[msm_1]

Hi

On my VR-4's, I currently use a pair of Classe DR-8's with each channel on one running the mid/weeter upper cabinet and the other 8 running the lower base cabinet and I'm using Red Dawn cables.

I'm switching my DR-8's to run a DR-9 and a tubed Rogue 88

I'm thinking that the 9 would be best on the lower base with the tubes on the mid/tweeter.

Anybody using similar setup or any ideas as to which should be used?

Thanks


Mike

[SundayNiagara]

What are the input sensitivities of those (Classe & Rogue) amps?

[McTwins]

Hi
Put the Rouge amp to the M/T and the Classe to the bass. Connect the Classe to the 4ohm tap and the Rouge amp to the 8ohm tap. I see that the Rouge amp seem to have 1 volt sensitivity but can't find the sensitivity about the Classe amp.
But if the sensitivity is fairly close this shoulden't be any problem driving the amps in this configuration.
Thanks

[msm_1]

Hi

This is all the information I found on the DR-9 ( Ihaven't located a manual  yet

The DR9 has 6 MJ15003/4's in parallel per rail, at 100mA bias each.
Makes it class A up to 1.2 amps, nearly 6 watts in 8 Ohm.
The DR9 employs a CRC powersupply, 60.000uF per rail.
With 250 watt MJ15024/25, proper heatsinking, and increased capacitor size to +200.000uF/channel it could run full class A on the 58VDC rails.
But then you are talking nearly 1000 watts dissipation. )

Thanks again

Mike

[SundayNiagara]

What is the voltage required to drive the DR-9 to full output.  This may or may not show up as the sensitivity spec.

[Coytee]

Dumb question...  (preface, I'll admit I know nothing about these amps)

What does the input sensativity matter?

I presume he's biamping.  I too am biamping.  I've used tubes, solid state and mixed the two. 

The only time I care about the input sensativity is when I'm setting things up so I can match the amps.  Once I match them, I personally don't care what their input sensativity ratings are.  What if anything am I missing on that?


By the way, for anyone who is biamping with different amps (differing input sensativities) you can use the forumla "20xlog(v1/v2)"  where V1 and V2 are the input sensativies of each amp.

For example, if you have an amp with 1.5 and another with 2.5 input sensativies, you would put "20xlog(1.5/2.5)" and get "-4.43697" as your answer.  This means you would want to attenuate the more sensative amp (the 1.5 input senativity amp) by 4.4 db's to match the other amp.  In my active, I am not sure if I can adjust in 1/2 db's or not...but you get the idea.

Side note, if you happen to use 20*log(2.5/1.5) you will get a POSITIVE 4.43697 so the point to keep in mind here is it does NOT MATTER which number you put on top/bottom, the only difference will be having a negative value or not in the end.  The actual number next to the negative will be the same number.


So, once we balance our active crossovers to compensate for differences in input sensativity, can anyone tell me why we care any more??


For the record, I'm currently using two Crown K2's for my biamp situation.  I recently swapped a K2 out for a Viva 300B SET amp and once I balanced for the differences in the inputs, the system worked and sounded fine up to the limitis of the 300B's output abilities.

[Coytee]

I'm thinking that the 9 would be best on the lower base with the tubes on the mid/tweeter.

Anybody using similar setup or any ideas as to which should be used?

If the 9 is solid state then that is how I'd do it.  Solid state on your woofers, tubes higher up.  When I did the Crown K2 mixed with a 300B, it put out a VERY VERY VERRRRRRRRRY sweet sound, up to the limit of the 300B.  I was mating something like 8 watts on my tophorn to what?....  400 or more on my woofers?  It was a power mismatch but I was only playing around.  Since I usually need more power (on 108db horns) I sold the 300B and put my other K2 back into service.

I'd love to find something like an OTL nearby to try on my top horns.

[srb]

What does the input sensativity matter?

If you're actively bi-amping with an active crossover that has adjustable input attenuation, then like you say, it doesn't matter.
 
If you're passively bi-amping, and the amplifiers themselves have level controls that can get them to the same level, you'll be fine.  If the amplifiers have no level controls, you would want them to have the same input sensitivity and gain.
 
Steve

[msm_1]

I can't find it on the DR-9 yet, but my DR-8's show it  as being 0.85

The DR-8's were rated at 70/channel and the 9's at 100/channel into 8ohm ( which most considered both were very underrated )

The DR-9 is the 8's bigger brother so I'm guessing it must be either similar or slightly higher.

[Coytee]

What does the input sensativity matter?

If you're actively bi-amping with an active crossover that has adjustable input attenuation, then like you say, it doesn't matter.
 
If you're passively bi-amping, and the amplifiers themselves have level controls that can get them to the same level, you'll be fine.  If the amplifiers have no level controls, you would want them to have the same input sensitivity and gain.

I see.  So if you are passive biamping, you are sending a full signal to your LF crossover (which is bleeding off the HF energy somehow?) and you are sending a full signal to the HF crossover (which is bleeding off the LF energy somehow?)

