Yes, Roger does mention: "It also reduces noise, raises damping factor, reduces distortion by 78% and allows for 80% more peak current when needed. The only loss is about 20% of the power rating or 1dB."
In my case my speakers Are nomnal 8 ohms and never below 6.5 ohms.
I'm interested in the variance in views between Roger and Ralph on the issue. It might be that Roger's recommendation only applies to his amps because of the way he designs the RM10s, and Ralph's take is true for most other amps. |
I suspect you are right, because I have to believe Ralph very well knows what his talking about. It was interesting to read years back on Audio Asylum how many folks simply did not believe Roger's specs for the amp - of course he did do what others thought impossible. |
Just to add to the conversation, Ralph added this comment in the Vandersteen thread I alluded to:
03-03-11: Atmasphere
Pubul57, the act of increasing the bias on the tubes has the effect of reducing their output impedance. This will change the relationship they have to the output transformer.
In addition, you have to also consider how the amplifier was designed. For example, many power tubes want to see about 3000 ohms plate to plate. But what if you had the transformer designed to be 3500 ohms plate to plate? You might loose a little power, but now you can experiment with different taps to affect the sound in different ways. This is because the transformer really does what it is called- it transforms impedance. The load that is on the output taps will affect the load that is on the tubes. Especially in the last 30 years, its been a good idea to build in a little reserve to deal with the many 4 ohm speakers out there.
So if in the above case you are loading the 4 ohm tap with an 8 ohm speaker, the result is that the tubes might see a load impedance that is much higher, perhaps 6000 ohms. Now in some cases the amplifier will not be able to make as much power, as the voltage that needs to be made across such a load to get the power is no longer available. But it may not matter if the power thus obtained is sufficient. |
Hi Al. To tell you the truth, I find they sound very, very similar both ways, but was predisposed to prefer the "light load" for the "benefits" in measured performance(but for power)and longer tube life that Roger mentions in his comments. I had no doubt Ralph was right as a general principal, and I do wonder if Roger just took an "roger" approach, as is his way, that made his recommendation valid - for his amp. |
There seem to be an awful lot of folks running RM9s for many years for them to be too unreliable. Now Roger did come to think of tubes on boards as being problematic over time so he went to point-to-point wiring on his RM9SE and the RM10s and 200s. Another thread questioned the reliability of Quicksilver amps to which I could only say that all manufactured goods can have a problem form time to time, but I certainly think that at least in my experience, Music Reference, Quicksilver, and Atma-sphere all are very reliable in the aggregate experience of owners.
I never heard the RM9, I owned an RM9 Special Edition and now the RM10 MKII - they are certainly quiet, but I have 89db speakers not 104db, which would proabably be the ultimate test. |
Eccletique, have you tried light loading? I assume, don't ask why, the Tannoys are nominal 8ohms? |
Pehare, is the 40h tao indeed light loading for your speakers? |
The Merlins VSMs are similar - 8ohm, 6.5 ohm minimum:) I
agree with you abut the RM10, it is one hell of good amp,
good enough that I sold the RM9 Special Edition ($10,000 -
162 watts!) While the RM 9 SE can drive many (any?)
speakers the RM10 might not be up to, but with the Merlins,
the little amp does the job without apologies. Combined with
an Lightspeed Attenuator, RM10 MKII, and 89db speakers with
smooth benign impedance curves, you have one heck of great
pre/amp combo capable of SOTA sound for $2,500 MSRP. |
It seems as if most owners have found light loading this particular amp works as Roger suggests it should - better. My take away is also that light loading is unlikely to be the right approach with other amps, for the reasons given by Viridian, Albert, and Ralph. Thank you for your thoughts. |
Not only 35 watts, but Roger claims 10,000 tube life on the EL84s. He also claims light loading will extend tube life. |
