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      11-24-2012, 10:14 AM   #1
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Does PDX 1.1000 accept differential balanced input?

Hi guys
I have searched it on this forum and on google but could not find the answer.

Looking at sticky section of Audio section, it suggests that PDX amplifiers can accepts differential balanced input, but there is a question mark next to it.


My current setup is

HU (coded to hi-fi) ---> straight to XD 600/6 which powers front, rear mids and under seats. No LOC and quality of sound is awsome.

I have added 1000W subs and added PDX 1.1000 to my setup. I have used Y splitters and shared the signals b/w XD 600/6 and PDX 1.1000 (front speakers input).

Bass on the sub is rubbish and becomes distorted easily. I have tried sealed, ported and infinite baffle system and tried 10W7, Alpine XD sub and pioneer sub. It is only sub system where bass is not clean. (XD 600/6 and drivers running on it are brillinat) I have also used Audison SRx 1D and results are same.


If I try same sub / amp in my wife's car, results are amazing. Bass is cleans and loud. So I take it that Alpine PDX 1.1000 cannot accept differential balanced input?


I wonder if somebody can suggest / share your experience, especially specialists like Technics, taibanl & Kaigoss.
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      11-24-2012, 01:34 PM   #2
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Sorry, can't comment other than my understanding is that PDX does accept balanced diff inputs.
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      11-27-2012, 12:44 PM   #3
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Quote:
Originally Posted by taibanl View Post
Sorry, can't comment other than my understanding is that PDX does accept balanced diff inputs.
taibanl
I have sent an e-mail to Alpine UK to find out if PDX series accepts diff. balanced input. I bought the amp purely after reading your sticky post (many thanks and it is very helpful to all others).

However I had serious issues with the amp and finally I had a response from Alpine UK.


Hi, the pdx only takes a single ended line level input, you will need a convertor to use it with the BMW system....

Alpine Electronics of UK Ltd.
Alpine House, Fletchamstead Highway, Coventry, CV4 9TW, United Kingdom

Technical/Customer Support. Tel: 0845 313 1660
Sales Desk. Tel: 0845 313 1650
Service Dept. Tel: 0845 313 1642
Spare Parts Dept. Tel: 0845 313 1644


I will be disposing my Alpine amp soon, but you may wish to update your sticky thread with a link to this.

Alpine PDX can be used with MS-8, bit ten / one as they convert the signals to sigle ended.

Also my finding are similar for Audison amps (unless stated on their packaging) and they do not accept differential balanced input.

Thanks.
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      11-27-2012, 02:41 PM   #4
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I am not an expert on input topology, Technic and VP=E are; however the answer you received doesn't sound on point. It sounds like they read your query on whether or not it accepts HIGH level inputs.

The balanced-diff input IS a LOW (Line) level input. Alpine Tech support may be assuming you are trying to use speaker inputs.

Again, I am not the expert on this, but PDX is a popular amp choice in this car.
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      11-27-2012, 04:00 PM   #5
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Quote:
Originally Posted by taibanl View Post
I am not an expert on input topology, Technic and VP=E are; however the answer you received doesn't sound on point. It sounds like they read your query on whether or not it accepts HIGH level inputs.

The balanced-diff input IS a LOW (Line) level input. Alpine Tech support may be assuming you are trying to use speaker inputs.

Again, I am not the expert on this, but PDX is a popular amp choice in this car.
Taibanl
You may be correct on their response.
I have clearly told them that I am using low level (hi fi coded HU) differential balanced input to this amp (also mentioned that JL amp is taking the same signals) directly.

And their response:

Quote:
Originally Posted by makkan00 View Post

pdx only takes a single ended line level input
Can somebody kindly explain it?

As far as I understand BMW sound system, both + and - wires carries siganls and -ve wires have different voltage to earth and that is what they are saying, pdx can take a single ended line level input.

Again, I may be wrong and possibly Technic / VP may chime in and elaborate it.

Also, most installtaion of PDX amp are done via DSP or LOC on this forum. I have not seen any installation (please excuse me if I have missed any) on this forum where they have used HI FI HU signals directly ---> PDX amp.
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      11-29-2012, 05:50 AM   #6
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Technic / VP, any comments?
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      11-29-2012, 06:53 AM   #7
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Quote:
Originally Posted by makkan00 View Post
Technic / VP, any comments?
Somewhere in here VP determined that the PDX amps single-ended inputs are referenced to 0V and not to ground. That's the reason that they work with the OEM HU balanced signals (double-ended outputs, as in both wires have voltage).

There is no balanced-signal circuitry per se in the PDX amps.
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      11-29-2012, 08:50 AM   #8
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Quote:
Originally Posted by Technic View Post
Somewhere in here VP determined that the PDX amps single-ended inputs are referenced to 0V and not to ground. That's the reason that they work with the OEM HU balanced signals (double-ended outputs, as in both wires have voltage).

