House voltage 122v and change

[Daddy Dee]

Well, I've been getting adventurous witn my Radio Shack multi-meter. Checking and setting bias on Mark III's and such.

Got curious about what what version of 110v current is coming in the house. Found out it is 122.2v or so.

Should this be a cause of concern for any of my gear? Does it make a difference in sound?

Any easy solutions? I noticed Dr. Bill has posted about using an RCA Iso-something.

Does a UPC put out 110v clean?

Any help appreciated.

[DRBILL]

DEE,

±122vac probably isn't much to worry about. After you have carefully set the bias, let the Mark-IIIs operate for about an hour, and in a dark room, inspect the plates on the output tubes for any suggestion of reddness. I think you told me that you are using 5U4s. That pretty much rules out any problems. Voltages tend to sag in the summer, so you might want to check again in the fall after everyone turns off the air-conditioners. As you get closer to 130vac, become nervous.

I am using GZ34/5AR4s and I had nothing but trouble with rosy plates until I bought the isotap. I can set it to exactly 117vac which is the DYNACO specification. Look up isotap on e-bay. You can probably get one for $10 or so. The catch is the weight, so beware. They are like a boat anchor.

You want the one with the third grounding prong on the line plug.

If you play loud, heavy bass music, you will notice some sag using the 5U4.

Is this starting to sound like "stone soup"?!

BILL

[Daddy Dee]

Dr.Bill,

Thanks. When you mention the third prong plug, are you speaking of the cord which powers the whole unit? or one of the options for plugging the amp into the isotap?

In my vintage house, I don't have any three prong outlets.

[DRBILL]

In that case, you can use either kind. Yes, I am referring to the plug that goes into the wall socket. I'm sure you are quite familiar with the adaptor thingy with the little wire hanging loose!

Or do you just cut the ground prong loose? The reason I ask, there can be some polarity issues that result in excessive hum. But that's a dissertation and is probably covered somewhere else on the forum.

While I have you on the line I'll mention the filter capacitors in the Mark III. It is the weakest link in the system and is driven almost to the failure point. Its 525v volt rating leaves no headroom for an AC surge. This is yet another reason to continue using the 5U4 or to invest in an isotap. If a filter cap ever blows, don't replace it with another "twistlock". Invest in a "cap board" (many are available) that installs either under the chassis (if you want to preserve the original visual profile) or in place of the present can.

"I could tell you more, but you would not be able to bear it!"

Seriously, it is a splendid amplifier. I would never have anything else. I Have never had ANY difficulties with mine. But there is the voltage issue that your tech mentioned. Fortunately, there are fairly easy ways to work around it. You asked the right questions, early.

BILL

[D-MAN]

Yes, the 110v rating is an optimistic "average". Most line AC fluctuates all over the place.

DM

[LarryC]

I also have a "vintage" house (1930s), and most of my outlets were 2-prong when I moved in. However, the wiring was "BX", a flexible metal cladding containing hot and neutral wires, that was made to be attached to the early 1980's service panel at one end, and the metal junction, outlet, or fixture boxes at the other.

So, to describe the obvious, I attached all the BX ends to the service panel and the various boxes, and ran green or bare wires from the grounding screws on the boxes to the receptacles, switches or fixtures everywhere I could get to them. Finally, I used one of those $6 3-light circuit testers on every receptacle to make sure the ground was intact and hot and neutral weren't reversed (they were in a couple of cases!). With corrections, everything was fine.

Now, it's much easier to use polarized plugs with grounding pins everywhere, and I've been able to install GCFI outlets in key places.

[Daddy Dee]

Bill,

Nope. Just use the three prong adapters.

Thanks all, this is helpful.

[Malcolm]

Any easy solutions? For what? You don't have a problem.

Where I live, the nominal voltage is 120V. The power company considers voltage satisfactoy if it is within +- 10% of nominal (118V to 132V). This is typical. Your gear won't have a problem with the voltage you report if it was designed for use in the U.S.A. Be aware, that if you measure the voltage again, it may be different. Voltage can and does vary over time. Shouldn't make an audible difference in your sound unless the smoke gets out.

You can get a UPS compatible with any standard voltage in the world. Clean power? Even with "pure sine wave" ouput, any UPS of the kind we typically think of for home use is going to generate some noise of its own noise.

[djk]

The utility company tries for 123V, they don't consider it high unless it goes above 127V.

This may be a bit much for older gear designed for 110V.

A regular 12V transformer may be wired as an autoformer to drop the 122V down to 110V.

[Daddy Dee]

djk,

That is an interesting idea. I suppose that is what is happening inside the RCA Isotap.

A homebrew option would be pretty cool. If done right.

[Steve Donalson]

"110vac" doesn't exist in the USA, it's 120vac. It's commonly called "110" or "115". The truth is that it's 120 with a +/- 10% tolerance, on single phase. You will find 108vac on 3 phase, however. The power company won't check into it unless it goes above 132 or below 108. If it's between 108 and 132 volts, to them, it's ok and within tolerance.

The incoming vac will fluctuate considerably throughout the day. It depends on the demand on the lines. Typically you will find the highest voltage of early morning and late evening. Lowest during business hours and/or on very hot days.

Same way for "220". "220" doesn't exist in the USA, it's 240, again, on single phase (which is what most have in their home). 2 120vac lines = 240vac +/- 10%.

Now, of course, stable line vac will affect what an amp can put out. The more channels driven at high levels the more strain it puts on the AC line. It's very expensive for the typical home owner to install the necessary equipment to truly maintain a constant incoming vac. But, the reality is...chances are you would never hear the difference.

[DRBILL]

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On 8/25/2005 9:26:50 AM Steve Donalson wrote:

All of that being said, you will not have any trouble with any equipment designed to operate on USA's "110vac" lines, even with the fluctuations we encounter on a daily, even hourly, basis.&nbsp.

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Sorry, Steve, but experience belies this. Anything above 125VAC puts classic Dynaco Mark III's in peril. Even voltage surges can take them out. Even when biased correctly, at 125VAC, using contemporary issue tubes, plates are apt to glow and grids are apt to incandesce. The electrolytic filter capacitors are only rated at 525vdc and are exposed to 490VDC at 117VAC! The headroom disappears at 125VAC. This is assuming a fresh NOS twistlok!

Ask Craig, or ANYBODY who deals with Dynaco amplifiers and you will get the same information. You have given advice that will prove costly and disastrous to owners of this equipment.

I urge a speedy retraction. As a moderator, we will hold you to a higher standard.

DRBILL

[Steve Donalson]

Per your request I have removed the statement regarding the useage of devices designed to run on USA voltage. I will admit my ignorance regarding these particular amplifiers.

However, I stand behind everything I said regarding the voltage supply provided to us in the USA. Anything not designed to work within our voltage tolerances I would seriously question. Contact your local power company and they will tell you the same thing. With THAT being said anyone who simply plugs these units into common 120vac, without an additional voltage regulator or some other form of protection from our daily supplied power, can encounter the disaterous problems from what you have stated.

Now, not trying to start any form of an argument, but after I personaly spoke with a technician at the "Audio Clinic" in Silver Spring, MD, (a Dynaco repair center) he stated to me exactly what I stated in my original post. These units were designed to work of US voltage, ranging from 120vac + and - 10%. For whatever that may be worth.