Massive newbie. Please help me out.

[Jaames93]

Amperage draw is the result of impedance and wattage. If you run the single woofer at the same power levels as the two you have now the Amperage draw will be the same.

will be running on the same amp so yeah power will be the same. Just annoying the bass keeps cutting out when turned up loud. Cuts out cuts back in, strange though as it doesn’t cut out so much on the powerful loud low notes it’s more the higher notes it cuts out on.

 

[02WS6]

Your voltage drop is probably still to high. I can't remember, have you done the Big 3 on your car yet? I think a Big 3 then alternator will fix all of your issues.

 

[Jaames93]

Your voltage drop is probably still to high. I can't remember, have you done the Big 3 on your car yet? I think a Big 3 then alternator will fix all of your issues.

I haven’t done the big 3 as of yet, purely because it’s such a PITA in this car to get to the alternator. Because it’s a VXR with the 2.0 turbo Petrol engine means space in the bay is limited, the alternator is located underneath the inlet manifold as such. Being in the U.K., H.O alternators are so difficult to come by and when I have found them they are not for my car. Does make 3 make a worthwhile difference to voltage drop?

 

[02WS6]

I haven’t done the big 3 as of yet, purely because it’s such a PITA in this car to get to the alternator. Because it’s a VXR with the 2.0 turbo Petrol engine means space in the bay is limited, the alternator is located underneath the inlet manifold as such. Being in the U.K., H.O alternators are so difficult to come by and when I have found them they are not for my car. Does make 3 make a worthwhile difference to voltage drop?

An Astra? Cool hot hatch!

I understand that its going to be a PITA, but know that you'll probably continue seeing cutouts until that is resolved.

Another thing, pick up a Haynes manual/shop manual for that Astra and double check any other major grounds/earths your vehicle has. Primarily the Battery grounds/earth, make sure you're using a copper lug on the end of your earths, on a non-painted area of the car that are clean. Wiring should be OFC or pure copper.

May want to post over here as these are all the Vauxhall owners and may have more specific experience with that platform: https://www.vauxhallownersnetwork.co.uk/

Also I'd call these guys and ask them 1. Do they offer HO Alts for your VXR or 2. If they don't can they recommend someone in the UK who produces HO Alts that you can order from. - https://www.westlancsautoelectrics.co.uk/

C'mon now! I've seen Top Gear, I know you Brits are a resourceful lot! I found all these resources from California, I know you can find more living there!

 

[Jaames93]

Yessir! That’s the one, good car, it’s around 300bhp now (240/250 standard) good bit of fun to be honest. Will attach photo at bottom of post.

yeah that exactly what I thought, may aswell go all out and make sure it’s all working correctly! I’ve ordered more 0awg copper cable with as you mentioned, copper lugs too.

I’ve posted on the VXROC page on Facebook hopefully someone can help me out there too.

fantastic I’ll give those guys a call! Hopefully they can point me in the right direction!

 

[Jaames93]

Okay so I watched the voltage meter today as the bass hit, at times it dropped down to 11 ball park and that’s when the bass cut out. I’m guessing the voltage is going too low and it’s putting the amp into protect? My alternator figures are as follows

13.9 on idle no load
13.3 on idle with headlights and heaters on (it’s cold here in the U.K.)

I’m guessing big 3 will help with voltage drop

 

[02WS6]

Yes - Big 3 will help a lot with the voltage drop - You can look up the specs on your Amp to see where it will go into protect mode, each manufacturer is different on those numbers. Big 3 will help but the Alt will then give you headroom to feed the system. You can also use batteries to act as load balancers if you're unable to find a HO alt. Just remember that the batteries are just that, and can drain down after extended use, causing your normal Alt to work even harder trying to fill the batteries back up as well as feeding your system.

 

[Jaames93]

Yes - Big 3 will help a lot with the voltage drop - You can look up the specs on your Amp to see where it will go into protect mode, each manufacturer is different on those numbers. Big 3 will help but the Alt will then give you headroom to feed the system. You can also use batteries to act as load balancers if you're unable to find a HO alt. Just remember that the batteries are just that, and can drain down after extended use, causing your normal Alt to work even harder trying to fill the batteries back up as well as feeding your system.

contacted a few people, they don’t make a HO alternator to fit my car, custom fabrication and brackets needed to make it fit which makes life even harder as rooms certainly limited cause of where the alternator is behind the inlet manifold. Big 3 is next on the list then for sure. I currently have a second battery run into the rear of the car so the car has 2 battery’s already, hoping the voltage drop is really helped by the big 3, the standard alternator is 120A so it’s not too low in terms of most alternators. Shame it’s not like 160/180A. Got some 0 awg coming to do the big 3

 

[Jaames93]

I’ve also got to set the gain on my amp. I’ve turned it right down low for now. Going to use a multi metre as I have no other method to hand. So can someone clarify I’ve got this right?

My subs are dual 4 ohm which I’m going to wire down to 2ohm to match the amp. The amp is 2400 rms at 2ohm.

So 2400 x 2 is 4800, square root of 4800 is 69, so I need to play a 50hz test tone at 3/4 volume and adjust the gain until the multi metre shows 69 on ac setting?

Is that correct or am I mistaken?

 

[n2audio 5,000+ posts]

Not 4800, 2400. Number of subs is not a factor, only the total impedance at the amp.

Another concern -- you have a PAIR of dual 4's, right? So you shouldn't be running at 2 ohms unless you're only using one coil per sub.

A pair of dual 4's gives you impedance options of 4 or 1 ohm. Need to verify that amp will run at 1.

If it will you'd be looking for Sqrt(PxR) or sqrt(2400)
49V.

 

[Jaames93]

Not 4800, 2400. Number of subs is not a factor, only the total impedance at the amp.

Another concern -- you have a PAIR of dual 4's, right? So you shouldn't be running at 2 ohms unless you're only using one coil per sub.

A pair of dual 4's gives you impedance options of 4 or 1 ohm. Need to verify that amp will run at 1.

If it will you'd be looking for Sqrt(PxR) or sqrt(2400)
49V.

I will be running 1 sub, waiting for the box to turn up once the guy has finished making it. I’ve only got 2 currently as that’s how I purchased them

 

[Jaames93]

Another question. Is it worth me upgrading my starter battery? It’s the battery that came with the car, nothing special, I believe it’s just a cheap OEM Spec battery which is 70aH, will this help my voltage drop issue? Haven’t got round to doing the big 3 yet cause the weather has been so bad here and I have no shelter to work under, I have however run a 2awg battery to chassis as that was easily accessible and quick to do with a break in the weather.

My peak volume is 27 before any distortion, at 23 my voltage was around 12.3-12.8, however knock the volume down to 20 and it sits happily at 13.8-14. Crank the volume up to 27 and the subs cut in and out, my voltage meter is showing 11.9 before it cuts. Would a bad battery cause voltage drops or is it purely alternator related? The alternator is a stock 120A and you can’t get HO alternators for my car unless you get custom brackets fabricated etc, I’ve rang so many company’s and it’s proving difficult.

 

[02WS6]

You'll still need Big 3 - Next option is getting two XS Power batteries. Replace the starter battery and install another in your boot. Here is the only authorized dealer in the UK for XS Power and their webpage. Ring them up and see what they recommend for your car.

Battery – BladeICE

www.bladeice.com

 

[02WS6]

Battery can be part of the problem but instead of just replacing your current battery with another "stock" lead acid, it would be better if you get the best AGM you can which would be an XS Power battery, especially if the HO Alternator is not an option or "easy" option.

 

[Jaames93]

Battery can be part of the problem but instead of just replacing your current battery with another "stock" lead acid, it would be better if you get the best AGM you can which would be an XS Power battery, especially if the HO Alternator is not an option or "easy" option.

What use an XS Power as a starter? I have another lead acid battery in the rear which is the same size as my starter battery.

Would I benefit better with an Xs power in the trunk opposed to the lead acid or not massively? Big 3 is the next job to be done but the fact I’m dropping down to below 12v I’m really not confident that the big 3 is gonna solve that issue and keep me at a decent voltage. On another note my box is now complete and being shipped over night to be with me tomorrow

High output alternator can be found but a lot of custom fabrication needed and the quotes I’ve had are in excess of $800 converting it to your currency. Which as you can imagine really isn’t a path I want to head unless I really really have to. For 2400rms the work needed is pretty crazy but it’s great fun learning about it all. I’ve got my race car got my drift Car and well on the way to building an audio car and loving every minute of it