Line level high pass filter for PL400

[AngrySailor]

I am making some changes to my setup involving crossover frequencies while at the same time making tri-amping an option. What I really need to make things work properly is a high pass filter around 70-80hz that I can put before my PL400. I have a crossover with a sub output which I will set to 70-80hz as this is the upper frequency response of my subs, however the stereo low outs on the crossover are 0hz-to the crossover set point with only a 30hz filter. I would like to eliminate these low frequencies before they get to the PL400 as they are covered by the subs. Any suggestions?

Thanks

 

[JustMike]

I am making some changes to my setup involving crossover frequencies while at the same time making tri-amping an option. What I really need to make things work properly is a high pass filter around 70-80hz that I can put before my PL400. I have a crossover with a sub output which I will set to 70-80hz as this is the upper frequency response of my subs, however the stereo low outs on the crossover are 0hz-to the crossover set point with only a 30hz filter. I would like to eliminate these low frequencies before they get to the PL400 as they are covered by the subs. Any suggestions?

Thanks

If you want to stay with the same vintage as the rest of your gear, look for a Pioneer SF850. There is a lot of info on
the web about these and there is one on Ebay up for grabs. I have been using one for years and its hard to beat for
its flexibility. Also the Pioneer D23 is a good one but rare and high priced.
Another Classic is the vintage Dahlquist Lp1.

 

[laatsch55]

I have both Mike...excellent units. But it sounds like he wants an 80hz and up bandpass correct?

 

[JustMike]

I have both Mike...excellent units. But it sounds like he wants an 80hz and up bandpass correct?

Yeah I agree Lee. He did mention tri-amping and the Pioneers would eliminate trying to set fixed crossover points with
caps and inductors. The flexibility with the Pioneers really give you the abilty to dial everything in including volume to
each driver. You know what I mean. I'm wondering why your not using that D23 on the K's. with three PL's.
Or maybe that is in your plans when the big mono's are built?

 

[laatsch55]

Amen Mike , and those are all good points. I don't think I'll need 6 or 7 hundred watts at 8 ohms for the K's. They'll be going to Steve in Phoenix. And I am saving the D-23 for tri-amping the K's. I still don't own a full comp WOPL 1000. The loaner will get the first conversion then one more 400. I do have the Pig which is ready to go...

 

[laatsch55]

Andrew what are the points on the crossover you have now? You've said it has a sub out, but what else?

 

[AngrySailor]

Thanks guys. Ok here's what I'm trying to do with what I've got...Right now, I'm running a Rotel RA-1412 preamp into a DOD sr835 crossover with the low (100hz) going to PL400 and the highs back to the Rotel. The PL is running band pass subs. They are barely able to make 100hz and I would like to lower the tuning as it was raised to smooth the response to 100hz at the sacrifice of cone control and response lower than 48hz. I want to re tune the bandpass to 30hz which won't allow it to produce much above 80hz. I have a line on a ART311 stereo crossover with a summed mono sub output which I can cut off at say 70-80hz. This signal will go to two comercial amps (one each sub) with a high pass at 30hz. Then the stereo lows would be sent to the PL 30hz up to about 800hz. The stereo highs would be sent back to the Rotel at 800hz up. Tri amped, with only a passive crossover for the horn. Problem is, I don't want to send the frequencies covered by the sub (80hz down) to the PL driving the mid bass driver who's frequency response is weak at those low frequencies and also wasting power of the pl as it would be producing f. Best I can do is a 30hz filter. This crossover seems to send the sub out as "additional" not cutting the lows from the stereo amp below the mono subs set frequency.

damn that's hard on my phone. Hope that makes sense.

Thanks

 

[laatsch55]

Amen on the phone stuff.....I'll defer to someone who knows more about this stuff Andrew...

 

[Gepetto]

I am making some changes to my setup involving crossover frequencies while at the same time making tri-amping an option. What I really need to make things work properly is a high pass filter around 70-80hz that I can put before my PL400. I have a crossover with a sub output which I will set to 70-80hz as this is the upper frequency response of my subs, however the stereo low outs on the crossover are 0hz-to the crossover set point with only a 30hz filter. I would like to eliminate these low frequencies before they get to the PL400 as they are covered by the subs. Any suggestions?

Thanks

Put a 0.039uF cap in each interconnect from your preamp into the PL400 and you should be good. Simple and effective.

The cap is in series with the signal...

