1 Ohm stable amplifiers (inexpensive)

[Seth=L]

If anyone would care to find the best value on amplifiers that are stable into 1 ohm loads that are not tube amplifiers I would be interested to know what they are and how much they are. My current Niles amplifier is rated to be stable a little below 3 ohms. I am hoping to find something with oomph below that impedance.

 

[highfigh]

Inexpensive and high current/low impedance don't usually go together.

Why do you want to drive such a difficult load? Wanna describe what you want to do?

 

[Seth=L]

Inexpensive and high current/low impedance don't usually go together.

Yeah, I know. Sucks a bunch.

Why do you want to drive such a difficult load? Wanna describe what you want to do?

Possibly electrostats, I am looking to get speakers that make my ears feel really warm and fuzzy and I remember that ESLs did that for my ears.

I would think some pro amplifiers would be capable of driving such low loads, but I can't recall seeing any that where rated to stably drive anything below 2 ohms.

 

[bandphan]

With Martin logans the low dips are at high frequencies which will not tax the amp that bad.

 

[Lordoftherings]

I will do a search into this.

I believe that some (rare) amps are stable down to a very low 0.2 ohm, or around that corner.
Well, some speakers (rare) dip lower than 1 ohm impedance. So, you need a matching amp, right?

 

[TLS Guy]

If anyone would care to find the best value on amplifiers that are stable into 1 ohm loads that are not tube amplifiers I would be interested to know what they are and how much they are. My current Niles amplifier is rated to be stable a little below 3 ohms. I am hoping to find something with oomph below that impedance.

Seth, your best bet is to find a Quad 303.

The one above is for sale on the UK. They do come up for sale though fairly regularly in North America, especially from Canada.

Here is a recently completed sale from Montreal.

Don't be put off by the fact that most of these amps will be 30 to 40 years old.

This was Peter Walkers first solid state design. It is also acknowledged to be the first solid state amp that was any good, but also a fine sweet sounding amp. As soon has they came out the BBC put them throughout their system, in every conceivable situation.

The point for you is that these amps are unconditionally stable into all loads. Quad of course made electrostatic loudspeakers. In the hey day of the 303 the speaker was what has been come to be known as the the Quad ESL 57, the year of its introduction.

The ESL 57 was a highly reactive capacitative load, that sent most amplifiers of the day into oscillation and destruction.

In a 303 you can even short the speaker leads at power and it won't complain. It won't even blow a fuse. A 1 ohm load it will laugh at. Power is 45 watts per channel. I suspect you are an apartment dweller so that will be plenty of power for you.

303s go for between $250 and $350, in the current downturn, they used to fetch a little more.

I bet over 90% of the 303 production is still in use. I have had three, one I sold with our GF house to power the built on living room system.

The other two I now powering my biamped speakers in our Eagan Quad home condo.

I can't use high spl there so they do fine.

Do not be put off by their age. I have never ad the top off a 303 for service!
The combined years of service for the three of them exceeds 100 years!

If you buy one that the seller says works, you can be more confident of longevity than for a piece of far Eastern goods produced last week!

I fail to understand why I seem to be the only member that uses Quad amplifiers.

 

[jostenmeat]

303s go for between $250 and $350, in the current downturn, they used to fetch a little more.

Man, these would be fun to try for such an affordable price. Affordable to the point that I wish I could try a pair in mono, but I guess that's not possible.

Last I cared to check, I very rarely ever get over 85 db, C weighted on the RS meter.

 

[PENG]

I would think some pro amplifiers would be capable of driving such low loads, but I can't recall seeing any that where rated to stably drive anything below 2 ohms.

That is true but in theory a pro amp (e.g. Crown) that is rated for say 700WPC into 2 ohms can get you at least 350WPC into 1 ohm or 175WPC into 0.5 ohm (half down) and will be completely stable because the current will be the same at half the rated power output into 8 ohms. So if you don't need a lot of power you have plenty of options.

 

[Seth=L]

That is true but in theory a pro amp (e.g. Crown) that is rated for say 700WPC into 2 ohms can get you at least 350WPC into 1 ohm or 175WPC into 0.5 ohm (half down) and will be completely stable because the current will be the same at half the rated power output into 8 ohms. So if you don't need a lot of power you have plenty of options.

That I didn't know. Now I am getting somewhere. I wonder what my Niles will do. It's rated 75watts x 2 @ 8ohms, 100watts x 2 @ 4 ohms and it states on the back that it's stable to 2.67 ohms. Do you think it would be fine to drive a pair of electrostatic panels that drop down to 1 ohm at near ultrasonic frequencies?

 

[TLS Guy]

That I didn't know. Now I am getting somewhere. I wonder what my Niles will do. It's rated 75watts x 2 @ 8ohms, 100watts x 2 @ 4 ohms and it states on the back that it's stable to 2.67 ohms. Do you think it would be fine to drive a pair of electrostatic panels that drop down to 1 ohm at near ultrasonic frequencies?

Seth, I really can't say. The problem with driving electrostatics is that they present a capacitance to the load which moving coil drivers do not. This makes most amps ring and a lot unstable with with supersonic oscillations and even audible oscillations. Generally electrostatics should be driven with exotic amps.

I recommended the Quad 303 as it has an unblemished record driving electrostatics. I can be certain that if you want to own electrostatics on a low budget, a vintage Quad 303 is by far your best solution.

The other bonus is that far more likely than not, it will work perfectly for the rest of your life. I have said before that one of the things that really distinguished Peter's designs was there longevity.