There is no balanced-signal circuitry per se in the PDX amps.
Thanks Technic.

I am still noob compared to many here and hence understood half of your response. So amp cannot take balanced signals as per specification but people still use it..?

I am having issues with the amp. On low gains it sounds fine but when gains are set propely, it does not sound good and clean.

If I send only +ve signals from HU and no -ve, would it work better?


(P.s: I have used the same amp + sub in my wife's car with Alpine HU from sub pre-out, and no issues there. So amp and sub are 100% working.)
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      11-29-2012, 11:54 AM   #9
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My PDX-5 will only accept line level input i.e. low level rca input, if you feed it speaker level input it will be too loud. Not sure if this answers your question.
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      11-29-2012, 12:02 PM   #10
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Quote:
Originally Posted by afsar
My PDX-5 will only accept line level input i.e. low level rca input, if you feed it speaker level input it will be too loud. Not sure if this answers your question.
Thanks afsar.
My HU is coded to hi-fi so signals are low level flat signals from the HU.

Other than high and low levels, it is differential balanced (not 3 wires system though) input which is restricting us from having any amp in our cars.
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      12-02-2012, 11:16 AM   #11
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One potential option might be to add something like an audiocontrol eq which can take differential balanced inputs and then it will give pre-amp outputs that can go into any amp.

I use a soundstream amp for my underseats which cannot take the diff inputs either but they are fed from the pre-amp outputs of my JL XD400 amp, works great.
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      12-02-2012, 12:44 PM   #12
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Quote:
Originally Posted by cdgatti View Post
One potential option might be to add something like an audiocontrol eq which can take differential balanced inputs and then it will give pre-amp outputs that can go into any amp.

I use a soundstream amp for my underseats which cannot take the diff inputs either but they are fed from the pre-amp outputs of my JL XD400 amp, works great.
Many thanks for the suggestion. Actually I thought about adding LOC in the sound system but to reduce any noise, I ended up buying JL 1000/1.

I had XD 400/4 and it had pre- amp out. it was brilliant.

I have XD 600/6 now and one draw back of it is no pre-amp out.

Good idea. I guess somebody should update the sticky thread with the info that alpine PDX CANNOT take differential balanced input.
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      12-02-2012, 01:04 PM   #13
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Quote:
Originally Posted by makkan00 View Post
Many thanks for the suggestion. Actually I thought about adding LOC in the sound system but to reduce any noise, I ended up buying JL 1000/1.

I had XD 400/4 and it had pre- amp out. it was brilliant.

I have XD 600/6 now and one draw back of it is no pre-amp out.

Good idea. I guess somebody should update the sticky thread with the info that alpine PDX CANNOT take differential balanced input.
Why are you running a 1000w amp when the sub is IB? It should require no more than half the rated power.
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      12-02-2012, 01:33 PM   #14
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Quote:
Originally Posted by kaigoss69 View Post
Why are you running a 1000w amp when the sub is IB? It should require no more than half the rated power.


I bought this beast, just in case if I cannot get decent SPL out of single 12 inch IB and if I wish to add another 12 inch driver.

I am still hunting for decent 12 inch driver for my IB setup.

For interim, I have added 2X12 inch pioneer drivers (500W RMS each) in a sealed box and they shake the car badly. Sounds awsome but I cannot sacrifice the boot space on long term basis.

Kaigoss, I am considering 12W7 as IB on parcel shelf vs Fi IB3 12 inches. I am looking forward to hear your opinions on this.

Here is specs comparison:

__________________JL 12 W7 --------VS----------Fi IB3 12
Fs:_________________27.2Hz ----------------------23.6Hz
Qts:________________0.482 ------------------------0.57
Vas:________________66L----------------------------83.2L
Xmas:_______________29mm-------------------------30mm
Efficiency (1W/1m)____ 86.2 dB-----------------------83.2 dB
RMS________________750W---------------------------550W


I am more inclined toward 12W7 as I could sell it on easily compared to Fi IB3 if needed. But Fi IB can be coned easily (just in case) compared to JL subs.

Any suggestions welcome.
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      12-02-2012, 01:49 PM   #15
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I'm not sure a single 12 will give you the output you want. From everything I've read, a single 15 is enough for SQ guys, but SPL lovers need at least two 15s or more.

Given those two drivers, the W7 reportedly works great IB, but I would still give the edge to the FI since it is specifically designed for that application and it has excellent reviews. Also take a look at AE SBP12 and SBP15. Supposedly one of the best IB drivers. Those however have a 4-6 week lead time.
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      12-02-2012, 03:05 PM   #16
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Quote:
Originally Posted by kaigoss69 View Post
I'm not sure a single 12 will give you the output you want. From everything I've read, a single 15 is enough for SQ guys, but SPL lovers need at least two 15s or more.
Very true. I guess I can bear with single 12 inch till you or somebody else can fit IB behind the rear seats. In that case, I could go max for 15 inches sub in the boot.

