Building C830 Center Channel to match Boston Acoustics T830, T930, T1030 - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

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 10th April 2012, 07:39 PM   #1
tvdantv is offline tvdantv  United States
diyAudio Member
 
Join Date: Jun 2007
Default Building C830 Center Channel to match Boston Acoustics T830, T930, T1030

History:
I own a T830 pair that I purchased in the mid 90's. I've had them in 4 different homes and at least 6 different rooms. I originally drove them w/ a Yamaha RX-300 receiver, then later w/ an Adcom GFA-535, and now currently w/ an Adcom GFA-2535 as LR of a HT.

I have always loved their reproduction of mid-bass up thru highs, but they lack low extension. I resolved this by adding an M&K MX-200 to the HT a few years ago and crossing them over at 80 Hz. In an effort to build out the HT, I tried a Velodyne CHT Front Row center channel for a while. And although the tweeter was close to the CFT 3, it was not the same. I eventually replaced the Velodyne w/ a CenterSat7 and have been using it for about 3 years.

Current State of my HT:
L/R are Boston T830, Center is Boston CenterSat7, Surrounds are Velodyne CHT Front Row satellites, Subwoofer is M&K MX-200. Receiver is Marantz SR4300 (used as pre/pro, and amp for surrounds). Amplifier is Adcom GFA-2535 in three channel config to drive L/R/C.

Issue:
Iím not happy w/ the CenterSat7 for a few reasons. First and foremost, the mids do not match the mids of the T830. There is no smooth transition across the sound stage. It does not present any portion of midrange (majority of vocal information) as well as the T830. Secondly (and I know that Iím being picky) design philosophies of early Boston products were completely abandoned. The enclosure is constructed of plastic, the grill not acoustically transparent, and it is bass reflex via passive radiator.

Project:
Build a C830 using drivers, cross-over and binding posts from a T830. The new enclosure needs to fit on my TV stand below the TV and not block any IR remote sensors. It will be made of MDF w/ finish to be determined. Original grill will be used, if possible, to cover the woofer. I will attempt to keep the vertical alignment of the drivers. The enclosure will most likely take the shape of a short inverted T with the mid and tweeter mounted to a Ďsailí sticking up from a woofer cabinet. The woofer cabinet will be taller in front than in the rear to accommodate the 8Ē woofer, but still fit between the bottom and middle shelves. It will be braced internally in the same manner as the T830.

To date I have acquired a Ďdonorí pair of T830ís, ordered replacement surrounds for the woofers, and reviewed a pencil sketch w/ a carpenter friend who will help w/ the cabinet construction.
Photos, trials and tribulations to follow. Iíd love any advice that veteran cabinet builders have to offer, especially when it comes to center channels. Has anyone else cared enough to undertake such a task?
  Reply With Quote
Old 12th April 2012, 10:04 PM   #2
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

There are some subtleties to centre and L+R matching often ignored.

Look at : Zaph|Audio - ZA5 Speaker Designs with ZA14W08 woofer and Vifa DQ25SC16-04 tweeter
and Zaph|Audio - ZDT3.5

Zaph is a mine of useful information.

rgds, sreten.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow
  Reply With Quote
Old 23rd April 2012, 10:48 AM   #3
tvdantv is offline tvdantv  United States
diyAudio Member
 
Join Date: Jun 2007
Donor speakers picked up off of Craigslist. The seller delivered w/in 15 min of my house and was as happy to get rid of them as I was to get them.
All drivers, w/ the exception of the woofer needing new surrounds, are perfect. One cabinet has been gutted. Removing the crossover w/o damaging the fiberboard proved extremely difficult.

