Peerless XLS Sub build

[Thooms]

Hi all,

Figured I'd make a thread to document the progress of my up-coming sub build

This will be my first speaker build, so it's going to be a bit of a learning curve, and I still have a couple of questions I was hoping I could have answered

The drivers I've picked are the Peerless XLS10, with the matching XLS10P passive radiator. I was going to go with a Dayton RSS265HO in a ported enclosure, but one day I looked and it had got 25% more expensive - so it was out of the question. Managed to find the Peerless drivers for the same price, and hopefully they should be as good, if not better.

Looking at other peoples designs and the application notes, it seems a volume of ~30L is optimum. I'm going to build a cube shaped enclosure, with the active driver on the front, and the passive on the underneath.

Power will be supplied by a used Paradigm PW2200 amp I found on a forum, which is apparently 371mm tall. I'm expecting this to arrive over the next couple of days, but this will set the side length of the enclosure.

The enclosure is going to be built from 18mm MDF (is this thick enough?), with a hefty brace down the middle. With an external side length of 371mm, this would put the volume at 37.6L, so with the brace, amp and drivers in there, I think it should be about right.

The passive radiator weighs 400g, so I've done some modeling in BB6. As far as I can tell, the system looks like it will perform well, in particular in the area of group delay - a property that was much higher with the Dayton drivers when I modeled them. This is important to me as the sub will mainly be used for music duties.

So far, I've got:

- A router
- Clamps
- Workbench
- Drivers
- Amp (on the way)
- Wood
- Roundover and a bigger cutter bit to recess drivers

I still need to get:

- Hardware for fixing drivers
- Glue
- More clamps
- Veneer
- Spikes?

Pretty much all I can think of so far. I've had a good look at several sites about enclosure construction etc - should be alright with that I hope. Measure twice and cut once and all that...

Gratuitous driver shot for good measure:

Image not available

Some simulations:


Images not available


Will be crossed at between 80 and 100hz with my main speakers. I imagine the room will help the sub out at very low frequencies to level the response out a bit more?

A few people who've built similar designs mention adding mass to the PR, to bring it up to about 600g - something I think I'll experiment with.

Is it worth ordering up a set of spikes for it?

I'll update this as/when anything else starts happening...

- Tom

Edit: Changed list of stuff.

[Carl V]

usually the active driver is placed down firing with the passive driver (PR)
in a Horizonatal position. Another popular option is for the drivers to be
placed oppossing, this cancels out some movement. And if any of your
drivers are indeed on the bottom you most assuredly need spikes or anything
to raise the enclosure at least 3" (75mm). Last time I used those drivers in a bass Bin was one 10" xlss & 2 passives all firing horizonaltally. Volume
was about the same. Used a Hypex plate amp with Rumble filter & a mild
boost at 25Hz. Your enclosure sounds fine, i'd add a another brace or
reinforcing 1x2 pice of timber i.e., not mdf along the unbraced panels.
You'll also want something on the walls e.g., dynamat BH5, bitumen pads etc.

Good luck & have fun.


PS
nice ride. I have a Gitane Cyclocross set up as as sgl speed with Front brakes I'm not a 'real man'.
Road bike is an old Bob Jackson lugged Columbus with old record stuff.

[JonMarsh]

Check whether either of the drivers are rated for vertical operation- most subs and PRs will sag too much in the suspension to be used that way. For that reason, I have to vote for Carl's recommendation of placement on opposing vertical sides, though as the PR and woofer motion patterns are quite literally out of sync (driver minimum motion at PR maximum motion for useful output), you don't get the same force cancellation as two active drivers on opposing sides.

Boundary lift should help with the balance between 100Hz and 20 hz. Keep in mind you'll most likely want a hi pass filter in your gain chain to prevent unloading the woofer below the PR effective region (18 Hz), because there are DVDs with material that low, and unlike a sealed system, there's nothing to limit excursion- quite the opposite below the max loading point.

[Thooms]

Thanks for the pointers gentlemen.

