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Power Conditioners for Tube Amplifiers: Yay or nay?


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I posted this on one of the Mesa Boogie FB groups, and recently it became active again. Since we've got a lot of really knowledgeable people here, I thought I'd bring it over.

Back in May, someone posted that power conditioners, like the ones that Furman markets to musicians, are actually not good for amplifiers.

I emailed Mesa, and they said "Power conditioners are best used for accessory items. Unless you are using a Voltage Regulator, the amp is best plugged directly into the wall."

On the other hand, Tripp-Lite power actually has articles for choosing the right power conditioner for a guitar amp. Power conditions are also usually rated for 15 amps. What are they designed to run, if not amplifiers? Most of the pro rack setups I see have a power conditioner at the top. I don't see how they can manage to have two power amps and several preamps hooked up at once if they all are connected directly to the wall.

Do they have custom setups? How do they get power to all those amps? Just simple line splitters?

One guy on the facebook group claimed that the power conditioners "choke" or "starve" the amplifier for power, which somehow can lead to the output transformer blowing the thermal fuse, or just out right blowing up.  I however simply cannot find any reason that a power conditioner would harm specifically a tube amplifier. I also like having some nice surge protection so I don't end up like Keith Richards.

https://blog.tripplite.com/https/blog.tripplite.com/how-to-choose-the-best-power-conditioner-for-guitar-amp

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Ive read about and been told about the pros and cons. I didnt know which way to go about it for a long time and put it off for a while.

One gig in particular cemented for me the worth of them, in my situation at least.

Old country pub with old wiring and a supplementary generator that wasnt keeping up with the draw. Big event with people travelling for miles. Out door lighting and temporary out door bar and fridges etc set up. Big PA and lightshow.

Bass player, other guitar player both using furmans, me, no power conditioner. My mesa, brittle, no bottom end, no fat mids. Might as well have been going direct through a ds1. The other guitarist sounded okay, bass player sounded full, as usual, vodka problem.

Its not like I needed it every time, just sometimes. If you have good power you might not need one. Ive never used one at home for example, good even power all day everyday even when the whole neighbourhood has their aircons and swimming pools running flat out. I know a lot of people use them all the time and have been for many years, its just part of their set up.

I dont know all the technical details or ins and outs, maybe it was shortening the life span of my amps, but running low power and sounding like crap wasnt an exciting prospect either. Either way, I still had to get through the gigs.

Thats my experience with them, other people have different experiences with them.

 

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5 hours ago, rockabilly69 said:

ooo! That IS nice, even for stuff at home. I know that Rivera amps give all their bias specs for 115VAC, and that my R-55 and Pubster are both labeled 115V on the back. Maybe time to buy a variac? Probably not.

I'm still just mystified though how a power conditioner could blow up an output transformer. It just doesn't make sense to me.

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I also couldn't possibly see how one could cause damage to the amp; it's just providing more consistent power levels, and with less chance of nuisances like 60 cycle hum and RF. 

Unless it was woefully underrated, or some ebay/amazon/wish/alibaba express cheap knockoff style conditioner... but then damaging an amp could be the least of your worries. 

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I've used one for over a decade.

+1 KBP.

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1 hour ago, kbp810 said:

I also couldn't possibly see how one could cause damage to the amp; it's just providing more consistent power levels, and with less chance of nuisances like 60 cycle hum and RF. 

Unless it was woefully underrated, or some ebay/amazon/wish/alibaba express cheap knockoff style conditioner... but then damaging an amp could be the least of your worries. 

Most of the threads I found discussing it were hi-fi people talking about the amplifiers for their very expensive stereo rig. Some say that there is some type of interaction between the circuitry in the power conditioner and the amplifier. Something about wanting a "stiff" power supply.

Quote

Powersupply conditioners are usually ok for equipment have regulated power supplies, sources like cdp's, phono stages, preamps tuners T/T etc;

But for most poweramp/s their output stages are not powered by regulated supplies, they're just rectified, these supplies need to be "stiff" (low esr) right back to the mains, and by introducing a power conditioner, they usually no longer remain "stiff" and the bass tightness will suffer in most cases, and sometimes the dynamics as well.

https://forum.audiogon.com/discussions/amplifier-is-now-off-the-power-conditioner

Edited by tbonesullivan
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The Hi Fi audiophile crowd in an interesting bunch.. and by interesting I really mean pedantic but with really good imaginations. They don't just sniff the corks, they lick the bottom of the bottle to make sure it was made from the right kind of glass. I mean, we're talking about the same crowd that at one time swore a $1000 gold plated power cord made all the difference; and you couldn't convince them otherwise. (I know that doesn't define the entire Hi Fi crowd; I've just seen enough baseless crazy talk over the years to make my head spin). 

A "stiff" power supply, would refer to one that provides adequate consistent power, without "sag"; if a power conditioner is introducing sag, it probably was ordered from wish, lol. Not sure why/how they are trying to tie in ESR to that, but if there is any excessive resistance introduced, it would again be a result of poor components or poor design; and most, if any, would be negated in the amp rectifier when it is converted to DC and subsequently filtered by the power caps; by what is ironically, a power supply that is typically desirable to sag (not be stiff). Not to mention that ESR typically only introduces a few extra ohms; well within the tolerance or swing of the components within the amp itself. I also hate to break the news to them... but they probably have other things that are also plugged in at their house on the same circuit breaker :)

If there was any perceived difference between wall plug and conditioner, it's probably because one was providing closer to 100 volts, while the other may have been closer to 120 volts; or there might have been other factors like hum or interference, that one could mistake for a desirable effect. Or maybe someone was eating chips too loudly during test A and it threw off their super human sensitive listening ears. 

Now I'm not saying one needs a power conditioner, or that it's always going to make a difference, for better or worse, in all scenarios; I'm just struggling to understand how it could have a significant negative effect or cause damage. 

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Good to see you back KBP.  +1

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Eric Johnson once said that he could tell the difference between a regular battery and a Duracell alkaline in his tube screamer. I believed him. He is just that kind of guy..

At any rate, I have been using power conditioners for years and have had no problem. I have two of these and they are amazing. However they add a little weight to the rack....

https://carvinaudio.com/products/ac120s-power-conditioner

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Wasn't one of the EVH tricks to use a Variac to lower the voltage of his early Marshall amp?   That would suggest that lowering voltages won't have a detrimental effect, unless you completely starve the tubes.

Early amps from years ago were usually rated for 110V, whereas the standard today is 120V.    I would think running overvoltage might have an effect to shorten tube life on those designs, but amps built today should be set for 120V. 

A power conditioner should help remove spikes and noise from the line, which I would think to be more detrimental to the amp.   I just use a Tripplite surge protector on my amps.   Its the same one I have brought to PSP the past 5 years or so.

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All I can remember  about the subject when I was trying to figure out what to do was filament voltage and plate voltage/draw(?)

The tech said to try a conditioner to clean up the power or use a modeling device that doesnt require much power.

I know not every amp responds well with dropping the power with a variac.

Another thought occurred to me, my fender concert spent its first 15yrs with me set to 220v, we are 240v. When I finally switched it to 240v I didnt notice any difference in sound at all. It still had its original tubes in it.

 The venues where my Mesa or Bad Cat sounded thin and brittle my Fender had never had the same problem, it just sounds like it does regardless.

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Another thought I just had: Mesa Boogie has BUILT IN variacs for many of their amps. They actually have a different tap on the power transformer to run the amplifier at a reduced voltage. They also use Tube Rectifiers SPECIFICALLY to get overall voltage/current sag.

Still, I just don't see how a power conditioner will really effect anything. Each socket is rated at around 15A, with the overall unit rated at 20A. I don't see how that could possibly be "choking" the power requirements of the amp, unless it was some cheap POS that couldn't actually handle 15A per outlet.

The 150 Watt Mesa Boogie triple rectifier uses a 4A fuse for 120V, and 2A for European 240V.  It's only slow blow for the filament draw when they first heat up. And that's MAX. Unless you are playing destroyer death metal in your house, it's unlikely you'll be drawing that much current. I also think that the huge amount of caps inside most amps also would somewhat smooth out power draw transients.

