pennektj Posted July 7, 2004 Share Posted July 7, 2004 I am building the 15" Tempest in the Adire Alignment box to replace my current 15" Cerwin Vega sub (I know... I was young and dumb). I have a quick question. I have finished the rough building of the box, have the sub and ports on order, and picked up the plate amp yesterday (turns out P.E. is only about 15 minutes away from me) Now for the question. My sub is located across the room from my Receiver. I have the sub cable (RCA) run under the floor all the way across the room. I have two options. Place the plate amp near the sub, and have a long run of RCA to get the signal to the amp, with a short speaker wire run... OR place the plate amp near the reciever, have a short signal run, and then run a long speaker wire run to the sub (across the room). Which is better? I am sooo excited to get this done... I can't wait to see what it sounds like. If anyone has first hand experience and can share what I can expect, please do. Also, if anyone knows were I can get gloss black (piano finish) laminate... let me know. Thanks for your help. Tim Quote Link to comment Share on other sites More sharing options...
Dustin B Posted July 7, 2004 Share Posted July 7, 2004 IMO the cable run options are six of one half dozen of the other. Which ever is cheaper/more convient for you will work fine. As for what to expect. A big silly grin on your face for several days. Quote Link to comment Share on other sites More sharing options...
hwatkins Posted July 7, 2004 Share Posted July 7, 2004 I recommend putting the amp on the sub both for the six of one/half dozen of another argument and to enhance the flexibility of the sub. If you end up selling, giving away or moving the sub to another system it is just that much simpler to do so. Quote Link to comment Share on other sites More sharing options...
sfogg Posted July 7, 2004 Share Posted July 7, 2004 Tim, " My sub is located across the room from my Receiver. I have the sub cable (RCA) run under the floor all the way across the room. I have two options. Place the plate amp near the sub, and have a long run of RCA to get the signal to the amp, with a short speaker wire run... OR place the plate amp near the reciever, have a short signal run, and then run a long speaker wire run to the sub (across the room). " Before you cut a hole in the box for your amp hook the amp up to your woofer and run however long of an RCA cable you need to to go from your equipment to the subs position. Then plug the amp into whatever AC outlet it would normally be using if the amp was mounted to the sub. This will be a quick and easy test to see if you are going to run into ground loop problems. If you do run into problems you can try to work through them. Or move the amp over to your equipment rack, plug it in there and run a long speaker cable to the sub and see if the ground loop goes away. I personally tend to like the amp seperate from the subs as it gives more flexibility for changing the amp driving the subs and you don't have to worry about having AC near the sub or potential ground loop problems. But I also have subs with amps built in too. Shawn Quote Link to comment Share on other sites More sharing options...
pennektj Posted July 7, 2004 Author Share Posted July 7, 2004 That for the advise. I like the thought of having the amp seperate because I can change the amps, sell the sub seperately... or simply hide the amp from site (make the sub look like funiture). I was thinking that having a long signal cable may cause the signal to pick up unwanted noise on the way to the amp... which would then be amplified by the amp and sent to the sub... rather than having the amplified signal be clean and sent over a long speaker wire run. I guess I was look for more of a signal / electrical engineer, to tell me what would be better. If it is about the same either way, then I guess I will just do what I think looks the best 1. Sounds Quality ALWAYS FIRST 2. Looks / Coolness factor SECOND Quote Link to comment Share on other sites More sharing options...
sfogg Posted July 7, 2004 Share Posted July 7, 2004 " I guess I was look for more of a signal / electrical engineer, to tell me what would be better. If it is about the same either way, then I guess I will just do what I think looks the best :)" There are arguments to be made both ways. The long RCA connection is more likely to pick up and RF/EMI noise which the amp on the other end will amplify like you said. And this method is also more likely to have ground loop problems. On the flip side the longer speaker run will have a higher resistance in the speaker cable which will lower the damping of the amp over the woofer. Use sufficient gauge wiring (12 gauge will cover you fine) and this won't be a problem. Really either method can be argued to be better then the other. It will depend on your own specific environment if you have problems with RF/EMI or ground loops or very long speaker level cable runs. In the end go with whichever works better for your needs. Shawn Quote Link to comment Share on other sites More sharing options...
