[charles28722]

Hi all:

I am currently vetically bi-amping my system with two identical SS amps.  The results are excellent but I want to introduce tubes into my system.  I used a highly regarded tube pre-amp for a while but did not like the loss of low end control.  Because half of each of my amps is driving the mid/hi drivers and the other half the low-end, it's easy to tell where the power is going.  After a couple of hours of listening at fairly high volume, the side driving the low end is quite warm, while the other side is barely warm.  So I had a thought - keep the SS amp on the low-end and horizontally bi-amp with a tube amp on top.  I know many people do this with great results but how do I intregrate a SS and tube amp and avoid loss of coherence, gain conflict, etc?

My system:
Analogue Sourece:   Well Tempered Amadeus
Digital Source:         Ayre C5xe
Pre-amp:                Parasound JC-2
Amps (two):            Parasound A21 stereo
Speakers:               Gamut L7
Digital Source:         Ayre C5xe
   
I am looking to improve on my current level of sound reproduction, which is as good as it's ever been.  I think the added warmth and tonal qualites of tubes on the top end would be a step in the right direction, while maintaining the bass control with SS hi-current power.

Since horizontal bi-amping can get expensive with the long cables it's a good time to make this change because I am about to upgrade speaker cables.  I am looking for advice and even specific amp recommendations.  Assuming a used purchase of a good condition tube stereo amp, i would like to keep it around $2,000.  Thanks in advance for your commentts.

Charles

[charles28722]

As an added note, it does not have to be used.  If I add tubes, I want it to sound like tubes.  I know there are a number of great companies on AC that make products that might be a perfect fit - it will not need to be a high-power amp. 

[JoshK]

It can be done well, but it isn't a no-brainer.  It take some care to do it right since the voltage sensitivities of SS and tube amps tend to be quite different. 

Often the tube amp has to be attenuated to match levels.  This isn't ideal for S/N.  Its best if you can try to find a good tube amp that has similar voltage (input) sensitivity to the Ayre amps.  Do you know what that is btw? 

You might take a look at the "what's your favorite tube amp" thread for ideas on amps people love.

You probably only need ~30 watts of power, if that.   That opens up a lot of choices.  Tube amps in this range tend to be cheaper and ironically often better too as it isn't easy to build high power tube amps without making lots of compromises.

[BobM]

Josh is right. To do this correctly you should proabably use an active crossover, but you can do it by attenuating the amp with the most gain (probably the SS amp).

On another note, what is the crossover point on your speakers from woofers to mid & tweeter (these are 3 ways right)? How do the L7's assign the speaker terminals (3 terminals or just 2? is the bass just the bass or bass + mids?)?

If the crossover is high, say around the usual 2000-3000Hz then you will be making a switch  from one amp to the other right in the midrange, which is where it will be most noticeable. I would only recommend doing this if you can control the bass below say, 200Hz and let the tubes run everything above that. That way you get all of the texture and presence of the tubes where you want it most.

[doug s.]

i tried to find info on the x-over of these speakers; none awailable on line.  i'd query gamut, for sure.  per bob, i also feel that if the passive x-over between the two binding posts, (assuming this is a 3-way, and that one binding post is for woofers, the other is for mids/tweets), is over 300-500hz, i would not recommend using a tube amp on top, and s/s amp on the bottom.  better, imo, to get an outboard active x-over, a single stereo tube amp (or monoblocks) to drive the gamuts from <80hz, and a s/s amp and a pair of subwoofers for the low bass.

i'd also recommend rewisiting the tube preamp option - any tube preamp that loses low end control is severely lacking, imo...

doug s.