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Subwoofer voltage for preouts

6K views 27 replies 8 participants last post by  bambino 
#1 ·
Wondering if anyone knows if the sub preout on a Denon 3808 has enough power to deliver signal to 4 subwoofer amplifiers or is there some type of line driver for home audio that would have to be used?:scratch: Thanks for any responses.:T
 
#2 ·
I suspect that you would not be able to get 4 subs to run to there full output off of one line feed. But really the only way to know for sure is to give it a try it wont hurt anything.
 
#4 ·
One of these would boost the signal.
 
#5 ·
Sorry for what may be a silly question but how does that work and get the job done? All the reveiws talk about using it as a mixer for there computers?:scratch:
I'm tottally new to this using proamps in the home thing so i hope you'll forgive my ignorance and numerous questions. Thanks again.:T
 
#6 ·
simply plug the sub output of the receiver into the input 1 on the mixer (you will need to buy a 1/4" TS adapter to rca from them as well) and then plug the two tape outputs (left and right) into the subs inputs two subs on each output.
 
#12 ·
#14 ·
Well I only have one sub but I would think you can split the signal coming out of the s-convert at least for 2 subs. 4 subs I don't know but I would still lean towards it working.
 
#17 · (Edited)
:T

When I started this hobby I had a Sony AVR with just one sub output, I connected a Velodyne sub, an Infinity sub and Buttkicker amp splitting the signal with "Y" cables; I didn't notice anything bad.

I think that as long as the pro-amp receives enough signal from AVR it will work fine, (just read the manual to see how much voltage do you need to get the most out of your pro-amp, in my case the Samson needs at least 1.24V(4dBu) to get full power, I'm not sure how much my Yamaha RXV2700 delivers on the sub pre-out) but they sound good.

EDIT: I just read the manual and Yamaha outputs 2.0V
 
#21 ·
There are two things to consider here, just like paralleling speakers: will the total load (impedance) be too low for the pre outs, and will the preouts have sufficient voltage to drive the amps to the level you want?

Not sure if mine do, have to check. I'll be using 2 HPSA1000r amps and 2 Crown xls802 amps.:dontknow:
I looked up the HPSA and it says it's Zin is 12kΩ and the XLS is 10kΩ (because the 3808 only has RCA out so you'll be driving it unbalanced). The XLS doesn't appear to have a 'parallel' input mode so you'll need to connect to both A and B unless your bridging.

So, assuming 2 x HPSA and 2 XLS bridged, then the total load seen by the 3808 will be 12k//12k//10k//10k = 2.73kΩ. (Not bridged XLS is 1.76kΩ)

The 3808 datasheets says the Pre Outs are 1.2V/10kΩ with the latter undoubtedly being the minimum recommended load, a bit higher than 2.73kΩ.

The pre outs will be driven by an opamp, and for decades most opamps have had little difficulty driving loads as low as 2kΩ, even a cruddy 4580 will do it with still low THD, 0.001% at 2V out.

The XLS says it needs 1.2V for full output into 4Ω, but that would be balanced, so you're 6dB shy, though you could probably boost it that much in the AVR. The Dayton doesn't give a sensitivity.

So after all that, my advice would be to try it with just splitter leads. If you don't get enough level or it's obviously distorting, get something like an S Convert.

4 is a bit much to drive the subs with Y adapters, but some sub amps have pass throughs (line in, line out), so you can daisy-chain them.
Most pass thru connections are simply a parallel via a short wire link from the 'In' to the 'Out' so it's no different electrically from a Y adapter. The there were some active buffering in the I/O loop, then that would make a difference as the Denon would only see the load of the first input, being electrically isolated.buffered from other devices connected downstream of it..
 
#22 ·
Remember guys, The signal will be split twice so to 4 different amps. With one y adapter you wont really notice a difference but two times (to 4 amps) is going to reduce the level too much. The Samson S-convert is another good option
 
#24 ·
Cutting the signal too low is what worries me, i want the amps to have there daily reccomended amount of voltage so they perform there best.:sn:

In my car audio days we had line drivers that would up the voltage from the head unit or preamp, in turn you ended up using less gain on the amps and could run multiple amps without worry.:dumbcrazy:
 
#23 ·
A9x, You are right the xls's will be bridged and the HPSA's are pretty strait forward.
I guess in short, are you saying i should be OK running all 4 amps off the 1 sub preout? I know what you were saying in your post but not sure i fully understand it. Thanks a mill for your time and knowledge.:T
 
#26 ·
I guess in short, are you saying i should be OK running all 4 amps off the 1 sub preout?
It should work fine, and I seriously doubt you'll do damage trying it, so my suggestion is to try it first before buying anything else especially if you have suitable leads to hand. If you are not happy after trying it and getting the outputs maxed form the 3808, which IIRC reportedly can output much more than 1.2VRMS, then spend for an S Convert (or whatever). This is certainly what I would do in your situation.
 
#28 ·
Thanks again A9x and everyone else i really appreciate this place and how helpful everyone always is, what a great world we live in.
If anyone else has thoughts or suggestions or i'll probly end up having more questions, Till then.........:T
 
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