Improving Orion 280GX for bass & Sub

[mitchyz250f]

I have 3 Orion 280GX bridged driving a sub and 12" JBL midbasses.

The sub is 4 ohm and has a sensitivity of 85 db. The midbasses are 8 ohm and have a sensitivity of 96 db. The amps don't seem to be working hard at all as the midbass amps are always stone cold no matter what the SPL. The sub amp gets a little warm, but usually it is hard to tell it is on by touching it. So they don't seem to be working hard at all and I am probably not using anything near full wattage.

Dynamics are very very good, BUT in the interest of ultimate dynamics is there anything that can be done to modify the amps for the specific current loading to improve dynamics? I also have a 2150GX, would running a midbasses off each channel be better?

[ultra]

Originally Posted by mitchyz250f

I have 3 Orion 280GX bridged driving a sub and 12" JBL midbasses.

The sub is 4 ohm and has a sensitivity of 85 db. The midbasses are 8 ohm and have a sensitivity of 96 db. The amps don't seem to be working hard at all as the midbass amps are always stone cold no matter what the SPL. The sub amp gets a little warm, but usually it is hard to tell it is on by touching it. So they don't seem to be working hard at all and I am probably not using anything near full wattage.

Dynamics are very very good, BUT in the interest of ultimate dynamics is there anything that can be done to modify the amps for the specific current loading to improve dynamics? I also have a 2150GX, would running a midbasses off each channel be better?

What i usually do is to rewind the HF transformer and change the primary secondary ratio according to the set up of the car.
That way the amp is tailored to the speakers that drives.
For example, if an amp faces a 4 ohm load, i increase the voltage of the pwm (and modify pwm output capacitors and associated feedback circuitry) so it produces its maximum output power at this load. This is a kind of severe mode but the results can be very satisfactory.

[Perry Babin]

It appears that you're not getting full power from the bass amp. These amps will get too hot to touch when pushed to the limits. Are you sure you have the gains high enough to drive the amp to full power?

[mitchyz250f]

Perry I may have stated my question poorly. My car has very solid midbass and gets plenty loud and I cannot stay in the car if I start turning the volume up at all. I believe this is mostly due to the midbasses I have chosen. The JBL 2204 and have a fairly high sensitivity of 96 db. At 10 watts each (per Unibox modeling) my SPL would be 112 db. Between that and the speakers being 8 ohm is why I have assumed the amps don’t get hot. So I have no reason to think the amps aren’t working correctly.
http://www.jblpro.com/pub/obsolete/2204h.pdf
I have read that the Orion GX line is very good at bass and sub bass for reasons I don’t understand. Considering that I am not using the full voltage of the amps, is there a tradeoff I can make, possibly exchanging maximum wattage for increased dynamics. If for example, I changed the 280 for an HCCA, (lower voltage less current) would that make an audible difference?

Ultra- That sounds very interesting. I am assuming you mods would give me more power by specifically modifying the amps to the speaker loading? Would that provide me with better dynamics?

[Perry Babin]

The fact that the sub amp only gets warm seems to indicate that you're not using the amp to its full potential.

Do you have a scope? If so, is the bass amp driven to clipping?

[mitchyz250f]

I have access to a scope, but the first chance to use it will be this weekend. Is there a method to accurately measure the amp output at max SPL?

[Perry Babin]

You can't accurately measure the output using speakers. You have to use dummy loads.

I'd be interested in knowing if you're driving the amp to full power. It's VERY unusual for a class B Orion amp to run only warm when driven into the lowest rated load at full power.

[ultra]

Ultra- That sounds very interesting. I am assuming you mods would give me more power by specifically modifying the amps to the speaker loading? Would that provide me with better dynamics?[/QUOTE]

Well, since i re-wind the HF transformers, i use either custom made, or industrial litz wire, and that allows me to increase the oscillating frequency of the pwm. I have done this successfully in a STEG K2.04, a Zapco C2K-4.0X, and i am about to mod a colossus.
Also did it in two Cadence amps (dont remember exact model. I remember there were twin toroids and that the amp could be loaded down to 1 ohm).
The result was excellent dynamics-really superior. The amps were transformed! In the case of the Cadence, the shop owner (who has installed dozens of these amps) immediately called on the phone the Cadence distributor to go over and listen to these amps...
Its worth mentioning that the mod is done in the pwm, and the benefit is in the "untouched" audio section.
I think the great Perry Babin will agree that the higher the frequencies, the higher the dynamics.

[mitchyz250f]

Perry, I don't believe I am using anywhere near the full power of the amps have. It would just be too loud in the car at that point. I really doubt if I am using 20 of the 160 watts (into 8 ohms) that I have avaliable.

testing amp output - I know the highest I will play the HU before it is too loud to stay in the car during bass hits. How would I test the amps output at that point?

[Perry Babin]

Generally 'dynamics' would indicate dynamic range and headroom but that's not an amplifier issuer if you're not driving the amps to full power.

How do you define 'dynamics'?

What is it that's not dynamic enough?

You can only determine the output voltage at the point where it's too loud. You can't calculate power with speakers. The impedance varies too greatly.