Digger8 Sub - diggity dig it all the way to 20Hz

[Pete Basel]

Re: Digger8 Sub - diggity dig it all the way to 20Hz

There is a version of the amp you used with 6 dB of boost at 30 Hz. It should be possible to lower the boost frequency by changing a few caps:

http://www.parts-express.com/pe/showdetl.cfm?partnumber=301-510

You might be able to do a passive shelving RC circuit if you have enough gain. Otherwise you just need an op amp.

[jsr]

Re: Digger8 Sub - diggity dig it all the way to 20Hz

Thanks Pete. I tried to get the best extension in as small a cab as possible without any EQ. I don't have any electronics that would add boost down that low. Perhaps in the future, but for now, I wanted it to be simple and low cost...just choosing the right driver and box alignment combination, with a efficient low-cost amp. I believe some of the O-Audio plate amps have adjustable EQs, but they cost considerably more than the Yung I used.
Modeled in a slightly larger 1.3cf cab, with a PR that has more excursion, it can hit an F3 of 15Hz and still take a decent amount of power.
What's the lowest cost method to add boost in the 20-25Hz range?

[Pete Basel]

Re: Digger8 Sub - diggity dig it all the way to 20Hz

Nice work, well thought out. It seemed too good to be true and looking over your sym I noticed that the true efficiency is a low 81.69 dB/W which makes sense for such a small box. The box will take a 12" and I have to wonder what the Infinity 1260 would do in that box sealed with say 6 dB of boost at 20 Hz. The PR and JBL driver are probably not too far off in price from the 1260. Curious just as a sanity check. I have simmed the 1260 but not recently and not in that small a box, I'll run one if I have some time. An LT would be ideal to fix any response problem with a 1260 but the 6 dB boost at 20 with the right stuffing might just work.
Again, nice design work, I like what you've come up with.

[jsr]

Re: Digger8 Sub - diggity dig it all the way to 20Hz

Hey Blenton! Glad to hear from you. Let me know when you get your machine up and running. I always have builds I'd like to explore. Yeah, these little Harmon 8's do impress me. I have an Alpine R8 in my car now and I do think it's cleaner, but doesn't go as low as the Harmon brothers. I need a bit of boost around 30Hz, but can't find a cheap method to do that yet (my external EQ only goes down to 50Hz).

Go rip that JBL out of your truck and DO IT!

I watched a movie a couple of weeks ago (forgot the actual movie), but was able to turn the sub up a bit and could feel my seat shaking from the LFE and no signs of stress on the PR.

[Blenton]

Re: Digger8 Sub - diggity dig it all the way to 20Hz

JSR!! Glad to see you finally got that thing put together! Sorry to hear those cnc'd panels didn't line up to too well - too bad I couldn't take a whack at machining some for you. Though, if things go as planned, I'll have my own machine in the next little while I'm glad you like that JBL. It looks awesome! Like I said, I've used both the JBL and Infinity Reference 8 (the 860w) in both cars and home systems and I'm super impressed with them. I would agree with your assessment of box sizes and configurations - car audio guys like the bump around 40 hz, while I usually tune mine to at least 30hz (ported) so they get extension in to the 20's. Sealed, with cabin gain, extension in to the 30's was definitely there, but you can forget about the 20's. They just seem to run out of gas, even with a little boost on the bottom end :( But seriously, for an 8 it has phenomenal performance. If it were a 10, it would still have great performance.

@upsman - It would be interesting to see what the Reference 8 with a Yung SD-300-6 would sound like for more music oriented systems. The small enclosure is very appealing and with a little boost down low, extension *shouldn't* suffer too horribly. But we'll see. 2 would be nice, but, heck, why not 4?!? In ~1.2 ft^3, that's barely the size of my single 10" home theater sub. I've got three sitting in the basement; if only I had one more, then I could try it... maybe I'll have to yank the JBL out of the back of my exploder and try it...

[jsr]

Re: Digger8 Sub - diggity dig it all the way to 20Hz

Hi Bob,
They only get to around 40Hz F3 without EQ in a 0.3cf. The recommendation online is for a car and doesn't quite work as well at home. I'll model it tomorrow to see how well it will do in a sealed box, but it will be larger. Or you can go with about 0.6 cf box with a PR...I think I modelled one that did pretty well.