Jon - I hadn't considered the vertical operation. I like the sound of mounting the drivers on opposing vertical faces, and particularly if I add another 200g of mass to the PR and it's mounted facing downwards, then it deffinetly makes sense that it would sag...

I think a high-pass filter is a good plan, as the excursion really shoots up past the resonance point. If I add 200g to the PR the excursion is pushed lower, but obviously it would still happen. Also, that pushes the GD down quite a bit low frequencywise - not sure how it'd affect the transient response though. Probably just best to try it and see. Loses about 2db as it approaches 20hz it seems, but I doubt 2db at that frequency would be that audible?

Images not available

So spikes are a yes? I'll look into that.

Carl - do you mean along the faces, or along the edges? Or both? I guess if I don't have anything on the bottom I don't have to raise it up as much, and I much prefer the aesthetic of doing doing that. Thanks for the advice.

I'm loving the bike - had it a little over a year. Very comfortable over long distances. Campag Mirage with a Compact crank - I do sometimes wish I had a triple on some of the hills around here

Your bikes sound cool. I'd like to get a steel-framed bike some time. Probably very nice on some of the crappy roads here...

[Amphiprion]

I have an XXLS 10" sub with two matching 10" passive radiators. I want to say it's thirty or forty liters tuned to 25Hz. I built it two or three years ago, and have never had the chance to listen to it. The measured impedance graph looked great though.

[Johnloudb]

I built it two or three years ago, and have never had the chance to listen to it.

Mark, can you tell us why? I want listening impressions.

I'm still trying to finish my sub crossover, for some subs I finished a year ago. It works, just getting it all together now, in my crossover enclosure.

[Carl V]

Glue 1'x2' wood (oak) across the unbraced interior sides of the enclosure.
This will stiffen the unbraced enclosure walls. Resonaces will be spread out
and/or more random....also it will more than likley raise the resonant freq.

And spikes might not be needed if you don't have any drivers or ports
exiting out the bottom.

You graphs appear fine. The Hypex amps had a 16 or 18Hz Hi pass thus
protecting the 10' driver. Like Mark I used two PR.

Steel bikes ride & handle nicely on the rougher roads. Are you running
a 7 speed free whel cog set up? Unless you have some killer hills I doubt
you'd need a triple chain ring. Increase your Crank arm length if you can.

[deewan]

Wow, this thread is perfect for me. A sub build using the same driver I am looking into buying and bikes. Funny though, your Bianchi looks faster than my road bike.

Image not available

Subscribed!

[Thooms]

Hmm, it seems a pair of passives is the way to go. I guess that nets you a lower unloading point? Would it be worth buying a second? I'd rather not as the budget is a bit tight, but if it would make a significant difference it could be worth it...

I'll try to get the bits and pieces ordered up over the next few weeks, and then start the build

Initially I was going to buy one of the Hypex amps, but this Paradigm plate came up at too good a deal to pass up. I'll see if I can borrow an oscilloscope to investigate if there are any highpass filters in there. If not, a single LR4 high pass filter shouldn't be too hard to knock together.

Carl - The Bianchi has a compact 10 speed setup on it - so it's 50/34 up front, and 12/25 on the back. We have the odd 1 in 3 hill here so sometimes it can be a bit of a struggle 8O

Deewan - I imagine the Bianchi is a bit quicker, but your bike looks quite a lot lighter than mine lol

[Amphiprion]

Mark, can you tell us why? I want listening impressions.

Lack of a good listening room. I move around a lot, and haven't bothered setting up a proper stereo system in two or three years. Besides, a sub in an apartment would just get me in trouble I'm a headphone guy these days. I've even been thinking about a headphone amp project at some point. The TPA6120 is calling to me.

I've actually been meaning to loan it to a friend of mine who is currently running a Lambda sub from back when Nick was making them. I figure it'd be a good comparison since he is mostly into music and moderate (not loud) home theater. He's got a good dedicated theater room and I trust his opinion, I just have to find the time to drag it over to Austin (I'm currently working in Houston).

