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JBL STX amplification and DSP


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#1 Sidhu

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Posted 05 March 2013 - 01:22 PM

Hello again!

We are almost certain of investing in an STX rig.

Currently looking at.

STX825 or the STX835
Powered with either the MA5000i or the Xti6002.


STX828
Powered using either the MA9000i or Xti6K bridged.

First, are these amps appropriate? We already use the Xti2002 in Bridged mode with an MRX528, and find that it clips before reaching the -10db mark. Current limiting I would presume.

Second, we find ourselves in a situation where the presets (which I like) for the STX series are only available for the Xti, or the ITech Hd (which we cannot afford).

Also considering using the Xti for the tops and the MA9000i for the subs, but then that would need us to use something to align the speakers cause of the latency, and a DSP for the subs ?

Kindly advise on the best way to go about this without having to invest in the ITech Hd.

Thanks and regards,
Sidhu

STX825/835 ratings. 1200/2400/4800
STX828 ratings. 2000/4000/8000





#2 dakos

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Posted 05 March 2013 - 06:28 PM

Dear Sidhu,
Congratulations on the comming upgrade. What DSP you will be using with the MAi configuration?

Since you will need an external DSP for the MAis, that has its own latency, and not for the XTis, the latency is not an issue.

I of course like the full MAi option better, I've heard of good sounding rigs that use an XTi 6002 bridged on each 825. I wouldn't recommend one of the XTis for the 828 but it can be done.

As for your problem with the 528 and XTi, make sure you have a high pass filter on it at 40hz 24dB/Octave butterworth to filter out the non reproducible sounds so the amp would work a little easier and the subs would be a bit protected, might give you what you need to get to that -10dB without hurting sound quality.

825 vs 835, the major difference between them is the dispersion angle so see which one you prefer.

If you need help with prices, since I'm not affiliated with anyone, I've been known to help with finding the best deals out there so PM me if you need help :)
Avi

#3 Sidhu

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Posted 06 March 2013 - 02:10 AM

Hey Avi!

As always, thanks a ton!
Im in India! But thank you so much for the offer!.

We would prolly go the MAi route only, but we have not decided on DSP. Mostly cause we ar already broke then.
Also, I like running subs off an aux, so that would mean a 3 input channel DSP/2 x dual input channel DSP's/

Or,

I might well consider going totally analog with a dbx223XS. And use outboard or board EQ for system voicing.

Sidhu

#4 dakos

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Posted 06 March 2013 - 02:30 PM

I have been thinking allot on what to answer you, I don't know how much everything cost in India, probably not cheap so to recommend an additional expensive DSP such as the BSS 366T, that I think is a good fit for this type of rig, might be a little too expensive and the price for the 2 MAis + BSS unit might be more then the price for 2 itechs but for aux fed subs you need an external DSP so what I consider the minimum DSP for what you want to do is the DR260.

The analog option is a very good one especially since used analog gear is pretty cheap these days.

Is used gear an option for you? You can also consider the SRX series if it's cheaper there since the sonic difference is not considered ground breaking and it's a bit less demanding on the amps. If you have DSP options for me to choose from it might make it easier... Do you have a DSP now?

One more thing I forgot to ask is since it's a business first of all, what rigs are other sound providers near you running?
Avi

#5 Sidhu

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Posted 07 March 2013 - 02:55 AM

Hey Avi,

2nd hand gear is an option, but very avoidable. China is next door, and most 725's aren't really 725's anymore.
However, used DR260's could probably be found. Im not very sure of the 260 sound. It is a very dated product.

My immediate alternative. The X32 mixer has filters available on all its Matrices that go up LR24db slopes. So that is an intermediate solution.

Then I would like to essentially have something which JBL develops presets for. And currently there is no standalone DSP unit they are doing that for. Only Xti's and the IT HD's. The Xti's are not powerful enough, and the HD's quite expensive. Still, my impression is that the presets are essentially eq curves, as the boxes run passive. And should not be hard to replicate.

If I manage to get a system voicing sounding similar to the v4 presets developed for the STX range, then I will run this rig and do an AB comparison using analog crossovers and outboard eq vs. Itech HD with the presets.

Im very surprised that you consider the SRX to be sonically close to the STX. That is not what I heard. I did a STX825 vs. SRX725, and the difference was quite a bit. Granted, was running the JBL preset through an IT HD driving the STX, the SRX was running without any DSP.

I think ill hold out the DSP purchase for a bit.

JBL is the dominant brand around here, where D&B making strides into the upperend. Everybody has some SRX boxes. But we are so tired of the lack of consistency with the JBL boxes of the same type  (not JBL's fault), that we have now decided to go get our own.

The IT Hd amps are way more expensive than the MA series + a BSS Omni/minidrive combo. And since we are looking at a total of 4 boxes, with 2 MA5K and 2 MA9K's, we still only need to get 1 x 366 or the DR4800. None we can afford right now.

Thanks as always. Ill keep you posted.

Regards,
Sidhu

#6 dakos

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Posted 07 March 2013 - 05:10 PM

View PostSidhu, on 07 March 2013 - 02:55 AM, said:

Hey Avi,

2nd hand gear is an option, but very avoidable. China is next door, and most 725's aren't really 725's anymore.
However, used DR260's could probably be found. Im not very sure of the 260 sound. It is a very dated product.
I did say the DR260 is what I consider the minimum processor for your type of rig, I agree it's dated but it still sounds great. By the way the DR4800 and the 366T are pretty dated as well. They all only update their firmware.

