[Glady86]

Anyone try bi-amp configuration? Thinking of trying 300B tube amp for the upper range and Solid state for the woofers. Wouldn’t be hard to change the crossover input to accept bi-amp connections. What issues could I run into, besides gain matching?

[Early B.]

Bi-amping with completely different amps creates two distinct sonic signatures between the highs and mids. It would be cheaper to smear some mud directly onto your drivers.   

[Glady86]

Bi-amping with completely different amps creates two distinct sonic signatures between the highs and mids. It would be cheaper to smear some mud directly onto your drivers.   

The tube amp would run the midrange and tweeter. The bass is already running with two amps, if you consider the sub amps. So solid state to run the bottom 4 drivers of the NX Otica. I’m not sure I’ll try it, firs I need to see if I like the sound of the Elekit 8900 I bought. So far I preferred my Odyssey amps over tubes, but thought I’d give it another try. My system is sounding excellent as is, not sure why I want to mess with it, I guess out of curiosity.

[Early B.]

The tube amp would run the midrange and tweeter. The bass is already running with two amps, if you consider the sub amps. So solid state to run the bottom 4 drivers of the NX Otica.

Still the same issue -- two different sonic signatures powering the same speaker. Those awesome NX-Oticas deserve the best amp you can feed them.

[mkrawcz]

I need to see if I like the sound of the Elekit 8900 I bought. So far I preferred my Odyssey amps over tubes, but thought I’d give it another try. My system is sounding excellent as is, not sure why I want to mess with it, I guess out of curiosity.

The TU-8900 is really good, especially with Lundahl transformers and copper coupling caps.

[Jaytor]

Still the same issue -- two different sonic signatures powering the same speaker. Those awesome NX-Oticas deserve the best amp you can feed them.

In my opinion, it's not this black and white. The drivers used for the woofers are not identical to the midrange drivers, and certainly not the tweeters. The fact that the NEO3 uses a completely different design approach to the other drivers and does not seem to detract from the overall top-to-bottom coherence of the NX-Otica is evidence that using the same amplifier design is probably not that critical.

Biamping into the crossover also has the advantage that the high-order harmonics generated by the woofer amp are filtered out by the crossover. It would probably be good to use at least a first order filter (i.e. inline cap) on the amp used with the upper frequency drivers to reduce the harmonics generated at lower frequencies.

I'd also consider using the tube amp on just the tweeters and the Odyssey amp for the woofers and mids.

[Glady86]

The TU-8900 is really good, especially with Lundahl transformers and copper coupling caps.

I bought the cheapest version directly from Japan. That 10% distortion has me second guessing my purchase, I hope the distortion levels at normal listening levels are acceptable.

[mkrawcz]

I bought the cheapest version directly from Japan. That 10% distortion has me second guessing my purchase, I hope the distortion levels at normal listening levels are acceptable.

I sit about 10 feet from my NX-Oticas and listen in the low 70s db and the 8900 has no problem. Those distortion numbers fade away once you hear the vocals and soundstage that come out of that amp.

[Glady86]

I sit about 10 feet from my NX-Oticas and listen in the low 70s db and the 8900 has no problem. Those distortion numbers fade away once you hear the vocals and soundstage that come out of that amp.

I noticed with the NX Oticas, they sound satisfying at lower volumes. I’d like that last bit of extra “emotion” from the vocals, that’s why I’m trying the 300b amps. Also, I might try to high pass the tube amps to allow the subs to handle more of the bass.

[mlundy57]

I basically do this with my MTM/sub combo. I use one type of amp for the MTM section and the A370 amps for the subs which play up to the mids. For the MTM section I have used used tube amps, SS amps and am currently using hybrid amps (tube input / SS output).

There have not been any mismatch sound issues. I expect bi-amping between the MTM and M165s would work just as well. I've heard this arrangement done many times with box speakers.

Taken to an extreme, I've heard large multi-driver horn speakers with each driver having it's own amp designed for that particular driver.

