EuroDude2k

Ok I'm a bit confused.

My CL9 (AUDM Accord Euro) does not have a stock Amplifier, as seen in this pic (The blue connector connects above into the HU):




Now correct me if I'm wrong, but wouldnt testing the voltage using a multimeter on the '+' and '-' speaker wires of a Balanced output, cause the voltage to fluctuate from '+' to '-' ? or just give you random voltage gibberish?

I used a multimeter on my Euro's Speakers, and they are constantly '+' (or constantly '-' if I swap the probes around). Off course the voltage fluctuates as the music plays, but never changes polarity.

So does this mean the AUDM Euro's have an Unbalanced output?



ps. My rear JL Audio speakers are hooked up to an Amp (Audison SRx3), and the Amp is receiving input from the stock rear speaker wires at high level. This gives a slight hiss but thats all. Sound quality is excellent. More details here:
https://acurazine.com/forums/showpos...7&postcount=94

mercman

You are connecting to the speaker level outputs, balanced lines are used for low level audio so don’t worry about that with your set up.

You can’t use a DVM to read phase of an AC signal, so forget about doing that.

Do a search on how to add an amp to your CL9.

jeff

EuroDude2k

Thats a relief, thanks for confirming that mercman.

Perhaps I just need a line filter to remove the hiss.
I turned down the gain on the Amp, and the hissing volume went lower, but even at the lowest gain, the hiss was audible.

Anyway I am installing a small Kenwood Amp at the front (to power Boston S55's in the doors), so it will be interesting to see if that hisses as well. I have a feeling the Signal-to-noise ratio on the Honda/Pioneer decks are no good, and the factory speakers are designed to "hide" the hissing (which is why many of us get hissing when we upgrade the tweeters).

mercman

Your hiss is not an S/N ratio problem with the deck. The problem is likely that you have the gain set too high or an install problem.

I don’t have a CL9 so I can’t tell you how to connect the amp. Lot’s of people have done this successfully and I’m sure if you check the FAQ section you will find your answer.

jeff

EuroDude2k

Ok I'll check the FAQ section. cheers.

Reach

Merc, you have a TSX right? That is also a CL9. Honda versioning is a whole other discussion.

EuroDude2k

Yep

CL7 = 2.0L Accord-R in Japan
CL8 = Wagon version I think
CL9 = 2.4L TSX, UK Accord, AU Accord Euro

Despite being the same chassis, the AU Euro's have a different sound system to the TSX. Its un-amped and the 03-05 models had a hissing problem which was improved with the 06/07 models but the stock speakers hide the hiss well. The hiss is audible when the speakers are upgraded, especially the tweeters. Well thats my theory anyway

EuroDude2k

UPDATE (Regarding the HISS)

Ok Ive installed a new Amp at the front, that also has the exact same hiss!


Everything points to the Head Unit.


Setup:

HU -> Stock Rear Speaker wires -> Rear Amp (high level input) -> 6x9's
HU -> Upgraded Front Speaker wires -> Front Amp (high level input) -> 5.25" door speakers.


The Head Unit hiss is only audible from VOL 1 to about VOL 10. After that hiss, the usual Gain/Volume hiss you normally get from Amplifiers takes over.

BOTH Amps have the exact same HU hiss. And both Amp's give the usual Gain/Volume hiss when the volume is high (with music paused).

The HU hiss is always the same volume when the Volume is above '0'
The HU hiss completely disappears when the HU Volume is set to '0'
The HU hiss was not there with the Stock Speakers.
The HU hiss was not there when the Stock 6x9's were running of the Rear Amp.
The HU hiss is audible from the Front and Rear speakers, no matter what the HU Fade is set to.
The HU hiss is audible from the Front and Rear speakers, no matter what the HU Balance is set to.
The HU hiss increases if the Amp's GAIN Screw is increased. But the Hiss is still audible if the GAIN Screw is at its lowest setting.
The HU hiss is heard from all speakers, if the engine is On or Off.



So Ive figured that the stock Honda/Pioneer Head Unit has a natural hiss. This hiss is hidden by the stock speakers. The stock speakers have been tuned to avoid the frequency of the hiss. As soon as you add decent speakers with tweeters, the hiss becomes unhidden and audible.


Solution? Replace the stock HU, or use a Line Filter.

mercman

If you can provide me the factory audio system pin out for your car perhaps I can help.
Also a diagram of what you have connected to where.

jeff

Castles_Saloon

Sounds like it could be a couple of things...
1- HU's noise floor. New speakers with greater ability to produce detail present more of the hiss and all its glory to you. i noticed this with my setup (tsx). All stock and there was some hiss, then new speakers and the hiss was more noticeable.

Perhaps if you find a low level output of the HU (intended to be amped), you may feed your amps that signal instead. (watch out for balanced/unbalanced connections)

2- Its possible that your hu's negative speaker output is at a different voltage than your amps negative input (i.e. driven output tied to gnd). if that's the case, then maybe mercman's balun could help!?

Do you have a voltmeter or oscilloscope? I'd be interested to see what dc and ac voltage components are at the point before the new amps (amps disconnected) and at your speakers (everything connected) with the volume set to 0 and 1. no source material played obviously, just looking for noise sources.

jiggaman

go this route for salvation

https://acurazine.com/forums/sho...03&page=2&pp=25

mercman

You said this hiss wasn’t there with the stock speakers; did you test with the stock speakers and aftermarket amps? This is an important clue so make sure you remember correctly.

I need to see a diagram and pin out for your system before I can really help. I don’t know how your amps are connected to the factory system. Line level, GLI’s LOCs’ you get my point. You could have a ground loop or maybe under driving your amps. There is no reason you can’t get the factory system to be quiet.

jeff

EuroDude2k

Here is a diagram. Sorry I dont have the proper pinouts - I used the color coding of the factory speaker wires to determine which wires to cut. The middle pins are the speaker wires that usually go directly to the stock speakers.




@Castles, I have a multimeter and when I have time, I will measure the volts before and after the Amp. The honda head unit does not have low level outputs, there is no factory Amp. I will also run the stock speaker wires directly to the new 6x9's and see if it hisses (I have a feeling it will).

@Jigga, that link doesnt work.

@mercman,
Yes I did:

No Hiss = HU -> Stock speakers
No Hiss = HU -> Amp -> Stock speakers
Hiss = HU -> Amp -> Decent speakers
(untested) = HU -> Decent Speakers


Earthing for front Amp is connected to a bolt going into the chassis below the center console.
Earthing for Rear Amp is connected to a bolt going into the chassis under the rear passenger seat.


Rear setup = Audison SRx3 Amp, JL Audio 3-way TR690-TXi 6x9's, Adire Shiva 12" DVC Sub
Front setup = Kenwood KAC-5202 Amp, Boston S55 5.25"s
(I am not using LOC's or RCA converters or anything, its all directly connected as you see in the diagram)

mercman

OK good, now we are getting somewhere.

Lets check to see if your HU is a BTL (bridge tied load) output. Set your DVM for AC volts and connect the black test lead to a good ground. With music playing take the red lead and probe each side of the speaker leads at the input of the amp. If you have a non BTL deck you will only see voltage fluctuations on the (+) speaker lead. If you have BTL then you will see fluctuations on both leads. If it is BTL you can remove the (-) speaker wire at the amp input and run a test wire from the amp (-) speaker input to a good ground to see if the hiss goes away. You have to do this for all channels or just disconnect the channels you are not testing or the test will be invalid.

If doing the test stops the hiss then go get some LOCs designed for high-powered decks for each HU speaker output.

Let me know how it goes. I have other tests for you to do but I think this is the must likely cause of your problem.
jeff

EuroDude2k

@mercman, ok I have done some testing.

BTL test:
HeadUnit set to volume 7/40 and played music
I set the multimeter to AC setting '2'
Black probe connected to a ground (door bolt)
Red probe connected to each speaker wire High Level Input on the Amp.
While the speaker wires were still connected to the Amp and playing music.

