Speakerplans.com Homepage
Forum Home Forum Home > General > Show Off Your Sound System
  New Posts New Posts RSS Feed - My hastily assembled system, for £2000
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

My hastily assembled system, for £2000

 Post Reply Post Reply Page  <12
Author
Message
bob4 View Drop Down
Old Croc
Old Croc
Avatar

Joined: 29 February 2004
Location: Finland/Germany
Status: Offline
Points: 1842
Post Options Post Options   Thanks (0) Thanks(0)   Quote bob4 Quote  Post ReplyReply Direct Link To This Post Posted: 16 June 2015 at 3:24pm
test if those spare drivers work well in the JBL mpro enclosures -> if yes, build two copies of the mpro cab -> then you have two sets of matching 4 x 18" reflex cabs :)
Back to Top
charlysays View Drop Down
Registered User
Registered User
Avatar

Joined: 16 June 2015
Location: Wales
Status: Offline
Points: 413
Post Options Post Options   Thanks (0) Thanks(0)   Quote charlysays Quote  Post ReplyReply Direct Link To This Post Posted: 16 June 2015 at 3:59pm
Originally posted by bob4 bob4 wrote:

test if those spare drivers work well in the JBL mpro enclosures -> if yes, build two copies of the mpro cab -> then you have two sets of matching 4 x 18" reflex cabs :)
 
Will be trying that out once a recone comes back - one of the M-pros was blown (I only paid £25 for the pair anyway) so it's off getting a new cone at the moment... The M Pro enclosures are pretty small though, fair bit smaller than the soundpower subs so not sure if they are big enough to make the most of the driver?
 
I would be tempted to clone the soundpowers, but I just have a feeling there are bigger deeper sounding enclosures that I can build?
Back to Top
fatfreddiescat View Drop Down
Young Croc
Young Croc
Avatar

Joined: 15 October 2010
Location: N.E.Wales
Status: Offline
Points: 1081
Post Options Post Options   Thanks (0) Thanks(0)   Quote fatfreddiescat Quote  Post ReplyReply Direct Link To This Post Posted: 16 June 2015 at 9:11pm
Just seen your post on freesp when looking for some info on the soundpro. JBL have an example of the 2241G i a 280L cab tuned to 30Hz, I'm not sure what size the 744 but it doesn't look as big so I guess they will also be tuned a little higher - you could try de tuning them a bit and adding a hi pass filter with a bit of boost around the box tuning frequency - should be able to get you down around the 30 - 35Hz with some solid output, great with the 3600VZ but do use your ears to set the limiters as the cones will probs be wanting to permanently exit the box at full tilt.
Your 100Hz xover to the tops looks like a sensible choice, try a 6dB xover here, might just work with this combination and give a broad overlap for plenty of headroom right where the kick likes to play, also can give a more natural integration between the cabs.
PV's would be ideal for the mids and tops - are the mid high's active or do they have a passive xover in there - make switchable if they have a xover and add a big capacitor to protect hf when in passive mode.
Lots more room for improvement if moving from passive to active.
Tap on the side of the mid tops, if they sound hollow then some extra bracing probs wouldn't go a miss as well as some panel damping material, if mostly going to be used with the subs then I would stuff them with lots of fibrous material to damp internal resonances which can make a huge difference to the quality of the mids, also make sure there is a couple of inches worth in the subs as well as can make a subtle but noticeable difference.
Let the fun beginSmile


Back to Top
njw View Drop Down
Old Croc
Old Croc
Avatar

Joined: 26 March 2010
Location: S. Wales
Status: Offline
Points: 2572
Post Options Post Options   Thanks (0) Thanks(0)   Quote njw Quote  Post ReplyReply Direct Link To This Post Posted: 16 June 2015 at 9:38pm
  Whereabouts will you be playing out mate? Always nice to see someone else from Wales on here.Smile
Back to Top
charlysays View Drop Down
Registered User
Registered User
Avatar

Joined: 16 June 2015
Location: Wales
Status: Offline
Points: 413
Post Options Post Options   Thanks (0) Thanks(0)   Quote charlysays Quote  Post ReplyReply Direct Link To This Post Posted: 17 June 2015 at 10:09am
Originally posted by fatfreddiescat fatfreddiescat wrote:

Just seen your post on freesp when looking for some info on the soundpro. JBL have an example of the 2241G i a 280L cab tuned to 30Hz, I'm not sure what size the 744 but it doesn't look as big so I guess they will also be tuned a little higher - you could try de tuning them a bit and adding a hi pass filter with a bit of boost around the box tuning frequency - should be able to get you down around the 30 - 35Hz with some solid output, great with the 3600VZ but do use your ears to set the limiters as the cones will probs be wanting to permanently exit the box at full tilt.
Your 100Hz xover to the tops looks like a sensible choice, try a 6dB xover here, might just work with this combination and give a broad overlap for plenty of headroom right where the kick likes to play, also can give a more natural integration between the cabs.
PV's would be ideal for the mids and tops - are the mid high's active or do they have a passive xover in there - make switchable if they have a xover and add a big capacitor to protect hf when in passive mode.
Lots more room for improvement if moving from passive to active.
Tap on the side of the mid tops, if they sound hollow then some extra bracing probs wouldn't go a miss as well as some panel damping material, if mostly going to be used with the subs then I would stuff them with lots of fibrous material to damp internal resonances which can make a huge difference to the quality of the mids, also make sure there is a couple of inches worth in the subs as well as can make a subtle but noticeable difference.
Let the fun beginSmile




Cheers for that post :)

Do you know the model number of that 30hz cab? If so I might build a couple...
I'll get measurements for the P744s. I emailed JBL about them and apparently they are "too old" and they have no info on them whatsoever! Seems pretty slack... seeing as they still have info on the old TCBs...

I think the Mid Tops have a passive Xover... all I know about it is that it also sends more of the lower frequencies to the bottom 15" driver, making a semi 3 way design.

http://www.jblproservice.com/pdf/sound%20factor/sf25.pdf

Will try the crossover settings you mention... is there anything wrong with using the PVs for the four ohm subs? I guess for the moment I could run two 8 ohm subs off one channel on the Crown, and then two four ohm subs off its other channel (it seems fine with 2 ohm loads), run the tops off one PV2600 and run the other two 4 ohm subs of the other PV. I had the PVs bench tested and they are actually over specified into 8 ohms (640w) and fall just a bit short at 4 ohms at 100hz (875w)  which was the lowest freq the technicians signal generator would run at.

Will definitely check out the panel damping situation and brace as appropriate... The Soundpower subs have blanket stapled to the inside for sure. The M-pros are empty but are a different box altogether.

Back to Top
charlysays View Drop Down
Registered User
Registered User
Avatar

Joined: 16 June 2015
Location: Wales
Status: Offline
Points: 413
Post Options Post Options   Thanks (0) Thanks(0)   Quote charlysays Quote  Post ReplyReply Direct Link To This Post Posted: 17 June 2015 at 10:11am
Originally posted by njw njw wrote:

  Whereabouts will you be playing out mate? Always nice to see someone else from Wales on here.Smile


in minnies nite spot in Haverfordwest... it's under new management and is playing lots of underground! At the moment way too much tech noise DnB but that will change. Where abouts are you based?
Back to Top
charlysays View Drop Down
Registered User
Registered User
Avatar

Joined: 16 June 2015
Location: Wales
Status: Offline
Points: 413
Post Options Post Options   Thanks (0) Thanks(0)   Quote charlysays Quote  Post ReplyReply Direct Link To This Post Posted: 17 June 2015 at 11:14pm
fatfreddiescat - the sound power P744 bins are about 155 litres by my calculations... 450x 540 x 630mm internally.
So that 2241 bin you mention is a fair bit bigger!!
Back to Top
fatfreddiescat View Drop Down
Young Croc
Young Croc
Avatar

Joined: 15 October 2010
Location: N.E.Wales
Status: Offline
Points: 1081
Post Options Post Options   Thanks (0) Thanks(0)   Quote fatfreddiescat Quote  Post ReplyReply Direct Link To This Post Posted: 18 June 2015 at 8:43am
Originally posted by charlysays charlysays wrote:

fatfreddiescat - the sound power P744 bins are about 155 litres by my calculations... 450x 540 x 630mm internally.
So that 2241 bin you mention is a fair bit bigger!!

