BI-AMPING


I HAVE LEGACY FOCUS SPEAKERS AND WANT TO BI AMP WITH A BAT VK-75SE TUBE AMP ON THE MIDS AND HIGHS AND SIM AUDIO ON THE BASS.MY PROBLEM IS THE GAIN ON THE BAT IS 25DB AND THE SIM IS 37 DB.ANY SOLUTION?
sound_lover
Look for some inline gain attenuators, like the Rothwell or Harrison Labs for instance. Place them at the input of your Sim amp, which should cut the gain by 12 dB and even things out.
even if you will use the gain control, you will sacrifice the dynamic performance of your system.
there are only 2 right ways:
1 is to remove built-in crossover and replace it by active between your amps. in this case you will sacrifice one of the main signatures of your speaker tha had been design to have a certain crossover at certain cut-off frequencies.
2nd is to use an identical amp for top and bottom(no crossover is necessary)
other ways are just for another toy purpose seriously.

The best result of achieving mix of tube and solid state is to have a tube preamp to your SIM.

the only good way i see your objective is to have another type of toy.
Why are you yelling?
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1361022973&openfrom&1&4#1
I don't have Legacy Focus loudspeakers but I have a pair of custom built loudspeakers that are of a similar design having a pair of 12" Peerless 1259 woofers per side as well as dual 6" Eton midbass drivers, and Eton metal dome mids and tweeters. I've been biamping them with different amps for several years now. I too prefer tubes on top but these speakers demand a good solid state to drivers the woofers.

Originally, I had a Consonance Droplet 5.0 CDP with remote volume control. This player has both XLR and RCA outputs which are active simultaneously. I ran the RCA outputs into a JAS Array 2.1 integrated amplifer and the XLR inputs into a Consonance Calaf integrated amplifier. Since the Droplet has variable outputs, I bypassed the JAS's preamp section and ran directly from the source. I used the Droplet to control the loudspeaker volume. I then used the volume control on the Calaf to adjust the woofer's output to suit the music or my mood.

I've since moved on to an Upgrade Co modded universal player and sold the Calaf. With the universal player, I run the mixed outputs to the JAS amp and use the volume control on that amp. I then use the full range Front L and Front R outputs to drive the woofers with a Face Audio F500TS pro amp which has volume pots on the face plate. I don't experience a compromise in dynamics or bass output by not having an active preamp. The sound is very clear and transparent with exceptional resolution above. Bass is also highly resolved and dynamic.

I suppose you could do the same if you had a preamp with 2 outputs or you could run 2 preamps if your source has 2 outputs. Either way would work and you wouldn't have to do anything with outboard attenuators nor mess with the internal crossovers nor get an external crossover. Hope this is of use to you.
Snofun,
FYI: sometimes it's hard to see lowercases especially for vision impaired.
Could be... but it's almost just hard for us that are not read all those caps...

Either way, bi-amping when done right can be quite successful, but done wrong, and it can be disastrous... you need to use two identical amps, or an active cross over
I use a Sim amp for highs and lows and SET amp for mids with my Emerald Physics 2.3. I connect all speaker cables directly to drivers. The DCX can be used as room correction as well as gain adjustment for using multiple different amps. I would also recommend downloading Room EQ Wizard,which will give filters to input to DCX for room correction.
In-line attenuators, as JMCGrogan suggests, will probably work fine. I happen to have volume pots on my ss amp that peform the same function, and that allows me to bi-amp a 170wpc ss amp with 60w tube monoblocks. Lovely sound, with the added benefit of being able to adjust the bass to taste. The result is smooth across the dynamic range.
You can build a custom resistor network to eq both. Use Metal Film 0.1% tolerance voltage dividers. Put the divider on the bass only which is where you need it anyway.

Other option is to use a passive Pre such as Axiom. This is a cheap easy way out.

The side effect of both of them is the impedance matching and change. It won't be an issue on your bass however when calculating the voltage divider, you will have to consider the source and destination impedance. That is why the passive pre is easier/better. Insert this between the Amp and pre for your sim.