n00b needs help with RL-p15 build

[jasonmac]

I was thinking of doing an RL-p15 build.

I'm trying hard to read up on subwoofer design but I was hoping to get pointed in the right direction to help guide me.

This is my room:



I'm renting, so the sub needs to be free standing. Due to the renting situation I'm not going to play it at extreme volumes but I still want some great bass that balances well with my system.

I'm handy but don't have a lot of tools so I would prefer a simpler construction method and prefer a box/cabinet to a tube. My daughter stays with me 2 nights a week so it needs to be 'robust'.

This is for HT only (I have separate hi-fi in my home office).

Where is a good sub position given my room layout and dimensions? I'm also currently planning some bass traps for the three room corners so I was thinking of using the rear wall between the two rear speakers. Any better ideas? I haven't done any room measurements yet but I have a mic on the way and plan to use REW ASAP.

Is the RL-p15 a good choice for me? As I live in Australia I would like to order it ASAP to allow shipping time.

I'm not too concerned about budget A man can live on bass alone right?

Any suggestions on sub design and dimensions?

Thanks for any help in trying to fast track this project!

[Rodny Alvarez]

Hey Jason!!

look at this designs..........



http://www.hometheatershack.com/foru...-database.html

[Mike P.]

The RL-p15 is an excellent sub. Is this for HT and what amp will you power it with?

[Rodny Alvarez]

Mike P. wrote:

The RL-p15 is an excellent sub. Is this for HT and what amp will you power it with?

I guess you don't have your glasses on.........again..............

This is for HT only!!

[Mike P.]

I did have them on! Obviously I need new ones!

[jasonmac]

For the amp I was thinking about using the SGR-501 Plate Amplifier (500W RMS / 4 Ω (1000W Peak)) but I was thinking the extra grunt of the EP2500 might be best for HT usage. Is this correct?

There are some awesome builds in that members thread. I'm thinking of a ported design atm.

Would the rear of the room be a good single sub position?

[Mike P.]

The EP2500 would be give you a 3 db advantage over the SGR-501, assuming the sub doesn't exceed Xmax in the box size you choose. You should contact the seller of the SGR-501 and find out if the amp has a high pass filter (rumble filter) and at what frequency. That is an advantage for the plate amp, the EP2500 doesn't have one.
Have you decided on a box size and tuning? As for sub position, some rooms work well with a rear placed sub, some don't. You'll have to experiment on room placement to find what works and sounds best for you.

[atledreier]

I have very similar room dimensions, only without the 'wart' in the front wall. Check out my build thread. I went for the 'standard' LLT configuration, but I went tube. A box should work equally well, but needs more care with bracing. EP2500 for a single p15 may be overkill, though, at least for a ported design. Maybe consider the EP1500? Or just go dual right away!

[Rodny Alvarez]

Can you post pictures of the room

[Ricci]

Hey Jasonmac,

How big are you willing to make the sub? Look around your room and visualize with a tape measure for help roughly how big you can go. We can get some better ideas on what to suggest from there.

[jasonmac]

Thankyou everyone for the help so far.

Mike P. wrote:

The EP2500 would be give you a 3 db advantage over the SGR-501, assuming the sub doesn't exceed Xmax in the box size you choose. You should contact the seller of the SGR-501 and find out if the amp has a high pass filter (rumble filter) and at what frequency. That is an advantage for the plate amp, the EP2500 doesn't have one.

Manufacturer says:

SRG Audio wrote:

Yes, it’s -3dB @ 12Hz 6th order filter by default. But I can make it whatever freq you want it.

This is a bit over my head.

I will take some size measurements and photos this weekend, but feedback on the amp would be appreciated.

Thanks!

[Mike P.]

A high pass filters purpose is to block the lower frequencies from causing your sub to exceed its Xmax. Box size and tuning determine what frequency the HPF should be set at. Once you decide on a box size and tuning we can determine the proper HPF frequency for the amp.

[jasonmac]

Here is a view of the room from rear to front:



And from the reverse angle:



Note that I've just moved in so no pictures up yet and the room is a little bare.

Looking at the floor plan, I've identified 4 potential sub positions as marked A, B, C, D.



Here is the right surround and position A. Available space is 80cm width x 60cm depth and no height restriction (ceiling is 2.5 metres high).



Here is the left surround and position B. Available space is 100cm width x 55cm depth and no height restriction.



Here is the rear wall and position C. Available space is 100cm width x 60cm depth x 80cm height for a max 480 litres.



Position D is not really desirable as I would have to cable across the hallway but anyhoo available space is 70cm width x 50cm depth and no height restriction.

I would like to hear suggestions on sizing and a potential tune. 300+ litres sounds easily feasible, but I can go bigger if it would suit the driver. Browsing through member designs, I like

Jerm357's best... a nice tall box.

I'm also thinking that I will use the EP1500 and not the plate amp for the extra headroom and it is a lot cheaper.

[jasonmac]

how about a 50cm x 50cm x 180cm box pillar sound for a 450 litre size? This would be flexible to move around the room quite a bit.

[jasonmac]

I have had my first go at WinISD so please pick apart my current proposed build:

RL-p15 D2 driver
400 litre net volume
13.0 Hz Tuning
1 15cm port (~6") @ 67.23cm length (~26.5 inches)
1st port resonance comes to 255.6Hz
EP1500 amp

Cheers,
Jason

[Mike P.]

Here's a comparison between 400 liters 13 hz and 300 liters 15 hz. The smaller higher tuning has the SPL advantage from 14.5 hz on up. Both models have the appropriate high pass filter applied to keep the sub within Xmax. Without a HPF, a 6 inch port is not possible due to the extremely high port air speed.

400 liters 13 hz HPF at 12 hz, 750 watts to reach Xmax.
300 liters 15 hz HPF at 14 hz, 1000 watts to reach Xmax.

[jasonmac]

Just getting back to this after a bit of a break.

I have my lovely new driver in my possesion so it's time to build something!

I would like to keep the sub dimensions within the following ratio as I have a specific look in mind

w * d * h = x * x * 2x

e.g. ignorning internal bracings:

56cm * 56cm * 112cm

Here is the port speed graph for two port options: a 15.0cm port (56.16 cm length) and a 22.5cm (134.59cm length) port design.



I chose those two sizes based on the following link (I live in Oz):

http://www.subwoofer-builder.com/pipe-sizes.htm

There does not seem to be any sizes in between.

I would prefer to use the 15.0 port diameter to fit within my cabinet dimensions.

I did the above graph with the following settings:

15Hz tune, 14Hz HPF (2nd order Butterworth), 350 litres, 750W (I'm going with the EP2500 as my magic eightball is telling me there is a second sub in my future ).

Is the 15cm port an option? Suggestions?

Thanks a ton.

Jason

[atledreier]

The 10" port will be too long. The lowest port resonance will be in the passband adn probably rather audible. The 6" port will need to be flared if you drive your sub hard, it's going to move alot of air pretty fast in there.

[Mike P.]

Another option would be to build a slot port, it's very simple and cheap.

[jasonmac]

A slot port should be easy enough.

How does this look now?



If ok I will draw up some plans and post for comment.

Thanks!

[ironglen]

Only thing I'm curious about is whether a slot port is susceptible to port resonance below 220hz like a tube port?
This will be a great build that you can move for best sound quality.

[jasonmac]

I would greatly appreciate it if someone could please recommend an optimal port configuration for my build. I can't seem to get a good balance between port velocity and resonance.

Thanks,
Jason

[jasonmac]

OK, here is my proposed build, please comment. I figure that the port velocity should be ok as I won't be driving it to insane levels.

[Mike P.]

Your modeling is right on.