hwatkins Posted July 7, 2004 Share Posted July 7, 2004 To be a bit two faced from my original recommendation, I have to side with Shawn on this a bit - I did have an amplified sub that was catching a radio station signal that was annoyingly being assisted by the resident plate amp. However, this anomaly was an overdriven transmission signal that could only be resolved by the offending radio transmission tower equipment. Quote Link to comment Share on other sites More sharing options...
pennektj Posted July 7, 2004 Author Share Posted July 7, 2004 This is exactly what I wanted to hear... There are benefits to each... and drawbacks to each. One is not the true blue, end all be all answer. I was planning on creating a seperate mounting enclosure for the plate amp, and running a long speaker wire to the sub... just wanted to make sure this wouldn't be the wrong thing to do. I am soo pumped. Going out to buy the polyfill after work today... Should be shaking things by end of next week... woo hoo. Tim Quote Link to comment Share on other sites More sharing options...
formica Posted July 11, 2004 Share Posted July 11, 2004 ---------------- On 7/7/2004 11:48:42 AM pennektj wrote: I was planning on creating a seperate mounting enclosure for the plate amp, and running a long speaker wire to the sub... just wanted to make sure this wouldn't be the wrong thing to do. ---------------- Having suffered from EMI/RFI, I feel there are more benefits of keeping the line-level runs short with longer speaker wires. Like mentioned, any interference picked up by the cable gets amplified... and longer cables have a great probability of crossing an electrical magnetic field (EMI) as well as acting as a "better" antenna (RFI). Also as mentioned plugging the amplifier into the same outlet as your receiver will eliminate the risk of a ground loop. Damping factor / resistance induced by the speaker wire is negligible versus those in the actual woofer... and therefore are a pretty mute point. You may want to look up some of John Warren's recent posts on the matter. The tempest should serve you well... later... Rob Quote Link to comment Share on other sites More sharing options...
tpg Posted July 11, 2004 Share Posted July 11, 2004 Just a note... there is a thread going on over at DIYAudio about polyfill in speaker boxes. The topic sort of deviated from the original point to include subs... The consensus was that polyfilling subs was NOT a good thing. I have done this with my sub and noticed less bass, less slam, less shake, less SPL... and so on. To paraphrase the thread... sub's produce such long wavelenghts that polyfill does nothing to dampen them because the box isn't even long enough for the entire wavelength. It was suggested to simply brace the box very well with MDF and leave out the polyfill altogether. I second that recommendation from my own experiences. Just wanted to pass that info along... Quote Link to comment Share on other sites More sharing options...
sfogg Posted July 11, 2004 Share Posted July 11, 2004 "Damping factor / resistance induced by the speaker wire is negligible versus those in the actual woofer... and therefore are a pretty mute point. " http://www.roger-russell.com/wire.htm Shawn Quote Link to comment Share on other sites More sharing options...
Dustin B Posted July 12, 2004 Share Posted July 12, 2004 The point of polyfill in a sub box isn't to absorb bass frequencies. The main use is to increase the appearant Vb the driver sees. http://www.integracaraudio.com/caraudio/resources/fiberfill/ Quote Link to comment Share on other sites More sharing options...
tpg Posted July 12, 2004 Share Posted July 12, 2004 Yes... I realize that... but if you are building such a large box anyway, there isn't any point to increase its volume any more. I was just pointing out that I stuffed my box as was customary and noticed a degradation in sound instead of an improvement. Quote Link to comment Share on other sites More sharing options...
formica Posted July 12, 2004 Share Posted July 12, 2004 ---------------- On 7/12/2004 10:56:09 AM tpg wrote: I stuffed my box as was customary and noticed a degradation in sound instead of an improvement. ---------------- Well, increasing the box size will reduce the Qtc... which, in general, will flatten the response of a sealed system. The max SPL will drop slightly... and bass will begin to roll off a little earlier but roll off slower. Yes, you can build the box bigger and not use polyfill... but I guess it depends on how large of a box you can live with. If you stick with the same size enclosure, which sounds better (a smaller Qtc versus a larger one) is more of a subjective characteristic. Rob Quote Link to comment Share on other sites More sharing options...
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