 

[PENG]

That I didn't know. Now I am getting somewhere. I wonder what my Niles will do. It's rated 75watts x 2 @ 8ohms, 100watts x 2 @ 4 ohms and it states on the back that it's stable to 2.67 ohms. Do you think it would be fine to drive a pair of electrostatic panels that drop down to 1 ohm at near ultrasonic frequencies?

As long as you use it like it is a 25WX2 amp (may be even 15WX2 just to be safe and stable) it can do it for you. You basically de-rate it to keep the current within its rated capability and then de-rate it some more to allow for the extra demand from a highly reactive (inductive or capacitive) load. It is all math and electrical theory, no magic to it.

 

[Seth=L]

As long as you use it like it is a 25WX2 amp (may be even 15WX2 just to be safe and stable) it can do it for you. You basically de-rate it to keep the current within its rated capability and then de-rate it some more to allow for the extra demand from a highly reactive (inductive or capacitive) load. It is all math and electrical theory, no magic to it.

That doesn't change the simple fact I currently don't understand it. Is there a simple equation for this?

 

[WmAx]

Behringer Ep2500 will provide transparent amplification and will drive any load you desire, even 1 Ohm. However, while the EP2500 will produce about 1100 x 2 into 2 Ohms, both channels driven, your maximum power will be reduced to 600 x 2 into 1 Ohms, both channels driven, as per 3rd party tests demonstrate. Practically speaking, this is far more power than you would need, and the EP2500 would run cool into the 1 Ohm load at the SPL levels you can actually use in a regular home environment, where you would on average use less then 10 watts with only very occasional peaks that exceed 100 watts.

-Chris

 

[3db]

Seth, I really can't say. The problem with driving electrostatics is that they present a capacitance to the load which moving coil drivers do not. This makes most amps ring and a lot unstable with with supersonic oscillations and even audible oscillations. Generally electrostatics should be driven with exotic amps.

I recommended the Quad 303 as it has an unblemished record driving electrostatics. I can be certain that if you want to own electrostatics on a low budget, a vintage Quad 303 is by far your best solution.

The other bonus is that far more likely than not, it will work perfectly for the rest of your life. I have said before that one of the things that really distinguished Peter's designs was there longevity.

I guess everyone is ignoring the fact that electrostats are way more reactive in nature then your typically loud speaker and that it requires stout amplifier to handle this. Having a phase angle greater than 75 degrees has gotta be tough to drive and throw in the low impedance of 1 ohm in there and that amp is really working.

 

[bandphan]

take a gander over at http://www.martinloganowners.com/forum/, you will see every thing from 30w tube amps, 100w intergrateds, to 600w mono blocks.

 

[Seth=L]

Behringer Ep2500 will provide transparent amplification and will drive any load you desire, even 1 Ohm. However, while the EP2500 will produce about 1100 x 2 into 2 Ohms, both channels driven, your maximum power will be reduced to 600 x 2 into 1 Ohms, both channels driven, as per 3rd party tests demonstrate. Practically speaking, this is far more power than you would need, and the EP2500 would run cool into the 1 Ohm load at the SPL levels you can actually use in a regular home environment, where you would on average use less then 10 watts with only very occasional peaks that exceed 100 watts.

-Chris

How about the Yamaha amplifiers you are using? I would rather fanless operation.

 

[lsiberian]

scientifically any amp can drive a 1 ohm load and probably can drive an electrostatic the question is how hard can it drive it. That is determined by the amount of current the amp can handle coming back at it. This isn't complex, but
I think the Quads would be more in line with your systems and preferences. You seem to be a vintage guy and they are proven effective many times.

I suggest a course in electronics or a book on it if you want a deeper understanding. Be preparred for headaches though. Electricity is something I still haven't grasped.

 

[3db]

scientifically any amp can drive a 1 ohm load and probably can drive an electrostatic the question is how hard can it drive it. That is determined by the amount of current the amp can handle coming back at it. This isn't complex, but
I think the Quads would be more in line with your systems and preferences. You seem to be a vintage guy and they are proven effective many times.

I suggest a course in electronics or a book on it if you want a deeper understanding. Be preparred for headaches though. Electricity is something I still haven't grasped.

This is more complex than you think since the load is almost purely reactive compared to that of a normal loudspeaker. This puts an adiitional strain on the amplifier since current is going to lead voltage by almost 90 degrees.

 

[lsiberian]

This is more complex than you think since the load is almost purely reactive compared to that of a normal loudspeaker. This puts an adiitional strain on the amplifier since current is going to lead voltage by almost 90 degrees.

In the interest in understanding. Why?

 

[3db]

From this article.. http://www.rocketroberts.com/techart/amp.htm

Heat Considerations: Operating an amplifier with a low impedance load (especially a low impedance reactive load) increases the heat dissipation of the amplifier (try it if you don't believe it!). This is because low impedance loads require more current, which taxes the amplifier’s power supply more severely. More current means more losses (which translates to more heat both in the power supply and output stage devices). Excessive heat is unhealthy for electronic devices and should be avoided. ......... Reactive loads will basically increase the power dissipated in the output device in an amplifier. The result is that heat sinks must be larger, devices need to have higher ratings than what otherwise might at first seem adequate. If you take nothing else away from this section, realize that (a) reactive loads (speakers) can reduce the efficiency of amplifiers and they can cause added stress to the output stage of amplifiers (they can make your amp overheat prematurely).

I'll keep looking for more info on this .....