[rockdrummer]

Hello everyone.
I had hoped to get the bottoms, two A370PEQ amps and four 12" servo drivers, to finish the super v tops I have, this summer. 

Now I'm sure I have bitten off more than I can chew because I looked into the HX800 and HX580 amps.  I am now thoroughly confused.  I have info from Brian at Rhythmik about prices for those amps with necessary OB mods, but I am unsure about how many 12" subs can be run by both.

In a recent thread Danny said the HX800 can run 6 subs.  Could someone clear up whether I should have two amps (a370) for my super v bottoms or can I just get the HX800 and run all four 12" drivers?  What subs do I need?  HELP?!?!?!?

Thanks,
Ben the perpetual noob.

[ebag4]

Hi Ben,
I'm sure Danny will chime in with the correct answer, however I thought I would throw this out; The servo wiring should remain as short as possible, that alone would likely require a second amp due to the distance between your SuperVs.  Then there is the fact that with the SuperV the servo subs play up to 200Hz (if they only played up to 80Hz or so the frequencies would be more omnidirectional so stereo bass would be less important), this means that you will want a set of stereo subs, not 4 drivers playing the same channel, so again you are into 2 of the servo amps.

I hope this helps.  BTW, I built my V1s the same way, coax first and ordered the subs later.  I can tell you that the whole is greater than the sum of it's parts.  The coax will sound like a different animal with the servos shoring up the bass frequencies.  You are in for a treat.

Best,
Ed

[rockdrummer]

Oh yeah, (he said sheepishly) I completely forgot about the proximity factor.  Thanks Ed.

Ben

[Danny Richie]

You need two A370PEQ amps and four SW-12-08FR woofers.

The HX500 and HX800 amps are two channel amps but they are mono amps using one input. They are not for driving stereo pairs.

[rockdrummer]

Thank you for the help gentlemen. 

I think I have never been clear on left and right sub inputs.  Could someone confirm this for me?
When setting up one single sub, if I plug a single sub output cable from my receiver into a left channel of a sub, the sub only passes the left channel material to the driver.  Likewise with the right input?  So I assume if I plug a full bass signal (L & R) each input only reads what it is labeled.
Am I making any sense?

Furthermore, do I plug my split preamp signal (one to a tube amp, one to a sub amp), left front main into left input and right front main into right input?  Even though they are the same material on the cable, each input only amplifies that particular side of the stereo signal?

I will just assume I am not making any sense if I don't hear any responses.  After re-reading it, I think it makes sense, but I'm still guessing.   
I did read up on this on other forums and some sub articles but all I read was that there are two inputs so you can have stereo signal.  That I knew, I didn't know how the inputs actually work.
Ben

[Tyson]

Yes, left signal from the preamp goes to the left input of the tube amp and the sub amp.  Right signal from the preamp goes to the right input of the tube amp and the right sub amp.

[rockdrummer]

Thanks Tyson

One more dumb question.  If my preamp is sending left channel info to my left side sub amp, what happens if I plug it into the right input of the sub amp?  No sound?  Same sound? I'm thinking that's where I should have started my first question.



Ben

[Tyson]

Well, you have 2 sub amps, not one.  A left sub amp and a right sub amp.  They are physically separate amps.  I don't understand why you would plug in your left audio signal into the right subwoofer amp, but if you did, it'd just play the left channel info on the right side sub.

[rockdrummer]

Okay, so it isn't mechanically different as far as the input is concerned.  The left and right are just there for organization purposes.

I guess somewhere along the line, I made erroneous conclusions on my own about what was actually happening. 

I do feel dumb though.

Ben

[Captainhemo]

Yes, left signal from the preamp goes to the left input of the tube amp and the sub amp.  Right signal from the preamp goes to the right input of the tube amp and the right sub amp.

I'll add a bit  for you Ben

If yo are using subs  on each side of the room (Like with yor super-V's) you want the left  pre out   (from preamp)  going to the sub amp paired with the  the left super v, the right going to the right  sub smp with the right super v.  Now , which  input on those amps yo use is basically irralevant, that amp will only will use the  signal passed to it no matter which input is used.  You  can actually use a  "Y"  (1 rca female to 2 rca males)  to split the  channels  sginal and  use both  inputs on  each of you sub amp, you'll usually get a bit more gain ( I thinkits around 6 db with the  A370PEQ). Even using both inputs,  you  still nly passing  the corresponding  signal  (left t kleft amp, right to right amp)

In the case above when you mention the  receiver with the single  LFE output, both left and right  low frequency info is combined in this case.   You'd have to use a  splitter and send the signal to both  of your sub amps, input on  amp  wouldn't matter unless only one inpt has the "auto on" trigger .  Again, if yo uwanted, you could use  the same splitter I mentioned above to increase the gain  of each amp by approx 6db

Just remember, it's the output from the pre amp that is the important part,  left to left side, right to right side, inputs on  the sub amps  dosn't really matter

jay

[Tyson]

Agreed, the RCA inputs on the sub amp itself are labeled Left/Right, but it does not matter which one you plug your cable into.

[bdp24]

Hello everyone.
I had hoped to get the bottoms, two A370PEQ amps and four 12" servo drivers, to finish the super v tops I have, this summer. 

Now I'm sure I have bitten off more than I can chew because I looked into the HX800 and HX580 amps.  I am now thoroughly confused.  I have info from Brian at Rhythmik about prices for those amps with necessary OB mods, but I am unsure about how many 12" subs can be run by both.

In a recent thread Danny said the HX800 can run 6 subs.  Could someone clear up whether I should have two amps (a370) for my super v bottoms or can I just get the HX800 and run all four 12" drivers?  What subs do I need?  HELP?!?!?!?

Thanks,
Ben the perpetual noob.

Just to sum it all up Ben: You want stereo subs, one per side/channel. So get a pair of A370 amps, one for each side, and each amp will drive either two 8 ohm 12" woofers or three 16 ohm 12" woofers, your choice. The output of two 8 ohm and three 16 ohm should be about the same.

[Captainhemo]

And if yo already  happen to have a pair  of the sw12-16FR's instead of the FR08's, they will work   fine too.

Here's a question for yo guys,   is the output really increased using the FR08's ? does it not  take more power to drive the lower impedence drivers to reach the same SPL ?

jay

[Danny Richie]

The output is greater with the three woofers.

[Captainhemo]

The output is greater with the three woofers.

yeah, I get that , what I was wondering is  regading  2 x 08FR  vs 2 x 16FR.  I realize  2 08's in parallel  give you  a 4 ohm load (assuming a true 8 ohm driver)  and the 2 16's  give and 8 ohm load.  The amp  will ouut  the full potntail at 4 but don't thre  8 ohm drivers  require that extra power to  reach the same  SPL of the 2 16's at a lower   power output?

[Danny Richie]

yeah, I get that , what I was wondering is  regading  2 x 08FR  vs 2 x 16FR.  I realize  2 08's in parallel  give you  a 4 ohm load (assuming a true 8 ohm driver)  and the 2 16's  give and 8 ohm load.  The amp  will ouut  the full potntail at 4 but don't thre  8 ohm drivers  require that extra power to  reach the same  SPL of the 2 16's at a lower   power output?

It isn't so much about how much power the amp can deliver as it is about how much air you can move.

[bdp24]

yeah, I get that , what I was wondering is  regading  2 x 08FR  vs 2 x 16FR.  I realize  2 08's in parallel  give you  a 4 ohm load (assuming a true 8 ohm driver)  and the 2 16's  give and 8 ohm load.  The amp  will ouut  the full potntail at 4 but don't thre  8 ohm drivers  require that extra power to  reach the same  SPL of the 2 16's at a lower   power output?

Cap---Two 8 ohm woofers present a little under a 4 ohm load to the amp (because each is actually a little under 8 ohms), and two "16" ohm woofers, being actually about 12 ohms each, present a 6 ohm load. Because the amp's power increases with descending load impedance, the amp produces more available power (headroom) driving the 4 ohm load of two 8 ohm woofers than it does driving the 6 ohm load of two 16 ohm. That does not necessarily mean there will be a difference in output level between the two pairings---that is a function of the difference, if any, between the sensitivity of the 8 ohm woofer and that of the 16 ohm (the 8 ohm woofer is about 1dB more sensitive than the 16 ohm----negligible). That is, until and unless you drive the amp to full output. The amp will reach a point where it has no more "unclipped" power with a 6 ohm load, while having a little more (1-2dB?) available for a 4 ohm one (headroom). What Danny is saying is that since the load presented to the amp by two 8 ohm woofers is about the same as that of three 16 ohm---4 ohms---the power available to the two combinations is about the same. However, three 16 ohm woofers, because of the extra radiating area of the 3rd woofer, will provide more SPL than will two 8 ohm. As to your question regarding whether or not two 8 ohm woofers require the extra power their lower impedance allows the amp to produce to reach the same SPL as two 16 ohm woofers? As above, no. That is, again, entirely a matter of the relative sensitivity of the 8 ohm and the 16 ohm woofers. If you look at the specs of the two woofers in the listing of drivers on the GR website, the 8 ohm 12" is only about 1dB more sensitive than is the 16 ohm---negligible.

[Captainhemo]

hey  bdp24
pretty much  had my head around most of that already,  just wasn't  clear on the lesser load being more sensitive.  I  also understood the lower load  lets the amp  output more power. Thinking theat typically   the lower ohm driver  needed more  power to reach the same SPL (less sensitive)   was why I was asking the  ?  regarding  using  2 8 ohm  drivers vs using 2 16 oh drivers.  Thinking they (the 8 ohm drivers) were  slightly less sensitive  didn't seem to make much ( the increased power  would  seem to be "offset' by the  decreased sensitivity)   but knowing the opposite  makes  it all make sense.

for some reason, I seeme dto  have it in my head that  lthe lower load drivers/speakers  were  less sensitive.
And yes,  understnd the   3 dirvers  moving more  air,  never a question  regarding that 

-jay

[bdp24]

hey  bdp24
pretty much  had my head around most of that already,  just wasn't  clear on the lesser load being more sensitive.  I  also understood the lower load  lets the amp  output more power. Thinking theat typically   the lower ohm driver  needed more  power to reach the same SPL (less sensitive)   was why I was asking the  ?  regarding  using  2 8 ohm  drivers vs using 2 16 oh drivers.  Thinking they (the 8 ohm drivers) were  slightly less sensitive  didn't seem to make much ( the increased power  would  seem to be "offset' by the  decreased sensitivity)   but knowing the opposite  makes  it all make sense.

for some reason, I seeme dto  have it in my head that  lthe lower load drivers/speakers  were  less sensitive.
And yes,  understnd the   3 dirvers  moving more  air,  never a question  regarding that 

-jay

Jay, I too think of lower impedance speakers as needing more power to reach a given SPL than do higher impedance ones. There's a good reason for that: it's usually true! Horns, high-sensitivity drivers, have traditionally been higher impedance (often 16 ohm), and Maggies, for instance, a low-sensitivity speaker, have been lower in impedance (they're 4 ohm); but they don't have to be. In his white paper on the design of the Eminent Technology magnetic-planar loudspeaker, Bruce Thigpen states that he could have made the m-p driver in his LFT speaker any impedance that he wanted, choosing 12 ohms (the nominal impedance of the LFT-8b loudspeaker is 8 ohms, but the m-p panel itself is 12) as a compromise between sensitivity and being an easy load for the power amp driving it. It's no coincidence that the earliest acoustic-suspension loudspeakers (such as the Acoustic Research AR-3) were both low-sensitivity and low-impedance---the AR design team chose to make the AR-3, a much less-sensitive speaker than the then-standard ported Bozaks and Altec-Lansings, a 4 ohm speaker so as to extract as much power as possible out of the new transistor amps that were becoming available, transistor's power increasing as impedance drops, the opposite of tubes. Fortuitous!