Problem with PE 1000w plate subamp (1 Viewer)

[Thomas J. Coyle III]

Hi LanceEAR,

Based on my email traffic with PE, I believe that PE does not consider the auto turn-on issue to be a defect in their new plate amps since all they did was offer to send me the plate amp schematic when it becomes available. If they were really interested in verifying that there is a problem with the auto turn-on circuit, I am sure that they would have initiated some meaningful email traffic with me concerning this issue.
Regards,
TCIII

 

[Mike Keith]

From my understanding you should always have the input gain as High as possible (without clipping) in all situations, this will keep the noise floor down and provide a far less distorted output.

 

[DarrenK]

Hey Guys,

I can assure you that we (Parts Express) is looking into the "auto-on" issue. It takes some time to do research and get all of the information on hand to be able to hand out correct advise.

There is one simple method to "fix" the auto-turn on issue. There are provisions on the PC board for a jumper to bypass the auto-on circuit completely. This would make the main power switch act a simple on-off switch, which you could leave "on" all the time. There is a spot labelled J2 on the right side of the power amp board, where you can connect the two pins to bypass the auto on.

When it is in "standby" mode, the inputs are muted, but the output section remains active. So, in terms of current draw there will not be a significant difference between the amp just sitting there in standby or just on but with no signal. Probably about 10 watts vs. 12 watts.

The only downside would be if your stereo system emits any turn-on thumps, but on most stereo systems this is not an issue.

If you want to send me an email to [email protected], we can look into some further options and possibilities to help solve your problem.

Best regards,

Darren

 

[DarrenK]

Hello Again,

Also, let me point out that this turn-on "issue" is not a defect in the manufacture of the amplifier. It is something that may come up on some systems depending on setup and the user's personal preference of settings. Out of the hundreds of the amplifiers that we have recently sold, we have only heard of issues about the auto-on a few times. I use one in my own home theater system, and the amp works great in my setup, I've never had any problems.

The above jumper comments are simply an easy way to make the amp work for you if you are having troubles.

For the majority of cases, the amp will work fine out-of-the-box.

Take care,

Darren

 

[Thomas J. Coyle III]

Hi Darren,

I never said that there was a manufacturing defect in the amp. If you notice, I said that it a very good subwoofer/plate amp combination. All I said was that I believed there was a design anomaly in the auto turn-on circuit.
I am an electrical engineer with 30 years of experience in circuit design and system engineering. I tried every reasonable combination of plate amp gain setting and pre/pro LFE output signal level. I tried a series of high output LFE levels from the pre/pro and low input gain settings on the plate amp. I also tried a series of low output LFE levels from the pre/pro and high input gin settings on the plate amp. In every case, once I adjusted the pre/pro LFE output and plate amp gain to get the proper subwoofer SPL output (75-80db) at the pre/amp Dolby reference volume level setting of "0", the plate amp would auto turn-on at home theater volume setting levels, but would fail to turn on at lower music listening volume levels. And, in every case, when I held the pre/pro LFE output level constant, the plate amp would always auto turn-on when I raised the plate amp gain up at least two more notches when listening at normal music levels. Several other people have also responded to me that they are having the same problem with the 500watt plate amp.
While we are at it, there is a disagreement between the plate amp manual and the subwoofer assembly instructions concerning the function of the plate amp pilot light. The manual states that the pilot light will be green in the standby mode, yellow in the operate mode and red in the overdrive mode. The subwoofer assembly manual states that the pilot light will be a dim green in the standby mode, bright green in the operate mode, yellow near clipping and red in the overdrive mode. From actual use, the subwoofer assembly manual has the correct description for the pilot light operation.
Also, I believe the plate amp manual states that the amplifier will go from the standby mode to the operate mode when it receives an input of 3mv. Just my pre/pro turning on will generate a LFE output signal of better than 3mv even when I am only playing the system at music listening levels. The PSB Sub Sonic 6 subwoofer, which the 15" MKIII subwoofer/plate amp combination replaced, would come on the second the pre/pro was turned on. The gain control for the Sub Sonic 6 was set at "3" and the LFE output of the 950 pre/pro was set at -7db. Therefore your implication that there is a LFE output problem with my 950 pre/pro does not appear to hold water.
I really want to cooperate here to resolve this auto turn-on issue, but I would also like to have the record set straight as to what was initially said about the auto turn-on problem here on Home Theater Forum.

