[Need] simple preamp and LPF based on 5532 for digital sources

godslayer

Member
2010-06-18 5:46 pm
hi friends,

i am looking for schematics for LPF(subwoofer) and a good quality preamp(for 4xtda 2050) to make my 2.1 system.

although i know chipamps dont need a preamp for their usage, but i think tda2050 can do with some gain love, especially when I have spare 4x ne5532's
in my drawers.

I indeed had a look at p88, but i cant get the pcbs imported (customs require some serious palm greasing down here very india-ish).

can someone help me with a simple preamp similar to p88 hopefully ready to etch?i dont have a lot of requirements.. only simple volume control and balance to juggle between the two channels.

I had also plan of variable active LPF cutoff filter using the similar IC, unfortunately lost it, can anyone please guide?:confused:

thanks for giving this thread your time :)
 
Been a day, no help from the astute. Basic op amp circuits are in http://www.diyaudio.com/forums/analog-line-level/167604-basic-mixer-design-need-input.html
The 5532 is a good choice. It is quiet plus also moderate slew rate so you don't need a lot of ceramic bypass caps or feedback resistor bypass ceramic caps.
For environmental reasons, the lack of an up to date computer, the inability to keep a printer cartridge (imported from *****) operating more than 6 weeks at low usage, I don't print masks and etch. I build circuits point to point on NEMA CE or LE laminate that I buy in bulk and drill myself. You can also use glass reinforced project board, but drilling that is a *****. I find the project boards available from farnell and mouser highly overpriced, but I like the sockets. There are DIP project boards available from taiwan, quite attractively priced, but of course my purchase source would be useless to you. They carry the legend "CIC 21-110" and "Datek 12-611b" if you can find an Indian distributor. I find DIP packages a little hard to attach the soldered wires to without creating solder bridges. I tried one project on polycarbonate plastic, but solder sticks to it too badly. I prefer teflon or efte insulated wire, as it doesn't burn when my soldering iron makes an unintended move. I prefer phosphor bronze DIP sockets to tin plated or brass ones. Note low gain d/a converter input op amps will need not very much gain, maybe 1.5 to 5x, which is the ratio of feedback resistor to input resistor.
If you really want to etch, Music From Outer Space - Your Synth-DIY Headquarters has some greyed out top view layouts. I was going to reccomend jhaible.de, but it appears he has abandoned his URL.
Good luck with what you have on hand.
 

godslayer

Member
2010-06-18 5:46 pm
Been a day, no help from the astute. Basic op amp circuits are in http://www.diyaudio.com/forums/analog-line-level/167604-basic-mixer-design-need-input.html
The 5532 is a good choice. It is quiet plus also moderate slew rate so you don't need a lot of ceramic bypass caps or feedback resistor bypass ceramic caps.
For environmental reasons, the lack of an up to date computer, the inability to keep a printer cartridge (imported from *****) operating more than 6 weeks at low usage, I don't print masks and etch. I build circuits point to point on NEMA CE or LE laminate that I buy in bulk and drill myself. You can also use glass reinforced project board, but drilling that is a *****. I find the project boards available from farnell and mouser highly overpriced, but I like the sockets. There are DIP project boards available from taiwan, quite attractively priced, but of course my purchase source would be useless to you. They carry the legend "CIC 21-110" and "Datek 12-611b" if you can find an Indian distributor. I find DIP packages a little hard to attach the soldered wires to without creating solder bridges. I tried one project on polycarbonate plastic, but solder sticks to it too badly. I prefer teflon or efte insulated wire, as it doesn't burn when my soldering iron makes an unintended move. I prefer phosphor bronze DIP sockets to tin plated or brass ones. Note low gain d/a converter input op amps will need not very much gain, maybe 1.5 to 5x, which is the ratio of feedback resistor to input resistor.
If you really want to etch, Music From Outer Space - Your Synth-DIY Headquarters has some greyed out top view layouts. I was going to reccomend jhaible.de, but it appears he has abandoned his URL.
Good luck with what you have on hand.

Thanks for the help, i too was thinking of going the p2p way on veroboard. but wont incorrectly designed tracks induce hum inside the circuits? i guess i will need to keep it really away from the power sources, i am looking for fairly simple opamp that should only eliminate hum and provide enough gain with balance and volume control. I seek nothing else.basic mixer seems "EDIBLE" will work on it :) thanks

for the LPF section, will something like this help?http://xtronic.org/circuit/amplifie...50-hz-ne5532-bass-filter-with-volume-control/
 
Last edited:
Look at this thread for the schematic diagram of a complete 10 band ? equalizer. You can pick one of the stages as your high cut stage to drive the subwoofer amp. The biamp sys eq-110. www.diyaudio.com/forums/analog-line-level/222217-biamp-eq-210-studio-eq.html
The rules for preventing oscillations on point to point soldered wire are similar to those for layout of a PWB: no long parallel runs between high gain points, inputs, and high current points, outputs. Also, decoupling the power supply near the IC with ceramic caps, and possibly putting a 20 pf cap across the feedback resistor. Although the 5532 is not very prone to oscillate, I hear.
Keeping hum out of a system IMHO has to do with the enclosure (steel), AC power layout, star grounding. Keeping RF (radio interference) out has to do with putting ceramic caps (100 pf is traditional) between inputs and signal ground, and keeping RF off the power inputs by putting chokes on either the AC inputs to the enclosure or the DC inputs if you use a wall transformer. I build systems in steel boxes like recipe file cabinets, and for line level I use wall transformers and put chokes on the DC inputs. I use chokes from the input sections of dead PCAT switching power supplies, or I salvage the transformer toroids out of them and unwind them down to a single 20 turn winding (which filters out CB/police radio effectively).
Vero board is $10 to $15 apiece here, whereas I can get a whole 6"x12" sheet of .062" NEMA LE laminate material for $10 from a company I order industrial hardware from. I can saw many projects out of one of those sheets. Hacksaws work fine on it, if you have a vise and a dirty shop area. Buying laminate on another order with drill bits or grinder bits or machine screws or nuts I can't buy locally, I save shipping charge. Other names for NEMA LE laminate are micarta, garolite, textolite. It is linen or cotton cloth embedded in phenolic plastic. I'm assembling a control board for a speaker disconnect circuit for an amp that didn't come with one on LE laminate right now. (Rainy KY Derby weekend). Fits in a 2"x4"x2.5" empty area in the amp case next to the AC cord entry.
Your upload is invisible to me.
 
Last edited: