Modding Pre-Amp Board on MTX TA81001D... - diyAudio
Go Back   Home > Forums > General Interest > Car Audio

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 1st September 2007, 10:38 AM   #1
diyAudio Member
 
Join Date: Sep 2007
Send a message via AIM to HsOffRoad
Default Modding Pre-Amp Board on MTX TA81001D...

I just picked up a pair of MTX Thunder TA81001D amps, and according to the engineers at MTX there is no way to disable the subsonic filter or bypass the built in EQ in the pre-amp board (which is a crock). The TA92001, TE4001, and TE1501 units all have a button to bypass all of this garbage, but no such button exists on the TA81001. If you take the pre-amp board out, you can clearly see a spot on the board for the bypass switch - Labeled as "S102". MTX refuses to give me a schematic or instructions on what needs to be jumpered, removed, etc. to
eliminate the EQ and Subsonic filter pieces. I'm about to tear into it myself, but figured I would ask here first. If anyone has experiencing modding these out, or access to to schematics for the TA92001, TE4001, or TE1501 pre-amp boards, It would be most appreciated.

Thanks Guys,

Hans
__________________
"Shut Up & Wheel Your Junk!"
  Reply With Quote
Old 2nd September 2007, 12:02 AM   #2
diyAudio Member
 
Join Date: Mar 2007
You say you can clearly see S102. Is this just the white silk screen, or can you see the traces and holes to mount the switch to? If there are traces and mounting holes, are there any jumpers or traces connecting any switch terminal to any other switch terminal?
__________________
If it ain't broke Don't fix it
  Reply With Quote
Old 2nd September 2007, 06:48 AM   #3
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
I agree with IAAI. Try that first.

I tried bypassing the preamp board on a 4601 and it was not happy with the high frequency signals. With driven full range, the amp drew excessive current even without a load. The current draw increased when loaded. In the newer amplifiers, there may be a circuit mod that allows you to bypass the crossovers without damaging the amplifier. I believe that the 4601 would self destruct if I ran it like this for any significant period of time.

When driven from the subwoofer output of the head unit, it didn't draw excessive as it did with the full range signal. It essentially performed normally (but with significanly lower gain -- a 2v head unit could not drive it to full power).

If you try this, do NOT run it higher than 100Hz. If you do, you run the risk of destroying the amp. Sometimes, when these amps fail, they do so dramatically (melted aluminum and severely charred fiberglass).

The following image shows the jumper positions I used on the 4601. These may not correspond to the same connections for your amp. Doing this on your amp may cause it to fail.

http://www.bcae1.com/IMG_3478b.jpg

If you try this, insert a 15 or 20 amp fuse in the B+ line feeding your amplifier. If there is a problem, the small fuse may help prevent damage to your amp.
  Reply With Quote
Old 3rd September 2007, 02:44 PM   #4
ppia600 is offline ppia600  United States
diyAudio Member
 
Join Date: Jun 2007
Location: Louis y ana
I understand the bypassing the subsonic filter part.. but why are you wanting to bypass the eq, are you talking about the crossover or bass boost? I wouldn't think the ouput design of this amp would be designed to play high frequencies. Just curious.
  Reply With Quote
Old 7th September 2007, 09:01 AM   #5
diyAudio Member
 
Join Date: Sep 2007
Default Need MTX 801D Schematic

I saw that OffRoad (I think that was his name) may have the schematics for the 801 D. If so, I REALLY need them.

My email is: ntanner@wavecable.com

Thank you SO much if you can provide this. In particular, I need to know what size capacitor goes in the C19 spot on the board.

Thank you,

Nick
  Reply With Quote
Old 7th September 2007, 12:17 PM   #6
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
You should start a new thread or ask a moderator to move this.

I have photos of the 801d but the capacitors are covering the circuit board designations. If you can tell me where it is, I'll see if I can read its value in the photo.
  Reply With Quote
Old 8th September 2007, 01:50 AM   #7
diyAudio Member
 
Join Date: Mar 2007
Hey Perry, what's the matter with your picture software? Just a couple weeks ago you removed a clamp to expose the transistors beneath it. But you can't remove a cap to read the silk screen on the board? I am Soooo disappointed.
__________________
If it ain't broke Don't fix it
  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
Sure Electronics New Tripath Board 4*100W class-D Amplifier Board 7788q Class D 337 13th May 2014 07:50 PM
Board to board soldering: BGA/SMD style NeoY2k Parts 0 7th December 2008 04:36 PM
My Cambridge 500SE, needs an output board (to replace internal DAC Board) slbender Digital Source 0 15th May 2008 01:36 AM
15V + - Regulator Board Brian GT Board. jleaman Solid State 16 9th March 2005 05:28 AM
Lost 1 Zv4 ckt board..looking to buy 1 circuit board Blues Pass Labs 1 22nd March 2004 10:09 PM


New To Site? Need Help?

All times are GMT. The time now is 08:44 PM.


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