Fix to Bass Volume Decrease?

ComaSkillz · Mar 4, 2023

I have recently added subs to my Explorer ST. The biggest issue is when running your LOC from the stock sub/amp, to the new amp, there’s a considerable bass volume decrease when playing at high volumes. A bass knob will not fix this issue as I have one and have to constantly turn it up and down when playing at high volumes to 1) stop the subs from clipping and 2) hear the bass from the initial hit of the subs. I left my subs off the replicate with the stock sound system and it’s definitely noticeable.

Is there a way to take the signal from the stock sub/amp and make it so the aftermarket amp is not dependent on the signal strength it’s receiving from the stock system?

I saw somewhere on the forum that the stock system is trying to compensate for a bad stock sub by lowering the bass at higher volumes, I’ve also heard that the car is trying to compensate for the mic. I’m not sure what to believe but I’d almost pay anything to fix it. I’m just not sure if there’s something I can disable or buy to buy pass whatever implementation they’ve implemented to cause the bass decrease at high volumes.

Cdubya · Mar 4, 2023

How high a volume are you talking about and what frequency of bass are you talking about? When I tested it, the stock system did not decrease low bass with increased volume. My AudioControl LC2i has an Accubass feature to try to address this behavior but I did not turn it on and see no bass attentuation. If your bass is rolling off, I would look at your equipment.

ComaSkillz · Mar 4, 2023

I should add, i took it to an audio shop near me to have them install everything being this is a new car and I can’t afford to mess up the wiring. They tapped into between the stock amp and the stock sub for the loc. I’m using a fairly cheap loc that has done very well in the past for me since all I’m looking for is base. I’m soon going to be downsizing my subs to 2 JL audio W7s since my trunk started to fall apart from these earth quake makers. Sound quality is really what I’m shooting for but I want to fix the issue of the bass getting quieter at high volumes before I even think about putting W7s in. I don’t believe electrical is the issue since I installed an XS Power D3100 battery with the stock battery. I understand things are run off of the Alternator when the car is on and plan to upgrade that in the near future.

ComaSkillz · Mar 4, 2023

Cdubya said:

It seems to happen when I turn it to above the level 24-25. I figured although my LOC is not the best, all it’s doing is taking the signal and sending it to the amp, Not much in changing the volume or signal strength. As for frequency, it doesn’t matter really. The subs get noticeably quieter no matter what frequency is being played on them. I’d say as much as 60-70% quieter which is a huge difference for 18” subs.

Cdubya · Mar 4, 2023

24-25 on the B&O?!?! OK, I did not test that high because the stock B&O system starts to distort at around 15. I think if you are after sound quality, you wouldn't just be adding a powered sub to fill in the stock system. Especially if you are after high SPL. The stock system simply will not play loud and sound even passable.

Also, where are you pulling signal from the stock sub? line level or speaker level?

ComaSkillz · Mar 4, 2023

Cdubya said:

I think the stock B&O sounds amazing. It gets loud to compensate for the amount of bass coming from the trunk. Without the subs on, it definitely gets distorted but all I need are the highs and lows . Still doesn’t fix my issue. I don’t even know where to start to even attempt to locate the source of this issue.

ComaSkillz · Mar 4, 2023

Cdubya said:

Between the amp and sub.

Cdubya · Mar 4, 2023

I would make sure that the sub has line level inputs not speaker level. I'd definitely get a better LOC. The LC2i is not that expensive.

Edit: Now that I look at the wiring info, I don't think it's possible to get line level inputs to the stock subwoofer. Accordingly, when the stock system starts to clip, you are going to get bass attenuation.

ComaSkillz · Mar 4, 2023

Cdubya said:

I’ll most likely get the LC2i. I just ran to the store, turned the subs off and turned it up to about 15 and noticed that the bass still gets significantly reduced after a couple seconds of continued bass. So I correct my statement from above about the volume levels. I’m convinced it’s not the LOC still due to the fact that without the subs, it’s still getting quieter. Is there someone I could contact about this?

Cdubya · Mar 4, 2023

You can't judge bass rolloff with volume from the stock system. It has no appreciable bass below 40Hz or so. The stock "subwoofer" is merely a woofer. Try this: Turn on your powered sub, use a 30 or 40hz test tone played from a USB thumb stick. Take your phone and use an SPL app. Start increasing volume up to about 15. I think you'll find that SPL incrementally increases (or it should). There is no leveling off. If there is, try flipping polarity or even unplugging the stock subwoofer with the thinking that maybe they are cancelling each other out. Also, maybe experiment with subwoofer positioning. I would also question that maybe the SKAR brand isn't all that.

ComaSkillz · Mar 4, 2023

Cdubya said:

You can't judge bass rolloff with volume from the stock system. It has no appreciable bass below 40Hz or so. The stock "subwoofer" is merely a woofer. Try this: Turn on your powered sub, use a 30 or 40hz test tone played from a USB thumb stick. Take your phone and use an SPL app. Start increasing volume up to about 15. I think you'll find that SPL incrementally increases (or it should). There is no leveling off. If there is, try flipping polarity or even unplugging the stock subwoofer with the thinking that maybe they are cancelling each other out. Also, maybe experiment with subwoofer positioning. I would also question that maybe the SKAR brand isn't all that.

I will try this, thank you!

Edit, I’ll be switching to W7s very shortly due to SQ wants and needs

Cdubya · Mar 4, 2023

Just now, I was perusing some SKAR products. I have to say at least on paper, pretty impressive. Not knowing what you have, one of their sub amps claims to be 1 ohm stable. I did see a sub like the two you have pictured. It claims to have dual 2ohm voice coils--one ohm at the terminals. If you have two of those in parallel, that is 0.5ohm which likely is more than your amp can muster. Look into that. You might want to just run one of those and seeing what it sounds like.

ComaSkillz · Mar 4, 2023

Cdubya said:

I followed their wiring diagram to get to 1 ohm. I have the RP-4500.1D and 2 ZVX-18v2 D1 1 ohm subs. I contacted ford today to ask about the issue and they recommended taking it to my local dealer so they can further assist me.

Cdubya · Mar 4, 2023

ComaSkillz said:

That is fine if you have each subwoofer wired for 2 ohms (ie. in series) and then run them in parallel to the amp.

Lightning Struck · Mar 5, 2023

ComaSkillz said:

The dealer isn't going to do a thing other than probably charge you to tell you they can't do anything. Ford is not liable for aftermarket equipment.

Bass attenuation at high volumes is a normal thing to keep Ford(or any OE) from having to warranty woofers because people naturally perceive distortion as loudness.

banniar · Mar 6, 2023

ComaSkillz said:

The volume that induces this varies depending on what you're playing. On heavy bass songs, this kicks in ~15. On songs with infrequent bass drum kicks, it tolerates much higher volume. It acts like it is some sort of thermal-based protection since it sometimes takes time to kick in and cycles on and off... very annoying. I tried lowering the bass on the head unit and increasing gain on the amp to compensate, but the factory sub EQ keeps the really low frequencies boosted and the sound is just way unbalanced when you do this. I believe I'll need to toss the B&O amp and aftermarket everything to get around it, but that sounds more painful and expensive than I want to worry with for now. Maybe I'll stave off deafness for a while longer since I'm limited to 15 on the volume knob.

TheCryptoTrain · Aug 9, 2023

Did you ever get the bass volume decreasing issue resolved? I have a sundown amp and 12 installed with a higher end LOC but when driving, the bass lessens and I cannot figure it out. I also cannot find a high output alternator anywhere online that I can buy for the 2020 explorer st.

WFO-TSi · Aug 9, 2023

@TheCryptoTrain, and anyone else looking to get the most out of their audio system...

Attached is a screenshot of the factory Ford tables that dictate the alternators output. As you can see the target voltage drop WAY BELOW the ideal range for maximizing an amplifiers output. Once the assumed battery temperature rises, voltage plummets. I'd suggest seeing if your tuner can adjust those tables before paying for an upgraded alternator that will still be stuck playing by Ford's rules.

If you don't believe me, do some datalogging to see how low voltages get during fairly normal conditions. After a quick look I found a file where it was 82* outside, and my alternator's logged output was 12.98V while cruising. My amps are all a few years old and input voltage matters. Maybe it's not a concern for the latest gen digital stuff.

banniar · Aug 9, 2023

The voltage to the amp is only going to affect where it clips, so this comes into play only at high output. With the way the stock DSP limits sub output at high volume, it will likely keep you away from that limit with a reasonably powerful amp and sub combo set up to balance the stock amp & speakers at lower volume (<15).

To answer @TheCryptoTrain, I never changed anything and still have the sub volume decrease issue. I don't think it can be avoided without bypassing the factory amp/dsp, installing something like the Zen-A2B and putting aftermarket amps on everything.

Edit: additional clarification

bradmo9 · Nov 18, 2023

Bringing up an old thread has anyone tried this on the explorer to see if it helps? I just ordered forscan tool so I can give it a go.

ForScan Flat EQ before key200.4? | MaverickTruckClub - 2022+ Ford Maverick Pickup Forum, News, Owners, Discussions

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Fix to Bass Volume Decrease?

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