need thoughts on this sub amp

drew spelts

It is made by bash and my subs I am using only handle 300 Watts RMS so I figure there is "no real need" to go too much bigger on the amps. Also I will be using two of these amps, one per subwoofer. I want two seperated cabinets.

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-750

tryrrthg

If you don't need all the bells and whistles of a plate amp then I would suggest you get a pro amp to drive your sub. You simply can't beat the value of the Nady XA-1100 for $150. 475 watts per channel into 4 ohms. The only drawback they have is fan noise, you can either disconnect the fans or replace them with quieter ones.

http://www.digitallyunique.com/xa-1100.html

http://www.musiciansfriend.com/srs7/g=live/search/detail/base_pid/482053/

I have one and it is a beast. 45+ pounds, HUGE transformer. It will power my DIY sub that I'm currently building.

unc2701

What receiver do you have that'll be feeding the input to the sub amp? What are your sub speakers?

drew spelts

It will be a harman kardon AVR 635 due to arrive in less than a week. The speakers are the Alpine type R's 12" do not know the model #'s by heart but they are the ones that handle 300 watts RMS. I just felt that I did not need anything bigger because My room is 12X12X9 at best. my rear surrounds I already have and they are RTi6's and I still have not been able to locate a decent deal on some RTi10's for the front (around $600). The center of course will be a CSi5. Please send any and all thoughts and opinions. But please do not try to discourage me from building these subs because I am fairly nervous about spending all this money and not having them turn out worth a ****.

unc2701

Ok, your AVR has a crossover on it for the bass, so you don't actually need to use a subwoofer plate amp- any power amp will do. Now, the drivers are 4 ohm DVC, so you're stuck with 8 ohm or 2 ohm and that BASH amp can't handle 2 ohm- so at 8 ohm, it only puts out 150 watts.

So the question becomes: can you do better than 150 watts per channel for less than $140 per channel? How about this:
http://www.musiciansfriend.com/srs7/g=home/search/detail/base_pid/481578/

For $330 ($165/channel), you can load it down to 2 ohms, and get 570 watts per channel. Only problem might be fan noise, but you'll get way more power, way more durability, and probably better sound...

drew spelts

hmmmmm. See I had just figured to come out of the receiver with the LFE cables and into the bash plate amp. I thought this would be a really good setup. So are you saying that I can not use the LFE outs to the Bash with a 4ohm load to achieve 300W RMS. Just incase you forgot, I pan on using two plate amps because I am building two subs. Thanks for the help so far keep it coming. I need to learn more.

unc2701

OK, in either case you'll use the LFE out- that's fine. If you only had a full-range output on your AVR, you'd need more gear than just a power amp.

Is this the sub driver?
http://www.crutchfield.com/S-SJqhYoyLEux/cgi-bin/ProdView.asp?g=520&I=500SWR1242

If so, you cannot get a 4ohm load with those speakers and TWO amps. Each speaker will be 2 ohms OR 8 ohms. There are two voice coils, at 4ohms each. parallel them and you get 2ohm; in series you get 8 ohm.

Now, if you set both speakers up with parallel voice coils and put the speakers in series, you'll get 4 ohms. Hook that up to ONE bash amp to drive the whole thing and it'll put out 300 watts or 150 watts into each.

Note that this is eactly where you'll be with TWO of those amps, each driving ONE 8 ohm load. A single amp will work a little harder and get a little hotter, but adding a second amp in this setup gets you no where.

drew spelts

First off it is not exactly that speaker because that is a newer model that handels 500 watts RMS. Mine is extremely similer though. So what I am understanding is that it is the dual voice coils that kinda screws me. So why they heck do they advertise those speakers as 4ohms. I am kinda pissed now because the speakers will be here on like tuesday or wensday and I had planed to use them as 4ohms. ****. Please let me know what can be done. thanks for all the help so far.

Dennis Gardner

You can use them as 4 ohms just use one voice coil. Output with that Bash amp will be the same hooking up one 4 ohm coil or hooking both up parallel as 8 ohms.


People do it all the time. It will be down 3 db from using 2-4 ohm coils driven with a 300 watt amp.

I am more concerned with your low extension due to a proper box design. are these being used for music or movies?

drew spelts

so maby I should series/parallel wire them for a total of a 4ohm load all in one box and then i can use this amp from parts express unless you have any better ideas.

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-806

See, the reason I want an amp with the "LFE in" on it is because I read that it is the cleanest and clearest way to go. I would also like opinions on this with my receiver (HKAVR635) Looks like I am going with a single box now,,,,,,,,hmmmmm oh well at least it will be easier to build than all the mitered cuts for two completely seperate boxes. probably for the best too because the floor space is sorta at a premium anyhow.

Dennis Gardner

Sealed, ported, isobaric, what is your design? Are their designs specific for the woofers you've chosen or are you wingin' it?

drew spelts

ok the design will be copletely sealed and extensively cross braced.

Dennis Gardner

Choose whatever amp/woofer combo trips your switch, since they will all be total overkill in a room as small as you have. I run dual 12 inch ported Adire Shivas with 320 watts in a room 11X16 and never get close to using full power with them tuned very low at 17hz. You are worrying about details that will never be noticed since you will have way more bass than your receiver will keep up with.

drew spelts

so you must have a ported box in order to tune it to 17Hz. I am just looking for about a good firm 25hz. any lower is almost not practical. i bought the subs because i have heard them before and because the looks sooooo cool. Thanks for the help so far and check your pm.

Dennis Gardner

drew spelts wrote:

so you must have a ported box in order to tune it to 17Hz. I am just looking for about a good firm 25hz. any lower is almost not practical. i bought the subs because i have heard them before and because the looks sooooo cool. Thanks for the help so far and check your pm.

10 cubic ft. box within 2-4 inch ports 19.5 inches long. I can troll in the deep end...........