2. amps-preamps
  3. 181844-134895

To Tube or not to Tube, that is the question

I've been building a collection of hifi equipment with an ear to sampling the major families of tech and their characteristic sounds. One thing I don't have is a tube amp, unless you count my Rogue Sphinx. I like DIY if the final product is of good quality and design. I'm not averse to used either. Budget range is $1000-2000.

Can anyone suggest a tube amp, either power or integrated that would bring a nice sound flavor to my sandbox and not break the bank. OR do you think the Sphinx and the Pass amps pretty well serve up most of what is to be had in terms of tubey goodness and maybe this is not a worthwhile venture?

Here is what I have got in the way of speakers to play with:

KEF LS50

Tangent RS4

Klipsch RP-160

DIY Lii F6/Caintuck

DIY Lii F15 (under construction)

AR 2ax

 

And here is the current line up of amps:
Rogue Sphinx     
ClassD Audio Mini Gan 5    
DIY Firstwatt F6    
DIY Pass ACA (2)    
Onkyo TX-6000 Receiver    

Thanks in advance for your opinion.

 

 
 
 
 
 
 
Ag insider logo xs@2xbruce19

Showing 2 responses by atmasphere

atmasphere's avatar
atmasphere
11,594 posts
 

This seems to be a typo, did you mean theST35 is a linear triode?

@bruce19 No.

The feedback is taken from the speaker terminals and then applied to an early point in the amplifier circuit; in this case the cathode of the input tube. In the original ST35 circuit, the input tube was a 7247, which is a dual triode 9-pin signal tube with one section being that of a 12AX7 (the input voltage amplifier) and the other being that of a 12AU7 (for driving the power tubes).

By contrast the ST70 uses a tube that has a pentode input section, which isn't as linear. They were able to get away with using the 7247 in the ST35 since the EL84 power tubes are so much easier to drive than the larger EL34s of the ST70, so less gain was needed.

Clear as mud??

 

atmasphere's avatar
atmasphere
11,594 posts
 

@bruce19 The advantage this amp has over the ST70 is twofold. First, the output transformers (if they are the same design as the original) have better performance. The second advantage is a bit harder to explain but I'll try:

Like the ST70 this amp uses feedback. A common problem which this amp also has is that the point where the feedback is applied isn't linear, which means that the feedback signal gets distorted before it can do its job of correction. So it adds distortion of its own.

However, the ST70 uses a pentode for this task, where the ST70 uses a much more linear triode. This means the feedback signal is less distorted and so more able to do its job. So overall its a more musical amplifier design since there is less higher ordered harmonic distortion.

 

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