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tube fanatic

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Posts posted by tube fanatic

  1. A graphic equalizer will probably ruin the sound of your system. I'm not familiar with the x-over mods that you made, but your comment suggests that the high end frequencies were accentuated after making the change. It might make sense to do a switchable arrangement with some different capacitor values to create a high frequency shelving control. I don't believe that Wright uses any kind of negative feedback in their triode designs (not sure about this, however). If they do, however, it would be fairly easy to implement a variable feedback feature and use that to shape the high frequency response of the amp to suit the program material. I've done this with many of my pentode amp designs and it works quite effectively (I don't use any feedback in my triode designs as a general rule). Hope this helps you a bit.....

  2. Since you have the Fortes connected in series (16 ohm impedance), when placed in parallel with the 8 ohm La Scalas, you will have an impedance of about 5.3 ohms. As you know, this isn't cast in stone, as speaker impedance varies with frequency. There's no reason why you can't try using all of them with either the 4 or 8 ohm taps of the 299. The slight mismatch will cause some sonic differences- use the tap which gives you more of the sound that you enjoy. The 299 is a great amp, and I'm sure you will enjoy using it!

  3. only down side is the lack of bass extension, and I'm left wondering if placing it in a corner will actually be of any help...

    Speaker placement is always a critical factor in bass response, as is listening position. Sometimes moving the speakers, or changing the listening position, a few inches can often have a profound effect at the bottom end. So, I wouldn't be afraid of the La Scalas somewhat limited bass specs. Good luck with whichever you purchase, and please post your comments about how things work out!

  4. Speaker impedance will not be an issue if the 299 is used as a preamp since the speakers will not be connected to it. However, because of the design of the 299, you will need to take the signal for driving the M2 from the "recorder out" jacks, and then use the input level controls of the M2 to adjust volume. The volume control of the 299 will not be usable in this application, and must be kept all the way down to avoid potential damage to the output tubes from being driven without a load (you could, of course, put a 4, 8, or 16 ohm/25watt resistor across the appropriate speaker terminals of the 299 to eliminate any concerns there). It's probably not worth using the 299 in that fashion. I'd use it in place of your current equipment and enjoy the true benefits of using such a fine amp.

  5. 7 wpc should be more than enough with either of the speakers. Many folks who claim the need for much greater power like to listen at ear damaging (in my opinion) sound pressure levels. In reality, even 1 wpc is more than enough with the Chorus or La Scala in most applications. Do you have access to a sound pressure level meter? If so, take a reading at your listening position at the loudest level that you are likely to use when listening. That will quickly allow you to determine how much power you need. Many of the people for whom I've designed and built amplifiers are amazed to find that they only need a fraction of a watt for room filling levels.

  6. I'm a bit confused about the wiring of the Fortes (getting old!). Do you have them connected in parallel (i.e. plus to plus and minus to minus, then connected to the speaker A terminals of the M2), or in series (plus to minus with the plus lead of one and the minus lead of the other going to the speaker A terminals)? If the former, the impedance that the amp "sees" when used simultaneously with the La Scalas is quite low. The 299 would have problems using such an arrangement. The series connection of the Fortes would work out better- impedance would be a bit high for the 4 ohm tap, and a bit low for the 8 ohm tap. If the critical caps have been replaced in the 299, the price isn't bad. Will the seller allow you to take it home to try for a few days, just to be sure that it serves your need?

  7. Just wondering how you have the speakers connected; do you run all of them simultaneously, or just one pair at a time? Is the Scott restored or not? If not, you need to consider the cost of a full restoration by a competent technician. Personally, I prefer the sound of the 299 over any solid state amp/preamp. It has more than enough power, especially driving the La Scalas. Using the the front end (preamp section) of the 299 will certainly alter the sound of your system. Only your ears can judge if the combination sounds good.

  8. Regarding the power you need, even 1-3 watts/channel will be more than sufficient if you do not listen to loud music. As far as building your own amp, do you have experience working with voltages which are potentially lethal? Tube amps operate at much higher voltages than solid state amps. Depending on the type of circuit employed, tube amps can have a very different sound from each other. A triode with a single output tube will sound quite different from a single pentode. Push-pull amps, which use 2 tubes in the output stage, have their own sound characteristics. For warm sound nothing can match a triode amplifier, but you need to accept that the bass will be somewhat "softer" and less "tight" than amps using pentodes; also, the power output of many triode designs is lower than with pentodes. There are many sites online with design information for simple triode amplifiers.

  9. The Quad II amps require 1.4V rms input for full output. The Shanling CD player, in spite of having a tube output stage, will only provide around 2V output maximum, which is basically the standard from any CD player. Given the efficiency of the Forte IIs, you should not have a problem driving the amps with either of the CD players, assuming that you aren't playing them at potentially ear damaging levels. I presume that you are going to use the input level controls on the amps as your volume controls.

  10. The philosophy behind adding or replacing the "stuffing" inside a speaker is to reduce cabinet resonances which can cause frequency response irregularities, some of which may be audible. Personally, I'd leave things as they are. Since most speakers are computer designed, and then refined in an anechoic chamber, one must assume that the factory knows what it's doing........

  11. The amount of bass you get from a tube amp is more dependent on the output transformer and power supply characteristics than the tubes themselves. It might pay to call the companies whose products interest you and discuss that aspect with one of their tech people. As mentioned before, no one can tell you if you will be pleased with the amount and quality of the bass you get with any particular tube amp. You must connect it in your own system, listen to your favorite music through it, and formulate your own conclusion. But, in general, tube amps do not provide the same bass output, and tightness, of a quality solid state amplifier.

  12. In addition to Jolida, I'd also investigate Cayin and PrimaLuna. The latter two companies also offer very good value for the money. Modern tube amplifiers are designed to provide a very flat frequency response, hence the elimination of tone controls which, unless they are very carefully designed/implemented, can reduce the sound quality. If you are really determined to have that option you are forced into buying a vintage tube amp (keeping in mind that it would need to be very carefully restored to provide safe and long term usability), or "tuning" the room by using various sound absorbing materials, changing carpeting, etc. K-horns sound incredible with tube amplification (in most situations, even 5 watts/channel is more than sufficient). But, sound quality is very subjective; the only way you will be able to make a judgment is to hook one up in your installation and listen to it. Some dealers will allow you to bring an amp home for audition, and others offer a money back guarantee if you are not satisfied with the purchase. With many tube amps, bass is not quite as "tight" or deep as with solid state amps. At the same time, I find tube amps to be far more pleasing through the midrange and top end rendering vocals much more pleasing and natural to listen to. As far as modifications go, you will find as many opinions as there are users. Again, you will have to make your own judgments here. Good luck!

  13. Shielding is generally unnecessary unless your equipment has noise pickup problems. However, if you want the lowest inductance and lowest capacitance speaker cable, RG-8 or RG-11 coax can be used. This cable is good for about 2KW of RF power so should be able to handle any amp you are likely to use.

    I disagree about using coax for a run of that length. RG8 type coax has a capacitance of around 26pf/foot, and RG11 around 20pf/foot. The total capacitance of a 44 foot run could affect your frequency response. Assuming that your house is wired with Romex (which can radiate powerline grunge quite nicely), and not BX cable (which is self shielding), you would be better off using a good quality #12, or even #10, wire routed through grounded steel conduit. In fact, I've had good luck using steel jacketed BX cable for speaker runs like that. It's relatively cost effective, and provides a nice low resistance signal path to the speakers.

  14. 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.

  15. 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.

  16. 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.............

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