I can post pictures of the build and the impedance measurements in a separate thread if you would like. I still have all the data on my home machine.

[Bear]

Hmm, it seems a pair of passives is the way to go. I guess that nets you a lower unloading point? Would it be worth buying a second? I'd rather not as the budget is a bit tight, but if it would make a significant difference it could be worth it...

The second drone only really helps by canceling the opposing force; it doesn't lower the resonance one lick. In fact, you need twice as much mass with two identical PRs as you do for a single one to hit the same tuning. The CSS APR10/APR12 always looked the most interesting to me from a price standpoint. The design is nice, too, when you are tweaking the mass loading.

Carl - The Bianchi has a compact 10 speed setup on it - so it's 50/34 up front, and 12/25 on the back. We have the odd 1 in 3 hill here so sometimes it can be a bit of a struggle 8O

It's not the transmission, but the motor. I run a 50/34 front mated to an 11/23 rear, and yes, on a 10% grade once I was wishing for a slightly larger rear cassette. It can be pretty hard to tell the difference between 17-18-19, so an 11-25 or 11-28 may be my next purchase in another 10k miles. :T

[Amphiprion]

The second drone only really helps by canceling the opposing force

In my case I used it to help intentionally raise the resonance by leaving the passives at their stock 400 gram weight. Making a little 10" sub reach into sub 20hz region was something I wanted to avoid for fear of over excursion of the active driver in the range above where the passives took over. I was shooting for a 25Hz tune and planning on adding some mass to get there; turns out I was at 26.5Hz without any weight and the impedance curve looked fantastic so I left it.

[Txgrizzly]

Check whether either of the drivers are rated for vertical operation- most subs and PRs will sag too much in the suspension to be used that way. For that reason, I have to vote for Carl's recommendation of placement on opposing vertical sides, though as the PR and woofer motion patterns are quite literally out of sync (driver minimum motion at PR maximum motion for useful output), you don't get the same force cancellation as two active drivers on opposing sides.

Boundary lift should help with the balance between 100Hz and 20 hz. Keep in mind you'll most likely want a hi pass filter in your gain chain to prevent unloading the woofer below the PR effective region (18 Hz), because there are DVDs with material that low, and unlike a sealed system, there's nothing to limit excursion- quite the opposite below the max loading point.

Jon,
i built a ported sonosub tuned at 17hz (15" Titanic MKIII and 500w Bash plate amp) and i think i am hitting xmax on some scenes on movies. do you have something that shows how to set up a hi-pass filter? i am using the sub output on my receiver so i didn't think i would need to do this but now i am not sure...

Sorry to hijack the thread...

[Thooms]

Got the amp today, whee!

For some reason the previous owner cut the connector rather than unplugging it (your guess is as good as mine...), so I need to find a spare - or failing that, a suitable replacement. Anyone know what this is?



Images not available



I think it's one of these , but I'm not sure

I'll draw up some dimensions of the box and what the plan is for bracing etc at some point tomorrow, hopefully going to get the wood over the weekend. Router bits should be here tomorrow as well...

Guessing the amp should be good for about 250-300W RMS, looking at the components. The transformer is rated at 500VA peak which I guess fits in with that.

On to the amp itself - it has two sets of vent holes on it. I think I should probably cover these up - I'll be able to size the cutout to do it on one side, but I'm not so sure about the other. How critical is the quality of the seal with a PR sub?



Images not available



Thinking of finishing the box in veneer. This is something I've never done before, so I'm going to use the iron-on stuff. Is this fairly easy to do? As someone who is, shall we say, 'artistically challenged', does it take a massive amount of skill to do it right?

Had a look at the cone displacement at some different power levels, and I think a fairly steep filter at 18hz should keep things under control for the power levels I'm looking at (not anticipating running at over 300W).

Bear - I've had a look but can't find the CSS stuff in the UK. Must be one of the things that is a US only deal

Hoping to do some modeling when I've built it. Going to build a measurment mic I think as a little side project to help me set it all up.

That's all for now...

