Sub-Woofer Neophyte

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Sub-Woofer Neophyte

Postby Ar Amytas » Fri Jan 29, 2010 2:20 pm

Hi I'm not well versed in the ways of the stereo but like other humans enjoy fine quality sound reproduction. I am currently working with what would be termed as a "garage system " which consists of a Kenwood M2A Amp, C2 Pre amp, some old Rectillnear Low-boys and Pioneer RT-701 and Pioneer Tuner, (Analog) with Finco FM antenna ( gotta get the weather ), Dual 1219 with a Shure Type III Improved Cartridge as source. I will probably remove the 1219 and the RT-701 from the mix in favor of the computer stuffed with MP-3's. So I have an old Harmon-Kardon Citation 16 and wanted to introduce the Citation to the system as a power unit for some subs. Any ideas?? Do I need some other kind of electronics to channel the lower freq's to the Citation?? Will I be allowed to turn it up after 10 p.m. ?? Could I just plug in my Hartke B-60 and use that for the sub woofer and just get on with it??

Thanks

Ar
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Re: Sub-Woofer Neophyte

Postby DVDdoug » Fri Jan 29, 2010 7:26 pm

Do I need some other kind of electronics to channel the lower freq's to the Citation??
You need some sort of crossover*.

There are 3 possibilities:

1. Most "home theater" subwoofers are "powered" (they have a built-in amplifier) and usually they have a built-in crossover** that combines the bass from the left & right channels and filters-out the non-bass frequencies. Sometimes the sub will have both "speaker" and line-level inputs. (The speaker input stll goes through the built-in amp.)

2. A home-theater receiver will have a built-in crossover and will have a line-level subwoofer output (but typically will not have a subwoofer "speaker" output). There are usually optional settings for "bass management", so that you can re-direct the bass from other speakers to the sub, or you can use the subwoofer just for the LFE (low frequency effects) channel from DVDs.

With a home theater receiver, you can use a powered sub, or a passive sub plus a separate amp. (I have passive subs and a separate amp.)

3. A stand-alone electronic crossover can be used with an amp + sub, or with a powered sub. In this case, the low-frequencies will be filtered-out of your main speakers. If you have a single subwoofer, you need a crossover that combines the left & right bass to a mono subwoofer output... This can be tricky... I have a "2-way + subwoofer" crossover (that I'm not currently using), which means if you want to use the subwoofer output, you have to use it as a 3-way, which requires 3 separate amps.


...Could I just plug in my Hartke B-60 and use that for the sub woofer and just get on with it??
Yes, you can do that (if you get a crossover, or a home theater receiver), but you should be aware that musical instrument amps/cabinets are designed to have particular sound characteristics. (A Hartke amp probably has a different "tone" than a Fender.) On the other hand, "hi fidelity" speakers are supposed to accurately reproduce whatever you feed into them without having any sound of their own. (Your bass amp will probably work better than a small/cheap subwoofer.)

- With your equipment, the easiest solution would be to get a powered subwoofer. (This is also the most common setup.)

- The lowest-cost solution would be to get a home theater receiver and use the Hartke as a subwoofer. (You can get home theater receivers for around $100 USD.) This would also open-up the possibility of getting 3 more speakers at some point for a surround sound setup.


* Most speaker systems have a passive crossover network inside that sends the appropriate signals to the woofer, mid, tweeter, etc. And electronic crossover splits-up the frequency band at line-level before the signals are sent to the amps.

** Most subs don't have a full crossover. They just have a low-pass filter for the sub. They don't filter the bass out of the signal that goes to your regular stereo speakers. This is perfectly OK if you have good full-range speakers.
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Re: Sub-Woofer Neophyte

Postby Ar Amytas » Sat Jan 30, 2010 4:26 am

I guess that I will opt for a "powered sub woofer set-up" The stereo is in a garage and I will eventually get 2 more speakers ( Maybe, maybe not, it sounds pretty good with 2, I mean I am usually under a hood or crouched by the HD) . I do not watch/play movies/DVD's so it will be strictly audio.I have used the Hartke for outside holiday enjoyment. It is a cobbled up rig that doesn't get both channells all the time, but it does work. I picked a two chanel plug-in at RadioShack for the Hartke. I guess that the upgrade will help next Summers' the bass amp /Pentium4 internet source sound system.

Thanks
Ar
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Re: Sub-Woofer Neophyte

Postby DVDdoug » Sat Jan 30, 2010 9:57 pm

I have used the Hartke for outside holiday enjoyment. It is a cobbled up rig that doesn't get both channells all the time, but it does work. I picked a two chanel plug-in at RadioShack for the Hartke.
Ummmm... Does your amp have 2 separate inputs? I hope you are NOT using a Y-adapter to connect the left & right channels together! (You should use a mixer, or you can build a simple "mixer" with a couple of resistors.)

The rule is: NEVER connect two outputs directly together!!!!

If I can get slightly technical... It puts a low-impedance load on the outputs which can possibly damage the electronics and will usually screw-up the sound*. Solid state outputs usually have very low internal source impedance, but they are not designed to drive low impedance loads. For example, a power amp typically has an internal source impedance of less than 1 ohm, but it's designed to drive a 4 or 8 ohm speaker. If you hook-up a 1 ohm load (i.e. another amplifer output) you will burn-up the amp. Preamps and line-level outputs can also have low source impedance of a few ohms or so, but they are usually designed to drive 5K or 10k ohm loads. (Damage is less likely with low-current line-level signals, but it's still a bad idea.)

It's perfectly OK to connect two inputs together. i.e. It's OK to connect a mono signal to a Y-adapter and run it into both left & right channels.


* Sometimes you are lucky and it works OK. Sometimes you'll get distortion. Sometimes you can get an "interesting effect" where "center channel" sounds (that come out of both speakers) are OK, but left-only & right-only sounds are killed.
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Re: Sub-Woofer Neophyte

Postby lizzyjakers » Wed May 19, 2010 5:19 pm

Most of the home theater speakers are digital. They have a built in sub-woofers. The sound is well adjusted for a better sound output.
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