car preamp with artificial earth(ESP)

[sagarverma]

anyone made car preamp with a.e from esp site.

suggest improvements.

i m setting gain at 3.

how is performance?is it worth?

advise please.

 

[sagarverma]

preamp done

any advise on how to inc the low freq resp. in the ckt itself so that the bass is heavy throughout the spectrum.
can preamp b modified ad-hoc or do i require a seperate ckt for the purpose.advise plz

 

[TO-3]

anyone made car preamp with a.e from esp site.

suggest improvements.

i m setting gain at 3.

how is performance?is it worth?

advise please.

Can you post a link or attach the schematic?

 

[sagarverma]

hi to3

thanks for reply

link is

http://www.sound.westhost.com/project32.htm

i have done it totally.though the pcb has provision for a.e circuitary also,i havent used it.

plz suggest the req mods to serve my desired purpose.

 

[TO-3]

Here are a couple things you can do. If you are confident in the circuitry before this circuit, remove C101, 102, 201, 202, or change them to polypropelyene. Never use electrolytics in the signal path. This will give you more bass as the electrolytics block those desired lower frequencies.

Another thing you can do is use good opamps. Using audio grade opamps will increase your signal-to-noise and lower your THD substantially. I always use AD 823s for my audio. These run about $4.50USD each, but they are dual channel and I think the AD821 or 822s are the singal channel version. But a good part is the Burr-Brown OPA2134(dual) or OPA134(singal) and they cost about half as much as the Analog Devices parts, but are still a much better choice then those horrible TL072s.

Here's a link to the Burr Brown devices:
http://focus.ti.com/docs/prod/folders/print/opa2134.html

 

[sagarverma]

hi to-3

how much do tlo72 cost u.it will help me do comparison bec i got 20 of them here at Rs12 per peice.opa2134,i suppose will suffice bec i have heard many a praises bout them.$2.25 as u sayin they cost,it equates to bout Rs100.very costly bec i got lm series amp chips for this price!!so tell me that r opa's worth the price.if they have excellent performance then i will buy them for pamp.tell accordingly

how bout ne5532?good or not?

i have used tl02 in lr xover from esp site.the filter works brilliantly.the opamps operate at unity gain so no cause of concern even if u use prehistoric 741.
****tl072 is a good ic,dont call it bad( i got 20 of them****

one point,are such vaues as 10 or 100 uf available in polypropylene?i doubt.even if they r they would b very huge and very costly.if they really have the performance to justify the bulk they carry,only then i should go for them.reply accordingly.

thanks in advance

 

[TO-3]

hi to-3

how much do tlo72 cost u.it will help me do comparison bec i got 20 of them here at Rs12 per peice.opa2134,i suppose will suffice bec i have heard many a praises bout them.$2.25 as u sayin they cost,it equates to bout Rs100.very costly bec i got lm series amp chips for this price!!so tell me that r opa's worth the price.if they have excellent performance then i will buy them for pamp.tell accordingly

how bout ne5532?good or not?

i have used tl02 in lr xover from esp site.the filter works brilliantly.the opamps operate at unity gain so no cause of concern even if u use prehistoric 741.
****tl072 is a good ic,dont call it bad( i got 20 of them****

one point,are such vaues as 10 or 100 uf available in polypropylene?i doubt.even if they r they would b very huge and very costly.if they really have the performance to justify the bulk they carry,only then i should go for them.reply accordingly.

thanks in advance

Just to give you an idea of the differences:

THD @ 1kHz with Rload= 2k ohms
TL072= .01%
OPA2134 = .00008%

Input noise margin @ 1kHz:

TL072 = 15nV/sqrt(freq)
OPA2134 = 8nV/sqrt(freq)

So the TL072 has almost twice the amount of noise.

I found these prices on www.digikey.com
TL072= $0.65
OPA2134 = $2.63

As for the NE5532, it costs around $0.80 and has low input noise, however. Unlike the other two, this can only swing +/-15V and the slew-rate is rather weak 9V/us(at unity), while the other two are 15V/us and better respectively. I would say no to that part.

Polypropelynes are usually larger than electrolytics. If you are confident in your other components, just lose the caps altogether. You will get less phase distortion, but at the cost of passing direct current through your circuit.

 

[sagarverma]

from your suggestions,i can deduce that switching over to opa2134 is really a good choice.
it will cost much less out here.in bulk much less
will change over to this chip on monday or so and will post the result.

what bout the bass boosting?any good tried and tested ckt?

 

[TO-3]

from your suggestions,i can deduce that switching over to opa2134 is really a good choice.
it will cost much less out here.in bulk much less
will change over to this chip on monday or so and will post the result.

what bout the bass boosting?any good tried and tested ckt?

I don't have any circuits, but after you ops in the circuit I am sure you will be pleased by the difference in sound.

I have a real project I need to get to someday. I have a PPI DEQ-230, a 1/3 octave crossover that I need to modify. I want to replace all of the crappy quad ops to some nice ones. The only thing that is stopping me is the cash. It has been awhile since I looked at the board, but there are at least 15 quads to replace.

