Need help picking my next subs

At $460 CAD for one, to check something once, ima pass. But I had thought about it.

 

See if you can lay hands on an affordable oscilloscope. It’ll do what a DD-1 will, verify your waveform isn’t clipping.

Lack of a subsonic filter COULD be part of the issue, might not be though. Can’t help the situation if you were playing really low freqs with a lot of volume. Though typically higher frequencies are harder on subs.

 

Thanks. I’ll keep my eye out for an O-scope, but I’m not sure where to start looking. I did, however, find a store here in Canuckistan that sells Sundown Audio. Two SD-4 D4’s coming my way.

 

https://www.seeedstudio.com/DSO-Nano-v3.html

This is what I started with

 

Thanks Ron. Looks like I can order an O-scope too. Much appreciated.

 

I'm one of those "gain knob is not a loudness knob" people. Getting a good clean signal does more good than anything. There are a good amount of videos on how to use the pocket o-scope on YouTube U.

 

I agree. Gain is NOT volume control. That O-scope you pointed me to looks like it’ll do the job. I’ll check out YouTube right now.

 

More than just protecting your equipment, proper gain setting makes everything SOUND better. I’ve seen and heard really great equipment installed by apes with horrible system tuning.

The end result is usually worse than what the individual started with. If you’re like me, car audio is never a “one and done”. Every install leads to another, and the tools and knowledge come in handy later.

 

You will destroy the formers on the SD4 before you see thermal failure. And there is no mistaking when you smack the former on the backplate. Like the SD3, the backplates aren't bumped. Due to low distortion all the way through stroke, you won't hear it coming. You'd want to set gains by voltage if anything in this case and maybe stay a little conservative.

If you're setting these up for 'normal' music, you should be getting nowhere near the subs' limits. Seeing how you have done it before though, it may be prudent to keep in mind that these aren't basshead subs. And they do have that Achilles heel. IMO you can't beat them for shallow subs and they're hard to beat in general. But unlike most of Sundown's offerings, overpowering these is dangerous. Definitely use a high pass and remember that you won't get any audible distortion beyond excursion limits to warn you...it's all hard parts on not as hard parts after that.

 

That’s good to know. I have an 8” SD4 going into my truck but wasn’t sure how much Sundown underrated this line. I know from their SA’s if they signal is clean they’ll take more than rated easily.

 

So, while waiting for my Sundown subs and O-scope, I re-read JLs instructions for tuning my amp. Start at 3/4volume, tune to 69.3VAC, then at moderate volume with everything reconnected, turn down gains. It says right in the instructions setting this way will allow for “moderate” clipping at full volume. I don’t believe that NOW. Going to set with the O-scope and make sure I don’t kill another pair of subs.

 

Which amp?

Never mind LOL

 

Yeah, I have issues with their instructions.

A. Yes, in theory, you can set gains using this method. But, when you set the gains for XXX power output at 3/4 volume on the head unit, any volume level above that is going to clip fairly quickly.

B. This method, in no way, accounts for distortion. If you pick a volume level on the head unit that is clipped, and set the gains properly, you’re still amplifying a clipped signal. If you start with clean input to the amp (from the radio), but then the gain up too high, you clip what was a once clean signal.

Alternatively, you could play a really awful recording that’s been “bass boosted” or modified in such a form that even with everything else set properly, your source signal is already clipped and nothing in your amp settings or head unit will correct it.

All that to say, there are a few “correct” ways to set amp gains, and a dozen ways that may or may not work. You need a way to verify you aren’t sending a clipped signal to the speakers, as much for sound quality as component longevity, and a DMM will never do that. A DD-1, or an oscilloscope, will. Some claim to be able to set gains by ear, but I lost half my hearing while enlisted so I certainly can’t.

 

I had the same issues with instructions for the VX1000/5i. I ended up calling JL and talking to one of their techs, who told me to do it the way I always have, and compare the results with the software (TuN). The DD1 and the TuN software gave me the same results (which was really cool)

 

12" Kicker CompR hit very very hard. I have a single 12 and it slaps. Doubt they will fit, but they are known to be able to withstand a lot.

 

Okay. After familiarizing myself with the O-scope, I got to work. On the “Low Voltage Input” setting, at full volume, at the lowest gain, I was clipping. Not good. So I flipped the amp to “High Voltage Input”, and tried again. SUCESS! On that input, I’m about a 1/3 up on the gain, and at full volume, I have a nice smooth sine wave. CLIPPING BANISHED! Subs arrive Monday, can’t wait to test it out.

 

Which scope did you wind up with?

 

Remind me, you’re using speaker level inputs to the amp?

A lot (not all) amps have “high level” and “low level” inputs. This is meant so you can configure the amp for either a “pre amp” input (RCA cable from an aftermarket head unit) or an already amplified signal “from the speaker outputs of any headunit.

 

It was a simple Kuman scope from Amazon. Seems to work well though.

I’m using line level inputs, but the deck is a 5V output. I’m not sure how JL has their amps set up, but 5V on the low input seemed too much.

 

Or, your head unit just clips at full volume which isn’t unheard of. One of the benefits of an oscilloscope, you can see that (even reading through the amp, bad signal in will be bad signal out).

As long as you’re not clipping I’m assuming you’re fine.