HTIB sub replacement

[chemicalbrother]

My buddy wants to upgrade his 5 year old Kenwood HTIB sub. It's still barely functioning, but a 6.5" driver with a torn spider wont last long with rap music.

We have about 2.5 cubic ft external to work with, $100, free wood, and the possibility of salvaging the amp from the current sub. Primary use will be for music- mostly rap and metal, with some video games and movies. Placement is in a living room of 18x12 ft that opens into a kitchen/eating area of 10x12 ft. I'd like to fit a ported 10", but a single 8 or pair of 6.5s wouldn't be out of the question.

Looking at the current amp's manual, it provides 70 Watts RMS @ 6 ohms with .7% thd, a built in non-adjustable low-pass filter set to 200hz, and a subsonic filter. Should we trust the numbers and use the amp anyway, or buy a new one with better features, such as the Dayton SA70 from Parts Express or Foster WF-100K from the NHT close out?

I'm trying to mess around with WINISD and different drivers. What should I be looking for in the curve? Anybody have personal experience with various woofers or amps?

[chris661]

When you're modelling drivers, look for bass that looks as flat as possible. Ideally, keep the curve between 0dB and -3dB for as low as you can.
Something else to look at is the excursion curve. You can change how much power is going in, so play around and see how much power each choice will take before you pass the red line. Below 20Hz, this won't matter, as the amplifier has a subsonic filter that will protect it there. Around 30Hz, you'll probably be Ok for excursion - few tracks have bass that low, and when they do, they're seriously reduced in volume to protect subwoofers. So, look at excursion from maybe 35Hz and upwards. If it passed the red line, think seriously about different drivers (assuming you're comparing them at the same power).

I doubt you'd gain much from a complete new amplifier. It sounds like the current one has been driven hard, so it might be an idea to replace the capacitors in it's power supply. With most commercial gear, they are seriously under-done, so putting new ones in will certainly help.

Chris
PS - some people have had good results with these
Parts-Express.comayton RSS210HF-4 8" Reference HF Subwoofer 4 Ohm | subwoofer Rss210hf-4 8" subwoofer dayton reference rs sub dayton loudspeaker

[Cokewithlime]

Originally Posted by chemicalbrother

I'm trying to mess around with WINISD and different drivers. What should I be looking for in the curve? Anybody have personal experience with various woofers or amps?

With only 70Watts to play with you will need a sub driver with pretty high efficiency to get reasonable output levels - one such driver is on sale at PE right now the Peerless10" XXLS Subwoofer (92 dB 1W/1m). In fact any drivers that you are considering for use with that amp should be at least 90 dB 1W/1m or better.

The Dayton 8" sub that chriss661 mentioned is a good driver but a poor choice( low efficiency, only 83.5 dB 1W/1m) if you are going to stick with the current 70W amp.

Also, since the current amp you have doesn't have any bass boost capability you will probably have to go with a ported cabinet design rather than sealed to get any reasonable amount of LF out of whatever driver you choose.

If you are open to replacing the entire old sub, figure out what sort of budget you want to spend and I'm sure many of us on here could help you with the best choices price/performance for the comonents.

[chris661]

Originally Posted by Cokewithlime

[SIZE=2]

The Dayton 8" sub that chriss661 mentioned is a good driver but a poor choice( low efficiency, only 83.5 dB 1W/1m) if you are going to stick with the current 70W amp.

That's a fair point. Should've checked that.
On saying that - how much power is needed? 70W at low distortion is more like a conventional 100-120W amp...
According to one reviewer, you'll hit Xmax at 30Hz with 40W, so perhaps it will be enough.
I suppose that needs clearing up a little. How loud will it be used? Constant party levels, or movies.......

Anyway, that driver was just an example.
http://www.parts-express.com/pe/show...number=264-833 has better efficiency, slightly higher resonance, looks more suited to a sealed box.

Here's a point - even pretty low efficiency speakers are generally used at 1 watt, maybe two. I find I'm pushing pretty hard at one watt into my system (efficiency in the mid-80s), woofers visibly moving etc.