Regards,
TCIII

 

[DarrenK]

Well, I was in no way trying to insinuate that you said the amplifier was defective. I was just trying to point out to other readers of the forum that the amplifier isn't "broken" and in need of "fixing". For most users, there won't be an issue in the first place, it just depends on your system and settings. Yes, there are a few options that can be explored if the amplifier isn't operating correctly in a particular situation.

I am looking forward to discussing the issue via email, I hope you take me up on my offer.

If you're having trouble getting an email through to my PE account, please send to [email protected]

Darren

 

[DarrenK]

Hi,

Oops, I did get the email that you sent already, sorry about that. I guess I hadn't checked my hotmail this morning.

Also, I forgot to respond to the LED issue. I did not actually write the manual for the amp or the sub system, but I should have caught that discrepancy before it was published. The correct form of functioning should be as follows: When the amp is powered on, but in standby, the LED will be a dim green; When the amp is on and fully active, it will be a bright green; As the amp is running hard, it will start turning a yellow color; when it finally starts to clip the LED will turn red.

With the whole yellow/red stuff, there is a gentle progression from green to red. It will not all of the sudden turn pure red or yellow.

Take care!

Darren

 

[Jack Gilvey]

Thanks for the info, Darren. Any way the amp can be modded by PE for On/Off before shipping?

 

[Jim Holtz]

I thought that I might add that I have 3 of the 500 watt plate amps for a project I'm working on so I've been following the thread with great interest. Darren has been great to help me out. Soldering the wire on the amp is super simple for even a "soldering challenged" person like myself. The light comes on bright green now.

I've done a lot of business with PE, Madisound and others in the DIY speaker business and I can assure who ever might have concerns, that PE will stand behind the products they sell and will also do everything with in reason to satisfy their customers. I haven't used the amps yet but I'm totally confident that they'll work extremely well and that PE will be there to help me out if I need it.

Best regards,

Jim Holtz

 

[DarrenK]

Thanks for adding your comments Jim!

With regards to Jack's question:

In general, I don't think it makes sense for us to modify all of the amps here in house. The main reason is that for most people, the auto-on will work fine as it is. If its going to work, most would probably rather still have it enabled than not.

Of course, if there are special cases, then we will investigate them individually. But, Jim is right, it really is a very simple modification that any DIYer could easily handle.

We are already in-process on working on some refinements to the auto-on circuit, so hopefully it won't be an issue in a couple of months.

See ya,

Darren

 

[Joey Skinner]

I am having Auto-On problems with my 500w amp and would like to bypass it. I read DarrenK's post on putting a jumper at the J2 pins on the 1000w amp. Would this be the same on the 500w amp? I found the J2 pins on my amp but I'm hesitant to join them without knowing for sure. The J2 pins I'm looking at are on the left side of the middle PC board(power amp). If anyone has done this I would appreciate any advice. It has been my experience that once you let the magic smoke out of an electical device it never works right again .
Thanks

 

[Jim Holtz]

Joey,

The jumper works fine but PE has come up with a different fix to improve the turn on sensitivity by adding a small resistor. It looks easier than the jumper. Email PE for details.

HTH

Jim

 

[DarrenK]

Hi Guys,

Since the initial discussions of the issue with the auto-turnon, we have devised a new "fix" for this. It is simply adjusting the value of one resistor, and I have received nothing but success stories of the mod's effectiveness. Just drop me an email at [email protected], or call technical support for a little "how-to" packet for doing the mod.

See ya,

Darren

 

[Joey Skinner]

The modification works! The PDF file contains detailed instructions with pictures making the procedure very easy.
Thanks Darren,
Joey S