# TORO RX4S - 80w x 4 @ 4Ohm Impressions and Review



## Stoopalini (Apr 16, 2021)

I was in the market for a 4 channel, 70 - 100 wpc class A/B amp for my mids and highs, and considering the TORO micro Class D amps seem to be getting good reviews, I thought I'd give this one a chance.

TORO RX4S | 80 Watts x 4 RMS @ 4Ω ~ 4 Channel Sound Quality Car Amplifier


RMS @ 4 Ohms80w x 4RMS @ 2 Ohms100w x 4Bridged RMS @ 4 Ohms200w x 2Min Impedance2 OhmLPF / HPF80Hz ~ 3kHz / Full ~ 3kHzTHD @ RMS Power<0.05% S/N (EIA Rated)>105 dBMax Voltage14.5vRCA Voltage200mV ~ 10VFreq. Response14Hz - 50kHzCrossover Slope12dB Rear ChannelSubsonic FilterN/ABass EQ OFF / 6dB / 12dBSubwoofer EQN/ADimensions Inches12.56 (in) x 2.0 (in) x 7.1 (in)Dimensions mm319mm x 54mm x 171mm 

The amp was originally marketed as 100w x 4 @ 4Ohms, but tey apparently changed the ratings after real-world testing revealed it was overrated. So that gives me a sense of comfort the 80w x 4 will be accurate. 

I bought it directly from the TORO website, and paid $179 for it. The 1st amp they sent me had some significant cosmetic issues, so I returned it and they sent a replacement. Their customer service was great, and had no issues getting a replacement out ASAP.

The replacement arrived in a Massive Audio TX5 shipping box, which isn't too surprising considering Massive owns Toro. 










pretty typical packaging and boxing ...





































The amp looks decent enough, although I'm not sure how I'll feel about the 4 LEDS under the TORO name. I guess I'll just have to see what I think once it's installed. 

Two things I noticed right away were that one of the 30A fuses was not seated fully, and the terminal block for the speaker connections is a bit skewed; meaning it's not squared up with the chassis. Other than those two things, it feels and looks solid.










One thing I was disappointed about is the crossover and gain control screws. All the marketing material on the website, as well as the pictures on the box, show them to be metal shafted potentiometers; but both units I received used plastic. I really like metal controls for an amp, and this was one of the factors which made me decide to give the RX4S a go ... but after conversing with support, they've confirmed all the RX4S units they have use plastic. They stated the factory must have changed this after taking the product shots, and they are working to update the images on the website, as well as the next batch will have updated product shots on the box too. 

The gain and crossover controls are smooth as well, with no detents. I think metal controls with detents really add a quality feel to an amp, but for this price point, I'm not surprised at the use of plastic. I just wish the marketing wasn't misleading on this.

I will say the two clipping indicators are a nice touch (one for CH 1+2, and one for CH 3+4).










The box and labeling on the amp also still say 100w x 4, which isn't a big deal in my opinion ... although it may make it more difficult to sell in the future if I try. But for such a low cost amp, not sure it would be worth trying to sell a used one anyway.










The rest of the amp's physical characteristics are pretty standard. Nice solid connection points for power and speakers, as well as threaded RCA jacks are nice.



















The amp has a nice feel in my hands, with some heft to it, and I do appreciate the minimal styling. I am hoping to get it installed in the next day or two, and spend some time with an RTA and O-Scope to see how it does.

I'm replacing two old school amps (a PPI 4240 and a RF Punch 250) with it. Both of these amps have been work horses for me over the years (bought them both back in 1998 or so), but I need a bit more wattage, and I'm sure the caps in these old amps are starting to reach end of life (I'm actually starting to get a bit of noise through the PPI now). 

More to come in the next few days, but if anyone has questions, or wants to see anything in particular on the amp ... just let me know.


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## rxh0272 (Jul 26, 2020)

Great review!
Thanks man. 

Curious to see how it performs when hooked up and tuned. I was discussing the Toro lineup in another thread, and then found your other threat that switched to this one. 

How heavy is it?
Is your birth sheet blank?
Are they really what they say they are? CTA rated stamped on it. Is it legit?
I'm not surprised at the fine details not being as refined as ... say a RF Punch or something like that, given the price range of the Toros.

I'm not sure about it though. I mean like how heavy is it? My RF P600X4 is like 12-15 pounds, and it's an AB. I just bought a RF R2-500X1 for a JL sub. Birth sheet says 601 W [email protected] weighs about 5.5 lb. Class D, so .... I should have gotten the T750X1bd so I have room to expand. Plus, it's so small.