Yeah, pretty huge for an 18",  the info came from the spec sheet for the 2241G, second page under the FR/impedance plot. It's a high Qts, high VAS driver so likes a big box to work in but will hit xmax somewhat before thermal rating becomes a problem, so you would trade upper bass power handling for low bass sensitivity, I think I would first play around with de tuning the existing cabs (longer ports) and use a little eq and a HPF.

http://jblpro.com/pub/components/2241.pdf


I missed the bit about 2 drivers  being 4ohm and 2 at 8ohm, the Crown would do the job but Peaveys would be more practical if putting one of each cab either side in a stereo setup. The Crowns are arguably one of the best of the sub amps but I would be tempted to sell the Peaveys and the Crown and go for something like a Matrix 4 channel SMPS and save for a second when funds allow - your back will thank you, especially at the end of an all nighter when unloading back at base.

Re the JBL SF25, I did wonder if they used frequency shading, I think I found the schematic here (top one):

http://www.audioheritage.org/vbulletin/showthread.php?32832-JRX1125-SR25-Driver-transplant-help-needed

Def lots of room for improvement using the DCX but would probs want to maintain the shading, that would need some mods on the crossover, ideally replacing 2 of the inductors with air heavy duty air cored - if you can lay your hands on some of a larger rating you can unwind them until you have the rating that works. Really you would need a measurement mic (berry ECM8000) and some software (room EQ Wizard or free trial of a pro software) to play with.
Remove the HF xover section and replace with a large cap (HF protection) and use the DCX with a 4th order HPF and tune the DCX to complement the modded internal xover for the lows. 
Set the limiters up on the DCX.

Other things I would consider is an AVC2 or similar and wheels for the subs if they are not already fitted.
PS did I mention wheels, nothing worse than having your half cut mates trying to carry the kit past half cut punters at the end of the night, when you could be wheeling all four in a row by yourself without the risk of dropping them on anybody and doing your back in at the same time - also makes it much less hassle to go and have some fun with it. Thumbs Up

edit: somehow missed sf25 pdf link.



Edited by fatfreddiescat - 18 June 2015 at 8:47am
Back to Top
charlysays View Drop Down
Registered User
Registered User
Avatar

Joined: 16 June 2015
Location: Wales
Status: Offline
Points: 413
Post Options Post Options   Thanks (0) Thanks(0)   Quote charlysays Quote  Post ReplyReply Direct Link To This Post Posted: 18 June 2015 at 10:43am
Originally posted by fatfreddiescat fatfreddiescat wrote:

Originally posted by charlysays charlysays wrote:

fatfreddiescat - the sound power P744 bins are about 155 litres by my calculations... 450x 540 x 630mm internally.
So that 2241 bin you mention is a fair bit bigger!!

Yeah, pretty huge for an 18",  the info came from the spec sheet for the 2241G, second page under the FR/impedance plot. It's a high Qts, high VAS driver so likes a big box to work in but will hit xmax somewhat before thermal rating becomes a problem, so you would trade upper bass power handling for low bass sensitivity, I think I would first play around with de tuning the existing cabs (longer ports) and use a little eq and a HPF.

http://jblpro.com/pub/components/2241.pdf


I missed the bit about 2 drivers  being 4ohm and 2 at 8ohm, the Crown would do the job but Peaveys would be more practical if putting one of each cab either side in a stereo setup. The Crowns are arguably one of the best of the sub amps but I would be tempted to sell the Peaveys and the Crown and go for something like a Matrix 4 channel SMPS and save for a second when funds allow - your back will thank you, especially at the end of an all nighter when unloading back at base.

Re the JBL SF25, I did wonder if they used frequency shading, I think I found the schematic here (top one):

http://www.audioheritage.org/vbulletin/showthread.php?32832-JRX1125-SR25-Driver-transplant-help-needed

Def lots of room for improvement using the DCX but would probs want to maintain the shading, that would need some mods on the crossover, ideally replacing 2 of the inductors with air heavy duty air cored - if you can lay your hands on some of a larger rating you can unwind them until you have the rating that works. Really you would need a measurement mic (berry ECM8000) and some software (room EQ Wizard or free trial of a pro software) to play with.
Remove the HF xover section and replace with a large cap (HF protection) and use the DCX with a 4th order HPF and tune the DCX to complement the modded internal xover for the lows. 
Set the limiters up on the DCX.

