tube fanatic

It's possible that the amp was subjected to a powerline surge when electrical service was restored. The best thing would be to have it checked by a qualified service technician who can determine the exact problem.

Tubes which sound incredible in one amp may sound very different in another. So many design parameters affect the ultimate sound that the only way to make a judgment is to try different ones in your particular amp. The best thing to do, if you don't want to buy a bunch of different tubes and try it yourself, is to find others who are using your particular amp and solicit their comments about what sounds best. That will at least narrow down your efforts somewhat. It isn't only midrange which can be affected. You may find a particular tube which gives you a wonderful midrange, but at the expense of the bottom or top end. As I've stated before in these forums, try to find a tube which gives you a pleasing overall result and stop your search there. Otherwise, you're going to drive yourself nuts chasing the elusive "sonic nirvana" which doesn't actually exist! And keep in mind that once you think you have found it on Monday, you may have a very different opinion when you listen again on Tuesday.

K-horns will give you a 100db sound pressure level (3000 cu. ft. room) with only 1 watt/channel. So, unless you want to rattle your foundation and put cracks in the sheetrock, you certainly don't need astronomical power! I have rarely been asked to design and build an amp of greater than 5 watts/channel for users of K-horns/LaScalas/Belle Klipsch/Cornwalls, and most of the folks I've done this for only wanted/needed 2-3 watts/channel. I would judge a replacement amp or receiver strictly by its sound quality with the horns, and don't even ask for or look at the power output.

I remember these from back in the '70s. If memory serves me correctly, the woofers have foam surrounds which may need replacement if they have rotted (a common occurrence). Bass output was very substantial, kind of reminding me of Cerwin Vega's design philosophy. The song used to demo them was Stevie Wonder's Living For the City; but the speakers are not overly efficient, so you my need some good "muscle" to get them to open up. Hope this helps somewhat.............

Shielded cable is shielded cable......................

It's easy to fall into the trap of remembering what another system sounds like. Auditory memory is extremely short. There's also the issue of psychoacoustics- I'm sure that you experienced days with your previous reference where it just didn't sound quite as incredible as it may have the day before. Moods and emotions play a role here. Have you ever tried nearfield listening? Doing that allows you to be encompassed by the soundstage- basically, you become part of it. I've listened that way for years and can no longer listen any other way.

The need to be fully immersed in the music to obtain full enjoyment is common. Why else do people spend countless hours and dollars tweaking their systems, or switch to headphones (which, of course, allow total immersion)?

The Mac 6200, as you are probably aware, has a built in equalizer which is quite useful for smoothing out frequency response irregularities. You will enjoy it!

About the cheapest stands you can get, which are amazingly effective, is to use cinderblocks. A plywood top can be easily attached for increased speaker stability, and the entire unit can be draped with your favorite cloth to make a very decorative, room coordinated, unit. The weight and concrete offer terrific acoustic isolation from the floor as well.

I'm thrilled that your experience is so positive! Given the terrific sound with mp3s, you will be even more amazed when you go to the cd player. Glad to be of help to you; if any other questions arise don't hesitate to post them. Enjoy!!!

I'm sure that this amp will work well. 40 watts/channel is plenty of power unless you plan to listen at ear damaging volume levels. You will also have fun trying it in triode mode. The sound, when used that way, is very different from ultralinear- much smoother through the midrange and high frequency range, but with somewhat softer bass (as you will find out when you listen to it at the dealer). Please post your impressions after getting the amp!

Cayin is another company whose amps have received very favorable reviews. They also provide great value for the cost. Are there any dealers/distributors near you who would allow you to take home an amplifier to audition in your system? I presume that you are not in the US based on the metric room measurement that you provided. Here, some distributors offer a 30 day money back guarantee on equipment purchased. It's a wonderful way to be absolutely sure that what you buy will satisfy your needs.