Quote:
Originally Posted by kaigoss69 View Post
Given those two drivers, the W7 reportedly works great IB, but I would still give the edge to the FI since it is specifically designed for that application and it has excellent reviews. Also take a look at AE SBP12 and SBP15. Supposedly one of the best IB drivers. Those however have a 4-6 week lead time.
I was reading the reviews on SBP15 last night. Brilliant driver.
However comparing it to Fi IB12, its xmas is limited and on 20Hz 250W RMS is enough to take it to its Xmas (though it is 7dB louder than Fi IB12) and that is coming straight out of John's posting.

Whereas Fi IB3 takes 500W RMS @ 20HZ to reach its Xmas. In a way it favours SBP15 as it takes less power to create more sound but then with Fi IB3, there are less chances of mechanical failure due to greater Xmas (unless I am missing a point here).

So considering that, I am getting confused which one would work out better in IB setup?
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      12-02-2012, 08:10 PM   #17
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Quote:
Originally Posted by makkan00 View Post
Very true. I guess I can bear with single 12 inch till you or somebody else can fit IB behind the rear seats. In that case, I could go max for 15 inches sub in the boot.



I was reading the reviews on SBP15 last night. Brilliant driver.
However comparing it to Fi IB12, its xmas is limited and on 20Hz 250W RMS is enough to take it to its Xmas (though it is 7dB louder than Fi IB12) and that is coming straight out of John's posting.

Whereas Fi IB3 takes 500W RMS @ 20HZ to reach its Xmas. In a way it favours SBP15 as it takes less power to create more sound but then with Fi IB3, there are less chances of mechanical failure due to greater Xmas (unless I am missing a point here).

So considering that, I am getting confused which one would work out better in IB setup?
The AE is more efficient which means it needs less power to reach max. excursion. The FI with its higher xmax has the capability to be a little louder below 30Hz but you have to ask yourself if you really want that. The AE, after having read numerous reviews on diyma.com and other sites, will give you almost ruler-flat response between 20 and 100Hz, and gets loud enough for most people.

You may want to get on touch with Mob17 who was planning on installing an FI driver, but I haven't heard from him in the last week or two.

In the end I'm sure both would be great subs for this application. I'm not sure yet what I'm going to do yet, I'm between using 2 Infinity subs I have in the attic, and the AE, but the FI may also be considered especially due to its lower price point and better availability. I'm planning on mounting the sub via an adapter plate directly against the back seat, and let it fire through the ski pass (which I still have to cut). I was hoping Mob17 would post the results of his install and it would give me some inspiration, and motivation.
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      12-03-2012, 11:13 AM   #18
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Quote:
Originally Posted by kaigoss69 View Post
The AE is more efficient which means it needs less power to reach max. excursion. The FI with its higher xmax has the capability to be a little louder below 30Hz but you have to ask yourself if you really want that. The AE, after having read numerous reviews on diyma.com and other sites, will give you almost ruler-flat response between 20 and 100Hz, and gets loud enough for most people.
Thanks Kaigoss. That explain the things better.

Quote:
Originally Posted by kaigoss69 View Post
In the end I'm sure both would be great subs for this application. I'm not sure yet what I'm going to do yet, I'm between using 2 Infinity subs I have in the attic, and the AE, but the FI may also be considered especially due to its lower price point and better availability. I'm planning on mounting the sub via an adapter plate directly against the back seat, and let it fire through the ski pass (which I still have to cut). I was hoping Mob17 would post the results of his install and it would give me some inspiration, and motivation.
Kaigoss, the idea of using an adaptor plate againts sky hole is brilliant. And I wish you and all others good luck with the installation.
I am sure it is not difficult but time consuming.

In my case, due to new comer in the family (baby) I have to install my sub on the rear shelf speaker so that I can use the trunk to its max capacity. And considering IB on rear parcel shelf, I will have to go for 12 Inch max.

Xmas time is here and weather is right bitchy. I will order 12 inch sub in few days and will fit when I get time.
Will update the results on my IB thread.

For the time being 2X12 in the boot are giving me best SPL so far and quality of sound is excellent.

Thanks for your suggestions, patience and guidance. Appreciate it and look forward to see your IB installation.
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      12-03-2012, 11:41 AM   #19
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Congrats!
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      12-03-2012, 02:56 PM   #20
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Yeah sorry guys the install has been delayed a bit. It should hopefully be installed by the end of next week. I think the festive period in the US has delayed a lot of deliveries I'll let you guys know once its all in place!
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      12-03-2012, 05:11 PM   #21
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Quote:
Originally Posted by kaigoss69 View Post
Congrats!
Thanks buddy.

Quote:
Originally Posted by mob17 View Post
Yeah sorry guys the install has been delayed a bit. It should hopefully be installed by the end of next week. I think the festive period in the US has delayed a lot of deliveries I'll let you guys know once its all in place!

All the best with the installation.
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