configuring 'frankenstack'

Lisa Lane-Collins

Lisa Lane-Collins

Sophomore
Dec 9, 2012
270
0
16
Adelaide, Australia
i have a couple of peavey fh1s lying around, kind of useless cos they dont go low enough to be subs. getting my head around their true identity as low mid boxes, i thought it might be kind of cool to frankenstein them into my two way system (subs and tops).

problem is, i don't know how to make it sound good.

they're currently in a stack with jbl prx 615s on top and a prx sub underneath (i know, butchering a perfectly good two way system here). i have a dbx driverack to process my signal. on the advice of another tech i tried the following cross over points 100, 350, with the powered tops and subs delayed by 2ms. it didnt sound particularly amazing.... very low middy really. im suspecting the peaveys have a lot more juice than the rest. tried turning them down via the driverack quite a bit, tried making the lower crossover point higher and lower (makes sense to me to have the peaveys throwing in a bit of extra vol where the kick drum is). tried making my shelves gentle/severe, tried varying the vol of the mids relative to the rest. realise i have no idea what im listening for and that probably the drive rack had a whole bunch of speaker appropriate eq etc deployed when it knew what speakers i was using (for some reason when i made my new preset it would only let me say what sub i was using).

so, question is, how do i get the best out of this configuration? (in case you are wondering why i am messing with the jbls the answer is, looking for more warmth, more volume, more clarity?? and the fh1s are just lying around otherwise.
 
Last edited:
Re: configuring 'frankenstack'

You added a low mid cab, and the low mids became muddy. I think I see the obvious solution. :lol:



A brief glance at Peavey's specs says they start to roll off around 60hz or so. I'd try running your subs to about 80hz, the PV 70-150 and the JBL top 100+. The PV is horn loaded, so you will need to delay the JBL's to line up. Your best bet is to run an 80hz tone through the sub & low, flip the polarity on the mid and start rolling the delay on the sub back until the tone gets a lot quieter. Then flip the polarity back to normal. If it gets a lot louder, you're good. If not, try again. Rinse and repeat at your mid/high crossover point.


This should tighten your rig up nicely. I'd think 2-3ms on the lows, and 3-5 on the tops.





Evan
 
Re: configuring 'frankenstack'

Evan Kirkendall said:
Your best bet is to run an 80hz tone through the sub & low, flip the polarity on the mid and start rolling the delay on the sub back until the tone gets a lot quieter. Then flip the polarity back to normal. If it gets a lot louder, you're good. If not, try again. Rinse and repeat at your mid/high crossover point.

Evan
Click to expand...
The problem with that method is that you may get 80Hz correct-but cause a notch somewhere else higher or lower in freq.

It is NOT just a single freq-but rather the freq RANGE of overlap that is of interest. Sometimes you have to have a little bit less of one thing to get a lot more of several others.

Of course if you do not have a way to actually measure the whole response-then that method will get you closer than just "guessing" and certainly closer than using physical distances-since that does not account for phase shifts inherent in crossovers etc.
 
Re: configuring 'frankenstack'

Evan Kirkendall said:
You added a low mid cab, and the low mids became muddy. I think I see the obvious solution. :lol:



A brief glance at Peavey's specs says they start to roll off around 60hz or so. I'd try running your subs to about 80hz, the PV 70-150 and the JBL top 100+. The PV is horn loaded, so you will need to delay the JBL's to line up. Your best bet is to run an 80hz tone through the sub & low, flip the polarity on the mid and start rolling the delay on the sub back until the tone gets a lot quieter. Then flip the polarity back to normal. If it gets a lot louder, you're good. If not, try again. Rinse and repeat at your mid/high crossover point.


This should tighten your rig up nicely. I'd think 2-3ms on the lows, and 3-5 on the tops.





Evan
Click to expand...