View PostSidhu, on 07 March 2013 - 02:55 AM, said:

My immediate alternative. The X32 mixer has filters available on all its Matrices that go up LR24db slopes. So that is an intermediate solution.
Didn't know you had that X32, this will have to do for now. Just don't forget that LR filters are defined by their -6dB points so for instance if you want a 100Hz Low Pass Filter you will need to set it at 125Hz.

View PostSidhu, on 07 March 2013 - 02:55 AM, said:

Then I would like to essentially have something which JBL develops presets for. And currently there is no standalone DSP unit they are doing that for. Only Xti's and the IT HD's. The Xti's are not powerful enough, and the HD's quite expensive. Still, my impression is that the presets are essentially eq curves, as the boxes run passive. And should not be hard to replicate.

If I manage to get a system voicing sounding similar to the v4 presets developed for the STX range, then I will run this rig and do an AB comparison using analog crossovers and outboard eq vs. Itech HD with the presets.
Every DSP has its own unique algorithms to do the "same" function so every DSP sounds a bit different, you can try to duplicate the specific parameters they have for your speakers but the AB tweaking afterwards is what's going to give you what you're looking for. One more thing is that the presets are a great staring point for you to get the sound you like, they are not to everyones liking but a good starting point does mean allot.

View PostSidhu, on 07 March 2013 - 02:55 AM, said:

Im very surprised that you consider the SRX to be sonically close to the STX. That is not what I heard. I did a STX825 vs. SRX725, and the difference was quite a bit. Granted, was running the JBL preset through an IT HD driving the STX, the SRX was running without any DSP.
I guess a question "in the other forum" is in place here but honestly I've heard so many people go this way or the other, some say the harshness of the HF driver is not as bad, others that got used to the JBL sound miss it, and some say these boxes are mainly a budget cut for JBL but when you AB them I don't think they are that much different. You probably know that when you do an AB comparison, it's essential that as many parameters will be the same, the amp, the EQ, the DSP, the placement of the speakers, their hight and angle and the DSP presets as well, I don't know but there could have been some EQing hiding within those presets as well, in other words so many things can make one speaker sound "better" then the other so no wonder it sounded "better". In order for it to be a true AB comparison, and some folks could argue with me, I would try to listen to both speakers with no presets at all with as little difference as possible regarding the other parameters.

If I were buying a new rig I would probably go for the STX as well but not for them being a real sonic upgrade but for other reasons such as future scalability using other sound providers gear (which will be STX in the near future) for the 10% of the jobs I need more rig to handle.

View PostSidhu, on 07 March 2013 - 02:55 AM, said:

I think ill hold out the DSP purchase for a bit.

JBL is the dominant brand around here, where D&B making strides into the upperend. Everybody has some SRX boxes. But we are so tired of the lack of consistency with the JBL boxes of the same type (not JBL's fault), that we have now decided to go get our own.

The IT Hd amps are way more expensive than the MA series + a BSS Omni/minidrive combo. And since we are looking at a total of 4 boxes, with 2 MA5K and 2 MA9K's, we still only need to get 1 x 366 or the DR4800. None we can afford right now.
Do you need the 4 amps to be independent? One MA12000i will handle two 828s and will cost less. Unfortunately you might also need to step up a bit the amps for the 825s since the STX a bit more power demanding then the 725 (you got the wattage quote wrong on your first post), the 9000i for a couple of 825 is a good fit whereas the 5000i output more then 3dB less of what the speakers can handle, might matter when you try to get everything out of what you got. So I count 2X9000i plus 1X12000i

Avi

#7 Sidhu

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Posted 08 March 2013 - 02:07 AM

Hey Avi!

My Bad. We are looking at a total of 8 boxes. 4 x 835 and 4x828.

Now, possible, for a start. To run these boxes at 2ohms, using the IT12K HD. And then at a later date get a couple if IT5/9K for the tops. Then running the whole rig at 4ohms.

Ill be happy giving these boxes programme power over Peak power.

Thanks as always.

Sidhu

#8 dakos

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Posted 08 March 2013 - 03:25 PM

Will you be able to impliment the aux fed subs with the matrix on the X32?

The itech and so will the MAi will handle those loads reliably, if that's good for you then we have a winner :)

#9 Sidhu

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Posted 08 March 2013 - 09:32 PM

Yes,

The X32 is a surprisingly capable mixer, and if we go with the 2 x HD12K's, instead of 4x MAi's, we have sorted our DSP problem also.

So it would start looking like this :

1. 4 x STX835. 2400w Programme per box.
2. 4 x STX828. 4000w programme per box.
3. 2 x IT12K HD. Each channel driving 3750watts into 2ohms.

Not ideal, but should get the job done atleast to Xti6K levels ?
With a future upgrade to add 2 x IT5000 or 9000 HD amps for the 835 boxes.

Avi, thank you, as always!
Sidhu

#10 dakos

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Posted 10 March 2013 - 05:03 AM

Your welcome :)

Just finished reading your post on PSW, nice reading.

Update us with pics as well if possible.

All the best.
Avi