Balanced Low Power Tube Monoblocks?
TVAD -- I don't know much about them, but the Einstein MK60 and MK23 appear to fit your requirements, other than price. There is an MK60 listed here now for $13.5K (the listing shows msrp of $32K). I'd assume that the MK23 is considerably less expensive. Here is the sales brochure on them: http://www.sensusaudio.com/images/einstein/Einstein_ProdK_engl.pdf Best, -- Al |
Ralph -- Thanks very much for your good response, with which I am in complete agreement. But please note that my post (the one dated Sept. 8) was not dealing with tube amplifiers, or with amplifiers or speakers designed based on the power paradigm. It was addressing the narrow situation in which a speaker having a low impedance in the bass (e.g., 4 ohms), and a higher impedance in the mids and treble (e.g. 8 ohms), is being driven by an amplifier (typically a solid state amplifier) having an output impedance which is negligibly small in relation to the speaker impedance at any frequency. And the question was whether or not such an amplifier driving such a speaker would produce an excessively bright response as a consequence of the amplifier not being able to double power into 4 ohms (relative to 8 ohms). And my contention is that it will not, as long as the volume levels are such that the amplifier is not called upon to deliver more current than it is capable of (and as long as the amp does not produce an excessively bright sound for other reasons). Best, -- Al |
Excellent points, Ralph, and I think we are now fully converged on this. Thanks! I would add, though, in relation to the particular issue I raised initially, that a "voltage paradigm" amplifier with very low output impedance that is capable of doubling power into 4 ohms (relative to the power it can deliver into 8 ohms) would not NECESSARILY be either better or worse with respect to odd-order harmonic generation than another voltage paradigm amplifier with similarly low output impedance that is not capable of doubling power into 4 ohms. Best regards, -- Al |
When you see speakers that are 4 ohms in the bass and 8 ohms in the mids and highs, quite often the speaker designer is using woofers that are 3 db less efficient, and expecting that the amplifier will double power with the 4 ohm load. This brings the woofer output up to the level that the mids and highs operate at, but you need transistors to do that properly. Ralph, This may seem like a matter of semantics, but I want to raise an issue in connection with this statement because I think it has been a point of confusion in some other recent threads. A speaker that has say a 4 ohm impedance in the lows, and an 8 ohm impedance in the mids and highs, and that may have woofers that are 3db less efficient than the other elements, will, as you say, generally be best suited for a solid state amplifier that can double power into 4 ohms. BUT, as long as the amplifier has an output impedance which is negligibly small in relation to 4 ohms, and as long as the volume levels it is called upon to deliver are within the limitations of both its voltage swing capability and its ability to deliver current, then a flat frequency response will result. It is not the ability to double power into 4 ohms per se which results in flat frequency response into such a speaker, but rather it is the ability of the amp to act essentially as a voltage source, up to some maximum volume level. In other words, to cite an example, a solid state amp having low output impedance, which is capable of 200W into 8 ohms but only 300W into 4 ohms, will deliver just as flat a frequency response into such a speaker as an amp which is capable of 200W into 8 ohms and 400W into 4 ohms, IF it is not called upon to generate more volume than its relatively limited current capability can support. Do you agree? Regards, -- Al |
TVAD -- What is most commonly specified is damping factor, which is almost always defined as output impedance divided into 8 ohms. So assuming that the specifications do not indicate that damping factor is defined relative to an impedance other than 8 ohms, just divide the specified damping factor into 8 ohms and that is the output impedance. Example: Damping factor = 40; output impedance = 8/40 = 0.2 ohms. Regards, -- Al |
Grant -- Best of luck with the new amps. Some approaches to consider if you want to try to find VINTAGE 2A3's, aside from the usual dealers who will of course charge very high prices when and if they have any for sale: 1)Take out a subscription to Antique Radio Classified, and run a free want ad there each month. 2)They were used in the power amplifier/power supply chassis of several very high end multi-chassis "radios" ca. 1935. Most notably, those made by E. H. Scott (no relation to H. H. Scott, the hifi manufacturer who came later). During the intervening 75 years, the power amp/power supply chassis have often become separated from the rest of the set, and sometimes appear for sale in ARC or on-line auctions. I found one via a local classified ad for $35 some years ago, complete with 4 good 2A3's. There were undoubtedly a lot of people in your particular neck of the woods who owned these sets, and some may still be sitting in basements, or become available through local auctions, tag sales, classifieds, etc. The particular Scott sets which used 2A3's were the Allwave 15 and the Allwave 23, also known as the Allwave Imperial or Allwave High Fidelity. 3)The Brook amplifiers of the early 1950's (designed by Lincoln Walsh) commonly used 2A3's (sometimes 300B's), although they appear infrequently and usually command high prices. Regards, -- Al |
