FEELER - Analog Allstars 500 series Pultec MEQ-5S - FEELER

mitsos

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May 4, 2007
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Hey everyone,

Niels and I have been working on this for a little while now.  It is mostly working but the PCB and inductors still need a couple of tweaks, so this would take a couple months.  The amplification stage is the same as the EQP-1S5 (all the SS pultecs used the same I/O transformers and opamp for gain).  Inductors are the same permalloy material as the EQP-1S5, same material used in the originals, polypropylene capacitors, Grayhill switches, conductive plastic pots.  6 frequencies shelf/bell on the high and low, and 12 frequencies on the mid.

Sound so far is sweet!

No firm pricing yet, best guess would be close to, but slightly more than the EQP-1S5, due to the 2 extra inductors.

Please post here if interested so we know if we should take this further. 

THANKS!

24pdrhf.jpg
 

mitsos

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May 4, 2007
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kante1603 said:
You must be kidding! ;D
Udo ;)
No way!  8)  I thought you'd like it!

emrr said:
I'm glad to see someone add the bell/shelf switches.  I have meant to go back and add that to the top of mine. 
We thought it would be useful too. You should be able to do it fairly easily to any MEQ.  I doubt you need help with this, but if so, PM me.
 

Gearsef

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Jan 5, 2012
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I'm definitely in! I'm also glad that someone finally offers the Pultec type EQs as solid state kits!
 

emrr

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mitsos said:
emrr said:
I'm glad to see someone add the bell/shelf switches.  I have meant to go back and add that to the top of mine. 
We thought it would be useful too. You should be able to do it fairly easily to any MEQ.  I doubt you need help with this, but if so, PM me.

Way ahead of you, did all these experiments with the MEQ500 project way back when.  Didn't publish the shelf/bell experiments; did them after I'd ordered panels and I never have gone back to drill the extra switch holes.  Might be some interesting mid pultec data for people to explore here in my various chart links. 

http://www.groupdiy.com/index.php?topic=27964.100

As I'm sure you guys figured out, taking the low position to 100 or lower gives almost a shelf response anyway with the standard L value.  I haven't personally seem much value in adding a shelf switch there, but definitely on the high band, as narrow as they bells are in this circuit.    Also worth noting that in shelf mode the panel frequency marking is pretty much out the window, but who cares? 

5207751647_043391ecaa_z.jpg
 

mitsos

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Nice work EMRR! Thanks for posting, will have a good read through it tonight. Once I get another revision of the PCB I'll try to get some sweeps done to compare to yours for educational purposes. 

Greg! You are a trooper! finish the one you have while you wait for this one to get done! 
 

poiesznbeats

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Sep 6, 2012
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I was just looking at the EQP-1S5 but I would be even more interested in this!!!

I'll keep an eye out.
 

allintothat

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Jul 16, 2012
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This looks promising!
Im planning to buy two of the EQP1S5 in the future, and would deffently add this to the list.

So im just asking for a word on the progress!

Keep up the nice work!
 

mitsos

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May 4, 2007
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well, as far as function, the prototype is working fine. I'm waiting on a new faceplate from the laser engravers next week so I can get rid of the printed faceplate.  I'll post pics as soon as I get it.

Unfortunately there hasn't been that much interest, but if we have a group of people interested I will see about getting a small batch of the inductors made. The other major parts are shared with the EQP-1S5, so we shouldn't have problems there..
 

mitsos

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I'll try to get some parts quotes for about a dozen EQs to get it started. Really the only thing are the extra inductors.  If we use the EQP inductor for the mids, then make just one more for the other two bands (not ideal, but it'll be cheaper to get 24 of one inductor than 12 of each of two different ones). 
What may be pricey in these quantities is metalwork; I'll try to get some quick quotes and we'll see where we go from there?
 

mitsos

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May 4, 2007
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Some sweeps of the last prototype...  For the various filters, I dont' know why I didn't copy the individual sweep names but the frequencies are in order, but a couple may need some tweaking of the cap value.

Bypass... Red line is relay bypass, blue line is EQ in with all controls at zero.
21nnomw.jpg


Low Bell
2d6mqdl.jpg


Low Shelf
5z4dnt.jpg


Mid Cut
6zrn1v.jpg


High Bell
2i1l46c.jpg


High Shelf
2afn5o2.jpg
 
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