@o_holter , Thanx! My understanding is that MA 1'a and MA 2's sound very much the same just more power in the MA 2's but in reality that only amounts to another 3 dB. This is a great example of matching the amp to the loudspeaker. With ESLs as the frequency drops the speaker's impedance rises and at 20 Hz can be as high as 30 ohms. Atma-Sphere amps do not lose power into high impedances like SS amps do. They maintain the same power regardless of load and are the only amps I know of that do this. This makes them ideal for driving ESLs.
WallySkater and Reference.
I finally spilled the cash and bought a WallySkater and WallyReference. Many will remember in the not to distant past I thought that the WallySkater was an overpriced Rube Goldberg device. I'd like to amend that opinion and add a new one on the reference.
I am one of the first to get the new updated Wallyskater. The old unit required adjusting thread lengths is a difficult fashion and endangered cartridges. So, Wallytools came up with a dual mini crane mechanism which works great and is way easier to use than the old method. Adjusting either thread length requires only a twist of a little knob, one knob for each thread.
The WallySkater is very nicely made. All the parts fit together perfectly. Most people are going to take it apart when they are done as it is easier to store broken down and I wonder if any play will develop over time but there could be considerable play and it would still be accurate, just a bit sloppy.
It works as advertised giving you repeatable readings responding immediately to a slight twist of the Schroder's magnetic anti skate control. Set to 10% of the VTF the cantilever does not deviate at all when gently let down on the record. The tonearm drifts slowly to the inside on a blank record. For anal retentives it is very reassuring. Is it worth the money? It is the only device I know of that is accurate. The one I made turned out not to be. If you are the only game in town then why not charge for it? The WallySkater will also give you an idea of the state of your horizontal bearing. A little tap on the side will get the tonearm doing a pendulum act and a health arm will slowly decrease the amplitude of the swings until it comes to rest. A bad arm will take a few swings then stick.
The WallyReference is a group of jigs to adjust your tonearm's azimuth and VTA. This assume that the cartridge is accurately made and in my experience the more expensive ones are. Along with the jigs you get a little rule to measure cartridge height and a set of shims so that the jigs match that height perfectly. You put the stylus down on a record and place the rule right up next to the cartridge and measure to the top of the cartridge. Then you screw the jig to the head shell with the right shims and adjust the arm so that the jig sits flat on the surface of the record. I used a 150 Gram record. My arm is designed so that azimuth does not change with altitude. After adjustment your head shell is perfectly parallel to the plane of the record in all directions. Again, the jigs are very nicely made and there are no wear points. The should last forever.
I think that for people who run around setting up other peoples arms these tools are a must along with a good protractor like the WallyTractor or the SmarTractor. A usb microscope would be nice in addition to evaluate the condition of the stylus and to make sure the cartridge was constructed accurately. As for the rest of us, they are very nice tools to have in your box. They are very reassuring for us anal retentives and in the context of other HiFi items not all that expensive.
I finally got the nuts to ask my wife for the down payment on a pair of Atma-Sphere MA-2's. I have a few bruises but I'm still alive:-)
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Dear Mijostyn, while I am a 25-year devotee of Atma amplifiers and OTL amplifiers in general to drive ESLs, I am afraid I must differ; Atma amps, like any other amplifier especially tube types are definitely sensitive to the load impedance, since all the named amplifiers have an output impedance significantly greater than zero. The point is that at very high frequencies where ESL impedance goes very low, the energy demand also goes very low. So the loss of power is not very noticeable or important. |
@lewm , now you have me very confused Lew. As the impedance of the load drops current demands increase and solid state amps will increase current to the point that their power supplies give up or something blows. Need I remind you of the high frequency balance control I burned out. I am no electronics engineer but I have heard Ralph say on several occasions that his amps maintain the same power output regardless of load. Perhaps I misunderstood him. More important to me is that the MA 2s do not loose power at the lower frequencies. What all this does to the frequency response of the system is an unknown to me, but I will know for sure once I get the amps as I have frequency response curves of the system with the JC 1s and will compare them to curves generated with the MA 2s. |
All amplifiers driving all speakers have to obey the same physical laws. Yes, SS amplifiers tend to have a vanishingly low output impedance (<<1 ohm) and can therefore drive very low Z speakers with aplomb. For tube amps, output impedance is determined by the output transformer and the amount of NFB used at the output. (SS amps also often use NFB to reduce both distortion and Z.) For an OTL, output Z is determined by the parallel electrical sum of the plate resistances of the output tubes. Plus also the effect of NFB if the user adds NFB. Modern consensus is to avoid global NFB so in most cases that’s a nonfactor. So one major advantage of the MA2 vs the MA1 is lower output Z because more output tubes. For driving our SL speakers, that’s more important than the added power, in my opinion, because the stock crossover causes an impedance dip at mid frequencies where there IS some need for power delivery. As I told you, I’ve ameliorated that issue in my speakers by essentially ditching the crossover. |
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