2. vintage
  3. 186527-147892

trying to add a subwoofer to a Mac system from before subs were a thing….

Ok, I have a vintage system. All McIntosh.

If you want specs on these pieces, please check out the awesome Mcintosh Compendium here: http://www.mcintoshcompendium.com

Pre-amp: C-30

Amplifiers: MC7300 (two of them) 

main Speakers: McIntosh XR-7

Subwoofer: McIntosh HT-12 passive 4 ohm sub and without built-in crossovers. 

My goal: add a sub in a system without an LF sub output. 

Attempts so far: Using the "speaker B" output on the pre-amp, I've done the following:

1, I took the 2nd MC7300 and parallel mono'd it, sending 600wpc to the sub using home-built "Y" cables. The entire un-modified signal, full frequency was amplified. Having a single 12" woofer meant there was a lil gain in lower end volume, but not much bump. 

2, I created a low-pass filter coil. This has removed highs, high-mid and most of the mids. Now when I switch from "speakers A" (the mains) to "speakers B" (the sub), the mains have soooo much more volume than the sub. The lows are so quiet.

When the mains are on, I can switch on/off the sub and frankly, hear zero difference. Maybe my coil is too big. I can try removing some but the more I remove, the more low-mid to mid I'm revealing and my goal is to feel the bass, not just hear more. 

An idea floated to me was a MiniDSP between the pre-amp and the amp. Maybe this way only the low frequencies I want will be amplified. However, that seems like a complex solution and might stretch my audio intellect on the set up. Example;The word "latency" was tossed around. Had to look it up.

What would you do? 

robvolz

Showing 1 response by robertc_f

robertc_f
13 posts
 

This is not a direct answer to your question, but I'd offer what I have done with a vintage Mac system and a newly added REL S/510 subwoofer.  The results have transformed my system with a new dimension of depth, and no hind of artificial or boomy bass.  The subwoofer simply disappears, but the added depth and spacial sense is transformative.  I have a Mc 2125 amp, C28 pre amp, XR 5 Mac speakers (along with the MQ 101 Environmental Equalizer and Speaker Control Relay Box).

The Rel S/510 is wired directly to my main speaker terminals on the Speaker Control Relay Box using REL's "standard high level connection cable."  The ground wire from the Rel connection is attached to the "c" terminal of my main speaker left output on my 2125 Amp (the right would work as well) to prevent a very nasty hum.  The Rel's are then adjusted for gain and Crossover frequency.  It was very easy to set up.  Hence in my system the Rel subwoofer is connected as "part of" my main speaker and receives the same signal from the pre amp, amp and speaker control relay box.  Trying to use the remote speaker option for the sub, and running it as essentially an entirely separate speaker, seems to me to complicate things and perhaps would make it more difficult to dial the sub in correctly.  I may be entirely wrong on this.  Anyway, hope this helps in a small way.

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