[Amphiprion]

Look on the connector for a manufacturer name. AMP, 3M, TYCO, HRS, something like that. I'll break out the Allied Electronics catalog and see if I can find a replacement for you. It's definitely a Mate-N-Lok connector. What's the center to center spacing of the conductors?

[Thooms]

It says 'AMP' on it in tiny letters, so I think that's what it must be

The conductor pitch looks to be a shade over 6mm, so guessing it's 1/4".

[Amphiprion]

OK, I think this should be an exact replacement, except it's black in color:

http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&WT.z_homepage_link=hp_go_button&KeyWords=1-480705-9&x=0&y=0

You'll probably need new socket crimp pins to terminate the wire and to insert into the plastic housing. If you look at the "Associated Products" list towards the bottom of the page, they will have a huge listing of pin and socket crimp pins. Just pick the right gauge socket crimp pin and you should be fine.

Also, Digikey will ship anything under 1/2 pound via USPS mail for $2.41 USD. Specify that in the comments in your order and they will do it. 2-3 day delivery time. Should save you a few bucks vs. Fedex or UPS.

Good luck!

[Amphiprion]

Nevermind, I just realized you're British. I've got no idea of the suppliers over there, maybe try Farnell? In any case the Digikey link will give you some manufacturer part numbers to search for. Hope that helps.

[Thooms]

Thanks for that Mark. They're just the job

They do have them at Farnell, but it's 'US Stock' - so it incurs a £16 delivery charge - on a £0.26 item! I'll see if I can get a pair on ebay.

Managed to get the wood yesterday - couldn't get the panels out of a smaller size sheet so ended up buying a 1220x2440mm sheet, and got them to cut it on their big saw as they'd probably have squarer edges with that than I could even dream of with a jigsaw...

So, got the panels for the sub cut, along with the panels to make one of CJDs RS150 MTMs, and a pair of ~20L standmount enclosures, which I've earmarked for some of Zaph's L18s. And some speaker stands. Should be enough to keep me busy.

Had my first play with the router today - was a bit apprehensive as I'd never used one before, but I was pleasantly surprised at how easy it is to handle. Trimmed a couple of panels a bit, and managed to cut the recesses for the drivers before rain stopped play.

Image not available

I'm definitely hooked.

[Amphiprion]

Hi Thooms,

Apparently Digi-key has a UK presence that I did not know about. They show the part as being in stock. Don't forget the crimp sockets too.

http://digikey.co.uk/

Cuts look good. Any ideas on how you are going to finish the box?

[oldloder]

Hi Thooms, looks like your hitting on a popular rig. I, too, am about to jump in with one of these setups. Actually, I've slowly been cutting and assembling cjd's RS150MT and was planning to add his MTM in the future! I was thinking about following along these lines:

http://www.tymphany.com/xls-subwoofer

but the PR I'll be getting comes with 265g. I suspect it'll be easy enough to add the requisite mass though.

I'd be interested in the box plans too if you drew any up. Did you go with the 1 PR or 2? And it might be worth a call to Paradigm to see if that amplifier has a rumble filter built in. Sometimes they aren't advertised, as when I talked to Parts Express asking about their sa240 plate amp that I ordered I was told that there was a rumble filter built in at 18 Hz - but there was no mention of it in any of their literature. LOL, I have to talk to them again tomorrow anyway, maybe I'll ask again just to make sure! If not I may ask for your high pass filter plans if it comes to that for you just in case!

I'm really looking forward to how yours turns out too, as I have about as much experience with this as it seems you do. Yup, hooked as well. I go with confidence with some stellar support though - my 9 year old son (actually who this is for) with his hands on every piece - we're learning together and will be following along.

[Thooms]

Not sure - I was going to do veneer but I'm not sure how easily that will go round the corners? I'm going to put a roundover on the edges so I think I'm going to paint it. My girlfriend suggested some kind of off white paint so I think I'll go with that, as it's destined for a shared bedroom.

Thanks for your help on the connectors Mark, hopefully I'll be able to find them somewhere, Digikey looks pretty promising.

oldloder - As it's my first DIY audio project I figured a tried+tested combo was the way to go. The PR has a bolt on the back so you should be able to add mass as needed. I'm going for 1 PR rather than 2, mainly down to budget. I'm going to build it with what I currently have, then maybe buy a second. It looks like the excursion on the passive gets excessive at low frequencies, so that's why the high-pass is sounding like a plan. If you're interested in filters (or pretty much anything else audio related!), this is a excellent site. All the projects are well documented, and the PCBs are of excellent quality. I've built an LM3886 amp on one of these boards which is just waiting for me to put it in a case

http://sound.westhost.com/

My box dimensions are a 372mm cube - so two panels 372x372, a pair 372x336, and finally a pair that are 336x336

[oldloder]

Agreed, great site and Beginner = tried and true, LOL. Nice thing about the PR's is you can just cut the hole and add it in and adjust mass. That's what I was going to do but the PR just went on sale at Madisound so I'll get one.

Thanks for the amp link and box dimensions. :T

[Thooms]

Update: Finished driver cutouts!

Image not available

Made a start on sorting the amp cutout but ran out of daylight. Hoping for good weather tomorrow

I'm hopefully going to order some hardware to mount the drivers. I'm thinking either self tapping screws, or threaded inserts. I can't get Hurricane nuts here as far as I can tell, and I'm not a fan of T-nuts.

Anyone used these? They screw in.



Should I go for them, or should self-tappers be fine? The material is 18mm MDF.

Ended up about 1mm round the edge. This is the passive - need to do a tiny bit of sanding for the active - but they both sit flush

Put a tiny chamfer on the edge too - mainly cos I wanted to try the bit out . Pleased so far, considering I've never used a router prior to starting this project.

Image not available

[soundemon]

I use the screw in threaded inserts you have pictured there - and I've never had any issue with them. I'll never go back to T-nuts. I highly recommend them, and against just using self tappers straight into the MDF. if you need to remove the driver, you're in trouble when you go to re-install...

[Thooms]

That was my thinking. I'd rather do it properly first time round than having to re-drill stuff or whatever. Thanks - I'll order those tonight

[Amphiprion]

Anyone used these? They screw in.

I absolutely hate them, and I think t-nuts are a much better deal. I used those threaded inserts on one subwoofer and will never use them again. I am, however, definitely in the minority with my views on t-nuts. YMMV.

That said, I hardly ever use either anymore. The black oxide pan head philips screws at Parts Express work fine and are cheap. Just set the torque setting on your drill low so you don't tear up the MDF, and you can remove and reinstall the driver several times without problem. And if you do tear up the holes, just fill them with wood putty and rotate the driver 45 degrees

[5th element]

I've used those in various constructions out of wood and MDF and like them a lot. I've never used them for securing a driver though, the one's I've got are M6, but I can't see why you'd have any problems.

[Thooms]

Update! Finished all the cutouts, though I might chamfer the amp cutout at some point.

Anyway, here are some photos:

Image not available

While probably not strictly necessary, for the sake of completeness (and because the novelty of the roundover bit hasn't worn off yet...), I scooped out some cuts to help the airflow around the driver.


Images not available


Amp cutout is the right size too which is nice - need to cut a couple of slots for the boards and heatsink on the amp though, but I was expecting that


Images not available


So, stuff I still need to do:

- Glue it all together
- Paint it
- Drill holes for amp/drivers/transformer
- Do some sanding

Not sure what to do with regards to clamping it together while I glue it - I'm thinking a pair of band clamps and a pair of corner clamps to keep everything square. Anyone had any experience of either of these?

[Thooms]

Well, it's more or less done!

Did all the gluing and installed the bits over the holidays - just need to do a bit of sanding and paint it.

Really really impressed. Bass seems very smooth, and it integrates beautifully with the rest of my system. I'd recommend this combo to anyone after a relatively small sub.

Only problem is that I get air leakage out of the phono sockets on the amp - not sure how to fix that one. Probably end up with some craftily applied bathroom sealant.

