diytube.com

What gauge power cable is recommended for a stock ST-70 with a diytube driver board. I have been testing the amp with a 18 AWG and it seems thin. Should I bump up to a 16 AWG? This is based on safety, and not sound.
Thanks,
Brad

18AWG power cable should be fine, I use that gauge in most of my builds.
The ST70 draws about 3 - 4 amps maximum, and18 GA can easily handle that with no problems. FWIW, the original Dynaco ST70s used the two conductor 18 gage "zip cord" type of power cords, and those were generally very cheaply made.

The usual power cord is about six feet long, so the actual resistance of the wire will be quite low, at about 6.5 milliohms (0.0065 ohms) per foot, so the resistance of each of the six foot long conductors will about 0.4 ohms. 18 GA wire is rated for 10 amps continuous duty, in a "bundled" multiple conductor cable, such as the modern three-conductor power cords in use today.

If you use the IEC AC input receptacles, then it is a simple matter of just swapping to another wire-gauge power cord if you want to, and that involves no soldering or cutting, just a simple swap-out.

HTH

/ed B

Thanks Ed.
I was hoping you weren't going to recommend a cable from Audio Advisor!!
Did the original ST-70's come with those ugly tan power cables that Dynaco used on the PAS and PAT preamps?
I am still using captive power cords, other than convenience I don't see the real advantage of IEC receptacles.

Brad

Those overpriced cables from "Audio Advisor" and other snake oil vendors, is what led to the original "Snake Oil" and the newer, more far-ranging "Advanced Snake Oil" topics.

Wire is wire, be it solid or stranded. Period. All the fancy buzz words and pseudo-scientific bovine fertilizer are there only to lure in the unsuspecting, and the gullible. PT Barnum had it right, a long time ago...
Cables do not have to be blessed by vestal virgins, or Tibetan monks, nor do they require the services of a paychic in order to be properly used.

IIRC the vintage ST70s had the black 2 conductor power cables, rather than those ugly brown or tan cables (which usually had cracked insulation after 40-50 years). I ALWAYS change out old power cables, it is not a matter of IF they will have problems, it's a matter of WHEN...

I use either captive or IEC power cords, it's just a matter of chassis space, and what I happen to have on hand at the moment. I've cut off more of the IEC ends than I could count, then I end up with a three wire "captive" power cord. The local hardware store has all the rubber "donut" and the hard plastic "grabber" grommets that I'll ever need, for any and all of my projects..

/ed B

EWBrown wrote:Wire is wire, be it solid or stranded. Period. All the fancy buzz words and pseudo-scientific bovine fertilizer are there only to lure in the unsuspecting, and the gullible. PT Barnum had it right, a long time ago...
Cables do not have to be blessed by vestal virgins, or Tibetan monks, nor do they require the services of a paychic in order to be properly used.

Pure gospel, brothuh

Cheers!

Thank God! Finally the truth about power cords has been exposed.

Bought a pair of 8417 Quicksilver mono block amps 10 years ago and some moron butchered the chassis trying to install some monster power cords. Its a tube amp dammit! Its not a monster Ampzilla that draws in excess of 15A of current. It doesn't make a rats butt difference if its gold plated wire or something from an 18 yr old virgin or from the local Ace Hardware store.

Even if one were foolisg and gullible enough to spend $400 for a power cord, and another $100 for a "fancy" duplex outlet, the wiring behind the wall, all the way back to the power plant is still the same old stuff.

After miles and megawatts, all the way to to the pole pig out on the street, to the 240VAC house drop, to the breaker box, to the house wiring, the last six feet of wiring isn't going to make ANY difference...

If the house power is "noisy", then go after the light dimmers, compact fluorescent bulbs and switcher power supplies. They can and will dirty up the power line big time.

I suppose a 100 dB insertion loss power line filter could help, but it will probably cost more than everything else in the sound system...

/ed B

THIS is what I've been telling people! But they phoolishly do not listen and repeatedly drop thousands for the geewhizbang power cables.

I have an el-cheapo line filter I made and it cuts what I wanted it to cut - CFL bulb rubbish. $30 parts new.

Cheers!

Oh c'mon guys -- you know it was never about what kind of cable you used, but all about which way you plugged it in that REALLY matters!!!

Dave

Seems to me that one would want the same size wire for a power cord as what's in the wall. Otherwise you're kinda choking off the power the amp needs.

There's some evidence that wire isn't "just wire".

http://www.theaudiobeat.com/visits/shun ... erview.htm

If you believe everything we know about the world around us is well-known and never changes then just wait and science will eventually teach us something new.

corndog71 wrote:Seems to me that one would want the same size wire for a power cord as what's in the wall. Otherwise you're kinda choking off the power the amp needs.

There's some evidence that wire isn't "just wire".

http://www.theaudiobeat.com/visits/shun ... erview.htm

Look at the amps draw on the test..... if your ST-70 is drawing 150 amps.... you MIIIIIIIIIIIIGHT have a problem

Cheers!

"only $99" I love this sh*t! I guess this is a strategy to survive defense department budget cuts...

corndog71 wrote:Seems to me that one would want the same size wire for a power cord as what's in the wall. Otherwise you're kinda choking off the power the amp needs.

There's some evidence that wire isn't "just wire".

http://www.theaudiobeat.com/visits/shun ... erview.htm

If you believe everything we know about the world around us is well-known and never changes then just wait and science will eventually teach us something new.

Geek wrote:

corndog71 wrote:Seems to me that one would want the same size wire for a power cord as what's in the wall. Otherwise you're kinda choking off the power the amp needs.

There's some evidence that wire isn't "just wire".

http://www.theaudiobeat.com/visits/shun ... erview.htm

Look at the amps draw on the test..... if your ST-70 is drawing 150 amps.... you MIIIIIIIIIIIIGHT have a problem

Cheers!

Yep, the 12 - 14 gauge wire in your wall is for powering space heaters and microwaves, up to 15 or 20 amps. You could use 14 gauge power cord, but it is kind of a waste. Why not get an electrician to come through and replace all house wiring with $20 a foot wire? It's a waste. And all that "instantaneous current delivery"? That's what capacitors and transformers are for.

0000 gauge coming to house, 14 gauge in the wall, 18 gauge power cord, 22 gauge wiring in amp, 28 gauge primary in the power transformer.

You forgot the 20 ga wiring inside the spks.

quote:

Seems to me that one would want the same size wire for a power cord as what's in the wall. Otherwise you're kinda choking off the power the amp needs.

There's some evidence that wire isn't "just wire".


Actually this is what they want you to believe. If they make a believer out of you they can sell you all those little devices that are supposed to make your system sound oh so great. The reality of it is the fancy connectors, power cords, spk wire, interconnect cables don't do squat. I work for a sound company and have access to all the toys to try and have done so.
Would you like to know what I use for spk wire? I use 14 ga commercial spk wire and it sound the same as the monster wire I bought 36 yrs ago.
Guess what? Just removed the mega power cables some idiot installed on a set of Quicksilver 8417 mono block amps and reinstalled the 18 ga they originally came from the factory with. Oh, no difference in sound but a hell of a lot easier the move the cord around.