Monacor SP-155X too good to be true? - diyAudio
Go Back   Home > Forums > Loudspeakers > Full Range

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 20th July 2015, 11:14 PM   #1
diyAudio Member
 
monty78pig's Avatar
 
Join Date: Aug 2011
Location: London
Send a message via Skype™ to monty78pig
Default Monacor SP-155X too good to be true?

I've been mucking around with BRs in WINisd recentley, and having previously built a stereo closed cabinet for Monacor's SP-155X, as an external speaker for a television to sit on top of (not too critical an application, hence the choice of a rather cheap driver), I decided to see if it could be used in a BR enclosure.

Plugging the values into WINisd and changing the box volume to 50l, tuning at 48Hz it looks pretty good, with an f3 of about 40Hz, although a little bumpy towards the end but I'm guessing that'll help compensate for baffle step error. It also seems to have some degree of this built into it's response making a baffle width of about 25-28cm ideal, which also fits into the golden ratio dimensions using 18mm MDF.

The sensitivity is also decent, about 93dB making it good for use with an SE pentode amp. However, Qts is high (which means bass will be less controlled? ) and the Xmax is limited to about 1mm.

It is a very cheap FR, about 40 for a pair, coupled with some MDF cabinets with some faux grain painting (something I'm very proud of being able to do ) could make for a cheap pair of speakers.

I'm sure there's a catch to all of this though, go on, tell me how I'm wrong !
Attached Images
File Type: gif SP-155X-8.gif (18.3 KB, 460 views)
File Type: png SP-155X 50l 48Hz.png (18.6 KB, 455 views)
Attached Files
File Type: pdf sp-155x.pdf (66.9 KB, 36 views)
__________________
78RPM Restorations https://soundcloud.com/monty78pig With perfect linearity, it is impossible to go off on a tangent.

Last edited by monty78pig; 20th July 2015 at 11:20 PM. Reason: Forgot attachments
  Reply With Quote
Old 21st July 2015, 06:23 AM   #2
jerryo is offline jerryo  Isle of Man
diyAudio Member
 
Join Date: Jun 2007
Nice to hear about someone doing graining. I did a bit myself a good few years ago. It can be very effective when done well. I recently came across a monumental amount of graining in a large Victiorian House undergoing a complete refurbishment a couple of years back whilst doing some set decorating on a film. All internal doors and frames including a huge set of double folding partition doors dividing a large reception room into two were figure grained in Oak, and done to a very, very high standard. Really impressive work of a master craftsman. A joy to behold.
  Reply With Quote
Old 21st July 2015, 11:58 AM   #3
diyAudio Member
 
monty78pig's Avatar
 
Join Date: Aug 2011
Location: London
Send a message via Skype™ to monty78pig
I find it quite fun, I think it looks amazing on MDF! I think it's not just about using the rubber tool but also using a coarse brush up and down along the faux grain while it's half dry to really get a good close up effect.

I'm not amazing at it, my first few attempts looked rather contrived as I was using the rubber tool in the same position on each stroke.
__________________
78RPM Restorations https://soundcloud.com/monty78pig With perfect linearity, it is impossible to go off on a tangent.
  Reply With Quote
Old 21st July 2015, 12:14 PM   #4
jerryo is offline jerryo  Isle of Man
diyAudio Member
 
Join Date: Jun 2007
I have good books on the subject if you ever wish to borrow one for improving technique.

Back to the Monacors: there are some drivers by Monacor named SPX200 wp which I am keen to find out about although they are hard to get hold of. I'm waiting to hear when they are in stock. They model really well on WinIsd Pro.
  Reply With Quote
Old 21st July 2015, 12:21 PM   #5
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
Very high Qts and a box much larger than VAS is going to result in a muddy sound. Check the group delay curve.

It's worth a build though as a listening and learning exercise.
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, modules and more.
  Reply With Quote
Old 21st July 2015, 12:45 PM   #6
diyAudio Member
 
monty78pig's Avatar
 
Join Date: Aug 2011
Location: London
Send a message via Skype™ to monty78pig
Hmm... The group delay is a little high, peaking at 23ms at 40Hz. Objectively speaking, will I hear this?

Here's the group delay graph, the lower trace is for a pair of MA A10P BRs I'm also rebuilding at the moment for comparison

I'd love to borrow your book but the Isle of Man is a long way away !
Attached Images
File Type: png Group Delay SP-155X vs Alpair 10P.png (24.6 KB, 400 views)
__________________
78RPM Restorations https://soundcloud.com/monty78pig With perfect linearity, it is impossible to go off on a tangent.
  Reply With Quote
Old 21st July 2015, 01:42 PM   #7
Squeak is offline Squeak  Denmark
diyAudio Member
 
Squeak's Avatar
 
Join Date: Jul 2007
Location: Frederiksberg
The catch? It's not that inexpensive. I just think you were lucky. The price is between 40 to 50 pounds where I checked.
At that price I'd much rather get a similar Fostex with lower Qts and better materials overall, at a small extra price increase if any.
  Reply With Quote
Old 21st July 2015, 11:26 PM   #8
diyAudio Member
 
monty78pig's Avatar
 
Join Date: Aug 2011
Location: London
Send a message via Skype™ to monty78pig
Hmm... I can get a pair of these drivers for 40 which is not bad at all. Factoring the cost of the MDF and grill it comes to just under 100.

They will be pretty big though 28x36x68cm!
__________________
78RPM Restorations https://soundcloud.com/monty78pig With perfect linearity, it is impossible to go off on a tangent.
  Reply With Quote
Old 22nd July 2015, 12:11 AM   #9
Squeak is offline Squeak  Denmark
diyAudio Member
 
Squeak's Avatar
 
Join Date: Jul 2007
Location: Frederiksberg
The extra dough for a pair of FE166 is well spent considering you could be living with them for a long time.
If not the resale value for Fostex is higher.
Alternatively FE126 is about the same, with likely a little less bottom, but more precision there and better dispersion and no wiz cone.
I'd say you get about what you pay for here.
If they had been something south of 30 it would start to look interesting.
  Reply With Quote
Old 22nd July 2015, 12:14 AM   #10
diyAudio Member
 
monty78pig's Avatar
 
Join Date: Aug 2011
Location: London
Send a message via Skype™ to monty78pig
FE166 don't perform well in BR, besides they would cost 140 just for the drivers .
__________________
78RPM Restorations https://soundcloud.com/monty78pig With perfect linearity, it is impossible to go off on a tangent.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Monacor SP-80x jayce996 Full Range 0 17th April 2013 09:55 AM
Monacor SP-80X, any experience? Indigestible Full Range 0 31st July 2009 03:05 PM
Monacor SP 60/8 needed Cambe Swap Meet 1 1st August 2002 12:59 PM


New To Site? Need Help?

All times are GMT. The time now is 04:44 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright 1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2