I'm rambling so I'll shut up now.
Chris

[Cokewithlime]

Originally Posted by chris661

Anyway, that driver was just an example.
Parts-Express.com:Tang Band W8-1363SB 8" Subwoofer | subwoofer 8" subwoofer neodynium subwoofer tangband tb speakers tangband-22008 has better efficiency, slightly higher resonance, looks more suited to a sealed box.
Chris

Chris - not to labour the point but that TB with 70Watts will only make about 100db below 80Hz. The OP suggested that the main use for the sub was listening to rap and metal - I don't think those LF levels will do it for them - - Especially in the size of the area that the OP wants to use it in.

The driver I mentioned earlier will easily get him 106+db with the same 70 Watts.

[chris661]

100dB is surprisingly loud...

Especially when you consider that most bass is around 12dB down on the rest of the music, the mains will be pushing over 110dB, which is getting silly.

Your driver suggestion is probably the right one for the job though.
Qts suggests vented box, but the fs is a little high. I'd expect decent extension to the mid-high 30s, given a good box. EBS would get it to go lower still. Good excursion, so I expect an EBS would be the way to go, assuming there's enough space...

Chris

Edit - I know it's a little more money, but http://www.parts-express.com/pe/show...umber=264-1106 has a much lower resonance, at the sacrifice of a few (2) decibels.

[chemicalbrother]

I doubt you'd gain much from a complete new amplifier. It sounds like the current one has been driven hard, so it might be an idea to replace the capacitors in it's power supply. With most commercial gear, they are seriously under-done, so putting new ones in will certainly help.

That's good news to me, as it means more money can be put towards the woofer. However, I don't have enough experience with electronics at that level to know exactly what I'm looking at and what the parts do. I could tell if a capacitor is leaking, and what "size" it is, but not much else.

Thanks for the WinISD tips, as well!

I suppose that needs clearing up a little. How loud will it be used? Constant party levels, or movies.......

It's not uncommon for my friend to have the sub at party levels for hours at a time nearly every day, regardless of distortion levels. Movies will typically be loud, but I suspect his 3" satellite speakers will be much quieter compared to the new sub.

He has since stated that he wont go smaller than 10", which seems fine by me. We aren't limited to 2.5 ft^3; as long as the enclosure is 20inX20in, the third dimension is variable. However, he is firm on the $100 price cap, and he wont actually be purchasing anything until sometime in March. I'm not opposed to buying used, if that is what it takes to stay in budget.

I've heard nothing but good things about Peerless and Dayton Reference, but will continue to model different options.

EBS would get it to go lower still. Good excursion, so I expect an EBS would be the way to go, assuming there's enough space...

I was under the impression that EBS alignments were good for movies and extremely low rumble effects only, am I mistaken: EBS alignments can provide an even signal across the same bandwidth with increased efficiency at the expense of a larger enclosure compared to conventional ported designs?

[Cokewithlime]

Originally Posted by chemicalbrother

I was under the impression that EBS alignments were good for movies and extremely low rumble effects only, am I mistaken: EBS alignments can provide an even signal across the same bandwidth with increased efficiency at the expense of a larger enclosure compared to conventional ported designs?

EBS alignments are just a way of extended the F3 point to achieve more LF (yes, at the expense of a large cabinet), however once you factor in typical room(boundary) gain (approx 3db)(something that WinISD won't show you) a well designed EBS alignment will come out very smooth overall.

In your look for drivers just remember that high efficiency (90w/1m) is probably more important to your situation than just Fs or xmax

[chris661]

You seem to be modelling drivers now, so give it a try. After selecting ported box, you have the option of selecting different styles. I'm not sure what they're all for, but the EBS -3 and -6dB mea you can get lower than normal.
As Cokewithlime said, room gains will happily flatten out the -3dB one, not sure about the -6dB dip, but somewhere in between might be worth a look.

Here's a nice link to some different kinds of cabinets - I find it's handy for reference.
LDSG Appendix A - Enclosures

Chris