[sizwej]

could someone please explain ( in layman's terms) the importance of the power supply in tubes amps.I have heard it's one of the most important components fro tube amps. I am confused as to what power we are referring to, are we talking about the power coming from the outlet ( in that case would a power conditioner solve that problem), or are we talking about the internals of the amp?

Sorry for the noob question but during my "research" i have read that the inadequate power supply is one reason to stay away from budget amps, which will factor in my decision for my next amp.

 

[FallenAngel]

I would say it depends on the design but for the most part, it's very important important. Most tube circuits are incredibly simple, almost all the parts in the amp are the power supply, just a few resistors and caps in the tube circuit.

 

[Clarkmc2]

Quote:

Originally Posted by sizwej;6127256I am confused as to what power we are referring to, are we talking about the power coming from the outlet ( in that case would a power conditioner solve that problem), or are we talking about the internals of the amp?

The power supply in question is part of the amp's circuit, not the AC cord or the power utility's current. It converts wall plug alternating current - AC - into the voltages and types (alternating current or direct - non alternating - current) the amplifier needs.

A tube, for instance, usually needs a six volt or twelve volt DC or AC current to heat the parts that need to be hot for the tube to work at all. A high DC voltage - much higher than the 120 or 240 volts the power company supplies - is needed for other things, typically what is called a plate or anode, just another part of the tube stuff inside the glass. Most of the supply currents needed by a tube amp - or any amp, really - are DC. These are supplied by the amp's power supply. Thus the name.

The AC is usually supplied by the music playback device (CD player, phono preamp, etc.) and the amp in turn makes the much stronger DC currents become big dog versions of the music AC signal. In other words, amplify the signal into enough current and voltage to power your headphones or speakers. How the amp does this - and how well it does it - are up to both the design of the power supply and the rest of the circuit. If the power supply is not clean enough or not powerful enough, both which require decent components and good circuit design, the rest of the amp will never be able to do a good job and will not be hifi, no matter how well the rest of the amp is designed and built.

Wouldn't you know it, the power supply components are the largest and most expensive parts in a tube amp. Even if you buy pretty expensive capacitors and tubes to build your amp, a really good power supply transformer will be the most expensive piece and the best ones are custom designed and built for each application. The tube amp designer Alan Kimmel, one fellow I am pretty familiar with, always designs the transformers for his amps from scratch. Each time. So the tail sort of wags the dog.

Clark

 

[cujobob]

The power supply in any amplifier or source is extremely important...if you skimp on parts quality, it can take away from the music greatly. Bad power supplies add noise, eliminating the blackness of the background and covering other details you'd normally hear.

 

[ruknd]

The power supply is important for SS and tube alike. There is a reason companies like Naim offer power supplies from $400 to over $4000.00...I have 3 separate power supplies on my 2 channel rig.

 

[Happy Camper]

So kids, the moral of the story is, you get what you pay for.

 

[sizwej]

Very informative responses, thanks all.I was always under the impression that only tube amps required a superior power supply,not solid state. I guess you learn something new everyday.

 

[darlim]

Quote:

Originally Posted by sizwej /img/forum/go_quote.gif Very informative responses, thanks all.I was always under the impression that only tube amps required a superior power supply,not solid state. I guess you learn something new everyday.

Actually power suppy goes beyond just the PSU. Power conditioning is an extremely important chain in getting the best possible music.

 

[Happy Camper]

For an amp to be a good all rounder, it has to have enough current reserves to offset the differences in impedance of your cans. I run some of the tougher hps for an otl amp. I upgraded the power supply parts to give me better performance on tougher loads. You can save some money by matching an amp to a particular set of hps but you're limited to that set.

As far as a SS amp needing more power supply, I use stats for my home theater setup. I tried Carver, NAD, Rotel and finally found an amp that does drive them. Would have saved some money if I had just tried not to save money in the beginning.

 

[Uncle Erik]

Quote:

Originally Posted by darlim /img/forum/go_quote.gif Actually power suppy goes beyond just the PSU. Power conditioning is an extremely important chain in getting the best possible music.

Well, a power supply really is a power conditioner. Power conditioning, for the most part, is redundant. It's like having two different washing machines for your clothes. Doesn't hurt (usually) but a redundant, expensive waste.