I saw on Youtube and others saying that the Toro birth sheet comes blank. 

I'm going to be watching this thread for your continued reviews.


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## Stoopalini (Apr 16, 2021)

rxh0272 said:


> How heavy is it?
> Is your birth sheet blank?
> Are they really what they say they are? CTA rated stamped on it. Is it legit?


The chassis is all aluminum, except the end plates which seem to be steel with a plastic cap. It weighs 6.4lbs











It didn't come with a birth sheet, and nothing in the manual shows a place for unit tested details. Not sure if it's supposed to though?

The CTA-2006 stamp is on the end plate, yes. The manual also states specs are at 14.4v. I believe this is why they had to lower the stated specs from 100w x 4 to 80w x 4










The chassis does feel well made, but I realize that's not too hard to do these days.

The engineer told me it was a dual sided PCB board, but I'm starting to doubt that. I didn't get a chance to hook it up yesterday, and am hoping to find some time before the weekend to do so. I will certainly keep the thread updated


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## Stoopalini (Apr 16, 2021)

So I finally got a chance to install the amp today. 

Since I've had my PPI and RF amps dialed in for awhile now, I wanted to be able to do a SQ comparison to what I've ben listening to. 
So to ensure a like-for-like comparison, I performed the following process:


Defeated all EQ on the 80PRS (both manual EQ and Auto EQ turned off/flat)
Muted the sub out (80PRS is running in network mode)
Disconnected my tweeters and midrange speakers from the PPI and RF amps
Then I docked my iPhone to the HU, and Turned the HU volume up to 45/62
Played a 1kHz test tone at -11dB level 
Measured the voltage being output by the RF amp (which was running my midranges)
Left = 14.1vac
Right = 11.1vac


Switched the test tone to a 6kHz tone at -11dB level
Measured the voltage being output by the PPI amp (which was running my tweeters)
Left = 10.8vac
Right = 7.1vac


Once I had these baseline voltages written down, I then proceeded to remove the amps and install the TORO RX4S.

Mounted the amp
Connected the power, ground, remote, and RCAs but left the speakers disconnected
Turned the system on, and again, turned the HU volume up to 45/62
Played a 1kHZ test tone at -11dB
Adjusted the gain level on the TORO amp for CH3/4 until CH3 vac read 14.1vac
Then I measured CH4, and it read 11.2vac

Played a 6kHz test tone at -11dB
Adjusted the gain level on the TORO amp for CH1/2 until CH1 read 10.9vac
Measured CH2, and it read 7.3vac

Then I turned the system off, and connected the speakers wires to the amp. 

I did this meticulous process so I could be sure any improvements or degradation in SQ would be due to the amp, and not different levels being played. I wanted a fair comparison of the sound quality.

Then I re-enabled the Auto EQ and my manual EQ in the HU. The manual EQ settings were done a couple of months back, with an iMM-6 calibrated microphone, pink noise being played through the system at -3dB level, and RTA measurements taken with AutioTools.

So I fired the system up, and played a song I know well .... "All my Friends" by Owl City. I like this album for evaluating car audio because of the incredibly clean post production value on it. It very well mixed, with clear separation between instruments. 

I have to say, my initial impressions are the amp sounds really, really good! I only listened to the one song, with the engine idling in the garage, and the volume cranked to about 95dB or so. It seems like my tweeters came alive when comparing to the old setup. The sound is crisp, clear, maybe refreshing? The midbass seems much more pronounced as well. More full sounding. Imaging seems improved too .... I really think my old PPI and RF amps have been degrading over the years, but I had no idea it was affecting the sound so much. Either that, or this RX4S amp is a real performer (or combination of both?).

I will say when I was playing test tones on the old amps, to take the baseline measurements ... I could hear the tones coming out of the PPI amp at a very low volume, even though there were no speakers connected. I don't know enough about electrical design to understand what this may mean, other than I'm sure it's an indication of components gone outside their tolerance range due to age. When I played the test tones on the RX4S, I did not experience this at all.

So as it stands right now, I'm really glad I took a chance on the amp. I will get some more extended listening time in when I can to make a more fair comparison ... but I have a feeling it's not going to disappoint!

The install isn't finalized yet, as I want to put the panels back in the trunk to hide the fuel tank again, but this will work for the short term.


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## Stoopalini (Apr 16, 2021)

I was able to find a review of the RX4 from Williston Audio Labs, where he showed a guts shot of the RX4. So I decided to compare it to the RX4S. Looks like there are some significant differences ... power supply filtering, output filtering maybe? An extra mosfet, etc ...

Here is the RX4 (rated 65w x 4 @ 4Ohm):










And here is the RX4S (80w x 4 @ 4Ohm):


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## rxh0272 (Jul 26, 2020)

Thanks for the great review. 
I mean they have the CTA stamp, but so does Rockville amps. So IDK anymore. That's why I was asking about the birth sheet.
I have limited to no equipment for testing. Do you have gear to do testing to make sure the signal is clean just to check it out? I'm curious about that too. 
I can probably find an older O scope on Ebay. 
The two amps do not look much different. I can see the power supplies sections are different. The 4s has jumpers in different location, and that small wire connector on the bottom is different.

See that jumper bar just below the ... what toroid? the jumper in the 4s is about at the middle and then goes off to the right, but the old version looks like it farther to the left side of the toroid. Maybe it's just the angle? 
the 2 bigger caps to the left of the power supply are moved to the left in on the 4s. There is no writing next to the resistors there, and the TORO name has been moved. The space between the 2 caps and the resistors is smaller. 
The top right of the pics: the amps are different.


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## Stoopalini (Apr 16, 2021)

My guess is the power supply has extra filtering, and the added jumpers on the right side of the RX4S may be for the added Mosfets on the top rail (6 on the RX4, 8 on the RX4S)

I do have access to an O-Scope, I just haven't had time to dig into that level of detail yet. I won't have time in the coming week, but will the one after (week of the 14th). 

Here's a link to the RX4 dyno test. At the time of testing, the RX4 was rated at 75w x 4 @ 4Ohm. TORO has since changed the rating to 65w x 4 @ 4Ohm; so it now aligns with this dyno test. They also changed the rating of the RX4S at the same time, from 100w x4 @ 4Ohm down to 80w x 4 @ 4Ohm. 

So I'm inclined to believe the specs are accurate, but would like to verify. 






I took a longer drive yesterday, and listened to some Dire Straits ... It really does sound good!  I'm impressed with the clarity, even with my cheap MB Quart OSC-216 midranges. I need to swap them out for the matching midranges for my Hertz tweeters, just haven't gotten around to it yet. I took delivery of some Second Skin products yesterday, and plan to treat the doors and swap the midranges at the same time.


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## rxh0272 (Jul 26, 2020)

Stoopalini said:


> My guess is the power supply has extra filtering, and the added jumpers on the right side of the RX4S may be for the added Mosfets on the top rail (6 on the RX4, 8 on the RX4S)
> 
> I do have access to an O-Scope, I just haven't had time to dig into that level of detail yet. I won't have time in the coming week, but will the one after (week of the 14th).
> 
> ...


Any updates?


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## Stoopalini (Apr 16, 2021)

rxh0272 said:


> Any updates?


Not yet, I just haven't had time. I'll definitely update the thread after I've been able to do some more testing on it.

Anecdotally, I am still enjoying the sound from it though! Every time I take a drive, the system makes me smile


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## bobgodd (May 11, 2021)

Stoopalini said:


> Not yet, I just haven't had time. I'll definitely update the thread after I've been able to do some more testing on it.
> 
> Anecdotally, I am still enjoying the sound from it though! Every time I take a drive, the system makes me smile


Still sounds good?


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## Stoopalini (Apr 16, 2021)

bobgodd said:


> Still sounds good?


Yep, still sounds great. I'm finally to the point where the final tuning can be done with an o-scope, and I'm hoping to do it tomorrow.

Over the past couple of weeks, I have treated the doors, front fenders, and entire rear passenger compartment with second skin's CLD, MLV and CCF products. I also replaced the 6.5" MB Quart mid-range door speakers with the 6.5" Hertz drivers which are a match for my tweeters.

Oh, and I also replaced the tires with Bridgestone Quiettracks. My old tires were 7 year old Nitto Motivos, which were quite noisy and unable to be balanced due to their age.

The car sounds really, really good ... both in terms of the stereo, but also significantly reduced road noise and zero rattles.


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## LimpCroissaint (May 18, 2021)

Any update on this boss? I just learned about Toro amps this afternoon and am doing some reading on them and am interested on what you've found/think. These sure do seem like an awesome value amp. And it has a bandpass crossover on channels 3 and 4?


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## Stoopalini (Apr 16, 2021)

LimpCroissaint said:


> Any update on this boss? I just learned about Toro amps this afternoon and am doing some reading on them and am interested on what you've found/think. These sure do seem like an awesome value amp. And it has a bandpass crossover on channels 3 and 4?


I've actually been traveling quite a bit, so haven't got around to using the o-scope on the amp yet. I have done some more tuning, in terms of using a calibration mic with AudioTools to set delays and proper EQ curve, as well as setting gains using a DMM; just haven't gotten around to using the o-scope to check out clipping thresholds.

The system still sounds really good though, and I wouldn't hesitate to recommend this amp for a budget SQ setup.

I did find some time to clean up the wiring and get a proper ground setup installed. Also added some circuit breakers in the trunk (in addition to the underhood fusing).




















With the fuel tank cover in place, it makes for a nice semi-stealth install. And it's really easy to disconnect the sub when I need to use the trunk space.











And ya, channels 3 and 4 can be bandpassed with the built in crossovers on the amp. I'm not using the amp's crossovers at all though, as I'm using my Pioneer 80PRS crossover's instead.


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## Theslaking (Oct 8, 2013)

LimpCroissaint said:


> I just learned about Toro amps this afternoon and am doing some reading on them and am interested on what you've found/think.


I assume you read the bigger thread on here started by Navy Chief?


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## bobgodd (May 11, 2021)

LimpCroissaint said:


> Any update on this boss? I just learned about Toro amps this afternoon and am doing some reading on them and am interested on what you've found/think. These sure do seem like an awesome value amp. And it has a bandpass crossover on channels 3 and 4?





Theslaking said:


> I assume you read the bigger thread on here started by Navy Chief?











Toro Tech Micro Rage amp review (MRx4, MRx2 and MR2)


I have been away from this site and others like it for a few years now. I have recently found the time to reengage into some things I want to do, and rebuilding the setup in my truck was high on that list. I have been shopping around for a few months now for new amps with the specific...




www.diymobileaudio.com


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## LimpCroissaint (May 18, 2021)

Stoopalini: Nice job, looks good. The band passing capability of that amp is a very cool feature and is very rare to find in a product near this price! I may have to grab one and give her a try.
Theslaking and Bobgodd: Yes I did read through Navychief's review and that combined with this have really impressed me on this little thing! Thank you for the link by the way.


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## Stoopalini (Apr 16, 2021)

As an update to this thread, I've recently begun experiencing issues with the amp. It'll cut off, intermittently, for a few seconds before coming back on. It's too fast for me to be able to exit the car and open the trunk to check the LED (to see if it's red and in protect mode), but my guess is that's whats happening. This happens regardless of volume. I can have the radio barely on, just playing softly in the background, and it'll happen. Or I can have the system cranked up, and it'll happen. The frequency of the intermittent cut-off doesn't seem to change, or be related, to the volume it's playing at either.

It started a couple of weeks ago, cutting out maybe once or twice on a 30min drive. I figured it may have been the speaker wires, since they're 12 or so years old and have been spliced a few times over the years. So I bought new 16 AWG wire, and rewired all 4 speakers from the amp, direct to each driver ... but that didn't fix it. To be clear, I ran all the way to each driver (no splices), soldered the speaker ends with heat shrink, and also added ferrules to the amp ends.

So I figured maybe it's the ground, and went ahead and redid the ground and power wiring as well ... but that didn't resolve it either.

I then thought maybe it was the remote turn on lead, since it is also connected to the OEM antennae booster. So I installed a opto-isolated relay, which uses the 12v power from the amp lines to feed the amplifier's turn on terminal. But that didn't resolve it either. When the Toro cuts out, the sub continues to play.

I'm assuming at this stage there's something wrong with the amp (over heating maybe?), and have a call into Toro for support, but haven't heard back from them yet.

Here's a diagram showing the system:










Here's a diagram showing the wiring layout:










And here's a couple of pictures of the trunk:


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## Theslaking (Oct 8, 2013)

Speaker wire plug/harness. I had one go bad.


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## Stoopalini (Apr 16, 2021)

Theslaking said:


> Speaker wire plug/harness. I had one go bad.


That was my first thought too, which is why I ran all new speaker wire. I ran new 16ga wire from the amp all the way to each speaker, so there are no harnesses or factory wire being used.


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## blammo585 (Feb 1, 2020)

I have the RX4, and, knock on wood, I like it. I use it in 3 channel mode to power my front speakers and a single sub. I will say that that thing gets really hot, but I have not had it cut off or go into protect. Perhaps tomorrow after work I'll give it a good test and play it hard all the way home from work, which is a 30 minute drive. It's supposed to be 92 tomorrow so it'll already be pretty hot in the trunk when I leave.


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## Stoopalini (Apr 16, 2021)

blammo585 said:


> I have the RX4, and, knock on wood, I like it. I use it in 3 channel mode to power my front speakers and a single sub. I will say that that thing gets really hot, but I have not had it cut off or go into protect. Perhaps tomorrow after work I'll give it a good test and play it hard all the way home from work, which is a 30 minute drive. It's supposed to be 92 tomorrow so it'll already be pretty hot in the trunk when I leave.


Thanks. The thing is, it happens even when I'm just listening on very low volume. Like driving with someone in the car, and we're talking with the radio barely playing in the background. Not even loud enough to really know what song is playing, and it'll just cut off. I did get out today when it happened and felt the amp. It had already turned back on by the time I unbuckled, got out, popped the trun, etc ... but it was very hot to the touch. I wonder if maybe it's over heating.


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## blammo585 (Feb 1, 2020)

Stoopalini said:


> Thanks. The thing is, it happens even when I'm just listening on very low volume. Like driving with someone in the car, and we're talking with the radio barely playing in the background. Not even loud enough to really know what song is playing, and it'll just cut off. I did get out today when it happened and felt the amp. It had already turned back on by the time I unbuckled, got out, popped the trun, etc ... but it was very hot to the touch. I wonder if maybe it's over heating.


It sounds like if it's getting hot at low volume then something else is going on. Also, you say it starts playing again before you can get back there and check it out. My Sony, when it went into protect mode would not come back on until my vehicle was cut off and restarted. If it's going out and coming back on pretty quickly I don't think it's heat. But I don't know.

Funny thing about my RX4, when I got it I was just using it with a sub. It was cool to the touch even when played hard. I thought, wow, class AB has really come a long way on heat. I finally connected my front speakers to it and began running it in 3 channel mode. The temperature shot up after that. When I play it loud for long periods it gets really hot. Burn your fingers hot. It's amazing how much hotter it got from those front speakers playing as opposed to just the sub.


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## Stoopalini (Apr 16, 2021)

Agreed, it does appear it is getting too hot and causing a problem. Since Toro mentioned the RCA cables, and mine have been in the car for a decade or so (they're cheap no-name cables) ... I decided to go ahead and replace them. Some Stinger 6000 series were just dropped off, and I hope to replace them this weekend.

As I was troubleshooting, I took a close look at the two 8ga power cables as well ... and it turns out they are CCA cables. When I was running my 30x4 PPI amp and Punch 250 amp (62.5x2), I never had a problem ... but now that I'm running the 80x4 Toro and 300x1 Rockford sub ... maybe the 10 year old 8ga CCA cable isn't up to the task? I could see a voltage drop causing the Toro to shut down, until the voltage came back up; although when playing at a low volume, I wouldn't expect it to occur due to minimal current flowing ... but who knows?

Here is a look at my existing power wiring schema:












Based on this, I decided to go ahead and buy all new OFC wiring, and up-size it while I'm at it. When I replaced the speaker wire, I went with 16ga OFC for them, which in theory would support up to 300w per channel. So in the spirit of having balanced future upgrade capability, I went ahead and ordered 2ga OFC for the feed from the battery to the trunk, and all new 4ga OFC for the amps power and grounds (as those are CCA as well). I'll also add an additional 2ga OFC wire as an extra ground from the battery to the chassis, just for good measure.

The new schema will be:











If this doesn't resolve it, then I'll be requesting an RMA from Toro.


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## lithium (Oct 29, 2008)

After you pull the CCA cut it open in a few sections. I'd bet its brittle and corroded.


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## Theslaking (Oct 8, 2013)

And was saying the actual plug in to the amp. Mine got a bit lose (which was likely my doing, whole nother story) and started cutting in and out. I messaged Toro and they sent a replacement. 

I don't think it's over heating. I wouldn't think it would turn back on that quick or without a power cycle. Maybe the antenna booster was sending to high of amperage signal and messed up the remote sense. I mean it only takes milliamps and some amps can't handle it.


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## Stoopalini (Apr 16, 2021)

lithium said:


> After you pull the CCA cut it open in a few sections. I'd bet its brittle and corroded.


Definitely will do.



Theslaking said:


> And was saying the actual plug in to the amp. Mine got a bit lose (which was likely my doing, whole nother story) and started cutting in and out. I messaged Toro and they sent a replacement.


Gotcha ... This isn't one of their micro amps though, so there is no harness plug on the amp side. 













Theslaking said:


> I don't think it's over heating. I wouldn't think it would turn back on that quick or without a power cycle.


It's definitely getting hot, but I'm wondering if the CCA cable has degraded enough where the voltage may be dropping below the amp's tolerance? If I have time later tonight, I'll meter it out with the volume cranked to see. 



Theslaking said:


> Maybe the antenna booster was sending to high of amperage signal and messed up the remote sense. I mean it only takes milliamps and some amps can't handle it.


I ended up putting in an opto-isolated relay module, to separate the HU's trigger from the amp's remote lead, still have the issue though.


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## Theslaking (Oct 8, 2013)

Stoopalini said:


> to separate the HU's trigger from the amp's remote lead


I'm suggesting the damage is done




Stoopalini said:


> It's definitely getting hot


Many amps are designed to get hotter than most humans can tolerate. Ask the what the operating range is. It will at least tell you if thermal failure is likely.




Stoopalini said:


> there is no harness plug on the amp side.


I see it in your pic. It's just not removable. 🤨

Wiggle it. Worth a try. Obviously that's a warranty issue on a stationary terminal but..



Stoopalini said:


> I'm wondering if the CCA cable has degraded enough where the voltage may be dropping below the amp's tolerance?


That's definitely a possibility. Many amps are very sensitive to low voltage.


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## Stoopalini (Apr 16, 2021)

The issues with the amp seem to be getting worse  Here's an email I sent to Toro support today ... 



email_to_Toro said:


> The issues with this amp seem to be getting worse. Channel 3 (my driver’s side midrange door speaker) developed an alternator whine late last week. It’s just on this one speaker/channel though and The other 3 are dead silent.
> The whine does not change loudness when adjusting the headunit’s volume, but changes pitch with the engine RPM.
> Strangely enough, the whine is still present (although at a lower volume) even when the headunit is off and the amp is also off?
> 
> ...


I really want to like this amp, as it sounds great ... but I won't keep it if it can't run silent. 

I am still planning to upgrade all my wiring to OFC, although I don't think that is going to have any impact on this new issue. If the whine was being caused by the power/ground wiring, I would expect it to be on all 4 channels, and not just channel 3.


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## lithium (Oct 29, 2008)

You could bypass the HU with a 3.5mm to rca cable connect to your phone. Probably result in the same conclusion. If the ground on the RCA might be bad internally maybe you can tie the RCA to ground with some spare wire.

Similar to this but at the amp. 


ground rca to chassis pioneer hu - Google Search


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## Stoopalini (Apr 16, 2021)

lithium said:


> You could bypass the HU with a 3.5mm to rca cable connect to your phone. Probably result in the same conclusion. If the ground on the RCA might be bad internally maybe you can tie the RCA to ground with some spare wire.
> 
> Similar to this but at the amp.
> 
> ...


Thanks, although I don't see a need to test with my phone and an adapter due to the noise being limited to ch.3 of the amp. I don't think I'm dealing with a HU issue (certainly not the pico fuse issue).

I would consider grounding the RCA jack as a workaround solution, but in this case, the amp is less than 90 days old and still covered under their warranty. I'm also not convinced it would work. If the noise was coming through the input side of the amp, I would expect the head unit volume to impact the noise volume; and it doesn't. The noise is the same level no matter the volume of the head unit. The noise's pitch changes with engine RPM, but the loudness stays the same.

The only thing which impacts the loudness of the noise, is whether the amp is on or off. When I turn the amp off, the noise reduces in volume but is still present.

I've dealt with alternator whine over the years, but have never experienced a situation where the whine is still present even when the amp is off. I can't think of anything other than a bad amp which could cause this.


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## blammo585 (Feb 1, 2020)

I have whine on my RX4 as well. It didn't do it when I first used it just as a sub amp, but when I started using it with the front speakers I could hear it (understandably since the whine wouldn't be in the low frequencies). I've always chalked mine up to using cheap Boss power cable as well as Boss RCAs and all of it is run down the same side together.


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## Stoopalini (Apr 16, 2021)

blammo585 said:


> I have whine on my RX4 as well. It didn't do it when I first used it just as a sub amp, but when I started using it with the front speakers I could hear it (understandably since the whine wouldn't be in the low frequencies). I've always chalked mine up to using cheap Boss power cable as well as Boss RCAs and all of it is run down the same side together.


Are you getting it from all 4 channels, or just one?


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## blammo585 (Feb 1, 2020)

Stoopalini said:


> Are you getting it from all 4 channels, or just one?


I'm getting it in the front two. The rear channels are bridged for the subwoofer, and I guess the low pass filter filters out any whine to the sub which is why I never noticed it when I first hooked it up.


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## blammo585 (Feb 1, 2020)

Stoopalini said:


> Are you getting it from all 4 channels, or just one?


Also, when I cut my head unit off the whine goes out immediately.


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## lithium (Oct 29, 2008)

blammo585 said:


> Also, when I cut my head unit off the whine goes out immediately.


That just sounds like a ground loop.


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## lithium (Oct 29, 2008)

Stoopalini said:


> Thanks, although I don't see a need to test with my phone and an adapter due to the noise being limited to ch.3 of the amp. I don't think I'm dealing with a HU issue (certainly not the pico fuse issue).
> 
> I would consider grounding the RCA jack as a workaround solution, but in this case, the amp is less than 90 days old and still covered under their warranty. I'm also not convinced it would work. If the noise was coming through the input side of the amp, I would expect the head unit volume to impact the noise volume; and it doesn't. The noise is the same level no matter the volume of the head unit. The noise's pitch changes with engine RPM, but the loudness stays the same.
> 
> ...


Just something to try for fun. Obviously I would warranty the amp and get that CCA out of there.


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## Stoopalini (Apr 16, 2021)

lithium said:


> Just something to try for fun. Obviously I would warranty the amp and get that CCA out of there.


Yep, that's the plan. I have the OFC sitting right here, just waiting for the underhood fuse block and distribution block to be delivered. I got the wire from Battery Cables USA ... I got their marine grade tinned OFC. $1.43 a foot for the 2 AWG and $0.83 a foot for the 4 AWG .. plus a couple of bucks extra for preinstalled ring terminals, and a flat shipping fee of $4 ... it was a no brainer. 










I ran a forum search for these guys and was surprised I didn't find anything on them. This appears to be high quality cable at a great price. Custom lengths, with ends pre-installed, makes it very convenient too.


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## blammo585 (Feb 1, 2020)

lithium said:


> That just sounds like a ground loop.


I went out while ago and ran a 3.5 to RCA from my phone to the front inputs on the amp. I cranked the car and played the music. Didn't hear any whine coming from the front speakers. I assume this means it's coming from the RCA and the power cable being ran together.


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## lithium (Oct 29, 2008)

blammo585 said:


> I went out while ago and ran a 3.5 to RCA from my phone to the front inputs on the amp. I cranked the car and played the music. Didn't hear any whine coming from the front speakers. I assume this means it's coming from the RCA and the power cable being ran together.


Running power cable next to RCA's is almost always NOT an issue, you have a ground loop. A ground loop is when there is a difference in voltage due to bad grounding. Your HU or amp ground is likely the issue. Since the noise went away when you disconnected the HU RCA's its likely the HU ground is the issue.


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## lithium (Oct 29, 2008)

Stoopalini said:


> Yep, that's the plan. I have the OFC sitting right here, just waiting for the underhood fuse block and distribution block to be delivered. I got the wire from Battery Cables USA ... I got their marine grade tinned OFC. $1.43 a foot for the 2 AWG and $0.83 a foot for the 4 AWG .. plus a couple of bucks extra for preinstalled ring terminals, and a flat shipping fee of $4 ... it was a no brainer.
> 
> View attachment 309919
> 
> ...


Sweet, I've used welding cable before to save cost. Most of the car audio branded stuff seems to be fancy colors or more flexible insulation.


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## blammo585 (Feb 1, 2020)

lithium said:


> Running power cable next to RCA's is almost always NOT an issue, you have a ground loop. A ground loop is when there is a difference in voltage due to bad grounding. Your HU or amp ground is likely the issue. Since the noise went away when you disconnected the HU RCA's its likely the HU ground is the issue.


But wouldn't the issue have been there in the beginning of using the amp when I was powering the front speakers from the head unit and the sub with the Toro amp? The grounds were still the same points.


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## Stoopalini (Apr 16, 2021)

lithium said:


> Sweet, I've used welding cable before to save cost. Most of the car audio branded stuff seems to be fancy colors or more flexible insulation.


Makes sense. I'm not too concerned with flashy colors, and this stuff is actually fairly flexible. I already installed the 2 AWG additional ground. If I had thought about it, I would have had them put a right angle ring terminal on the battery side, but this works.


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## Stoopalini (Apr 16, 2021)

blammo585 said:


> But wouldn't the issue have been there in the beginning of using the amp when I was powering the front speakers from the head unit and the sub with the Toro amp? The grounds were still the same points.


You probably did have the issue, but as you pointed out earlier, the low pass filter would have prevented it from being audible. 



blammo585 said:


> I'm getting it in the front two. The rear channels are bridged for the subwoofer, and I guess the low pass filter filters out any whine to the sub which is why I never noticed it when I first hooked it up.


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## lithium (Oct 29, 2008)

blammo585 said:


> But wouldn't the issue have been there in the beginning of using the amp when I was powering the front speakers from the head unit and the sub with the Toro amp? The grounds were still the same points.


If the noise goes away when you disconnect the HU RCA's than its not the amp. So this is unrelated to Op's issue. The LPF in combo w/ only the sub powered likely hid the noise issue to some extent.


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## Stoopalini (Apr 16, 2021)

Just as an update to this: I ended up sending the RX4S in on RMA, so I grabbed my old school PPI 4240 (30w X 4) out of the attic and installed it while I wait for the replacement.

The whine is gone with the PPI, so this confirms for me it is an issue with ch.3 of the Toro amp. I will say the PPI doesn't image as well as the Toro does though. My front stage pretty much fell apart after swapping the amp. I did a quick tuning on the PPI, but didn't spend too much time on it, as I'll just be swapping it back out when the replacement RX4S shows up.

The old RX4S was delivered to Toro yesterday, so I expect the new one to ship out to me within a day or two.


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## Stoopalini (Apr 16, 2021)

The new RX4S arrived yesterday, and I installed it last night ... idling in the garage, there's no whine from any speaker. The old one would whine from channel 3, even just idling ... so I'm fairly confident the issue is resolved. I'll take it for a drive later tonight though, just to be sure. 

I have to say Toro support has been great to deal with ... it's nice dealing with a company who stands behind their product like this


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## Stoopalini (Apr 16, 2021)

I finally had a chance to drive the car on a few trips, and unfortunately, the whine is back  It seems to be coming from channel 3 again.

I haven't tried swapping RCA or speaker wires again, but it wasn't present when I had my PPI amp in its place. I'm starting to think this is being caused from a design flaw in the unit? 

The whine is very low in volume, and I only hear it between songs, or in low volume music passages. Engine RPM impacts the pitch, but not the loudness of the whine. The head unit volume also does not impact the loudness of the whine. 

My car is very quiet now, after adding all the sound treatment, and I imagine before I did so, I probably wouldn't have heard the noise, as it's that low in loudness. 

I suppose it could be ground related, although I've done quite a bit to address the power and ground delivery. I do have my ground attached to a chassis bolt in the trunk. When I crank the system and measure the voltage at the amp terminals, I'm seeing very low (like 0.2) voltage drop when compared to the battery.

Here is a current view of my wiring config. If the whine was being caused by a grounding issue, I would expect it to show on all channels though, and not just ch.3 .... right?











I also upgraded the ground from the battery to both the chassis and the engine block to 2ga OFC wiring. 

I'm starting to wonder if the Toro amp just isn't up to the quality level I want. I suppose I could try a noise isolator on the RCAs ....


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## blammo585 (Feb 1, 2020)

Stoopalini said:


> I finally had a chance to drive the car on a few trips, and unfortunately, the whine is back  It seems to be coming from channel 3 again.
> 
> I haven't tried swapping RCA or speaker wires again, but it wasn't present when I had my PPI amp in its place. I'm starting to think this is being caused from a design flaw in the unit?
> 
> ...


I wonder the same thing. You know I have whine with a very similar model Toro. You have had whine with two different amps now. It might just be Toro.

I have my amp grounded in the trunk as well. I will admit my ground is pretty rough. I think my terminal or my spot is a little rusty.


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## KFXGUY (Jun 11, 2021)

I had a whine through my highs amp, I though it was because my rcas where kinda close to my power cable. I pulled it all out and separated them. Still there. then i put an isolator on the sub amp becuase I noticed the whine would go away if I unplugged the sub amp. what? Ok, whatever. i put a filter on the sun amp and the whine stopped on the highs amp. yea. weird. I think it was a ground loop coming through the head unit.


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