I'd say give it a try. If you don't like it, you can always bridge the tube connectors.

[Early B.]

I basically do this with my MTM/sub combo. I use one type of amp for the MTM section and the A370 amps for the subs which play up to the mids. For the MTM section I have used used tube amps, SS amps and am currently using hybrid amps (tube input / SS output).

I have powered subs, too, but never considered it as bi-amping. I believe the OP also has powered subs, so bi-amping for him is powering the highs and mids of his NX-Oticas with a tube amp and the low-range drivers ("woofers") with a solid-state amp.
   

[SoCalWJS]

What frequency are you looking at for the crossover?

If it’s low enough, the difference in sound signature in the amps isn’t as critical IMO. If it starts creeping up into the lowest male vocal range, it can be an issue.

I had stacked, bi-amped Advents for quite awhile and thoroughly enjoyed tubes from about 100hz on up and SS down low. Dynaco Mk IV’s on top and bridged ST120’s for the bottom. External adjustable volume crossover. Never seemed to be an issue for me.

[Glady86]

I’m not sure, but I think the 4 woofers play higher than 100hz. It’s only one inductor in the woofer crossover.

[mkrawcz]

I noticed with the NX Oticas, they sound satisfying at lower volumes. I’d like that last bit of extra “emotion” from the vocals, that’s why I’m trying the 300b amps. Also, I might try to high pass the tube amps to allow the subs to handle more of the bass.

Btw, try the new PSVane Horizon 300b tubes. They are really good and are very inexpensive.

[Glady86]

I found an old thread that mentions this, basically it seems a 300b should drive the speakers full range at high enough levels without any problems. Also, the woofers are crossed at around 100hz, and bi-amp configuration is possibly a better solution, but a bit more tinkering to get right.

So the plan is I’ll try the amp full range, then add high pass, then experiment with bi-amp configuration.

[Glady86]

I canceled the eBay order, those Elekit kits  are 100v. Instead of buying a transformer, I cancelled that order and bought from tube depot. I saved 10% for being first time buyer and signed Up to receive their newsletter.

[Jon L]

I canceled the eBay order, those Elekit kits  are 100v. Instead of buying a transformer, I cancelled that order and bought from tube depot. I saved 10% for being first time buyer and signed Up to receive their newsletter.

You ordered Elekit TU-8900 300B/2A3 switchable amp? Either case, start looking for some good NOS 12BH7 tubes to use in the 12AU7 spot.  In my Elekit TU-8600, I like Sylvania black plates.

[Glady86]

You ordered Elekit TU-8900 300B/2A3 switchable amp? Either case, start looking for some good NOS 12BH7 tubes to use in the 12AU7 spot.  In my Elekit TU-8600, I like Sylvania black plates.

Thanks for the advice. I already have RCA 12au7 clear tops and Gold Lion 300b tubes, so I’ll start with those. I bought the 8900 on Thursday and it will be here Saturday. I can recommend Tube depot for their fast processing.

Is your unit fitted with stock transformers? I read all the hype about the Lindha, but didn’t go for that to start.

[mkrawcz]

Thanks for the advice. I already have RCA 12au7 clear tops and Gold Lion 300b tubes, so I’ll start with those. I bought the 8900 on Thursday and it will be here Saturday. I can recommend Tube depot for their fast processing.

Is your unit fitted with stock transformers? I read all the hype about the Lindha, but didn’t go for that to start.

I bought mine stock from Tubedepot. Great company. The stock transformers aren’t bad at all. If you want to get the Lundahls, I got mine from VKMusic. Viktor is the North American distributor for Elekit.

[Jon L]

Is your unit fitted with stock transformers? I read all the hype about the Lindha, but didn’t go for that to start.

I've got the Lundahl output transformers and soldered in Jupiter Copper Foils caps (my favorite).  Nicer coupling caps are highly recommended in these Elekits.  I could have used Miflex copper foil caps, but they are so much larger than Jupiter and would not fit..