Power comes in through the line, then goes into a transformer. This usually boosts the power from 120V to, say, 300V. From there, the power goes to a rectifier. The rectifier takes the AC and turns it into DC. You can do this with tubes or diodes, sometimes you can do it with both tubes and diodes in a hybrid.

From there, the DC sometimes goes to a regulator, which ensures that the power doesn't vary.

After that, the power usually goes through a network of capacitors to smooth the power and resistors to get a precise voltage. The bigger and better the capacitors, the smoother the sound. Also, big caps help provide a good reserve of power. If the amp circuit draws a lot of power for a stiff transient or a loud sound, then it will draw power off the big caps instead of crapping out.

You can also use chokes to smooth the power further. A choke looks like a transformer - and costs nearly as much. But there's nothing better for smoothing DC into gorgeous sound. They also consume some power off the circuit, so that means you need a bigger power transformer.

And for all of this, I'm just talking about the B+ in the amp. You can go through all the same things for providing power to the filaments, which is also important.

Of course, the more of this stuff you use, the more complex the amp and the more expensive it gets.

The circuit is usually cheap - a few caps, resistors and tubes. If it's an OTL, then maybe $50-$100 for boutique parts. But if you want good power transformers, separate filament transformers (some like separate, dedicated ones), chokes, big caps, etc., etc., can set you back a couple thousand or more.

So you can spend a couple hundred on the amplification section, but then go on to a couple thousand to run them in the most ideal way possible.

I know that seems weird and upside down (especially with the flogging tuberolling gets around here) but the power supply is monstrously important to the sound you get. I'd much rather have average Russian tubes and a couple thousand in the power supply than some $300 tube amp with futzy NOS tubes.

 

[Clarkmc2]

I find myself in total agreement. That is a great explanation of why a power supply is the most important part of an amp. I have a little tube EL84 class amp with both an awesome power supply and a brilliant circuit, especially the preamp section. Not only is it the best sounding amp I have ever heard, but the headroom and power reserve is like nothing else I or my friends have ever experienced. The thing never seems to run out of steam.

Power conditioning is for me like wire. If you want to ignore the laws of electromagnetics and send someone else's daughter through an Ivy League college, be my guest. If only you had spent the money - or even a fraction of it - on things that actually audibly matter re: sound quality, you would have the best rig in town. No doubt.

Crappy, substandard power supplies (the usual) do need power conditioners, because they are not doing their job. But the combination will still not sound nearly as good as having a good PS in the first place. And a power conditioner will not yield any more power reserve, either.

Sorry about the tone but I am so tired of seeing people being ripped off. It is their money, but larceny is larceny.

Clark

 

[snejk]

Very informative posts, thanks for sharing.

 

[pedalhead]

Thanks guys, educational stuff. Having just spent quite a few £££ on a nice tube amp, this is really useful learning material to help me understand what's going on inside.

 

[Spareribs]

Power supply makes a difference in refinement of over all sound. A heavy tube amp is a good sign usually because the power supply is the heaviest componant. I'm all about power supply baby.

 

[Uncle Erik]

Quote:

Originally Posted by Spareribs /img/forum/go_quote.gif Power supply makes a difference in refinement of over all sound. A heavy tube amp is a good sign usually because the power supply is the heaviest componant. I'm all about power supply baby.

Yes! The heavier they are, the better the quality. Sounds funny, but the more iron in there, the better.

I've been toying with the idea of a three chassis amp. There's a preamp in Sound Practices magazine (highly recommended, by the way) that just uses a single tube per channel and recommends input transformers, as well.

I'm toying with the idea of building it to use 45, 46 or 71A tubes and going overboard on the power supply.

One chassis for the amp circuit, one chassis for the B+ (aka the power for the amp circuit) and another for the filament supplies.

The B+ would have plenty of big caps, chokes, tube rectifier, and tubed regulation. However, I'd build an equally elaborate supply with tubed rectifiers and regulators for the filaments of all the tubes.

You don't find many tube regulators in commercial designs, but they're awesome. They're the tubes that give off a blue/purple glow that you may have seen.

I'd also build an isolation transformer and RFI/EMI filters into each power supply chassis. That will take all the noise, garbage and DC off the line.

The power supply would be very complex, however the amp circuit would only have an attenuator (likely one of the transformer based volume controls), input transformer, one tube, one capacitor, one resistor, and one output transformer per channel. That's my ultimate amp - the absolute minimum in the amp circuit and lots of complexity in the power supply.