New surrounds are in the shop. I decided to go w/ the kit from Midwest Speaker Repair that includes shims for the voice coil. This will be my second time re-foaming, but first time cutting off the dust cap and shimming. Midwest Speaker Repair - Refoam Kits


Terminal cup for outboard mounting of the mid and tweet arrived.
Amazon.com: Bi-wire Terminal Cup: Electronics


Enclosure design is complete and in CAD. Should have it cut on the CNC router this week.
Attached Images
File Type: jpg 544654_3096243483433_1184462532_32503564_326120527_n.jpg (95.1 KB, 73 views)
  Reply With Quote
Old 23rd April 2012, 12:04 PM   #4
diyAudio Member
 
David Gatti's Avatar
 
Join Date: Mar 2004
Location: Melbourne, Australia
You should get a vacuum cleaner onto that dustcap.
  Reply With Quote
Old 25th April 2012, 12:45 AM   #5
tvdantv is offline tvdantv  United States
diyAudio Member
 
Join Date: Jun 2007
"Napkin sketch"

2D CAD to come shortly.
Attached Images
File Type: jpg IMG_3827.jpg (719.1 KB, 69 views)
  Reply With Quote
Old 6th May 2012, 11:03 AM   #6
tvdantv is offline tvdantv  United States
diyAudio Member
 
Join Date: Jun 2007
Ran into 'fit' troubles. CNC router was off by 1/32" on all cuts. This made each hole for the drivers and terminal cups 1/16" too small. My carpenter friend is guessing that the CNC bit is either worn, or was just sharpened. Also, the I did not account for the width of the woofer's mounting lip. The woofer's hole needs to move up 1/4" so that the lip does not overhang the bottom of the enclosure.

I can work it out for the terminal cups as they are plastic and have a ramped edges. A rubber mallet pops them in and out. But the drivers will not go in. The plan is to cut off the face of the box w/ a table saw and build a new face.
  Reply With Quote
Old 6th May 2012, 11:33 PM   #7
tvdantv is offline tvdantv  United States
diyAudio Member
 
Join Date: Jun 2007
Pics of components (have not installed new surround or dust cap yet) and the first attempt at the enclosure. Face will be re-cut this week w/ larger holes and 1/4" additional space below the woofer.

Fit in the TV stand is perfect.
Attached Images
File Type: jpg DSCN0195.jpg (1.03 MB, 58 views)
File Type: jpg DSCN0196.jpg (707.7 KB, 57 views)
File Type: jpg DSCN0198.jpg (791.9 KB, 54 views)
File Type: jpg DSCN0199.jpg (782.3 KB, 18 views)
  Reply With Quote
Old 28th May 2012, 01:22 AM   #8
tvdantv is offline tvdantv  United States
diyAudio Member
 
Join Date: Jun 2007
Fit test on the new face. Much better.
Attached Images
File Type: jpg DSCN0227.jpg (799.7 KB, 20 views)
  Reply With Quote
Old 4th June 2012, 10:46 AM   #9
tvdantv is offline tvdantv  United States
diyAudio Member
 
Join Date: Jun 2007
Donor and patient, front w/ finished woofer (midwest speaker repair kit worked great), rear of unit.

Finish will be applied later in the summer.
Attached Images
File Type: jpg DSCN0230.jpg (959.5 KB, 17 views)
File Type: jpg DSCN0231.jpg (721.9 KB, 12 views)
File Type: jpg DSCN0228.jpg (687.5 KB, 13 views)
  Reply With Quote
Old 4th June 2012, 11:00 AM   #10
tvdantv is offline tvdantv  United States
diyAudio Member
 
Join Date: Jun 2007
In place and RX re-calibrated. The Center sees the bridged side of an Adcom GFA-2535.

Adcom GFA-2535

I'm extremely happy w/ the results. It will be very difficult to go back to the the CenterSat7 later in the summer so that I can dismantle the C830 to apply a finish. I'm going to apply a black lacquer that will require multiple coats and may take up to a month to complete.
Attached Images
File Type: jpg IMG_3850.jpg (558.6 KB, 19 views)
  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
Has anybody listened to the Boston Acoustics T830 speakers? Jim85IROC Multi-Way 31 6th September 2012 02:06 AM
Boston Acoustics T830 Tower speakers Space1 Multi-Way 3 3rd July 2009 05:19 PM
Boston Acoustics T830 / rebuild vs change to Polk Monitor 10s mattias Multi-Way 1 23rd January 2009 11:00 PM
Center channel to match Exodus 2641 Jim McPherson Multi-Way 1 29th November 2008 07:07 PM
Boston Acoustics 8" woofer needed for T830 todd12345 Multi-Way 4 7th July 2007 07:16 AM


New To Site? Need Help?

All times are GMT. The time now is 10:14 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2