Re: Cables

[Kim Flint <kflint@loopers-delight.com>]

At 03:25 PM 1/25/2002, Alex Stahl wrote:
>Just to play devil's advocate, my goal for some thirty years has been to 
>run my entire studio off of one or a couple DC voltages, supplied at home 
>by a single power supply resembling a wall more than a wart (PV panels in 
>the cabin) and on the road by car batteries or whatever. Equipment which 
>already has DC input jacks makes it slightly easier to pretend I'm ever 
>going to complete this transition.

A fine idea, and in fact that is often how telco and data center racks 
work. You generally have 48V DC running to each device. The DC supply is 
generated from a power supply shelf where you'll have fully redundant 
power 
supply modules converting the AC supply from the power company into the 
48V 
DC. That's the sort of environment the networking system I'm currently 
designing goes into, so we don't need to deal with AC conversion. One key 
reason that is possible is that a standard exists for this power, and 
every 
device follows it and there are many vendors for the external supplies. 
Such a standard doesn't exist for music gear, so you'll probably never 
easily accomplish your goal. Of course, in the stuff I'm doing at the 
moment, the power shelf alone probably costs far more than most home 
studios...


>It's also just not true that wall warts necessarily radiate more hum into 
>audio paths than internal power supplies.

I think your statement should read "internal power supplies don't 
necessarily radiate less hum than wall warts".

If the internal supply is badly designed, than sure it will cause a 
problem. However, the problem is "bad design", not "internal". A well 
designed internal supply will not have such a problem, and will always 
beat 
a wall wart for performance.


>The transformer inside one very expensive piece of gear I own is directly 
>beneath the mic preamp in another unit which I would like to have mounted 
>in an adjacent rack space. Oh well, not much I can do about that.

that's bad design. You the customer shouldn't tolerate that designer's 
choice any more than a choice to use a wall wart.


>The internal power supply in another very popular multi-effects processor 
>is a horribly noisy piece of crap which not only generates more 60Hz than 
>a PG&E substation but only puts out more RF than Sutro Tower. Oh well, 
>not 
>much I can do about that either.

again, bad design. what you do about it is don't buy crap like that, and 
tell the manufacturer the reason why.

My low-end Mackie 1202 mixer has an internal power supply and it causes no 
hum in the audio that I can hear. In fact, it's my belief that the 
internal 
supply is part of the reason the Mackie is as clean as it is for the 
price. 
It clearly didn't add too much to the cost, since the mixer was cheap 
enough to be an impulse buy for me. That's because the engineer who 
designed it did a good job.

The power supply is an incredibly important part of any audio gear. You 
the 
customer should realize that and it should carry much more weight in your 
buying decisions than it apparently does for most people.


>At least with a wall wart it's really simple to relocate the hum 
>generator, keep all the AC in the bottom of the rack, or even replace the 
>power supply with something cleaner than any manufacturer puts inside 
>their gear if it's still a problem.

I don't find that simple. I find it to be a pain in the ass actually that 
I 
should ever have to consider these options.


>Oh yeah, there's a decent chance that the first thing to fail in your 
>rack 
>will be a power supply, and it's kinda cool to be able to carry cheap 
>spares and replace them in 30 seconds.

That's also design. A well designed supply will take reliability into 
account, and it will will outlast most other parts of the system. The 
worst 
thing you have to worry about with a good internal supply is finding a 
standard IEC power cable or a fuse, either of which can be found 
practically anywhere in the world on short notice.

All of the power problems I ever have are wall warts either breaking or 
getting lost, or a device getting fried because the wrong wall wart got 
plugged into it. Wall warts are designed for sitting behind desks where 
they never move. They usually have wimpy wires and wimpy connectors and 
not 
very rugged construction that was never intended for the real world that a 
musician will put it in. So they break easily. Plus, every company seems 
to 
use a different wall wart, so when it breaks it's often hard to find a 
replacement. Oftentimes you can only get it by special order from the 
manufacturer! You don't have those headaches with proper internal supplies.

>Like I said, just playing devil's advocate. My only real pet peeve is the 
>Yamaha stuff which has an internal supply but a hardwired, way too long, 
>too stiff, unrepairable AC cord.

that's also bad design, because in addition to what you mention it also 
means you can't switch plugs when you take it to another country with 
different power standards. bad, bad, bad. all supplies should use the 
standard IEC connector and support worldwide power voltages.

kim


>At 10:17 PM -0800 1/25/02, max valentino wrote:
>>Absolutely right, Kim....thanks for continuing to say it.  Who knows 
>>maybe someone will listen!
>>Max
>>
>>
>>  > there is no excuse for wall warts in products intended for
>>>professional
>>>audio use.

______________________________________________________________________
Kim Flint                     | Looper's Delight
kflint@loopers-delight.com    | http://www.loopers-delight.com