MEQ mid-range EQ pultec style (was meq500)

[buschfsu]

guys i wanted to put this meq500 into a channel strip with a mic pre so i didn't add the input transformer.  will this circuit have any issue with a normal 600ohm load from my mic preamp or do i need the input iron.  on the output side i have a carnhill 600:600.

thanks

 

[emrr]

Should be fine.

 

[lassoharp]

guys i wanted to put this meq500 into a channel strip with a mic pre so i didn't add the input transformer.  will this circuit have any issue with a normal 600ohm load from my mic preamp or do i need the input iron.  on the output side i have a carnhill 600:600.

thanks

I was thinking of doing the same with a particular project.  As long as you terminate the OT on the preamp with a 6xx resistor it should do ok.  When I was recently building my MEQ I was running program material from a line amp output to the MEQ input and A/Bing the MEQ input w/ & w/o input transformer - w/o using a 620r resistor and it worked well. 

 

[emrr]

the MEQ500 has a 620 termination already. 

 

[mata_haze]

Hello,
I am building this beast right now, but I am not sure to understand how to achieve che narrow/broad with the switch?!
can somebody quickly explain it / draw a diaghram?

thank you!


Mattia.

 

[lassoharp]

Short/bypass the 270R resistor.

 

[emrr]

and look back at my plots in this thread, which made me decide it was a pointless exercise. 

 

[mata_haze]

thank you guys!

Mattia.

 

[lassoharp]

I omitted this switch as well in the MEQ I recently completed.  I really couldn't hear the difference on source material well enough to justify it.

I experimented with several different inductors for the mid dip section and getting the broader sounding curves would've meant committing to a different inductor (with a different Q value).  I wound up using the Cinemag which felt about right for 11 positions.

 

[lassoharp]

Here's some pics of an MEQ style program EQ I recently built.  The high boost section was rearranged a bit with boost points at 1K, 2.5K, 10K, 14K, & 16K.  Mid dip section is as the original.  The low boost section goes from 30Hz, 60Hz, 200Hz, 300Hz, 500Hz, & 700Hz.  As you might guess this was somewhat of an attempt at combining the EQP1A frequency range with MEQ mid cut/boost abilities.

Make up amp is a two stage PP tube type that gives an additional 10db gain past unity or -28db if needed.

 

[jensenmann]

Just a quick note on Doug´s handdrawn schematic: the second half of the 5532 hybrid amp is drawn with the inputs reversed. Negative input (Pin 6) should be tied to the output (Pin7) and positive input (Pin5) should be tied to ground.

Did anyone try the midcut with more than 270Ohm for a lower Q? I guess I´ll try that....

 

[emrr]

Drawing fixed and replaced, funny no one caught it till now. 

More than 270 won't change the shape, just limit the depth further. 

 

[jensenmann]

More than 270 won't change the shape, just limit the depth further.

Ok, then I´ll stick with 270Ohm. Thanks for saving me some time ;-)



First one is up and running. The output transistors are running quite hot. Still touchable, but definitely hot. Did anybody run into trouble with that, yet?
Soundwise it eats up quite some lowend which is perfect for my task since it will reside on backing vocal group in my FoH rack. That way I can forget about engaging HPFs in 5 backingvocal channels. The other PCB in the background´s going to be a bassdrum version with custom LF inductor for different frequency choices, INA134 sand input instead of iron and Edcor XS1100 at the output for increased LF harmonics. Frontpanels were done by our member Frank of nrg-cnc.de

Thanks to everybody involved in this project!

 

[emrr]

Are you liking what 7K, 10K and 14K boost give you?  I didn't find it useful myself.  Or maybe you changed them to shelves? 

You shouldn't be losing lows with the INA134 input, unless it's having problems driving the 620.  That's why I went with the THAT1646 driver as part of the input scheme.  Or maybe I misunderstand your meaning. 

So far in 2 years the provided op amp hasn't burned up on either of mine, it does run very hot.  I intend to get 2520's in there when I can find the time. 

 

[jensenmann]

According to the datasheet INA134 should be able to drive 60mA to Vrail-1,4V. That should be good enough to drive the filter. I saw your post and read the threads you were pointing to regarding the debal. circuit. Very interesting! You didn´t misunderstand me, I chose the INA because I want not to loose LF in my Kickdrum version of this EQ.

I´m not sure about the 7/10/14kHz boosts. They sounded very narrow and unnatural to me. But I finished it only one hour ago so I had not much possibilities to test it, only sending some CD tracks through it. I have a gig next weekend where it will be put into reallife use. I´ll give you a feedback what I think about it. The idea of changing the highest frequencies to shelving is very good, though. Maybe I should give it a try, shelving could be much more useful to what I want to achieve with it.

 

[emrr]

Shelf would be easy.  I thought about that and a lot of other changes after I'd already made panels; too late. 

 

[jensenmann]

Just a quick note about the additional frequencies I´ve added to the HF boost (7k, 10k, 14k). My original intention was to use the MEQ on backingvocal subgroup to add some air and cut out some mids to leave space for the leadvocalist. Yesterday we had the first show since my MEQ is finished and I put it on a subgroup as well as an EQN on another subgroup for comparison. The 7k and 10k HF boost kind of did what I expected but sounded a bit narrow and unnatural, not so silky and pleasing as the EQN HF shelv did. Besides the general sound difference between both units I prefered to have shelv over bell for the "air". The MEQ midcut was very effective and exactly fitted my need and the general LF absence because of the input tranny worked as a feature rather than a bug in this application. So I guess I´ll give it another try with the 7k-14k frequencies modded into shelving. The other frequencies below worked pretty good in bell and are worth to be kept that way. Maybe I´ll have a look at different DOAs, maybe I can make the MEQ behave a little smoother.... or simply get another EQN  :

 

[emrr]

That's what I expected to hear about those highs, thanks. 

 

[weiss]

is anyone supplying pcb's?