Velo rebuild project

[j_garcia]

I've got this old F1200 servo that is relatively dead. Amp appears to work but it pops and makes a few tones when powered up and then does not play anything with signal applied. SO, the cabinet is still in good shape, more or less a 16" cube, sealed, with the amp internal to that space (not sure if it is enclosed internally). Guessing it is about 2ft cubed internal volume. What might be a good driver to go in there? I am thinking about just pulling the driver and amp, and dropping another driver in there, filling in the hole from the amp with a cover plate and posts to be fed from an external amp. I might not mind dropping a few hundred bucks into it including an amp, but since it is just a fun project, it would probably be better to keep it on the cheaper side. Thoughts?

I sent Velodyne an email to see if they had any input as to whether or not that amp might be usable for something; waiting to hear back.

 

[adwilk]

Are you wanting to stay with the same size driver?

 

[j_garcia]

Yes, the easiest I would say would be to stick with a 12" driver so mounting would be straight forward. Why? I could drop down to 10" and I already have a 10" free air driver laying around somewhere I think, but just screwing another 12" in means nothing to fabricate.

 

[adwilk]

I can't imagine the amp not being useful. I'm trying to figure out how to get these programs to work backwards into recommending a driver. There has to be a way. I'm sure somebody will know a 12" driver that works under those parameters. I'd imagine you'd have a handful of pretty good options- even leaving the amp in place if the enclosure were modified even a little bit.

EDIT: Oh, the amp doesn't work.. nevermind

 

[j_garcia]

I think the amp works, seems like the driver is the issue. Guessing it is the servo feedback system and could be either in the amp or the driver, so depending on what Velodyne says, I may still be able to use the amp. No doubt there are going to be drivers that will work in this box.

 

[Swerd]

The Parts Express RSS315HF works well in a sealed cabinet 1.8 to 2.0 ft³.

It requires an 11 1/8" diameter cut-out hole for non-flush mounting. Overall diameter is 12 3/8".

 

[BoredSysAdmin]

The Parts Express RSS315HF works well in a sealed cabinet 1.8 to 2.0 ft³.

TLS already modeled this one
http://www.drmarksays.com/wp-content/uploads/2008/12/dayton-rss315hf-4-12-sealedt.pdf

but in vented it really shines

 

[TLS Guy]

TLS already modeled this one
http://www.drmarksays.com/wp-content/uploads/2008/12/dayton-rss315hf-4-12-sealedt.pdf

but in vented it really shines

The problem is that driver sealed has a high F3 and little room for Eq as xmax is only 14 mm. So you have a choice of high F3 or limited spl.

Your best solution is a new 10" woofer/ABR combo from SEAS. This unit has a an xmax of 28 mm and is pretty sensitive.

With the ABR in your enclosure you would have good output to 20 Hz. You would need to screw on the 20 GM wt for your 2 cuft enclosure, which is about 50 liters. If you think the volume with driver and ABR would be 1.4 cu ft or 40 liters you would need no mass added.

This combination looks like a very easy way to design good compact subs. All you need is the chart in the ABR pdf.

This system ought to be a good seller in the DIY market.

 

[j_garcia]

$240 for the driver alone is a bit more than I'd like to spend. I haven't even opened it up to see what kind of bracing or structure is in there, but I could put the driver on the bottom and the PR in the front if there is no bracing to remove.

 

[TLS Guy]

$240 for the driver alone is a bit more than I'd like to spend. I haven't even opened it up to see what kind of bracing or structure is in there, but I could put the driver on the bottom and the PR in the front if there is no bracing to remove.

It is pretty hard to brace an already finished cabinet. I would do as you suggest. You can get the Dayton woofer tester to add just the right mass to the ABR.

The solution I suggested will get the most bass out of that volume and be cheaper than more expensive drivers a lot of amp power and equalizers.

 

[j_garcia]

Velodyne hasn't responded I am guessing they don't like the idea. What I was saying about the bracing is, if there is already bracing in there, I don't want to have to remove it to install the drivers, so that may complicate things to be able to install a PR and driver. That's why I was looking to go with just a sufficient driver to work in that volume.

I just moved this weekend, so I don't even have time to take it apart right now. Maybe later in the week.

 

[TLS Guy]

Velodyne hasn't responded I am guessing they don't like the idea. What I was saying about the bracing is, if there is already bracing in there, I don't want to have to remove it to install the drivers, so that may complicate things to be able to install a PR and driver. That's why I was looking to go with just a sufficient driver to work in that volume.

I just moved this weekend, so I don't even have time to take it apart right now. Maybe later in the week.

The thing to do is look when you get time.

To get good bass out of that unit, you will have to have a driver that will take some serious Eq and the amp power to drive it.

Servo control is just one way of providing Eq, to a speaker. It has actually not been shown to have significant advantages over simple calculated Eq, with a high quality linear driver, in fact the reverse.

If you want to use that space without Eq then an ABR is about your only option.

 

[lsiberian]

Honestly I wonder if it's worth the effort.

 

[j_garcia]

Well, there are always the Rythmik servo kits. Both a GR and a Rythmik offering, so servo is a possiblity, but both kits are $500 and $550 currently. I will shoot Rythmik and GR an email and see if either will work in that box.

Honestly I wonder if it's worth the effort.

Yeah, that's almost what it sounds like. That's why I said would prefer to do it cheap. Not something that will remove paint from the walls, just something functional. And at $500 I could just buy another sub

 

[j_garcia]

Velo responded and said there isn't another driver that will work with that amp, so pulling both. They did send me a schematic for the amp.

 

[TLS Guy]

Velo responded and said there isn't another driver that will work with that amp, so pulling both. They did send me a schematic for the amp.

So that makes that amp potentially repairable.

 

[j_garcia]

Yes, but I am not sure the amp is the issue. It powers on, gives a green light and provides signal to the driver. I presume it is testing the servo feedback loop and when it can't, it simply doesn't send signal. There's a dude in town who fixes old gear like this, maybe I can take it to him with the schematic and have him look at it. What they are saying is, if the driver is the problem, there's no replacement for it so the amp does me no good; in which case I would put it up for sale as there may be someone out there who has one with a dead amp.

 

[TLS Guy]

Yes, but I am not sure the amp is the issue. It powers on, gives a green light and provides signal to the driver. I presume it is testing the servo feedback loop and when it can't, it simply doesn't send signal. There's a dude in town who fixes old gear like this, maybe I can take it to him with the schematic and have him look at it.

When you take it out make sure the accelerometer has not fallen off the driver, far from an unkown problem. That would be an easy fix.

 

[BoredSysAdmin]

you could try to snag JL 12W7 of ebay

It would work very well in 2ft3 sealed box and would kill any commercial built $500 sub... Only issue is you would need [strike]a 1.21 Gigawatts[/strike] 1000 watts of continuous power, like announaki built 7 years ago:
http://forums.audioholics.com/forums/diy-corner-tips-techniques/15445-beast-its-lair.html


I don't know if 12W7-3 is similar to 12W7, but there are few more for sale:
http://www.ebay.com/itm/1-JL-Audio-JL12W7-3-1-Way-12-Car-Subwoofer-/260974738137?pt=Car_Subwoofers_Enclosures&hash=item3cc34e7ad9#ht_500wt_1413
http://www.ebay.com/itm/JL-Audio-JL12W7-3-1-Way-12-Car-Subwoofer-/300675441983?pt=Car_Subwoofers_Enclosures&hash=item4601a7253f#ht_500wt_1156

 

[lsiberian]

I honestly am opposed to this for a new builder. If you give me the dimensions i can reverse engineer the volume and maybe find a good match.