 

[sagarverma]

hi to3
see this.is it worth??

http://www.sound.westhost.com/project28.htm

know anything more(practical) bout simulated inductors.i read in details bout them in my 2nd year(final year elect. n comm. engg.).
but that was all theory with derivations etc.i need the practical day to day usage and performance info.any idea or link?

i didnt understand parametric equaliser.parametric amp was in syllabus too but i never bothered to read it then.any info bout it too.

see it if any improvements possible.


advise::
in your xover,r the opamps operating at unity gain????if its that then forget bout changing the ics bec NO IMPROVEMENT will b there.if the ics have gain,only then change.
-----------------------------------------------------------------------------
calculations
::::quads:unit price=Rs350 approx.for 15 its approx Rs5000=price of a good sony amp.but here,quads will cost 1/5 or less of what u pay.dunno y but its a pleasant reality

 

[TO-3]

The reason for using a 1/3 octave eq is to attenuate or boost a particular frequency. The parametric eq usually can be configured for the particular freqs you wish to "enhance". Also with the parametric eq, usually you can adjust the Q to be very wide or very narrow.

Never heard the term "simulated inductor" but since a cap is theoretically the opposite of a capacitor, you attenuate the higher frequencies to ground via a cap instead of placing a choke in-line. Either way, a cap or inductor will add a phase-shift to your circuit.

hi to3
see this.is it worth??

http://www.sound.westhost.com/project28.htm

know anything more(practical) bout simulated inductors.i read in details bout them in my 2nd year(final year elect. n comm. engg.).
but that was all theory with derivations etc.i need the practical day to day usage and performance info.any idea or link?

i didnt understand parametric equaliser.parametric amp was in syllabus too but i never bothered to read it then.any info bout it too.

see it if any improvements possible.


advise::
in your xover,r the opamps operating at unity gain????if its that then forget bout changing the ics bec NO IMPROVEMENT will b there.if the ics have gain,only then change.
-----------------------------------------------------------------------------
calculations
::::quads:unit price=Rs350 approx.for 15 its approx Rs5000=price of a good sony amp.but here,quads will cost 1/5 or less of what u pay.dunno y but its a pleasant reality

 

[sagarverma]

i/p is from sony discman which has rather suppressed bass,(pleasant for ears but not speakers)
i suppose parametric is way to go(as u sayin)

will complete it surely and will post accordingly

 

[sagarverma]

done it

beautiful opamps.looks as well as performance.so quite,clear,magic!!
parametric also done.used freq from 35-150(two controls for better control),150-550hz(one control).result::::even that weak sony sounds blasting
thanks for all help.

******got them cheap(as compared to what u pay),Rs30 per unit(dual).got ten units..i dunno y but its good$1=Rs45.)

 

[TO-3]

done it

beautiful opamps.looks as well as performance.so quite,clear,magic!!
parametric also done.used freq from 35-150(two controls for better control),150-550hz(one control).result::::even that weak sony sounds blasting
thanks for all help.

******got them cheap(as compared to what u pay),Rs30 per unit(dual).got ten units..i dunno y but its good$1=Rs45.)

Did you go with the OPA's? They definately add that low-end that seems to get all muddied in the TL072s.

POST PICS. I want to see naked amplifiers!!!!

 

[sagarverma]

obviously opa!!

great peices.

ic bases.with wonder chips in them.

pic resolution too low bec had to use windows to click pic.(software expired).pcb placed on print out of the pcb layout.

will post high reso asap.

 

[sagarverma]

and the rear.
artifical earth not used although provision on pcb(designed by me)

 

[TO-3]

Looks good!!
For fun, you should get a couple AD823s and find out how they sound against the OPAs. Look at the data sheets and check out the specifications.

 

[sagarverma]

hey
the improvement in sound clarity has been great.the sound preamplification has more clarity and richer details to it that were surely lacking in 072's.

result is that the bases are more clear(withou para eq.).on conecting para eq. also,the result is simply awesome.heavy bass (thrrrrrrrrrrrr thrrrrrrrrrrr sound) o/p .the system will be integrated soon in my car.

will try out ad's also as u saying,but i dont think the difference will b much noticiable(opa is a gem!).

how bout your mod drive of 1/3 octave?

 

[TO-3]

.....

will try out ad's also as u saying,but i dont think the difference will b much noticiable(opa is a gem!).

You might be suprised again.

My project has been on hold for a couple years. I modded all of my Tube Driver stuff with the AD823s. I have the Phase Audio crossover and that had 22 ops to replace. That dented my wallet. But for right now, I don't have a good car and any stereo that I could put in it would only make my car cost more. I have plenty of equipment, but nowhere to put them.

 

[sagarverma]

will try out ad's whenever i find time to go to the elect. market.r they really worth so much money?how would u rate the performance difference vis-a-vis opa?(u have used both)