Rockford R750-1D (750W) vs Sundown SALT-2 (2000W) barely any difference in volume? No voltage drop when clipping?

[Terrum 10+ year member]

As per a previous thread I was looking to upgrade my single Sundown SA-12 Classic (750W) to dual Sundown SA-12 V.2s (2x1000W). I took the plunge to spend out a little more than intended for an amp that would work best with my lacking alternator (90A) but my aftermarket battery (Stinger 1850W) so got myself the Sundown SALT-2 merely because it is supposed to perform great even at low voltages.

I got a little excited and installed it early with the risk in mind that it would blow my SA-12 Classic if I cranked it. I started out with the sub disconnected from the amp and tuning the gains to a 0db 40Hz tone with the bass knob halfway (for headroom with quieter songs and on-demand control with the clipping light) and the headunit maxed (but unclipped).

I was disappointed to say the least when I connected the sub back to the amp and barely noticed a difference in volume even when I took the risk to put full load on the sub and it only seemed slightly louder at max volume (without clipping on either the headunit or amp) compared to my Rockford R750-1D.

The voltage on the bass knob stays within 13-14v even when clipping. No smells and no mechanical noise - I know the SA-12 Classic's power is underrated but I didn't think it could handle 2000W I also noticed that the SALT seems to be louder on the 'punchier' notes (kicks) but quieter on the basslines, compared to my Rockford R750-1D (750W) where both the kicks and basslines were pretty equal.

Another thing I will mention is that my headunit only has a single (mono) RCA output for amplifiers. Rockford confirmed that the left channel works as mono when only one RCA is plugged in, Sundown have yet to respond to me but for now I have kept the RCA cable in the left channel of the SALT amp. When playing a stereo bass tone (that wipes from left to right channels) the SALT amp still plays both channels. I know that a Y splitter will increase the signal but I don't know if that means an increase in volume without clipping or if I have just made up for that lesser signal by upping the gains with one RCA connected.

I've tuned both amps very similarly with subsonic filters turned as low as possible, and low pass filters turned to around 100Hz, I'm just a little confused as to why I'm getting very little difference in volume considering the huge jump in RMS wattage and wondering if anyone has any tips or advice.

Just to be clear everything I have described above is accurate regardless of whether the car is on (@14.4v) or off (@12.6v).

Many thanks for reading and I look forward to any discussions

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[Firewalker]

Subsonic is set to 2-3hz below box tuning and set low pass filter at 80hz not 100hz

 

[Terrum 10+ year member]

Subsonic is set to 2-3hz below box tuning and set low pass filter at 80hz not 100hz

Hi Coolhand20th, although I don't think that would make a significant difference to the problem I am facing I'll be sure to set those and see what difference it makes Actually the main reason I brought those up was merely to confirm that both amplifiers were tuned similarly so that shouldn't affect the issue I'm facing.

I do wonder though how accurate the clipping light is on the bass knob. I haven't cranked it past the clipping light considerably but maybe I should get an oscilloscope on it.

Many thanks and I look forward to any other discussions/tips etc.

 

[deez283 10+ year member]

What ohm load is each amp seeing?

 

[Terrum 10+ year member]

What ohm load is each amp seeing?

Both amps should have been seeing a 1 ohm load. I know that the SALT is currently seeing a 1 ohm load for sure as I checked the speaker terminals with a multimeter before tuning.

 

[Bobbytwonames 5,000+ posts]

Have you done the big 3? You might not be getting a 3db increase by changing amps. It usually takes 3db to notice a difference. Put a meter on both setups and see if they meter the same.subsonic should be about 7hz. lower than your box tuning. Try 70hz. instead.

 

[winkychevelle 10+ year member]

As per a previous thread I was looking to upgrade my single Sundown SA-12 Classic (750W) to dual Sundown SA-12 V.2s (2x1000W). I took the plunge to spend out a little more than intended for an amp that would work best with my lacking alternator (90A) but my aftermarket battery (Stinger 1850W) so got myself the Sundown SALT-2 merely because it is supposed to perform great even at low voltages.

I got a little excited and installed it early with the risk in mind that it would blow my SA-12 Classic if I cranked it. I started out with the sub disconnected from the amp and tuning the gains to a 0db 40Hz tone with the bass knob halfway (for headroom with quieter songs and on-demand control with the clipping light) and the headunit maxed (but unclipped).

I was disappointed to say the least when I connected the sub back to the amp and barely noticed a difference in volume even when I took the risk to put full load on the sub and it only seemed slightly louder at max volume (without clipping on either the headunit or amp) compared to my Rockford R750-1D.

The voltage on the bass knob stays within 13-14v even when clipping. No smells and no mechanical noise - I know the SA-12 Classic's power is underrated but I didn't think it could handle 2000W I also noticed that the SALT seems to be louder on the 'punchier' notes (kicks) but quieter on the basslines, compared to my Rockford R750-1D (750W) where both the kicks and basslines were pretty equal.

Another thing I will mention is that my headunit only has a single (mono) RCA output for amplifiers. Rockford confirmed that the left channel works as mono when only one RCA is plugged in, Sundown have yet to respond to me but for now I have kept the RCA cable in the left channel of the SALT amp. When playing a stereo bass tone (that wipes from left to right channels) the SALT amp still plays both channels. I know that a Y splitter will increase the signal but I don't know if that means an increase in volume without clipping or if I have just made up for that lesser signal by upping the gains with one RCA connected.

I've tuned both amps very similarly with subsonic filters turned as low as possible, and low pass filters turned to around 100Hz, I'm just a little confused as to why I'm getting very little difference in volume considering the huge jump in RMS wattage and wondering if anyone has any tips or advice.

Just to be clear everything I have described above is accurate regardless of whether the car is on (@14.4v) or off (@12.6v).

Many thanks for reading and I look forward to any discussions

Doubling of power is usually good for 3db on smaller systems 3db is considered the lowest margin you ear can hear the difference. Granted unless you used ohms law to set the salt 2 to 2k the salt amp can make a lot more power but it's not gonna blow the doors off with the same driver.

Once you double the cone area and double the power you should be 6db louder which is a fairly big change. 10db is often considered 2x as loud.

The sundown classic is a 2.5inch coil. Most 2.5inch coiled subs can handle 1000w RMS all day unless designed poorly. The sundown could fairly easily handle 1500w daily. But that's stressing it. Thus why the v2 uses a 2.75inch coil.

Sundown subs are underrated power handling wise.

That Rockford I'm assuming had a birthsheet around 900w.

 

[Bobbytwonames 5,000+ posts]

Doubling of power is usually good for 3db on smaller systems 3db is considered the lowest margin you ear can hear the difference. Granted unless you used ohms law to set the salt 2 to 2k the salt amp can make a lot more power but it's not gonna blow the doors off with the same driver.

Once you double the cone area and double the power you should be 6db louder which is a fairly big change. 10db is often considered 2x as loud.

The sundown classic is a 2.5inch coil. Most 2.5inch coiled subs can handle 1000w RMS all day unless designed poorly. The sundown could fairly easily handle 1500w daily. But that's stressing it. Thus why the v2 uses a 2.75inch coil.

Sundown subs are underrated power handling wise.

That Rockford I'm assuming had a birthsheet around 900w.

I've only seen SALT amps do rated at ½ ohm. Clamp it.

 

[winkychevelle 10+ year member]

I've only seen SALT amps do rated at ½ ohm. Clamp it.

They do very well on the Dyno.

As far as your clamp it statement that's a fair point. Box rise may put the amp into an ohm load that it isn't optimized for whereas the Rockford may perform better at the higher ohm load.

I still hang to my statement that doubling power isn't really that big of a change at this level.

Plus who knows what kinda wire he is using to feed the amp. 4awg isn't big enough oversized car audio 1/0 cca would be minimum with car audio 1/0 ofc being optimal


I do think the JP amps are a better value though

 

[Bobbytwonames 5,000+ posts]

They do very well on the Dyno.

As far as your clamp it statement that's a fair point. Box rise may put the amp into an ohm load that it isn't optimized for whereas the Rockford may perform better at the higher ohm load.

I still hang to my statement that doubling power isn't really that big of a change at this level.

Plus who knows what kinda wire he is using to feed the amp. 4awg isn't big enough oversized car audio 1/0 cca would be minimum with car audio 1/0 ofc being optimal


I do think the JP amps are a better value though

I think the SIA amps are the best value these days. Any word of the SIA's failing?

 

[winkychevelle 10+ year member]

I think the SIA amps are the best value these days. Any word of the SIA's failing?

Not that I'm aware of. Though I can't say I'm involved enough in the car audio scene to have enough experience with them

 

[Terrum 10+ year member]

Have you done the big 3?

Not yet, but I'd have thought if it was an issue with current then the voltage would drop during the clips, would it not? The 'Big 3' is definitely next on my list though as I've already got myself the Sky High 1/0 OFC Big 3 upgrade kit.

Put a meter on both setups and see if they meter the same

By 'a meter', I assume you mean to measure the wattage? I can't use a multimeter as all I've come across cap at 10A so I can't measure the current to calculate the wattage. I guess I'm going to need recommendations on the cheapest tool to measure wattage.

Doubling of power is usually good for 3db on smaller systems 3db is considered the lowest margin you ear can hear the difference.

I guess I'm less disappointed by the difference in dB, but the fact that 2000W is not blowing the SA-12 Classic. My thought process was that 750W to 2000W is such a big jump that before the amp even started clipping the sub would stop getting louder and start smelling or making mechanical noise because more power than it can handle is being driven into it.

But if this is not the case, then is it possible that the wattage is being limited by the cone area and other enclosure/driver issues? If so then I guess I still have hopes of achieving a higher dB when I upgrade to 2x SA-12 V.2s

unless you used ohms law to set the salt 2 to 2k the salt amp can make a lot more power

I didn't, but I assumed that if the speaker terminals are showing 1ohm then it would make the amp capable of outputting 2k. Correct me if I'm wrong and by all means keep sharing more tips/suggestions as I love to learn about these things and find out what I am potentially doing wrong

Plus who knows what kinda wire he is using to feed the amp. 4awg isn't big enough oversized car audio 1/0 cca would be minimum with car audio 1/0 ofc being optimal

The amp has brand new 1/0 OFC power and ground cables

 

[1aespinoza 10+ year member]

I didn't, but I assumed that if the speaker terminals are showing 1ohm then it would make the amp capable of outputting 2k. Correct me if I'm wrong and by all means keep sharing more tips/suggestions as I love to learn about these things and find out what I am potentially doing wrong

(AC) Voltage = square root of watts x ohms
Did you use this formula? If yes, you should get around 45 volts AC on your multimeter when setting Gain.

 

[Terrum 10+ year member]

(AC) Voltage = square root of watts x ohms
Did you use this formula? If yes, you should get around 45 volts AC on your multimeter when setting Gain.

Apologies for my ignorance, but what exactly is it I need to do? The formula is accurate (44.72VAC = √2000W x 1Ω) so when measuring the speaker terminal's voltage I'll be looking for ~45V, but do I need to do this when playing a tone just before the clipping point?

I've had a little play around today with the subsonic and LPF and got it to start outputting better, it actually drops voltage when clipping now and the coils start smelling (so I know for sure I'm getting the best output now) so that solves most of this thread.

But I am still curious as to why the kicks are louder than the basslines (e.g: in trap/rap music you have a kick then a long bassline after it). Currently it clips on the kicks so now I'm getting very loud kicks but quieter basslines with the same songs I've used for testing for years on many amps that haven't had any trouble equalizing the kicks and basslines.

 

[1aespinoza 10+ year member]

Apologies for my ignorance, but what exactly is it I need to do? The formula is accurate (44.72VAC = √2000W x 1Ω) so when measuring the speaker terminal's voltage I'll be looking for ~45V, but do I need to do this when playing a tone just before the clipping point?

No worries. With a 40Hz. tone and radio volume at 75% (in your case 100% since you know the signal is clean) ,you will look to acheive 45vac. That is ONLY if you want to put 2kW into that one sub. For lower wattage input the square root you want to use on the sub. TBH, I do not know if you can acheive over 1200 watts on that 90 Amp alternator.