Sound system sounds worse with speaker amp installed

[hans030390]

A couple days ago I installed a Blaupunkt THA475 amp for my speakers, and I've noticed quite a few things that just don't sound as good as I think they should. In fact, at this point I rather wish I had just left my speakers hooked up to my HU.

- Certain parts of songs are missing, as it it's just cutting them out (maybe a frequency range or something?)...for example, Children of Bodom's "Tie My Rope" starts with a synth intro, then brings in a quiet distorted guitar sound that is quite noticeable, but I can't hear it anymore. Also, on Lamb of God's "Laid to Rest", it's hard to notice the guitars and exactly what they're playing (in the intro, there's a sort of higher part that's played before the vocal parts...you can barely hear it).

- My speakers distort at MUCH lower volumes than before (I can barely do 27/34 with my amp, where as I could do almost 30/34 before noticing bad distortion with my HU...)

- My speakers don't get as loud as they used to (and, as mentioned above, setting up the gain to correct this just brings in the distortion)

- Vocals stand out way too much now (too hard to fix with an EQ...vocals are mostly metal/screaming)

- Speakers seem to have even less bass than off the HU

My current setup is like this:

Sony CDX-GT100 HU, which outputs RCA cables to my Blaupunkt 275 sub amp (which powers my 12" Blaupunkt sub). The sub amp outputs to my speaker amp, which is currently only set to power the front speakers and nothing else (I had it running through an EQ, which would then enable me to run RCA cables to the front and rear section of the speaker amp, but I noticed more distortion there).

My speaker amp is currently set to provide 75 watts RMS each to my front speakers. My front speakers are Boston Acoustic SX65s (2-50 watts RMS).

I'm fairly positive I did all of my wiring correctly (speaker wire is 12 gauge, btw), and I'm also fairly sure my crossover/frequency settings and gain settings are properly set on my amps.

So, why am I so disappointed with my new speaker amp? My first guess would be that it's too overpowering for my front speakers, causing them to distort and such. What are some possible causes of these problems?

 

[Aharami]

why are you going from HU --> sub amp --> speaker amp? Doesn't your HU have separate preouts for front, rear, and sub? That could be why you're getting crappy output. How is sub amp connected to the speaker amp?

 

[hans030390]

Originally posted by: Aharami
why are you going from HU --> sub amp --> speaker amp? Doesn't your HU have separate preouts for front, rear, and sub? That could be why you're getting crappy output. How is sub amp connected to the speaker amp?

No, my HU only has one preout, and I don't have enough money to upgrade that.

My RCA cables go from the HU to the sub amp, and my sub amp has an RCA output (just outputs the RCA signal that's input into it). I can also use my EQ, which splits the RCA cable into 3 outputs.

 

[Doodoo]

I would check to make sure you have the positive and negatives on the speaker wire hooked up correctly. Also make sure there are no crossover settings that are affecting the amp. I wonder if the cross over on the sub amp is cutting out frequencies on the signal before it sends it to the other amp.

 

[Raduque]

It's possible the sub amp applies an HPF to the RCA output. It might be switchable. If you can get 3 RCA outputs from a single input on your EQ, why not have the EQ be the first hop? HU > EQ = sub amp/speaker amp.

 

[amdhunter]

Speakers seem to have even less bass than off the HU

Speakers wired out of phase?

 

[MixMasterTang]

Also for a quick test, bypass the sub-amp and hook up only the newly installed amp and see if the problems exists.

 

[hans030390]

Originally posted by: Doodoo
I would check to make sure you have the positive and negatives on the speaker wire hooked up correctly. Also make sure there are no crossover settings that are affecting the amp. I wonder if the cross over on the sub amp is cutting out frequencies on the signal before it sends it to the other amp.

Yeah, I'm going to check the polarity tomorrow. It SHOULD be right...my friend and I, while installing it, made sure that the wire with the big stripe on it was always positive.

By crossover settings, I mean the stuff on the amp.

And no, the sub amp does not apply and crossover/gain settings to the speaker amp. I've checked that.

Originally posted by: MixMasterTang
Also for a quick test, bypass the sub-amp and hook up only the newly installed amp and see if the problems exists.

I've done that, and it sounds the same.

 

[hans030390]

Originally posted by: Raduque
It's possible the sub amp applies an HPF to the RCA output. It might be switchable. If you can get 3 RCA outputs from a single input on your EQ, why not have the EQ be the first hop? HU > EQ = sub amp/speaker amp.