I'll post some pics when I find the card reader...

[Bear]

Only problem is that I get air leakage out of the phono sockets on the amp - not sure how to fix that one. Probably end up with some craftily applied bathroom sealant.

Silicone sealant is your easiest route. Just don't go overboard. Your next option in terms of PITA factor would be to build a sealed box around the backside of the amp. However, that is something that is typically best done during design, and not after finished construction. :T

[Thooms]

Silicone sealant will be my first step I think. Building a sub-enclosure sounds like a mahoosive mission!

Sanded it today. Been enjoying it too much to take it apart and do more work too it

Image not available

Any advice here? Is the transformer too close to the speaker? Doesn't hum, but could the fields be interacting and causing issues for anything? Would I be better off putting it further away from the magnet, or is it alright where it is?

Image not available

When I took it out it seemed quite hot, even though the system was basically idle (yes, it was unplugged and the filter caps had been checked to insure there wasn't a huge amount of energy still stored)

Image not available

Finally, wiring. It's a bit messy at the moment. Anyone got any nifty products I can use to tame this a bit? The tape doesn't really cut it

The autofocus got in a bit of a pickle - sorry about that.

Image not available

Where we're up to for now:

Image not available

So far, I'm -loving- it. Going to invest in a processor or something to get a bit more control over the crossover (currently using the pre-out from my Cambridge Audio amp, so my speakers are still running full range). Might build something nifty - haven't decided yet. Also need to brace the interior walls. Can't decide if I'm getting cabinet resonance, and I can barely lift it as it is, but I'm going to do it anyway in light of previous recommendations.

Jobs still left to do (in no particular order):

- Paint
- Make some felt seals for the dials/plate amp
- Sort out the leak from the phono sockets
- Get some nicer fastenners on the amp (just crappy woodscrews atm, thinking some cool cap headed self tappers)
- Add some bracing
- Get some feet or spikes or something
- Listen to more music
- Get something a bit more sophisticated to handle the x-over

Currently, listening to stuff is at the top of the list. It's my first sub and I'm just loving it. Hearing stuff I've never heard before (my Mordaunt Short speakers go pretty low for smallish stand-mount speakers, but the sub is obviously in a league of its own), and some stuff is just so fun to listen to with the sub. Watched 'Transformers 2' (or most of it - it was a bit late and it's not a very good film), and the bass is insane. Done some experimenting with placement and it seems to sound great after a few experiments with location/phase/x-over.

Hardly ever seem to be making use of that huge excursion too - quite scary really. 'Julie and Candy' by Boards of Canada is a real eye-opener

Really impressed. Always puts a smile on my face, which I guess is what it's all about. Also keeps getting better seemingly, I guess it's a break-in type situation - or something.

[Amphiprion]

If you can't detect any 60Hz (or 50Hz) hum coming through, then I would think the transformer position is perfectly fine.

[Thooms]

Another update:

Well since getting stuff inside it and working I've had less and less desire to take it apart and mess with it lol

BUT, I took it back to my parents house over the holidays to get the bracing done - what a transformation!

I was more than satisfied with it before, but with one song in particular a certain bass note would be much louder than the rest. I initially put this down to the room, but it turns out this was actually due to the walls flexing.

The person who lived in our old house before we did was a joiner, and he left some big bits of lovely hardwood in the shed which we couldn't bring ourselves to burn, and had been saving for a project. Well, 13 years (!) down the line, they've found a home!

I cut some 45 degree angles in the end of some huge (40mm x 40mm?) bits of mahogany, and glued them across the two empty walls, with some other bits across the bottom and some blocks in the corner - a really fantastic difference - excellent call Carl! Certainly the best value for money thing I've done on the project so far :lol:

The sub seems to disappear a bit better now. I also tried hooking up the driver with the polarity reversed, as I was having difficulty in getting the phase alignment right with my main speakers, and wondered if the PR has a strange phase response or something. This seems to have worked very well too. Using the pre-out on the amp, the gain on the sub is set to about 20% and it matches great.

