# Subwoofer voltage for preouts



## bambino (Feb 21, 2010)

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


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## tonyvdb (Sep 5, 2007)

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.


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## bambino (Feb 21, 2010)

No worries of burning the preout up?
If they aren't getting full voltage is there anything that can be used to perk up the signal? Thanks.


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## tonyvdb (Sep 5, 2007)

One of these would boost the signal.


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## bambino (Feb 21, 2010)

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


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## tonyvdb (Sep 5, 2007)

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.


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## bambino (Feb 21, 2010)

Exellent tony! Thank you very much.:sn:


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## Anthony (Oct 5, 2006)

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.


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## bambino (Feb 21, 2010)

Not sure if mine do, have to check. I'll be using 2 HPSA1000r amps and 2 Crown xls802 amps.:dontknow:


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## Anthony (Oct 5, 2006)

I have the hpsa 1000 standalone amp and it does not have a line out.  Just stereo in and line in.

Not sure if the plate amps from the same company (with similar product numbers) have the line out.


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## bambino (Feb 21, 2010)

Yeah, mine are the standalones too, bummer! Any suggestions other then what tony advised doing? Thanks.:T


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## tcarcio (Jun 27, 2007)

I use the samson s-convert with my amps. It works very well. http://www.audiolines.com/product.php?productid=11877


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## bambino (Feb 21, 2010)

Does that bump up the audio signal from the preout so you can run multiple amps without preout voltage drops and all 4 amps get the signal they need?:huh: Thanks.


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## tcarcio (Jun 27, 2007)

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.


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## salvasol (Oct 31, 2006)

bambino said:


> Does that bump up the audio signal from the preout so you can run multiple amps without preout voltage drops and all 4 amps get the signal they need?:huh: Thanks.


Maybe I'm mistaken, but I read somewhere (Can't remember), that using a Y cable from AVR to split the signal doesn't affect/degrade it.

Will you be using DIY subs????


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## bambino (Feb 21, 2010)

Guess all i can do is try.:dontknow:If anyone else has some ideas or suggestions throw'em out there. Thanks,Bambino.:T


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## salvasol (Oct 31, 2006)

bambino said:


> Guess all i can do is try.:dontknow:If anyone else has some ideas or suggestions throw'em out there. Thanks,Bambino.:T


: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


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## bambino (Feb 21, 2010)

I better brake out the holy bible of Denon and see what it says. Thanks for the insight.:T


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## bambino (Feb 21, 2010)

Well looks like i'll have to call Denon tomorrow as i can't find the specifics on voltage.:hissyfit::scratch:


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## laser188139 (Sep 19, 2009)

Obviously the voltage level depends on the volume setting, the sub trim in the receiver, any equalization, ... In the Audyssey thread, there was a discussion of the Denon 2809 and peak voltages of near 6V were observed, before clipping happened in the Denon. 

Bill


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## Lucky7! (Jan 7, 2008)

bambino said:


> 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


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?



bambino said:


> 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.



Anthony said:


> 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..


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## tonyvdb (Sep 5, 2007)

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


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## bambino (Feb 21, 2010)

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


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## bambino (Feb 21, 2010)

tonyvdb said:


> 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


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:


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## Lucky7! (Jan 7, 2008)

tonyvdb said:


> 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.


Sorry, not correct.

Even if the 3808 Zout is 200Ω (and it's probably not this high) and the worst case load is 1.76kΩ (from previous post) then the difference in level between 1 x 10kΩ load and 1.76kΩ is ~0.75dB.


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## Lucky7! (Jan 7, 2008)

bambino said:


> 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.


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## lsiberian (Mar 24, 2009)

tonyvdb said:


> 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


It is the preferred device for this application, but is usually unnecessary in my experience in going from consumer to pro. It is more necessary in going from pro to consumer. I'd not recommend the mixer for an application like this. It's a lot larger for and harder to stick where a person would want it. 

Now if you have a dedicated theater room the mixer might actually be a good idea, but even then mixers often times prefer a Samson or ART.


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## bambino (Feb 21, 2010)

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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