I got the exact same fluctuating voltages on all the four input wires. The Multimeter showed 0.018~0.026 AC Voltage.

So it gotta be BTL, correct?

ok so I removed one channel by disconnecting the RHS (+) and (-) high level input, and removed the LHS (-) high level input, then connected the Amps LHS (-) High level input to ground, SQUAAAK! omg I thought the Left speaker blew. It gave a very loud electric/static sound so I instantly removed the grounded input to avoid damage (speaker still works by the way). So does that mean its not BTL?

------------------------------------------

I did some more testing.

Head Unit On
Music turned Off
All high level input wires (coming from HU) removed from Amp, I tested the voltage of the stock speaker wires coming straight from the Honda HU.

[Red probe to (+), black probe to (-)]
Multimeter DC(2) test at VOL 0 = 0.005v
Multimeter DC(2) test at VOL 7 = 0.012v

If I swap the probes around, the Multimeter shows the same voltages, but they were Negative instead of Positive.

So there is an extra 0.007v DC from the Head Unit when the VOL is above 0
I also tested with the Multimeter on AC(2), it gave no voltage readings at all.

When I disconnected one of the High Level speaker channels (the wires coming from the head unit), the corresponding speaker gave out no Hiss. So its not noise sourced from the Amp.

------------------------------------------

I was going to connect a rear speaker directly to the stock Head Unit speaker wires (to bypass the Amp), but my battery went very low lol. I had to roll the car in reverse in pitch black down the driveway, then steer and roll the car down a hill and jam it in 2nd gear. Steering and braking in a rolling TSX/Euro is not fun! The brakes are almost useless with no power. Lucky for the handbrake

Anyway I will try bypassing the Amp later. Any ideas in the meantime?

mercman

You have A BTL audio amp in you HU. There is a good chance that your amp speaker level inputs cannot deal with this. The other big item that I hope you checked and rechecked is the amp ground. The fact that you got a loud noise when you tied the (-) speaker input to ground makes me suspect this. As far as the loud noise, you did remove all the other channel spkr level input leads before the ground test didn’t you?

The next step is to go to the car audio store and pick up a set of LOCs designed for high-powered decks. The will have the proper configuration for the BTL output. Disconnect all spkr level inputs and use the locs on the front channel amp line inputs.

Let me know what you get doing this. Please double-check your grounds. They have to be on a clean spot welded part of the chassis. Parts that are bolted on are poor grounds (like the braces behind the rear seats).

jeff

mercman

Do the high power LOC test first. If you still have noise try these two tests.

The next test will be to place an 8 ohm resistor across the speaker lines at the amp input. Go to radio Shack and pick up a pair of 8 ohm non inductive resistors (cat # 271-120) and four 0.1uf capacitors 272-1069.
Disconnect all but the front channels and place an 8 ohm resistor across the speaker leads at the amp input. This will simulate a load on the HU output. I don’t know how you extended the speaker wires from the 20 pin connector but you should disconnect the wires at both the amp and factory connector. What you want to avoid is any un-terminated (on load) wires that will act like antennas.

The 8 ohm resistor will lower the impedance of the speaker line and help shut any high frequency noise pick up.

The next test will be to place one capacitor at each end of your spker wire extensions (HU to amp). Place the cap at the point of your splice and the other at the amp in terminals or at the splice (if you have a connector input).

Remember you are only testing one amp and just the front channels. All other speaker level cables (HU to amps) should be disconnected from the car and amps.

jeff

EuroDude2k

Yes I did remove the other channel spkr level input leads before the ground test, but only on the Rear Amp. Should I have done the same to the front Amp as well?

I will check the ground tomorrow, or perhaps simply disconnect the rear Amp power and see if the front Amp hisses. And will also connect a rear speaker straight to the HU to test for a Hiss.

mercman

Yes, the only channels that get connected are the one(s) you are actually testing. There are a lot of reasons for this and you need to do it that way so we can isolate your problem.

jeff

EuroDude2k

Ok I disconnected all the channels (front and rear) and tried this:

(+) speaker wire from HU --> to a 6x9 (+)
Ground --> to a 6x9 (-)

I got the static sound again but not as loud since it was not amped. I even held it for a few seconds, no music at all.