The EQ seemed to introduce slightly more distortion due to its fader (it crackles and such when you change it and other stuff), and it's just easier to test things if only the front speakers are hooked up. Since I don't technically need the EQ if I'm just running my front speakers and my sub (until I get this all sorted out), I decided to just ignore the EQ for now.

I'll be checking the polarity stuff tomorrow, but if that doesn't help anything, what then?

 

[hans030390]

Update: I checked the polarity. It sounds the exact same reversed or not. I tried that coming straight from the HU. Also, just to test, I hooked one speaker up to my sub amp (it also outputs 75W RMS when not in bridged mode), and it still sounds the same.

So, I have a new theory. I believe my HU is to blame for all of this. Since the RCA outputs on it are meant for the sub (and the sub only), I believe it's not fit to run speakers with it. It's likely causing these sound problems I've been noticing, since the RCA outputs are not dedicated for (or really even planned to run) speakers.

I also think I'm likely still overpowering them a bit too much, though that's likely the least of my worries.

So, perhaps I DO need a new HU. If that's the case, then I'll make room in my budget for it.

Edit: Also, it sounds like my speakers are running in mono mode...I get all the same sounds out of both of them, or so it seems. I also believe my headunit's RCA output is to blame for this...I think it just assumes there will be a sub, which is one driver and needs both left and right channels fed into it...but I think it just combines them for some reason.

For example, say I hook my HU's RCA cable up to my speaker amp and disconnect the right RCA input...it will only play out of the left speaker, and vice versa. However, it doesn't sound like the left and right channels are playing different things...it all sounds the same (mono). That might also be a clue to what my problem is.

 

[hans030390]

I got it figured out. Turns out I won't need a new HU. I did some research and was looking through my HU's manual (which I had to find online), and there was a setting I needed to change. For my preamp setting, it can be set as either Sub or Rear. It had always been on sub, and setting it on rear completely fixed it. It sounds great now.

I never knew about that setting because it's "hidden" pretty well. The only way anyone would likely find it is by reading the manual, but I never had a physical copy of it (nor did I really need one until today).

 

[Raduque]

Well, that's good you solved it. Another option would've been to use high-level (speaker-level) inputs if your amp had them.

 

[alkemyst]

Originally posted by: hans030390

Originally posted by: Aharami
why are you going from HU --> sub amp --> speaker amp? Doesn't your HU have separate preouts for front, rear, and sub? That could be why you're getting crappy output. How is sub amp connected to the speaker amp?

No, my HU only has one preout, and I don't have enough money to upgrade that.

My RCA cables go from the HU to the sub amp, and my sub amp has an RCA output (just outputs the RCA signal that's input into it). I can also use my EQ, which splits the RCA cable into 3 outputs.

Make sure the sub out is a full range output.

I'd split the rca at the deck though.

Also your deck may have a setting to turn of the internal amp.

 

[hans030390]

Originally posted by: alkemyst

Originally posted by: hans030390

Originally posted by: Aharami
why are you going from HU --> sub amp --> speaker amp? Doesn't your HU have separate preouts for front, rear, and sub? That could be why you're getting crappy output. How is sub amp connected to the speaker amp?

No, my HU only has one preout, and I don't have enough money to upgrade that.

My RCA cables go from the HU to the sub amp, and my sub amp has an RCA output (just outputs the RCA signal that's input into it). I can also use my EQ, which splits the RCA cable into 3 outputs.

Make sure the sub out is a full range output.

I'd split the rca at the deck though.

Also your deck may have a setting to turn of the internal amp.

Heh, did you read my latest post? I got it figured out yesterday.

 

[alkemyst]

Originally posted by: hans030390

Originally posted by: alkemyst

Originally posted by: hans030390

Originally posted by: Aharami
why are you going from HU --> sub amp --> speaker amp? Doesn't your HU have separate preouts for front, rear, and sub? That could be why you're getting crappy output. How is sub amp connected to the speaker amp?

No, my HU only has one preout, and I don't have enough money to upgrade that.

My RCA cables go from the HU to the sub amp, and my sub amp has an RCA output (just outputs the RCA signal that's input into it). I can also use my EQ, which splits the RCA cable into 3 outputs.

Make sure the sub out is a full range output.

I'd split the rca at the deck though.

Also your deck may have a setting to turn of the internal amp.

Heh, did you read my latest post? I got it figured out yesterday.

you should always update your first post.