2. amps-preamps
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interstage transformers vs. coupling capacitors

Got a question for all you dht/set types. Looking to purchase a 300b kit from either sun audio or audio note. The fundamental difference between these amps is the sun uses an interstage xformer while the audio note uses a coupling capacitor. The sun is also 2000 bucks more expensive. Does anyone care to compare/contrast these amp designs. My speakers are living voice avatar obx @94db and 6 ohms. Both amps are parallel single ended as I'm afraid one 300b at 9 watts would not be enough. I listen to many double bass concertos (Edgar Meyer). Also, to any of you 2a3 users out there, do you get enough badwidth on the lowther and similar type drivers to be satisfied with my music tastes listed above? One other thing, anyone care to compare a DRD (direct reactance drive), with the above configurations?
Thanks,
Mark
mdoughty
audio999
178 posts
 
Mark,

What Audio Note amp are you talking about ?

I have the Audio Note Quest mono 9watts ($4000) with Silverline La Folia 92db 8 ohm for my second system. Believe me or not,they are perfect match and much better than my previous Cary CAD300 Sigature which cost $1000 more expensive than the Quest.

I'm using WE300B instead of the original tubes.

Price has nothing to do with MUSIC.

I'm sure you can use single 300B for your speaker.
twl
3,251 posts
 
If interstage transformers are done right, they can sound better than resistor/capacitor coupling. Sun Audio does it right. Harvey(Dr Gizmo) Rosenberg was orgasmic over the Sun Audio kits.

I agree that if your speakers can go as deep as you need, the single 300b can do it. The single will not be as tight in bass dynamics as a SS amp, but the tone quality will be very good, and will likely be better with a single 300B.

I believe that Direct Reactance Drive is another name for choke-loading, and is a very good way to provide better linearity in the circuit. My 45 SET amp is using choke loading and I like it real well.

Lowther type speakers generally will reach only as low as the lower 40's in bass response. The driver's resonant frequency is about 36Hz, and there is a large impedance spike at that point, that limits performance below that. However, everything else is quite nice for a SET amp. If you can live with 40Hz, fine,then Lowthers will do beautifully.
sean
6,231 posts
 
Sorry to sidetrack the thread here, but Twl inadvertantly brought up another point that i don't think that he was even aware that he was making !!! Since OTL designs would typically have a higher output impedance, wouldn't it be able to control / deliver more power to a woofer with a large impedance peak at resonance ? After all, we only run into problems in this area as SS designs put out less power at high impedances and transformer coupled tube designs are somewhat "hobbled" by the limited range of taps on the output. I wonder if Ralph at Atma or the folks at Tenor, etc... have ever played around with this theory and done testing ???

As to the original question, i would think that it would depend more on the design and the parts used than the actual method of coupling. I'm sure that either method can sound quite phenomenal with each having their own specific drawbacks. Sean
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