Modern tube amplifiers are designed to provide a very flat frequency response across the audio band, or even beyond. So, the thinking is that any kind of tone control will detract from the quality of the sound. I'm sure that there is also a cost consideration- implementing sophisticated tone control circuitry definitely adds to the cost of the amplifier. But, with the RF82s, I can't imagine that you should run into any problems which can't be fixed by varying the speaker position slightly, or playing around with various types of sound absorbent materials (like books, carpets, etc.). Best of luck, and please post after you make the changes!

Perhaps you may want to consider looking into amps made by Primaluna. They are very well regarded, reasonably priced, and should provide enough power for loud listening in a room of that size. http://www.primaluna.nl/indexN.htm

A nice tube amp should make a huge difference. How loudly do you listen, and how big is your listening room?

Well, regarding the rectifier tubes, you need to be careful. If the amp uses a standard CRC or CLC filter, switching to the 5R4 could subject the electrolytic caps to a much higher voltage than was intended. The 5AR4 is a cathode type rectifier which tends to warm up somewhat slowly thereby limiting the voltage to the electrolytics. The 5R4, however, being a filament type rectifier, warms up almost instantaneously; this will allow the electrolytics to "see" a much higher voltage until the remaining tubes in the amp warm up and start drawing current. The 5751 can be swapped for the 12AX7; as to which arrangement will sound better, why not just swap them around and draw your own conclusion? Hope this helps you a bit......

The pix you posted are of a radio chassis which, of course, includes an amplifier section. In some cases, the amplifier can be utilized separately from the tuner section. Is there any other information that you can provide, such as a number on the chassis, or perhaps a sticker on the side wall of the cabinet?

Capacitors can affect almost anything in an amplifier depending on where in the circuit they are located- frequency response, hum, noise, voltage, etc. How old an amplifier are you talking about? Assuming you are speaking about a vintage amp, say 30+ years old, the electrolytic caps should be replaced at the very least (keeping in mind that amount of use and operating temperatures may necessitate replacement in much newer amps too). Please be more specific about the amp in question.

If you reverse the channel connections from the TT, does the imbalance switch to the other side?

Another solution is to go with a passive line stage (basically, a single resistor and a potentiometer) between your source component and the power amplifier. With extremely efficient speakers, like K-horns, it allows them to be driven to ear shattering levels; and many consider the sound quality to surpass that of any preamp since you are eliminating all of the noise generated by another power supply and numerous resistors, capacitors, switches, etc. If you are handy, one can be made for around 20 bucks!

Are you looking to do a multi-channel tube setup, or just stereo?

For forty dollars buy it and find a place for it!!! More than likely, someone will buy it, throw away the amp/speakers, and use it for something ridiculous...............

It depends on how nostalgic you are! As a restorer of antique radios, vintage audio equipment, etc, I'd certainly leave it intact to preserve the history. However, it may be possible to arrange switching which will allow you to play the amp either through the existing speakers, or through the Cornwalls. I don't remember what kind of inputs the amp has, but it may also be possible to connect your CD player to an auxiliary high level input so you can use it for that as well. How much is the asking price, and are there any knowledgeable audio folks in your area who can assist you?

If the price is right, I'd grab it, particularly if it is playing. With Cornwalls, you can't go wrong with almost any decent tube amplifier. If memory serves, the RP91 is the same as the RP90 which used a nice push-pull output stage with 6CM6 tubes (electrically the same as 6V6s). Power output is probably in the range of 10wpc which is plenty.

Well, looking at the pix, it is a very basic emissions type tester which is of limited value. Yes, it will tell you if the tube is working, and will let you compare tubes of the same type to see which has more "output." You would probably get more information by just putting the tube into a working amplifier and using your ears to judge whether it is good. The other question is whether this tester is operating or not, and whether it is properly calibrated. Buying a tester without having its calibration instructions is chancy. If not properly set, a tube with poor emission may show as "good" on the meter, or vice versa. $75 seems a bit high for a unit of this type.