Now there are actually wires going to the Tweeters as well, or perhaps they are piggy backed off the front HU speaker wires. When I removed both the front stock speakers (disconnected the speaker wires), the tweeters didnt work anymore. I think the tweeters were working when only one front HU channel was connected to a speaker.
So perhaps since the tweeters are still connected (somehow), they are interfering with BTL and causing the rear speaker to squark when grounded at (-)



I connected the HU speaker wires directly to the Rear Amp - that hisses as well.


Strange thing is, when I pulled out the HU speaker wires from the Amp, and tested them using the Multimeter in DC mode, only the Left Rear speaker wires gave a voltage. The Right Rear Speaker wires gave nothing at all. But the Right speaker wires work fine when connected into the Amp or directly to the 6x9. Very Strange.

I may go and buy a LOC (perhaps using RCA output) now and see how that goes. The front hiss is minimal, so I may just get one for the Rear Amp.

EuroDude2k

I bought a LOC (The Stinger SALOC 2ch 50w max) for the Rear Amp.

The Hiss is still there

The LOC has a level output adjustment, so if I increase that, and decrease the Gain on the Amp, the Hiss is about half the volume.

But now with the LOC, the problem is:
1) If the Head Unit is above 25/40, the bass is now distorted. Even if I turn down the Level Adjustment on the LOC, that doesnt improve the bass distortion at all, the volume is just lowered. Its not the 6x9's or the Amp, because the bass sounded crystal clear when using High Level Input. So obviously the LOC cannot handle high wattage from the Head Unit (despite being 50w max, which I doubt the HU can reach anyway).
2) There is now a slight mid-high pitch electrical hum as well. You only notice it when no music is playing though.
3) The sound sounds dirtier now, it has lost some clarity and does not sound as dynamic as when I was using High Level Inputs.
4) Now I can hear some electrical pops when the engine cooling fan turns on or off.


I tried improving the ground by connecting an 8gauge cable from the existing copper ground wire (near where its attached to the bolt under the seat), to various other ground locations on the chassis. That made absolutely no difference at all.




I definitely prefer it without the LOC. The Hiss is annoying but I cannot hear it when playing music unless its very low, which in this case, I usually turn the Volume to 0 to remove the Hiss.


I just think the Head Unit's High Level speaker output (its internal amplifier) is not that good, causing the hiss. And Honda tuned the speaker designs so that the Hiss is inaudible.

EuroDude2k

Sorry I meant to say "I connected the HU speaker wires directly to the Rear Speaker - that hisses as well."

Oh, and the LOC outputs to RCA into the Amp.


not liking the Post Editing timeout other forums give you months to edit your posts

mercman

Try putting the 0.1uf capacitors at each end of you speaker cable extensions. If you can hear the hiss without the amps (just putting a speaker at the end of your speaker line) then it will make troubleshooting easier. In fact you just about have it nailed.

Make sure that all the extensions that you are not testing are disconnected or have the capacitor installed at each end. The caps are easy to use; just connect them across the speaker wires. One cap lead on the (+) and one on the (-). Connect your test speakers and listen for the hiss.

Another test you can do is to use a short (30cm) section of speaker wire to connect your test speaker to the factory connector. The idea here is to eliminate you long speaker wires.

Remember anything you leave connected to the factory wiring is going to act as an antenna and spoil the test.

jeff

EuroDude2k

ok so let me get this straight.

I disconnect all channels except one.
I simply "short" a capacitor from the (+) speaker wire to the (-) speaker wire, while the speaker wires are still connected.
(One capacitor on the Amp side, the other on the HU side)


Is that to filter out the Hiss from the HU?
Or is that to remove interference that may be picked up via that OEM speaker wire?



Re the 20pin HU connector:

The rear speaker wires coming from the HU have not been touched on the HU side, so I cant really cut those for testing.
The front HU speaker wires have been cut at the HU, and I have soldered new speaker wires that go to the Amp at the front which is only a meter or so away. Due to the location of the HU connector (it connects into the rear of the HU, not the bottom - its a HUGE pain to remove and reconnect), the speaker wires have become fragile/fatigued. I already had to replace part of the 12v HU wire due to metal fatigue. In fact I would just prefer to live with the Hiss, rather than fiddle with that connector again :p

Can I add just one capacitor on the Amp side? Or must you have one on the HU side as well? If there must be two, can I tap the Cap into the wires a meter from the HU?



Is there another way to do the test? Perhaps disconnect the rear amp and add Caps to its speaker wire inputs on the Amp side only? Then focus on the Front Amp?

mercman

You can start by connecting the caps at the amp. If you get an improvement then make every effort to place the caps at the HU also.

Here is what is likely happening. The factory wires are shielded (I don’t know for sure) when you add standard zip cord speaker wire you create an antenna for radio frequency pick up. Normally you wouldn’t think this would be a problem since you can’t here RF. The problem comes when the RF travels along the speaker wires in to the HU. Once in the HU it is free to jump around and find a non linear device (that’s a fancy way of saying a diode) and have the RF energy converted to audio noise amplified and sent to the speaker. The caps will act as a short circuit to RF energy and an open to the audio.

This is a test, if the noise is reduced but not eliminated we can try different configurations. For now just start at the amp and be sure that all the “antennas are disconnected or shunted with a cap. The caps will be most effective at the HU though.

jeff

EuroDude2k

The OEM speaker wires are not shielded, they are the exact same Honda/Acura wires found in the rest of the car.

The only Head Unit wires I replaced were the front HU speaker wires, which I only replaced a week ago. Before that, it was just the Rear Amp installed. The front was totally stock.

The Rear Amp is using the original HU speaker wires that were once connected directly to the stock 6x9's.

So basically, with all the Head Unit wires completely stock, all you need to do is directly replace a stock speaker with a decent speaker, and the hiss will surface.

Mind you I did have the power cable running through the car before the hiss started, but there was no hiss at all with the stock rear speakers connected to the Amp. (The power cable is not near the speaker cables at all. It comes into the passenger area, through the center of the car and into the boot. The OEM rear speaker wires travel on the Right side).

So in saying that, wouldnt you think the stock tweeters at the front would give out hiss? If the front tweeters are designed to hide the frequency of the hiss, that wouldnt leave much frequency for other high frequency levels. So perhaps the stock speakers are "BTL" speakers? If there is such a thing.




Anyway I will try the capacitor test when I get a chance (on the weekend).

I will also try disconnecting the rear Amp's speaker inputs and power cable, and see if the front hisses (I'm quite sure it will).

By the way, I have an IceLink connected to the HU's CDC connector - that wouldnt cause the hiss would it? (It hisses while in Radio and CD mode as well, so I have doubts the IceLink is the cause). I will also try disconnecting that - just in case.

jiggaman

my brain hurts from reading this thread!

mercman

Lets make sure we are talking about the same thing. A hiss is a wide band noise that sounds like a radio that is not tuned to a station. If the noise is only coming from the tweeters then it is more of a whine. In any case, speakers cannot be designed to block hiss since his is a product of every audible frequency. Both hiss and whine can be caused by ground loops and/or poor grounds, but whine is more often the result.

Yes you should disconnect all external devices to troubleshoot the noise.

It is possible that the xovers on the aftermarket speakers are picking up the noise or it could be just the new speaker wires. The capacitor test should help us nail down the problem.

jeff

EuroDude2k

The hiss is about the same frequency as air escaping from a tyre.

I'll try the capacitor test and a few other things, and go from there.

EuroDude2k

It just occurred to me, perhaps the HU is outputting 2ohms or 8 ohms or something like that?

I know the 6x9's are 4 ohms. Can 4ohm speakers hiss if they receive 2ohms?

Castles_Saloon

too low of an impedance, say 1 ohm, can cause an amplifier to go unstable. But i doubt that relates to your hiss problem. you could try a different 8 ohm speaker in place of the stock to verify. you could intentionally buy less efficient speakers (many nice speakers fall into this category) that require more volume to play. By default, the volume of hiss would reduce since they require more energy to produce sound.

Follow mercman's directions and the noise should be removed unless the equipment you are using is incompatible based on their internal grounding circuitry. Or its the Hu performance you are stuck with and its just more audible with your new speakers.

While you are at it, you might as well disconnect the icelink (if you haven't already), in case their is a ground current caused by it.

EuroDude2k

^ yep I'll try all that on the weekend when I have some spare time.

Ive read that the 03-05 Euro had a really bad hissing problem, which was 'improved' in the 06-07 Euro. So I have a suspicion its simply the quality of the internal HU Amp.

The TSX has a separate factory Amp, which doesnt possess the hissing problem

EuroDude2k

ok I got some resistors 8 ohm non inductive resistors, but had trouble picking the correct capacitor. I bought a 0.1uf 35v green cap for testing, but i'm not sure if its the same as Radio Shacks 272-1069 (we use Jaycar for components here in AUS). Does the cap need to be bipolar? Does it matter what voltage I get?

So I short the cap to the speaker input wire, what do I do with the resistor? Short that as well at the same time?

mercman

The caps are good and there is on polarity with this type of cap.
The tests are for two different things so first test with the resistor at the amp end of the speaker lead from the HU. Then remove the resistor and test with the caps at each end of the cable. Remember, for the tests to be valid all the unused speaker wires feeding the amps must be disconnected at the HU and amp. But especially at the HU.

You can try the resistor and caps at the same time but I need to know the results of the separate tests.

jeff

EuroDude2k

Alright I will short the speaker wires at the rear channels with the resistor, then again with the capacitor. (The rear is more accessible so I will test at the rear amp)

I only got one capacitor since I didnt know they were the correct caps when buying, so I guess I can simply disconnect all but one channel and short the cap on the active channel.

I'll try this within a few days and report back.

mercman

Any word one this?

jeff

EuroDude2k

Hi mercman, I haven't had a chance yet. Hopefully I'll get some spare time to test it this weekend

mercman

When you do try it is important to install the capacitor as close to the HU as possible (on the back of the HU would be best). I’m fairly confident that you have a parasitic oscillation caused by the HU BTL output stage. A lot of car audio output amp chips are prone to this type of problem. This might explain why the factory speakers “mask” the hiss. They are not masking the hiss just providing a load the HU can deal with and not oscillate. The added speaker wires and hi input impedance of the LOCs just make it easy for the problem to occur. This is why I want you to do all four channels or complete disconnect the ones you are not testing. Any channel can oscillate and interfere with the others.

How’s that for a bit of rocket science to make your head hurt!

jeff

EuroDude2k

A bit of Rocket science doesn't bother me :p

When you say Load, do you mean ohm rating? I probed the factory speaker using ohms, it gave me 3.8 (they are 4ohm speakers I guess). The aftermarket speakers are also 4 ohms, but they hiss.

What I may also try is reconnect a factory speaker and listen for the hiss when really close to it. Perhaps they also hiss, but at a much lower level inaudible from a distance.
And I'll also try connecting a rear speaker directly to the factory speaker wire. I have doubts but the extra 1 meter of wire (connecting the stock rear HU speaker wires to the Amp High Leve input) may be causing more hiss


ps. I removed the LOC, the sound quality was no good.

mercman

When I say load I’m talking about the complex impedance that the amp sees. It is made up of the DC resistance of the voice coil (what you measured with the meter), the inductance of the voice coil and speaker wire and the capacitance of the voice coil and speaker wire. Impedance varies with frequency and causes phase shifts of varying degrees at different frequencies. The amp also has a complex output impedance that interacts with the load impedance. The .1 uf caps basically look like a very low impedance to frequencies higher then audio and prevent the HU from becoming a noise generator.

jeff