 

[AngrySailor]

Wow Pretty confusing.
Lets see if I can sort this out somewhat.
First off the Rotel is an integrated amp. Correct? Not A preamp only.
And the DOD crossover will only go as low as 100 hz. correct?
So you are coming out of the preamp section of the Rotel to the DOD crossover and sending the low out at 100 hz to the
Pl400 amp to drive the base bins.
Then sending the 100hz above from the DOD crossover back to the amp in section on the Rotel Integrated. The Rotel
amp section is then sent to the horns.

Is this what we have now before you want to do mods?

Correct except the Rotel power amp is currently running 3 way cabinets with passive crossovers. It's a bi-amp deal right now.

With the mods I'm leaning towards the Rotel driving the mids and horns.

 

[AngrySailor]

Put a 0.039uF cap in each interconnect from your preamp into the PL400 and you should be good. Simple and effective.

The cap is in series with the signal...

Simple enough, that would give a 6dB/Oct roll off right?

 

[Gepetto]

Simple enough, that would give a 6dB/Oct roll off right?

Yes, any frequencies lower than 83 Hz will be rolled off at 6dB/octave starting at that critical frequency...

It works as a high pass filter in conjunction with the input impedance of the amp which is approximately 49K ohms.

 

[AngrySailor]

Yes, any frequencies lower than 83 Hz will be rolled off at 6dB/octave starting at that critical frequency...It works as a high pass filter in conjunction with the input impedance of the amp which is approximately 49K ohms.

I think I'll give that a try, 6dB/oct should be plenty off roll off. I just want to keep the power from the PL from being wasted reproducing frequencies that the sub covers. Which type of cap must I use for this application? Next decision... do I run the PL at 83Hz-800 as a mid bass amp only and the Rotel as mid and horns (this is what I'm leaning towards as the Rotel has plenty of power), or should I run the PL on the mid bass and mids, say 800-3k with a passive crossover and use the Rotel for horns only. This last option seems a little excessive for high frequency.Then, when I get my hands on a wopl'd 700b (or two) I have to rethink again!

 

[Gepetto]

I think I'll give that a try, 6dB/oct should be plenty off roll off. I just want to keep the power from the PL from being wasted reproducing frequencies that the sub covers. Which type of cap must I use for this application? Next decision... do I run the PL at 83Hz-800 as a mid bass amp only and the Rotel as mid and horns (this is what I'm leaning towards as the Rotel has plenty of power), or should I run the PL on the mid bass and mids, say 800-3k with a passive crossover and use the Rotel for horns only. This last option seems a little excessive for high frequency.Then, when I get my hands on a wopl'd 700b (or two) I have to rethink again!

Nonpolar Polypropylene cap would be best.

Something like this from Mouser...

598-DPFF4S39J-F

 

[laatsch55]

The PL's are extremerly good bass amps, good on the rest too when The're WOPL'd, besides being flat down to 10 hz,( ok, not flat , but down only .point 10db at 10hz) after WOPLing they get real clean on top. I see a 700 and 400 WOPL in your future...

 

[AngrySailor]

The PL's are extremerly good bass amps, good on the rest too when The're WOPL'd, besides being flat down to 10 hz,( ok, not flat , but down only .point 10db at 10hz) after WOPLing they get real clean on top. I see a 700 and 400 WOPL in your future...

Hell yeah! I'm very surprised how well the 400 drives those subs. Before I replaced the speakers, I had them tuned to a lower response and she would really dig down to 20hz and below (until they melted). Now, they are tuned a bit higher and I can tell. It sounds great, just doesn't hit you like it used to. I'm going to try changing the tuning and crossover points as stated earlier, but the Definimax seems to roll off below 35hz. That's still better than the 48hz it's tuned to now. I've relieved the 400 of its stressful duties at 100hz down for now in favor of trying a QSC USA900 mono bridged on each sub cabinet. I haven't fired this new combo up yet as I'm (angrily) sailing the friggin north atlantic till January.

 

[laatsch55]

You're at sea right now??

 

[AngrySailor]

You're at sea right now??

Yeah, I'm Engineer on a bulk carrier. We sail the east coast of Canada, mostly around Newfoundland and the Gulf of St. Lawrence. We're headed inland towards Montreal right now. Gotta pay for stereo shit somehow!

 

[laatsch55]

Ok Andrew, I didn't understand you could browse the internet while at sea......coolness...

 

[Northwinds]

Ok Andrew, I didn't understand you could browse the internet while at sea......coolness...

The beauty of satellites and nothing to get in the way of the signal