EDIT:

Here's what I get for a 8.5L (0.3cf) net sealed enclosure with no EQ:
F3 = 37.8 Hz
F6 = 30 Hz
F10 = 23 Hz

With +4dB boost at 35Hz, you get an F3 = 31.4 Hz, but without EQ, it doesn't go very deep. I had the Infinity REF860W in my car in a ~0.3cf box (was about 0.28cf net) sealed and while it sounded good, it really didn't extend very low (and my car is small so I don't get too much cabin gain at the really low frequencies). Most car audio guys like a strong output around 40Hz, so most recommended tuning for car setups tend to either heighten that area or are fine with it rolling off immediately after that. I prefer it extending to at least low 30s in the car (but my current setup still doesn't due to space constraints).
The Infinity is very similar to the JBL...you can swap the 2 and not notice a difference. The Digger8 can be made with the REF860W also and have almost identical performance numbers.

[upsman]

Re: Digger8 Sub - diggity dig it all the way to 20Hz

JSR, Any idea how these would sound sealed. Amazon reviews say you can put into .3 ft/3 and get excellent results, dont know how deep they would go but maybe two for music might do the trick....I bought one to try out with a Bash amp.....


BobC upsman

[jsr]

Re: Digger8 Sub - diggity dig it all the way to 20Hz

Yeah, I mentioned a few times that the PR will reach xmax before the JBL, and that I have another PR I'm looking at should the Dayton not work well. So far I've not had a problem with excursion. The amp was chosen because it's not much more cost for much more power. It's not getting used at full amp power, but I have more power should I repurpose the amp.
I didn't use a HPF in the model because the Yung amps don't have one per info on PEs site...what PE tech said.

[johnnyrichards]

Re: Digger8 Sub - diggity dig it all the way to 20Hz

It is important to remember that most, (if not all) plate amps use some kind of rumble filter. I think the Dayton uses a 2nd order centered at 19hz, for example. It is not a spec they usually advertise, either.

[fastbike1]

Re: Digger8 Sub - diggity dig it all the way to 20Hz

The difference in our models is that I habitually use a highpass filter. If you look at your excursion plot you will see that it looks pretty ugly for the PR below ~25Hz and similarly ugly for the JBL below ~20 Hz. If you're running the sub to waht the amp is capable of, you are likely to shred the PR.

Here's the WBCD captures for the TyKy Digger8.

LR2 used for model because the Yung amps use a 2nd order filter. I don't know the type, so just LR since it's typically the most popular.

I'm really "diggin" this sub...so far it's been great with the LFE on movies. I haven't had a chance to run much music through it at decent volumes since my baby is usually sleeping in the same room.

[jsr]

Re: Digger8 Sub - diggity dig it all the way to 20Hz

I like the specs on the AE PRs and will likely go that route if I find I hit xmax too often on the Dayton. The AE's prices are more reasonable for me. Just their leadtimes are long (and often much longer than their quoted times). The Peerless doesn't seem available anymore unfortunately.

[dougc]

Re: Digger8 Sub - diggity dig it all the way to 20Hz

I dont know if their still available but I use the Peerless XLS 12" passive with the Dayton RSS315. The Peerless passive is awsome.

[jsr]

Re: Digger8 Sub - diggity dig it all the way to 20Hz

Here's the WBCD captures for the TyKy Digger8.

LR2 used for model because the Yung amps use a 2nd order filter. I don't know the type, so just LR since it's typically the most popular.

I'm really "diggin" this sub...so far it's been great with the LFE on movies. I haven't had a chance to run much music through it at decent volumes since my baby is usually sleeping in the same room.

[jsr]

Re: Digger8 Sub - diggity dig it all the way to 20Hz

I used JBL's specs as Bryan found. I think JR mentioned his old Infinity measured pretty close to mfr's specs. All are Harmon, so their testing and consistency should be the same. They have some nice low end umph while watching movies.

[bkeane1259]

Re: Digger8 Sub - diggity dig it all the way to 20Hz

the JBL driver looks pretty good for $47! Did you measure it or take JBL's specs? What are the specs? Can't read em at Amazon

http://www.jbl.com/estore/jbl/us/product/productDetails.jsp?pid=GTO804

Just scroll down till you hit the T/S parms