Bottlehead Forum

Bottlehead Kits => Eros Phono => Topic started by: d_composer on December 16, 2018, 12:27:06 PM

Title: Subwoofer?
Post by: d_composer on December 16, 2018, 12:27:06 PM
Hi - my system currently consists of an Eros going into a stereomour II. I want to add a subwoofer and the manual of the one I’m looking at says to connect it to my pre-amp. That would mean my Eros, right? If so, there is only one RCA out from the Eros so I’d have to split it somehow? Or do I tap the speaker out from the Stereomour II? If that’s the case, what’s the best way to do that?Thanks so much!
Title: Re: Subwoofer?
Post by: galyons on December 16, 2018, 01:23:21 PM
No. The Eros is not a preamplifier. It is a phono stage, actually a specialized pre-preamplifier with RIAA equalization.  The Stereomour is an integrated amplifier.  The volume pot is used in lieu of a seperate line stage, (preamplifier).  I'll leave it to the inhouse BH guru's for ideas!!

Cheers,
Geary
Title: Re: Subwoofer?
Post by: d_composer on December 16, 2018, 01:53:55 PM
Ah, thanks so much for the clarification!
Title: Re: Subwoofer?
Post by: Paul Birkeland on December 16, 2018, 05:38:22 PM
Does your subwoofer have speaker level connections?
Title: Re: Subwoofer?
Post by: d_composer on December 17, 2018, 02:01:59 AM
No, just a line in seems. There is a great deal on the Klipsch R-100SW right now but will it not work with my setup? Here’s the relevant part of the manual:

Quote
“LINE IN” Connection - Most of today’s surround receivers (and pre-amplifiers) have a line level subwoofer output labeled Subwoofer Pre Out, Sub Out, SW Out, etc. If you have this output, connect one end of a subwoofer cable to it and connect the other end of the cable into the subwoofer line input labeled LEFT/LFE. This connection allows the subwoofer to operate with both music and surround sound movies (refer to your receiver manual). In absence of a subwoofer output on your receiver, as an alternative hookup, you can connect Left and Right channel Pre-Amp Outputs from your receiver (if provided) to the Left/LFE and Right input on the subwoofer.
Title: Re: Subwoofer?
Post by: Karl5150 on December 17, 2018, 02:47:43 AM
You could try a speaker-level to RCA converter (High to Low), pretty much the same thing that's built into a powered subwoofer with speaker-level inputs.
Title: Re: Subwoofer?
Post by: d_composer on December 17, 2018, 08:00:11 AM
Oh cool! Maybe something as simple as this then? https://www.crutchfield.com/p_543ADP12/Russound-ADP-1-2-Speaker-level-to-Line-level-Adapter.html?awkw=78572876905&awat=pla&awnw=g&awcr=50190041905&awdv=m&awug=9004354&gclid=Cj0KCQiAr93gBRDSARIsADvHiOq7HFrz6kyPKaS1CY-kaI4O7S0I6PtAUCrikhu9rajiA9AEBoU5d-4aApIqEALw_wcB (https://www.crutchfield.com/p_543ADP12/Russound-ADP-1-2-Speaker-level-to-Line-level-Adapter.html?awkw=78572876905&awat=pla&awnw=g&awcr=50190041905&awdv=m&awug=9004354&gclid=Cj0KCQiAr93gBRDSARIsADvHiOq7HFrz6kyPKaS1CY-kaI4O7S0I6PtAUCrikhu9rajiA9AEBoU5d-4aApIqEALw_wcB)

And just shove those speaker wires into the terminals where my other speakers are attached?
Title: Re: Subwoofer?
Post by: d_composer on December 17, 2018, 08:02:07 AM
Hah! Review #2:

Quote
Perfect for my need! I needed a way to hook up a subwoofer to a tube amp with no preouts. This little item did the trick.

I think I’m onto something ;D
Title: Re: Subwoofer?
Post by: fullheadofnothing on December 17, 2018, 08:13:16 AM
If you tack those $40 onto your subwoofer budget, can you find a subwoofer that already has speaker level inputs?
Title: Re: Subwoofer?
Post by: d_composer on December 17, 2018, 08:22:14 AM
It’s less of a budget and more of a protracted impulse buy! All in this would be ~$200... any suggestions? Also, the DIY side of me hates the idea of buying this since it’s just 4 resistors on a pcb. Nice markup!
Title: Re: Subwoofer?
Post by: Paul Birkeland on December 17, 2018, 09:31:42 AM
Do you have a Stereomour 1 or Stereomour 2? 

You can make a pair of speaker to RCA cables and skip on the external adapters.  The voltage output available from the Stereomour 1/2 isn't huge (just over 5V RMS on the 8 ohm tap), so it's debatable as to whether you'd need any padding resistors at all.

Title: Re: Subwoofer?
Post by: d_composer on December 17, 2018, 09:36:57 AM
Stereomour II. Thanks, that’s great news!
Title: Re: Subwoofer?
Post by: Paul Birkeland on December 17, 2018, 09:51:30 AM
You can just get a pair of banana plugs and a pair of RCA plugs and wire them up (black binding post to RCA shell, red binding post to center pin).

If the volume control on the subwoofer seems extremely sensitive, you can put a 100 ohm resistor between the red wire and center pin of each RCA jack, then a 10 ohm resistor from each center pin to ground.  This will provide significant attenuation (-21dB) and give you more range on the level control of the subwoofer.  There are no concerns for additional loading on the outputs of the Stereomour. 

-PB
Title: Re: Subwoofer?
Post by: d_composer on December 17, 2018, 09:54:35 AM
Thanks so much!!
Title: Re: Subwoofer?
Post by: d_composer on December 20, 2018, 09:28:33 AM
Update: worked like a charm :) thanks again!!