I would have thought to get the most from biamping, someone would have an active crossover in the path to divide the signal prior to the amps.

Never thought of the way you're mentioning it, I see why in that example someone WOULD indeed care about the input sensativities.

[srb]

I would have thought to get the most from biamping, someone would have an active crossover in the path to divide the signal prior to the amps.

Never thought of the way you're mentioning it, I see why in that example someone WOULD indeed care about the input sensativities.

And you would be absolutely right.  Active bi-amping requires an active crossover, and either the speakers are wired for it (no internal crossover), or you have removed or disconnected the internal crossover and wired directly to the binding posts.  It adds some complexity that many people do not want to undertake.
 
But passive bi-amping is quite popular because it is easy, though it can often result in marginal improvement because the internal crossovers in use are still soaking up power and adding phase distortion, etc.  Yet some people claim the improvement is more than marginal in their systems.  But one thing it can still accomplish is the ability to give a solid state grip and control to the woofers, and the liquidity of tubes to the mids and highs, if you're using both solid state and tube amps and prefer those attributes.
 
Steve

[Coytee]

And you would be absolutely right.  Active bi-amping requires an active crossover, and either the speakers are wired for it (no internal crossover), or you have removed or disconnected the internal crossover and wired directly to the binding posts.  It adds some complexity that many people do not want to undertake.
 
But passive bi-amping is quite popular because it is easy, though it can often result in marginal improvement because the internal crossovers in use are still soaking up power and adding phase distortion, etc.  Yet some people claim the improvement is more than marginal in their systems.  But one thing it can still accomplish is the ability to give a solid state grip and control to the woofers, and the liquidity of tubes to the mids and highs, if you're using both solid state and tube amps and prefer those attributes.
 
Steve

Truth be told, I agree with 100% of what you are saying.  Since I'm brand new on this site, I didn't want to come outright and say the bold part and sound like I was trying to educate everyone.

As a reference point, I have NEVER in my life biamped until very recently and have done so by going with a full blown active (EV Dx38) and a pair of Crown K2's.  I figured if I was going to do it, I was going to try to do the traditional way.  (no disrespect meant to anyone who's not using an active)

 

[JackD201]

Here's a thought

Personally this is what I would do especially if I wanted to get as much juice for the bass modules as possible while making the most of the VR's passive XO which in my opinion is the heart and soul of VR family's sound and the reason we own them.

I would use a direct full frequency signal into the MT amp but still use an active XO for the bass amp. I would however set cut off and slope slightly above the bass modules passive XO so as to make full use of the VR's contours. This would provide the bass amp with a few more watts of headroom and the gain control on the active XO would be able to provide boost as well as attenuation. In effect this turns the bass amp into a no holds barred plate amp and the VR bass modules into world class powered subs with no integration hassles.

Why full range into the MT amp? Well first psychologically folks normally want a simpler signal path from source to the speaker. MT carries the bulk of the music and can be harmed if the active XO becomes the weakest link when it comes to signal purity and transparency. Analog Active XOs may introduce phase shifts while digital ones may impart a hard sound. By going full range in MT one need not be so critical of the quality of the active XO.

Why not actively crossover the MT and save some headroom for their amps as well? Aside from what I stated above, you would need to active XOs to cross the signal over below the MT's native slopes while crossing the Bass module's signal above theirs. If one set the Q wide enough to do so in an active, the global gain control would affect the overall tonal balance by acting like an EQ.

[Hoosierdaddy]

Here is Albert's view on this, if you have not already seen it...

http://www.audiocircle.com/index.php?topic=59529.0

Regards,
Hoosierdaddy

[Coytee]

Second side comment...

I've got a pair of Electrovoice Interface D speakers (bought them new in 1978).  They have 4 inputs, meaning...two pair of red/black.  There is a plug that goes into the base of them that is switchable with another plug.

Change plugs on the bottom and it reconfigures the passive inside the speaker such that it can be biamped.  You toss an active in there, cross at 500 (if I recall, these are not in current use) and each passive section takes care of each half. 

I would think a pretty simple analog active could be used in this kind of speaker to simply divide the signal at 500 hz.

I would wonder if something simple like this would work in your situation(s) ?

 

[msm_1]

Thanks for the replies

I forgot about that post ( thanks for bringing it back ) I do have the pair of Rogue 88's still, but only one is functional, the other keeps blowing tubes and actually blew a fuse the last time I hooked it up.
I haven't sent it away yet to be looked at ( Rogue said they would upgrade it to a ST-90 for $1100.00us if I sent it to them . in California....I live in Ontario Canada, so shipping for the 65lbs would be a killer! )

http://www.rogueaudio.com/Products_90.htm

http://www.avrev.com/home-theater-power-amplifiers/stereo-amplifiers/rogue-audio-eighty-eight-magnum-stereo-power-amplifier.html

So I've got it collecting dust and that's why I thought about running it with the DR-9 ( which is SS )


Thanks again


Mike