![]() ![]() Nerd shit: small polystyrene caps for the high freqs, yellow polycarbonate phillips caps and notice the giant silver Russian 10 uf film caps! no electrolytics in my filter! ![]() Measuring all the caps and re-calculating frequencies Most vintage capacitors have tolerance values of 5%, 10% 20% and i was using tons of vintage stuff from my stash, so i needed measure, especialy for a passive eq. If you don’t measure parts, or limit yourself to using an available brand of expensive -1% parts, the frequencies will vary from the calculated values and the spacing of the freqs can be weird, too far or bunched together. ![]() This is an advantage of home made electronics, because of parts tolerance it would be very expensive for a manufacturer to exactly match all units. I matched all the inductors values and cap to less than 1% and got all the frequencies i wanted spot on. It’s a long and tedious process but it’s way easier than it seems once you get the hang of it. Pretty much the same process for all the other eq’s. I had a 24 positions switch for the high band, compared to 5 frequencies on the original, so, alot more math, measuring etc. re-calculate freqs with the caps and inductors real world values.Measure shit loads of capacitors and paralleling them to get all the calculated values right.re-calculate all the frequencies with the tolerance of my inductor.measure the inductor for exact inductance values.Wind a multi-tap inductor with all the taps i needed.Calculated for all the in-between and extra frequencies i wanted to add.I re-calculated all the original Meq eq frequencies, inductance and capacitance.The way i did it to get all the frequencies right : I studied the circuit to understand the filter topology and then found some online calculators to help with the math. I am goin with the “solid state” version using Api 2520 discrete op-amp for make up-gain, so i won’t need the expensive interstage transformer as needed for the original tube version. The Filter circuit is a bit more complex than the EQP, Using 3 multi-tap inductors. So i started by studying the schematic of the filter circuit: (credit to Gyraf, Thanks man!) The first tube version has a make-up gain amp a little different than the EQP but the solid-state version is very similar, this is the one i wanted to clone. It’s a “passive” eq followed by make-up gain. It is basicaly a mid-range eq with low-mid boost, mid-cut and high mid boost. The MEQ-5 is a little less famous than the EQP-1a and probably a little rarer but selling for a little less than the EQP because it is less sought after. Here’s a pic of an original, tube version. See Part.1 for the intro and the eqp-1a cloneĪight, next up in my Pultec eq’s cloning saga, the MEQ-5 mid-range equaliser. Trio de Pultec from scratch Pt.2 – The MEQ-5 ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |