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This is a very cool concept, but an amp that is a great "base" for upgrading and then upgrade the parts that need to go. I wonder if this is as straight forward as it seems because there is a lot of engineering that goes into this things. Is something as simple as changing some parts will make a "positive" difference? It would also be nice if whomever is upgrading this amp could do some sort of A/B test of the before and after to see what kind of differences we are looking at.
 

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I wonder if anyone could go to a manufacturer and make a custom order with the changes that you made. Do you think a manufacturer would make those alterations (that you did) in a special order? This way, maybe someone could get that upgraded amp and keep the manufacturer's warranty...maybe.
No. Those Amps are made overseas and shipped here.
If this customization is something you are looking to do, I would follow the path that DeltaB has laid out. If you want to see it at a larger scale, your best bet is to find yourself a pile of cash, find out who the actual amplifier manufacturer is, and meet their minimum order requirements for a run of amps built to your spec. Congratulations, you're in the car audio "manupackturer" business. Good luck with that. :D;)
 

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This is a very cool concept, but an amp that is a great "base" for upgrading and then upgrade the parts that need to go. I wonder if this is as straight forward as it seems because there is a lot of engineering that goes into this things. Is something as simple as changing some parts will make a "positive" difference? It would also be nice if whomever is upgrading this amp could do some sort of A/B test of the before and after to see what kind of differences we are looking at.
Normally you are correct. But based on the suggested upgrades, we are using the same value components, just higher quality. So its not like we are adding caps or op-amps. Also it was already done with just the listed mods. I really think your right with a nice comparison though. I plan to do a pair of these 5 channel amps, maybe when i get to it, i can do 1 and then have someone test them or i can do a a/b swap out and provide a more real world comparison. Its been awhile since i did a review so this could be a nice project for this fall. Kinda wish Wldock = Walt was still here in Michigan to have another pair of seasoned ears.
 

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This is a very cool concept, but an amp that is a great "base" for upgrading and then upgrade the parts that need to go. I wonder if this is as straight forward as it seems because there is a lot of engineering that goes into this things. Is something as simple as changing some parts will make a "positive" difference? It would also be nice if whomever is upgrading this amp could do some sort of A/B test of the before and after to see what kind of differences we are looking at.
It isn't a concept. It is as strait forward in this case, as it has already been done. I own one. There isn't any real magic here.
 

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This is a very cool concept, but an amp that is a great "base" for upgrading and then upgrade the parts that need to go. I wonder if this is as straight forward as it seems because there is a lot of engineering that goes into this things. Is something as simple as changing some parts will make a "positive" difference? It would also be nice if whomever is upgrading this amp could do some sort of A/B test of the before and after to see what kind of differences we are looking at.
A few years back I was providing a service for Nissan SR20DE/DET ecu upgrades. The upgrade involved adding a daughterboard and reflashed eproms. Concept was to take a well engineered oem part and mod it for power upgrades. Point is that oem will get you so far but mods will make it that much better.

Burson Audio has a link that demonstrates the desoldering/soldering for opamp upgrades. Nifty video.
 

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Subbed for future reference. I assume this mod will work with the PPI Phantom series??
I don't have a schematic, so I would actually have to see the amp to comment on what buffers they are using.

Concerning the usage of signal path upgrade caps, that is universal. The reason we use coupling caps before and after the op-amp, is to isolate DC from it's input and protect it's output, and only AC passes. It's a DC block. Since all of the signal going in, and coming out of that buffer circuit through them, it is certainly applicable, and audible.

Concerning the op-amp, if it is using a TI TL072, then yes, you can do a drop in replacement with a Burr-Brown OPA1642. If you were to use SPICE data to construct a buffer with a JFET, you would find the data for gain structure the same, and since you don't have to worry about the need for feedback, like you have to deal with on some bi-polar designs, it makes an easy choice. TL072's have no place in audio circuits. They're slow, noisy, overshoot and invert phase at higher levels.
 

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I really want to try the ST-4SQ but I don't know about cutting my power in half. I do like it loud from time to time when the windows are down on the high way.
How much power do you need? The ST4X P version is 80x4 instead of 65x4 in the SQ version. If you are worried about mid power bridged 2 channels is more than enough. Unless you would be using this on a sub or 2 than different story.

This might be a dumb question concerning 5 channels as I've never owned one. Specs always list 4ohm and 2 ohm. Can the amp be ran at 2ohms on the sub channel and 4 ohms on the 4 other channels. I was worried about some kind of limitation when wiring this route. I always wire my subs at 1-2 ohm load
 

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How much power do you need? The ST4X P version is 80x4 instead of 65x4 in the SQ version. If you are worried about mid power bridged 2 channels is more than enough. Unless you would be using this on a sub or 2 than different story.

This might be a dumb question concerning 5 channels as I've never owned one. Specs always list 4ohm and 2 ohm. Can the amp be ran at 2ohms on the sub channel and 4 ohms on the 4 other channels. I was worried about some kind of limitation when wiring this route. I always wire my subs at 1-2 ohm load
While I understand that many want to run subs at 1~2ohm, for SQ it is preferable to run at least 4ohm due to damping factor and output impedance of Class D operation.

From Brian Morelli @ NVX Tech;

Minimum impedance for all channels is 2ohms. You can have different loads on different channels. (4ohm on the fronts/rear, 2ohm on sub).

The damping factor for all JADs is greater than 200

NVX Tech
 

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While I understand that many want to run subs at 1~2ohm, for SQ it is preferable to run at least 4ohm due to damping factor and output impedance of Class D operation.

From Brian Morelli @ NVX Tech;

Minimum impedance for all channels is 2ohms. You can have different loads on different channels. (4ohm on the fronts/rear, 2ohm on sub).

The damping factor for all JADs is greater than 200

NVX Tech
Thanks, exactly what I wanted to know. It might have been the amps I used in the past but I was running a Fosgate 500x2 at 2 ohms vs 250x2 at 4 ohms but couldn't audibly hear a difference other than SPL. I understand an amp will work harder. I ran that amp for years. Aside from metering differences with various equipment seeing the difference how much difference can someone hear with 2 ohms vs 4 ohms given the same quality and power output is equal?
 

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Thanks, exactly what I wanted to know. It might have been the amps I used in the past but I was running a Fosgate 500x2 at 2 ohms vs 250x2 at 4 ohms but couldn't audibly hear a difference other than SPL. I understand an amp will work harder. I ran that amp for years. Aside from metering differences with various equipment seeing the difference how much difference can someone hear with 2 ohms vs 4 ohms given the same quality and power output is equal?
From Crown Audio Engineers; "Loudspeakers have a mind of their own. You send them a signal and they add their own twist to it. They keep on vibrating after the signal has stopped, due to inertia. That's called "ringing" or "time smearing." In other words, the speaker produces sound waves that are not part of the original signal. Suppose the incoming signal is a "tight" kick drum with a short attack and decay in its signal envelope. When the kick-drum signal stops, the speaker continues to vibrate. The cone bounces back and forth in its suspension. So that nice, snappy kick drum turns into a boomy throb. Fortunately, a power amplifier can exert control over the loudspeaker and prevent ringing. Damping is the ability of a power amplifier to control loudspeaker motion. It's measured in Damping Factor, which is load impedance divided by amplifier output impedance. High damping factor equals tight bass."
 

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I didn't own one. I do have one coming now. Then I will grab another one. Then I plan to send one in have it done, then compare the 2. But I have a lot going on right now at work and at home. I'm thinking I might get the one done and send them to a trusted member to do some testing on them. And I only got a quote back from one place.
 

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Question. In regards to the subwoofer channel x-over can it do full pass. If not what is the highest freq that is allowed on the mono channel? I'm asking because I want to run a active 3 way setup and use the mono channels for the mid-bass drivers. Of course using 2 5 channels.
 

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Thank you to DeltaB. For those who are not sure what to order i have included my order sheet. Now my qty is for 2 amplifiers modifications, so just cut my qty in half for 1 amp. Now i'm searching for a shop to perform these upgrades.
I just put in my order to do one amp only. Can't wait to get this done. Thanks.
 
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