Do I need more power?

This brings up a question for more of a tech'ster like Sean. Tube amps are transformer coupled at the output and if I am not mistaken they will not put out more power into a lower impedence load like most solid state designs.Is this correct? I have never had trouble with reasonably low loads with smallish tube amps. Is my experience different from others? The other questions that remain are, is this a very large room, and how loud is "realy loud"? The speakers are as far as I can tell from the info I can find, about 89db in terms of sensitivity. for realy loud in a big room with a 60 watt tube amp, which is in reality quite a bit of real world juice, i would say you need to look into the Silverline speakers like the SonataII( Lots'O $$$!) which is rated at something like 95db(which would play quite loud with an 8 watt SET amp ) or go for the Bi-amp subwoofer sugestion mentioned by Elevick, which is what I have done. I like the sub set up with my 45 watt tube amp, 88db sensitivity speakers,300 watt sub, moderate room dimensions. It will play louder that you really should listed at times.

To address Maxgain's question about tube amp output at lower impedances: If, as Natalie and I have suggested, the tube amp's output transformer's output impedance is well-matched to the speaker load, a good tube amp should be able to output an equal, or somewhat greater, amount of power into a lower impedance speaker load, but will not be capable of "doubling down" as some SS amps can accomplish. HOWEVER, be they tube or SS, ALL amps are limited by their power supplies when it comes to their ultimate current output capabilities.

This is why 2001impala's explanation above is unfortunately a bit too simplistic. A better way to look at the situation is that a nomimal 4-ohm speaker DEMANDS more current (about twice as much) from an amplifier to reproduce the same signal as a nominal 8-ohm speaker would. Current output capability is not the strongest point of either smaller tube amps in general (tubes being better at voltage gain than current gain), or of small integrateds in general (which usually feature a shared power supply for the amp and preamp sections, and usually not a terribly large one at that). Hence, 8-ohm speakers are often recommended for moderately powered tube amplifiers, and this should help explain why the SS Yamaha could go louder in comparision (but did it sound as good?!).

Still, as long as you are using the correct output taps on the amp, I doubt you have created a serious mismatch with your amp and speakers here. Rather, I think Maxgain's points about room size, and what exactly constitutes "loud" to you, are very well-taken. You MAY have a slight mismatch on your hands between your system, your room, and your listening preferences. Despite Natalie's misgivings, Elevick and Maxgain are entirely correct when they state that adding a powered subwoofer (doesn't have to be a Velodyne) will extend system headroom, PROVIDED:

1) The sub must be run crossed-over to the speakers, rather than simply supplementing their full-range output.

2) For the amp as well as the speakers to be relieved of the power-sucking bass-reproduction duties, the crossover will have to be implemented at line-level (between the preamp and amp), rather than at the speaker level (between the amp and the speakers). This will require that your integrated feature preamp out/amp in jacks - something many integrateds lack - and for the subwoofer to be designed to operate in this manner, which most subs are not (they lack the external crossover). (For more info on this type of setup, you might want to visit the Vandersteen website and read the links pertaining to use of their 2Wq subwoofer.)

However, although such a set-up will accomplish the increased dynamic capability you desire, I am not necessarily recommending it, as the odds are actually rather iffy that the result will SOUND as good as running the system straight-up the way you presently are. Integrating a subwoofer successfully into your system in the manner I refer to above, especially when it will have to be run fairly high up in frequency to have a beneficial effect on your amp and speakers' dynamic capabilities, can be extremely difficult, and may not be worth the expense or trouble as opposed to just upgrading your speakers and amp eventually. It CAN be done in certain cases, but there are no guarantees - most audiophiles who use a sub prefer it to just supplement the extreme low-end of the spectrum while still employing true full-range speakers which are run that way (not crossed-over), a solution that can potentially benefit the sound quality, but not the system's dynamic capability.

Both your amp and your speakers are best suited for small to medium rooms, and neither qualifies as headbanger material. If you feel that you have achieved a step-up in sound quality with the Rogue amp, and are not a headbanger with a large listening room, then my first suggestion would be just enjoy it within its limits, and learn to listen at a slightly lower volume if need be. One possibly helpful approach, though, is contained on the Audio Physic website. If you don't already have your speakers set up to listen in the nearfield, this is what AP happens to recommend. The farther away you sit, the more power is needed to achieve the same apparent volume. AP speakers, unlike many others, are actually designed to be listened to close up. Their website details the particulars, and if you haven't tried this already, doing so should result in an increase in perceived volume capability. Best of luck, and happy listening!

Ok, thanks to all for the advice. I guess I have one last thing I dont understand: The old amp was 120 watts and I was able to play things at higher maximum volume than the rogue without breaking up. But the rogue clearly has a better sound. Is there some comparable integrated tube amp to the rogue that simply has more power? Maybe not 120, but more than 60? (Or cld go separates route if it doesnt become too outrageously expensive.)

Mr. Harris - Glancing at the Rogue Audio website, it says that your Tempest is equipped with preamp outputs that will allow it to function as a preamplifier when used with a separate power amplifier. It also says that an optional feature (which I don't know if you got) is an amplifier input that allows a separate preamplifier to be used with the Tempest's power amplifier. (If you have both sets of jacks on yours, then it meets the criteria I discussed above for being able to accept a line-level crossed-over subwoofer.)

But another option appears like it may be acquiring one of Rogue's Model 88 power amps, which seems from the info available on the website to be a match for the Tempest's power amp section. If this is so, then there may be a way you could add an 88 to your Tempest using the preamp outputs, and go to a bi-amped setup, IF your speakers have dual sets of separate (presently jumpered) input jacks for the woofer and the tweeter (also known as biwire-able inputs). This would effectively double your available power, but would also require the use of another set of speaker cables along with the 88 ("shotgun" configured speaker cables, as internally biwired single runs are known, will not work for bi-amping), as well as another two pairs of interconnects to go from the preamp outs to the amp inputs, and a way splitting the pre-outs to get two line-level outputs per channel, one set for each amp (unless the Tempest can feed its pre-out and still simultaneously feed its power amp section internally, in which case only one interconnect set and no splitter will be needed).

If you really like the Rogue sound, and your speakers are biwire-able (or you will get speakers that are), then you should call Rogue to see if this upgrade route is feasible, since it will allow you to keep your Tempest without having to start over again with all separates, or another manufacturer's more powerful integrated. There are also two kinds of bi-amping possible, vertical (where one stereo amp has one of its channels powering one speaker's woofer, and the other channel powering the same speaker's tweeter, with the other amp hooked up to the other speaker in the same manner) and horizontal (where one stereo amp has one of its channels powering one speaker's woofer, and the other channel powering the other speaker's woofer, while the other amp has one of its channels powering one of the speaker's tweeters, with the other channel powering the other speaker's tweeter). When using two functionally identical stereo amplifiers, either method may be employed, but the vertical method should yield the greatest increase in dynamic headroom, since each amp's power supply will only be called upon to deal with one woofer apiece (BTW, the speaker input jumpers will be removed when bi-amping).

If you were to try this, my bet would be that the bi-amped Rogue set-up would then blow away your old 120w SS amp in terms of total volume capability, as well as sound quality. But as you can see, such a rig is not the exactly the height of simplicity, so you should really contact Rogue or your dealer in any case for their advice if you are considering ways to expand your system's power while holding on to your Tempest. (And besides, though I can tell you about this stuff, I've never run this kind of set-up myself, so please don't take my word as the last!) Best of luck to you, Z.