Just to add to this good advice if you don't have a FFT measurement system. Be sure to play the sub alone first with a test tone set at your crossover point . Bring it up to 95 DBs as an example then mute its output. Then play the FH1 midrange alone at 95 dbs with the same tone. Then turn them both on and see what happens. If you don't get around 101 dbs then reverse polarity on the sub and see what happens. If you still don't get 101 dbs then add delay until you get the the lowest output then set the polarity to normal and see again what you get. You should get close to 101 dbs if both are in good phase at the crossover freq.
After this is done then you can adjust your midranges level to what you need to blend with the subwoofer. With the test tone, reverse polarity for the lowest output method to set delay I always start with both bandpasses running at the same level set one at a time and shoot for as close to a 6db gain as I can get with both bandpass sections turned on. (of course at the spl meter location)
I had 4 fh1's many years ago. I seem to remember them being about 103db's 1 watt 1 meter depending on freq. Find your subs 1w1m output and turn the fh1 crossover gain down to match your subs output. It could be 6 dbs or more.
When you match levels as in above you'll get a better idea as to how much you'll need to turn the fh1s down.

Douglas R. Allen

Edit: Peavey rates them at 104dbs 1w1m
http://www.peavey.com/assets/literature/manuals/80301013.pdf
 
Re: configuring 'frankenstack'

Phase inversion trick is genius, I shall try that and those recommended cross over points, and doing the volume matching thing.

I think I might actually have an rta mic though it's behringer not dbx. Would it be worth plugging it into the driverack and letting the driverack have a go?

Douglas, question specific to you as you've owned the same set of four fh1s, what did you use them for?
 
Re: configuring 'frankenstack'

Lisa Lane-Collins said:
Phase inversion trick is genius, I shall try that and those recommended cross over points, and doing the volume matching thing.

I think I might actually have an rta mic though it's behringer not dbx. Would it be worth plugging it into the driverack and letting the driverack have a go?

Douglas, question specific to you as you've owned the same set of four fh1s, what did you use them for?
Click to expand...

Not much difference between the Behringer and dbx mics, at least below 8k.

The "wizard in the box" has little magic; he'll disappoint you. Or at least mislead you. Follow Mr. Allen's procedure and relish the learning experience. :D
 
Re: configuring 'frankenstack'

Tim McCulloch said:
Follow Mr. Allen's procedure and relish the learning experience. :D
Click to expand...
And don't get upset if the results don't "come out right". That is all part of the learning experience.

The REAL learning starts when you try to figure out WHY the results did not turn out as expected.

And it doesn't come quick or easy-most of us who have doing it for many years are still trying to figure it out------------------------
 
Re: configuring 'frankenstack'

Lisa Lane-Collins said:
Phase inversion trick is genius, I shall try that and those recommended cross over points, and doing the volume matching thing.

I think I might actually have an rta mic though it's behringer not dbx. Would it be worth plugging it into the driverack and letting the driverack have a go?

Douglas, question specific to you as you've owned the same set of four fh1s, what did you use them for?
Click to expand...

I used them for all kinds of things. You have to remember when they came out the Lowest of Lows needed really wasn't that low....
They punched pretty good within their range. This was when a CS800 with a 40 hz 48db low cut and 150hz high cut crossover can ruled the bar scene in my area.
For the most part I'd run a Sp2 with 1 or 2 per side depending on room size.
Sometimes 2 on each side set on top of each other or 1 per side with 2 in the middle or just 2.
In the small rooms I'd run the sp2's full range on tripods and have the subs sitting in front ahead about 3 feet. They blended pretty well in the 70hz range with this physical seperation. Toward the end before I sold them I started doing the Aux fed bass drum to them and they worked well this way. This was a long time ago but I made them work best I could for what they were.

Douglas R. Allen
 

Attachments

  • Doug 1991 02.JPG
    Doug 1991 02.JPG
    103.9 KB · Views: 0
As mentioned before, if you don't have access to tools such as a FFT, flip polarity of a passband and aim for cancellation with tone. BUT always verify! There should be a noticeable addition when everything is running in alignment.

Last summer, I changed laptop cases to a Pelican Hardback, and my 'oh crap!' backup stereo input (Giffin iMic) didn't fit. With doing back to back fly dates out of multiple offices, my ground transport flypack didn't make several festivals and my smaart rig sometimes didn't make the trailer. Knowing the rigs (both trap and line arrays) I was working on and that trick got me into 95% of the rig tuned every time with headlining BE just adding their 'voicing' while using their smaart.

I find the same thing lately, if the venue/time schedule is too big/tight, most is done by ear, and since most times I'm the BE and SE, it works out. I'd toss out smaart if I had slightly longer time than to do 2 out of 15+ measurements (cabling/interconnect is a pain in any measurement system)....... or cut into my one break/meal time .....

BRad
 
Top Bottom