Other things I would consider is an AVC2 or similar and wheels for the subs if they are not already fitted.
PS did I mention wheels, nothing worse than having your half cut mates trying to carry the kit past half cut punters at the end of the night, when you could be wheeling all four in a row by yourself without the risk of dropping them on anybody and doing your back in at the same time - also makes it much less hassle to go and have some fun with it. Thumbs Up

edit: somehow missed sf25 pdf link.

 
So is detuning a case of buying some cardboard tube of the right diameter, another bit that is large enough to act as a sleeve to enable you to join a bit onto the end of what's already there and just play around with it until it's hitting the right spot or is there a calculation that will give a measurement that is close enough so I know how much to add on? I need to do some reading...
 
Actually four of the drivers are 4 ohm, and four are 8 ohm. There are four JBL 2241G (4 ohm) which should be fitted in either the soundpower or M-pro subs. There are two JBL 2243H (8 ohm) and two Fane Studio bass 18 (8 ohm). 8 drivers in total... two spare, and three sheets of good birch ply and a woodworking shop ;)
 
I see what you mean about a Class D 4 channel amp... I'm just sceptical of how easy it'd be to repair such an amp by your typical AV repair guy and the depreciation you get on brand new gear is frightening as I luckily realised in time with those Alto Subs I started with. For the price of four of those I now have an entire sound system and atleast a third more subs!
Atleast the old heavey stuff like Macrotechs and the Peaveys have suffered all the depreciation and are quite repairable if heavy. The Macrotechs are apparently incredibly reliable and as you say are a renowned sub amp.
I'm actually considering getting a 5000vz... will look into the cost of one of those Matrix amps before I do that though. I have a 10% off voucher on ebay on Electronics which is valid until the 26th, so I'm very tempted to use that on a spend of several hundred quid.
 
Nice one for the PDFs and SF25 schematic :)
 
Will look up an AVC2 now,.. no idea what that is! The P744 subs all have wheels. The M-pros don't so I might fit them. Very good points re transporting... I've already made it clear to anyone who will be involved in using this rig that I have no intention of moving the whole lot by myself. All of it will ideally be a two man lift. At the moment the amp box is too heavy... lol. If I got an MA5000 I would ditch the peaveys or just have a peavey in a single box to run the tops and use the big box just for sub amps.
 
 
 
 
 
 
Back to Top
fatfreddiescat View Drop Down
Young Croc
Young Croc
Avatar

Joined: 15 October 2010
Location: N.E.Wales
Status: Offline
Points: 1081
Post Options Post Options   Thanks (0) Thanks(0)   Quote fatfreddiescat Quote  Post ReplyReply Direct Link To This Post Posted: 18 June 2015 at 1:38pm
Re tuning, sleeves and more tube or make adaptor plates and use plastic soil pipe etc. you can model it to a reasonable degree of accuracy with hornresponse by David McBean, best to make up a lead to work with room eq wizard and measure the impedance plot or less accurate, a resistor and a multimeter to measure the voltage across the driver like this:
http://www.ehow.com/how_7580337_test-speakers-air-resonance.html
except you would be looking for minimum resistance in the 25-45 Hz range, use a PC and freeware sinewave generator for an input signal with the driver in the box, with 4 ohm driver use around a 4.7 ohm resistor and at very low output unless you have a very chunky resistor.

Re Matrix - look up RobinMatrix and andyamp on here, Crowns depreciate very rapidly when they do go wrong, as can be very expensive to repair and only a limited number of people really know how to properly.

Another that may be worth a look at on the budget side is the Thomann TSA 4-1300 - £350 with a 3 year warranty.




Back to Top
njw View Drop Down
Old Croc
Old Croc
Avatar

Joined: 26 March 2010
Location: S. Wales
Status: Offline
Points: 2572
Post Options Post Options   Thanks (0) Thanks(0)   Quote njw Quote  Post ReplyReply Direct Link To This Post Posted: 19 June 2015 at 8:55pm
Originally posted by charlysays charlysays wrote:

Originally posted by njw njw wrote:

  Whereabouts will you be playing out mate? Always nice to see someone else from Wales on here.Smile


in minnies nite spot in Haverfordwest... it's under new management and is playing lots of underground! At the moment way too much tech noise DnB but that will change. Where abouts are you based?
   
 
I'm right at the other end of Wales in Ebbw Vale!
Back to Top
 Post Reply Post Reply Page  <12

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.06
Copyright ©2001-2023 Web Wiz Ltd.

This page was generated in 0.078 seconds.