I still haven't got the sealant done. I think I'm going to try some hot-melt glue. A couple of other jobs to do with sealing the amp, but the felt gaskets i made for it and the drivers seem to have made a positive difference too. There is certainly less noise greater amounts of excursion than there was previously - perhaps when I sanded it it wasn't a completely uniform surface.

It's like getting a whole new sub...essentially for free! (Well, I did steal a bit of glue, and the felt set me back about £0.80, but I can't really complain lol)

These Peerless drivers continue to impress.

Remaining jobs:
- A few more jobs with sealing the amp
- Paint
- Some feet/spikes

[Dresden]

No! Don't Do It!

@Thooms: I was browsing for information on this driver when I bumped into this forum discussion, which is quite informative.

I realize it's an old thread, but nevertheless...

In reference to your last posting, I advise you to NOT use adhesive silicone, nor adhesive anything, nor hot glue--they are not necessary to form a proper seal of driver and/or plate amp to the enclosure. (If you do use adhesive, you will most likely succeed in partially ruining the enclosure, given that removal of any component will prove difficult, if not impossible, without damaging said enclosure.)

You could, however, use regular silicone--the type used to seal bathtub liners--so as to avoid any permanent adhesion. (And it's very important that it is not an 'adhesive' type silicone product.)

You'll thank yourself later, should a need for modification or repair arise.

[Thooms]

Hi there Dresden,

Sorry I missed your post - I don't check back often enough it seems!

I did try some hot melt to bridge the gap between the plate and the phono sockets, but it just made it leak somewhere else.

Right now my plan is to build a new amp from scratch - a 6mm plate of roughly the right size isn't too costly, and as I'm mid-way through an active speaker project I already have the crossover.

Not sure I trust this paradigm amp. It has way more components than it looks like it should - no idea what all the filters are or what they're doing - I'd prefer to do it myself and know exactly what's in there.

Will probably just go with the minimum of connectors - AC in, mono RCA in, gain and a phase switch. Will probably use some kind of input detection so I don't need a switch on there to power it up.

That's the plan anyway - but it's still working great at the moment

Makes stuff rattle with ease - it's turned up to about 20-25% at the moment.

In light of how efficient it seems to be, I'll probably build a 150-200W mono amp. Maybe a switchmode amp

There's no hot melt on the cabinet though - that would indeed be a nightmare!

Edit: Forgot to say - this hasn't completely halted. I'm working on some feet at the moment. Just figuring out what to use for spikes...

[cosmindaniel12]

If you're building the new amp from scratch, try to add a phase controller with a knob, instead of a 0-180 degrees switch. It would help integration with the satellites.

Bracing was indeed required for this sub, as 18 mm MDF is pretty thin for a subwoofer this size and power. You could try connecting opposite panels. Something like this would be great:

http://www.vikash.info/audio/xls10/images/brace01.jpg

but this would also work well:

http://www.subwoofer-building.com/enclosure/images/pics/my-diy-subwoofer-bracing.jpg

Other than this, great build! Congratulations!

[JonP]

I did try some hot melt to bridge the gap between the plate and the phono sockets, but it just made it leak somewhere else.

Sealing well is a good thing, you might have a bit more to gain if you're leaking some.

Lots of folks build a enclosure for the amp, so it doesn't have to be airtight. Not all of them seal well, as you're seeing. Don't know if adding one would cost you too much volume, and a retrofit would be a lot of work... You might try globs of some adhesive materiel on the backs of connectors, etc... Be sure it won't have solvents or chemicals that might negatively affect electronics (some silicones with acetic acid)

If your leaks are fairly small, they probably have little effect and won't be worth major work to fix.

[Thooms]

Well, I've managed to procure a suitably sized piece of 1/4" aluminium at a price I couldn't refuse (read: Free 8O), so I guess the amp build is on - current plan is a switch-mode amplifier and a phase adjustment.

The plate should be sufficiently thick to brace the other side with, and I could do another brace top to bottom.

