was reading through headphone.com a while back, and apparently they use a DC/DC transformer or converter in their portable amp. this allows the amp to use only one 9 V battery, and also run the opamp at a higher voltage.

is this a "GOOD IDEA"? if not, why has nobody tried this? (which implies this is not a good idea..)

 

[Apheared]

Yes. No. Depends.

You might be able to filter out all the switching noise; then again... You might get one with an adjustable switching frequency or one that's high enough that you don't hear it, then again... you might not have to shield it or move it as far away from your analog amp stage as possible, then again...

I mean, I'm not a competent engineer - I've tried it with a couple of them. With a beefy Pi filter, noise on the line can be very low... a couple mV.. but it still sounds different than batteries. "raspy-er", is that a valid term?

Your mileage may vary. Me, I just carry big battery packs.

 

[ppl]

I totaly Agree with Apheared on this. I have tried as well as listen to Equipment using DC to DC Converters and Thay sound Harsh Cloud up Detail and lack Slam with Low Z Cans. Prior to My 1998 Portable Amp I origenaly Designed and since Upgraded i was all set on a Headroom Suprreme But wen i heared thay used a DC to DC converter I was Turned Right off. And the Supreme would have Been A good solution at that time for me because Designing an amp from scratch and laying out the Board as well as the Small Mechanical Details is A Pain. and I am lazy Why Build when you can Buy. But I Build because what i want is Not available so i Build Rethink Build again.... Again..... Again....... This madness has got to stop i am to Old for this Kind of Addiction.

 

[aos]

All chips that I've seen for this purpose can supply only low currents - low 100's of mA range, even lower as the voltage goes up. That would cause low Z cans to lack "slam", just as ppl observed. I copied schematics of Total Airhead's DC/DC when one of HeadWizers posted excellent pictures of both sides of PCB. This kind of solution is a compromise between using a few batteries and sound quality. Most people here do not compromise

.

 

[thomas]

According to headroom, the problems with the original total airhead were caused by the DC-DC converters running out of steam, causing lots of distortion... I ordered a few of the same maxim DC-DC converters a while back, but i still haven't had the time to try them...

The maxim converters are qute cheep, but they have very low current and voltage outputs. There are better ones that output +/-15V, but those are really expensive

 

[ppl]

Tomas:Evean High Current DCto DC converters Have so mutch RFI and Satuation Problems i just cant recomend this technology.Switching power supplys may be great for computors but have no Porpose in an Audio Circuit. Just My 2cent's worth.