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Hello,
First off, yeah I know I am cheap and after looking at some of the systems on here I am a bit embarrassed to post this but ... I appreciate any insight you may have on the issue I am currently experiencing.


I recently installed a Xtrons TD-723 head unit (cheap Chinese double DIN DVD, etc). Everything appeared to be good to go until I installed an amp and sub.


Currently I have the following installed:
Xtrons TD-723 HU (single RCA out)
Kicker DS60 - front speakers (driven by HU)
Sony XM-GTX1821 - amp driving sub
Sony Xplod XS-GTX121LW - sub


The issue is that my sub pulsates/deflects to the point of damage. Perhaps at a rate of 2 times per second???


If I disconnect the RCA inputs to the amp the sub does NOT pulse.
If I connect a MP3 player to the amp the Sub does NOT pulsate.


It appears that the sub pulsates no matter if the amp is run normal or bridged when connected to the HU.


I do not know what to do so...
I tried grounding the RCA cable output to the HU body, but it had no affect - still sub pulse.
Checked and double checked and created a good chassis ground for the amp.


Any ideas????

SumDumGuy wrote:Hello,
First off, yeah I know I am cheap and after looking at some of the systems on here I am a bit embarrassed to post this but ... I appreciate any insight you may have on the issue I am currently experiencing.


I recently installed a Xtrons TD-723 head unit (cheap Chinese double DIN DVD, etc). Everything appeared to be good to go until I installed an amp and sub.


Currently I have the following installed:
Xtrons TD-723 HU (single RCA out)
Kicker DS60 - front speakers (driven by HU)
Sony XM-GTX1821 - amp driving sub
Sony Xplod XS-GTX121LW - sub


The issue is that my sub pulsates/deflects to the point of damage. Perhaps at a rate of 2 times per second???


If I disconnect the RCA inputs to the amp the sub does NOT pulse.
If I connect a MP3 player to the amp the Sub does NOT pulsate.


It appears that the sub pulsates no matter if the amp is run normal or bridged when connected to the HU.


I do not know what to do so...
I tried grounding the RCA cable output to the HU body, but it had no affect - still sub pulse.
Checked and double checked and created a good chassis ground for the amp.


Any ideas????

hmm, that's a tough one.
when you hook the MP3 player to the amp, are you using the same RCA's that are connected to the deck?
If not, try using those and see what happens.

But I have a feeling it's going to be something in the deck that is causing it. Since it's a cheap deck, it might be adding some sort of noise to the amp.

Thanks for the reply....

I did not use the same RCA's when I hooked up the MP3 player, just a converter (mini to RCA) at the amp.
I'll have to try the check again with the MP3 using the "normal" RCA cable.

Currently I have the setup with a Y-splitter at the output of the HU, both RCA cables connected at the amp, and the sub powered off of one channel. There is no pulsing now, but there is not a lot of thump. :)
However, the second I try to bridge the amp while running from the HU the pulsing starts.

Weird stuff,

I need to go ahead and run a couple more checks using the MP3 player; verify that all is good (amp bridged) with the MP3 as source. Kind of a quick sanity check.
\
Thanks!

SumDumGuy wrote:Thanks for the reply....

I did not use the same RCA's when I hooked up the MP3 player, just a converter (mini to RCA) at the amp.
I'll have to try the check again with the MP3 using the "normal" RCA cable.

Currently I have the setup with a Y-splitter at the output of the HU, both RCA cables connected at the amp, and the sub powered off of one channel. There is no pulsing now, but there is not a lot of thump. :)
However, the second I try to bridge the amp while running from the HU the pulsing starts.

Weird stuff,

I need to go ahead and run a couple more checks using the MP3 player; verify that all is good (amp bridged) with the MP3 as source. Kind of a quick sanity check.
\
Thanks!

Any Luck?

Well, as I mentioned I had the amp running a single channel to the sub and thought that there was no pulsing. I was wrong, there is indeed still pulsing, but at a lot less frequent rate and deflection.

So, I went ahead and ran another RCA cable from the HU to the amp. Connected it all up with the amp bridged - pulsing.

Grabbed the MP3 player again for some bridged amp testing.
MP3 player directly to amp - no pulsing.
MP3 player to amp via new RCA cables - no pulsing.
MP3 player to amp via original RCA cables - no pulsing.

At this point I am running out of ideas and patience. :)

There are some pre-outs for front and rear speakers that are not in use (I am using the HU powered outputs for the other speakers), and I am considering using the rears for running the sub.
My only concerns with this setup are:
I do not like the idea of the sub being hooked to the fade.
I don't know if I will be clean (no pulsing) with these connections.

I'll try the rear pre-outs today and see what comes of that.

SumDumGuy wrote:Well, as I mentioned I had the amp running a single channel to the sub and thought that there was no pulsing. I was wrong, there is indeed still pulsing, but at a lot less frequent rate and deflection.

So, I went ahead and ran another RCA cable from the HU to the amp. Connected it all up with the amp bridged - pulsing.

Grabbed the MP3 player again for some bridged amp testing.
MP3 player directly to amp - no pulsing.
MP3 player to amp via new RCA cables - no pulsing.
MP3 player to amp via original RCA cables - no pulsing.

At this point I am running out of ideas and patience. :)

There are some pre-outs for front and rear speakers that are not in use (I am using the HU powered outputs for the other speakers), and I am considering using the rears for running the sub.
My only concerns with this setup are:
I do not like the idea of the sub being hooked to the fade.
I don't know if I will be clean (no pulsing) with these connections.

I'll try the rear pre-outs today and see what comes of that.

It does sound like you're starting to narrow it down to the head unit itself.
Just one thing to verify, this is with the engine off with both the head unit and the MP3 player right?

I have a feeling the solution will be a new deck.

Chris from Washington wrote:It does sound like you're starting to narrow it down to the head unit itself.
Just one thing to verify, this is with the engine off with both the head unit and the MP3 player right?

I have a feeling the solution will be a new deck.

The testing was performed with the engine on and off.

Unfortunately I am thinking that you are correct about the solution.

I put in a request for support at the forums for this model of player. However, since it is in China the reply will probably be something like "Have you tried using a different CD."

I think you guys have it figured out. It sounds like the RCA output stage on the deck is fried. Good luck getting it replaced. Hopefully they don't give you to much crap.

SumDumGuy wrote:The testing was performed with the engine on and off.

Unfortunately I am thinking that you are correct about the solution.

I put in a request for support at the forums for this model of player. However, since it is in China the reply will probably be something like "Have you tried using a different CD."

Any Luck?

Nothing new; I've been out of town so I haven't done much else.
I did hook the amp/sub to one of the rear speaker pre-outs, and have a bit better sound.
I received a reply to my query on the xtrons support board. I'll put it here for amusement....
Hi,
I am afraid your sub doesn't match to our unit, you may try to change another sub, and the voltage of the sub should within 2-4v.
Regards,