When I built the thing I didn't have a whole lot of extra volume to play with, as I wanted to make the thing as small as possible. The paradigm amp is quite deep as there's a big sticky-out PCB so it'd eat a good few litres to build an enclosure.

Using some O-rings or something it should be possible to get a nigh-on perfect seal.

Currently the leak is only apparent at high volumes and/or extremely low frequencies, but I'd still like to get it sorted. Plus, then the whole thing'll be DIY, which has got to be good

I'll post up some progress when I get somewhere with the amp.

[Johnloudb]

I bought a couple of these for a sub amplifier build, but haven't used them yet. But, the parts quality is really high for only $43.00 a board. It has 10 Toshiba output transistors rated at close 150W per device as I recall. It should be capable of much more that the 300W with a robust +/- 60volt supply and heatsinking, though as you stated your needs are less. It's an efficient sub so you wouldn't need a 60 volt supply, of course.

http://cgi.ebay.com/New-300W-LME49810-Mono-channel-Audio-Amplifier-Board-/230538976582?pt=AU_Car_Parts_Accessories&hash=item35ad319d46

It uses the LME49810 national power amp driver chip which is capable of very low distortion.

http://www.national.com/pf/LM/LME49810.html#Overview

So, to the naked eye it looks good, though I haven't powered them up yet.

Class D is more efficient of course, with less heat.

Just thought I'd point this board out, given the low cost.

[Thooms]

That does look interesting, thanks John!

I'm building a couple of TC2002/STA517B chipamps for the mid in my biamped system, tempted to bag another for sub duty.

Do you have one of those kits? I've heard conflicting reports about them, counterfeit semiconductors etc - the board looks pretty decent though.

Tempted to have a stab at one, spotted a couple of JLH Class A boards on there too which seems like an interesting proposition

http://cgi.ebay.co.uk/Pure-Class-SEPP-amplifier-PCB-JLH-1969-original-/320591444821?pt=LH_DefaultDomain_0&hash=item4aa4bd3b55

Edit: I hasten to add, these aren't the plan for a sub amp lol

[Johnloudb]

Yes, I have two of the stuffed boards which come with a schematic. The schematic is slightly different from the actual board in that it has only 6 output transistors.







I don't why they say not use a supply with more than 45 to 48v DC, cause all the caps are rated at 100 volts. The transistors as I remember are rated above 100 volts as well.

However to get more power you also have to up the voltage on the LME49810 from 60 to maybe 85 volts. It can handle as much as 200v DC I think, but that would mean replacing some caps with higher rated ones too.

So this board needs two power supplies, one for the output stage and a small one for the driver chip.

Best I can tell all is legit, but I have yet to actually fire one up, so I can't say for certain. To fake something like this would probably cost them more money, I think.

Yeah, I've heard the JLH was quite an amp. You might know Nelson Pass also did a mod of that amp converting it to Mosfets and changing it slightly. He called it the PLH!

Don't if there are any boards for that though. Someone might have done one at DIY audio though.

John

[Amphiprion]

The reason for the power supply voltage limit is due to the SOA (safe operating area) of the transistors. You have to derate their voltage handling at a given current level / temperature. Attached is the SOA chart for the transistor in the schematic linked to on the ebay page (2SC5200). Basically if you want an amp or more out of each transistor you better be well under 100V rails not even accounting for temp increase (which is going to depend on your heatsink).

http://sound.westhost.com/soa.htm

[Johnloudb]

Thanks Mark, that's good to know. I figured there was a catch somewhere.

Well, I knew you had to derate the power with increase in temperature, just didn't think it would be that drastic.

John

[Johnloudb]

Not trying to hijack the thread, but just took another look at the data sheet for the output devices. I see that just one complimentary pair of output devices is recommended for a 100 watt amplifier. So, I think there is likely a lot of safety margin with this board, probably cause it is DIY. Though, I haven't done any calculations.

When you put more current into the load, the voltage across the output device also decreases. So the power dissipated by the device doesn't increase linearly with output current.

With good heat sinking I think the case temperature should remain well below 50 degrees C.