#pq1549

[cochlearkill-blog]

Mot Q - Calrec PQ1549 Equalizer  

My first piece of DIY studio gear made several years ago. This EQ is taken from the legendary Calrec "Polar" Consoles. Gyraf made the PCB layout. I Made my own front panel with frontpanelexpress.com

You can hear it in action on Chroming in the post below.

[irfrench]

PQ1549 - The finish!?

Back at the start of November I posted about re-purposing an old rack mount unit into a channel of Calrec PQ1549 EQ.

I wanted to do it for less than £65 ALL IN so I needed to wait for the necessary components and opportunities to arise so that I could keep costs down.  Well finally everything came together:

A really good opportunity to use up some spare components...

I've run out of etching equipment/chemicals/supplies so it would have been just as expensive to restock as opposed to buy the PCBs from Gustav and supporting his great business.

Doesn't take long to populate a well laid out board...

Using the etch-highlighting method as shown HERE the front panel is ready.

Then the existing front of the case needed drilling/preparing to allow the new occupants room to be themselves.

And all buttoned up.  Did the usual preliminary checks for correct voltages at IC pins, all worked out so I went for it.  Mercifully she worked first time!  Hurrah?!

Sweet.

And proof that it works?  Well - I only did one set of sweeps (the 'LOW' band) as this EQ is so damn flexible.  Can't wait to try it on a few things - Kick and Electric Guitars spring to mind - and HEAR what it does, but until then a set of sweeps will have to do:

So far I'm really chuffed with how it came out, I may change my mind if it sounds like poo, but if it sounds as good as it is meant to then I'm defo going to be happy.

So how did I do on the costs front?  Well here is a break down of the things I needed to buy:

PCBs - (£25.80)

Tantalum caps - £2.89 (eBay)

Switches - £6.94 (Mouser)

C100K Dual gang pots - £5.99 (eBay)

Front panel (£11.90)

Grand total spent: £53.52!!!

Now - I'm not condoning spending as little as possible on audio equipment, hell - spend as much as you want, I think generally you DO get better equipment when you spend more on components.  

However.

There are some circumstances when cost is a priority and this goes to show that you do not need to spend £££s to make professional-grade equipment.  I also learnt that a well designed circuit goes a long way and it is definitely possible to get great results out of 'standard' components...

I'll correct all this when I have a listen and hate what the EQ does, unless of course all the praise givers are right...

Anyway - I'm off to prep the house for Christmas decorations...

I can't wait for Christmas!

X

[irfrench]

PQ1549 - The Start

Evening,

So, previously I mentioned about a £65 budget EQ... One of the most costly bits is finding a case and sorting the power out.

Well, in the summer one of our offices closed, and being an old acoustics company there were some old electronics bits of 'junk' going wanting.  Naturally these were snaffled up including one old rack case.  It has been in my mind to re-purpose this case so I thought I'd give it the once over:

I knew there was a helpful power connector and fuse, along with 2 pre-drilled jack holes and a power switch so I was confident I could at least use some of this.

On closer inspection though I noticed:

Or more specifically:

Or even more specifically the heat-sink mounted 7815 and 7915 voltage regulators!  

"Does this mean that the psu is already installed and perfectly suited to this EQ project?"

A quick check with a multimeter, and YES. Yes it does mean that!  Sweet, not only has that saved me some cash (£20ish) I also don't have to build that bit! Hurrah! 

So all I had to do was remove the not-needed bits, tidy the wiring to keep the AC wiring as far from the EQ circuit as possible and get it prep'd:

FROM THIS:

TO THIS:

Hopefully now this will be a very willing host to a lovely sounding EQ.  Also, helpfully, the vero boards of the original circuit hosted a number of TL072s.  Those could come in very handy for this circuit!

Total cost so far = £0

x