RF-5s - tube amping friendly?

[Deang]

"I doubt one can run 96 dB/watt efficient speakers at 50 watts over their continuous power handling rating in a small room and still not have enough volume."

The RB-5's can take 400 watt peaks, and I took them there often. I never said it wasn't loud enough, because it was. Like I said, it's not a matter of just "loudness", but of fully reproducing dynamics and transients. The Luxman I used had clipping indicators, and they would light up when exceeding the amp's 300 watts peak capability. Good solid state definitely has it's advantages of over tube amps -- but it better be GOOD solid state.

All of the Jolidas on Audiogon right now are units being sold by dealers. Be patient, something will pop up soon. The Cayin's are also very good sounding for the money. I believe those can be bought new for about $450. There is also the vintage route, but maybe a little out of your range right now once you factor in the tech bill for getting them up to snuff. At any rate, there are some other options in your price range, but it's almost 3 A.M. and my brain is shutting down.

[Thasp]

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On 5/23/2004 12:28:02 AM MrMcGoo wrote:

Dean has it right. You can listen at 1 watt, but then a 20 db transient in the bass frequencies comes along. The 20 db peak requires 100 times the power, i.e., 100 watts. Audio amplifiers are all about headroom.

Bill

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So I should go with solid state?

I'm looking hard for a good dealer nearby that has tube amps so I can compare side by side with {any} solid state to see if they work nicely with Klipsch RF floorstandings, since this is confusing(20 watts will blow your ears out, 60 watts won't be enough, etc..)

Do any decently priced tube amps have that kind of headroom?

[Deang]

Where did anyone say that 60 watts wouldn't be enough? I think it's more than enough. As a matter of fact, I think 30 or 40 is plenty. You said "Metallica", and "getting it done" -- and so I'm thinking you need at least 40 watts. Now, if you listen to Metal and Rock at lounge or elevator music levels, then no -- you don't need 40 watts. As a matter of fact, you wouldn't even need a 1/2 watt.

With tubes, the secret is figuring out much power it takes to cleanly reach the loudest level you are likely to listen to, and then multiply that number by five. This will ensure that you have adequate headroom at the loudest level. It also ensures that at lower or moderate listening levels -- the amp will be running the tubes closer to their ideal operating point -- or "sweet spot".

With a tube amp, you should run the RF-5's off of the 4 ohm taps. Tube amps come with two sets of output terminals to wire your speakers to. Typically 4 ohm and 8 ohm. Now, even though the RF-5 is 8 ohm "nominal", it does take some low impedance dips. You'll get tighter bass and smoother highs if you use the 4 ohm taps. The downside is the RF-5's won't play quite as loud with the same amount of power (as compared to using the 8 ohm taps). Basically, you lose about 3db of sensitivity -- that's the easiest way to explain it. So -- the RF-5 becomes a 4 ohm, 96db/w speaker.

I say with Metal and Rock music, you're definitely going to be listening to 90 to 95 db levels fairly often, and you're going to want it tight, controlled, and well -- awesome sounding in that Rock/Metal kind of way, right?

A great way to figure out how much power you need is to use something like the calculator at the provided link. I use 6db of headroom in my calculations.

http://www.crownaudio.com/apps_htm/cts_design/amp-pwr.htm

[MrMcGoo]

I have read the posts of an engineer that mixes movie sound tracks. He uses a 60 watt tube amp to run the bass drivers in his VOT speakers and lower wattage to drive the higher frequencies.

My post above was meant to point out that low watt amps cannot reproduce transients in movies and music as accurately as a well designed higher watt amp.

The general consensus is that fewer watts are needed with tubes, but there is less consensus as to the actual number of watts needed.

Bill

[Deang]

The theory is that less watts are needed because "tube watts are more than solid state watts" -- which is pure nonsense. This stuff is perpetuated by people who can't hear soft clipping. When a solid state amp reaches it limits, it immediately goes harsh in the worst kind of way. Tube amps tend to clip "softly", and when driven into clipping, the distortion isn't anywhere near as obnoxious. So, a tube amp can be driven past its limits, and do it in a much more forgiving way.

[burtlively]

my rotel rb930ax 30 wpc hooked up to some kg 5.2's will run you out of my basement bedroom (18x18).

[SILVERSPIKE]

Good Morning,

I'm pushing a pair of KG 5.5's with a restored and upgraded 1964 H/K A700 integrated tube amp rated at 40wpc...the speakers are 98 db and with the gain set at 11:00 the system rocks....smooth, detailed, tight bass and no harshness. Tubes love horns, and Klipsch, any Klipsch, sound great with tubes. SS needs some matching for good amp to speaker combo's, since not all SS amps match well to any particular set of Klipsch speakers.