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Your circuit breakers in the box are probably rated at either 15 or 20A.    I've run three or four amps off the same breaker at band practices without ever tripping anything.  That included a PA with a QSC RMX1450 power amp.    A 15A breaker will handle 1800 watts.  A measly 150W amp won't choke on that.

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17 hours ago, TalismanRich said:

Your circuit breakers in the box are probably rated at either 15 or 20A.    I've run three or four amps off the same breaker at band practices without ever tripping anything.  That included a PA with a QSC RMX1450 power amp.    A 15A breaker will handle 1800 watts.  A measly 150W amp won't choke on that.

I guess it's time to get out my half stack and blow up my house!

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A power conditioner is most effective in providing consistent voltage.  It usually gives a consistent voltage, regardless of input voltage (within reason).   Consistent input voltage provides a solid foundation for your favorite amp settings every time you turn it on.  It also protects against other current/voltage drains on the circuit into which you've plugged.  Imagine you're playing and sounding great, suddenly the amp sounds defective, even for just a moment.  The change is often associated with a motor starting in the circuit - vacuum, fridge, the furnace, etc.  Now, put yourself in a bar with shoddy wiring.  The register rings, the freezer turns on and off and so on.  It's no wonder your amp sounds like a piece of crap.  That's when you need a conditioner.

The conditioner also provides isolated outlets.  It should negate ground loops between everything you've plugged in.  I use a conditioner to play multiple amps simultaneously; it works like a charm.

Edited by Steiner
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Double post

Edited by Steiner
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I use a Furman Power Strip, mostly for my pedalboard and cutting down noise through the electrical, plus it has a long cord allowing my amp and pedalboard to be further away from the outlet.

Long extension cords can be rather dangerous, as the cable thickness should be heavy enough to carry the current needed to draw the correct amount.

I was in a training exercise where there was one generator with a single 110 outlet, the command center I was supporting daisy chained their power.  I watched computers and printers literally go up in smoke because the end device was drawing a current forcing higher current further up the chain.  So that is a real danger.  Don't daisy chain/split outlets through multiple power strips.  Serious fire hazard.  The sheer amount of amperage being drawn was insane.   

Electrical devices usually draw what they need, but that's amperage.  Voltage is a little different, it just takes a number of volts for the push of electricity to be used.  Sort of an on/off, but does allow trickling. Using a Variac, which is a very common device for "starving" amps to produce a particular sound goes back decades.  But those are people that like dirty amp tones, no super clean jazz, chimey tones.  I suspect its like using a preamp to make the amp sound dirtier.

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There is a linear drop in voltage over long runs.  That is to say that if you throw down 100' of thin wire, the voltage will be many volts lower from start to finish.  When the voltage drops, the amp's feel changes.  It's subtle but noticeable.  I don't notice difference in gain with lower voltage.  The difference is certainly nothing like any pedal I've used.  I need to hook the variac on the Fenders and play...

If memory serves, EVH dropped the voltage in his 1959SLP Marshall to 94-97 volts.  My home is currently (get it?) at 123 volts.  It was 117 volts before the local substation got revamped and they installed a new transformer on the pole.

Variacs drop the voltage by a % of the input voltage.  If you use one, have a volt meter on hand and don't starve the amplifier or you may just let the smoke out.

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5 hours ago, Steiner said:

There is a linear drop in voltage over long runs.  That is to say that if you throw down 100' of thin wire, the voltage will be many volts lower from start to finish.  When the voltage drops, the amp's feel changes.  It's subtle but noticeable.  I don't notice difference in gain with lower voltage.  The difference is certainly nothing like any pedal I've used.  I need to hook the variac on the Fenders and play...

If memory serves, EVH dropped the voltage in his 1959SLP Marshall to 94-97 volts.  My home is currently (get it?) at 123 volts.  It was 117 volts before the local substation got revamped and they installed a new transformer on the pole.

Variacs drop the voltage by a % of the input voltage.  If you use one, have a volt meter on hand and don't starve the amplifier or you may just let the smoke out.

So you had better tone before DTE "upgraded" your power?

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2 hours ago, DetroitBlues said:

So you had better tone before DTE "upgraded" your power?

No, most amps are plugged into the power conditioner.  The one in the living room has its own built in variac :)!

It's a good life!

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