boobs n booze
ok now that i have your attention!!
I need some help>
I have the schems (partial) for a zapco crossover circuti I need to modify.
I want to change the variable freq range from 55-270 to somethign fixed like 4K
I also want to replace the crappy TL074 op amps with some 627 or 2132
or what ever I can.
I'm a ME and forgot most of my electrical circuit design I took in college(I remember p=i^2*R) but I do know which end of a soldering iron is hot!
so any suggestions guys..THANKS.. now] to figure out how to post schem!
ok now that i have your attention!!
I need some help>
I have the schems (partial) for a zapco crossover circuti I need to modify.
I want to change the variable freq range from 55-270 to somethign fixed like 4K
I also want to replace the crappy TL074 op amps with some 627 or 2132
or what ever I can.
I'm a ME and forgot most of my electrical circuit design I took in college(I remember p=i^2*R) but I do know which end of a soldering iron is hot!
so any suggestions guys..THANKS.. now] to figure out how to post schem!
Minor but important point. Your unused opamp stages shouldn't just be left 'dangling'. For voltage feedback amps like your TL-074s, tie the '-' input to the output and the '+' input to ground so that it doesn't possibly break into oscillation. If you're planning ahead, make those 2 connections as resistors to make it easier to modify if you need another amp stage for some reason.
G²
G²
The biggest problem with the TL074 is its limited output drive, 2K is about as low as you can go for full voltage swing (and that's what some of these stages see in your circuit). As to sound quality, well it can be a pretty decent performer.
There is an OPA4132 if you can get hold of one or if you are using your own layout why not try the OPA604 or 2604 which I personally prefer.
There is an OPA4132 if you can get hold of one or if you are using your own layout why not try the OPA604 or 2604 which I personally prefer.
no I just want to get rid of the TL074..I'm no circuit designer.. but i have heard crossovers with 627 and man they are clean sounding..I also would like to replace the crappy NE5532's also. I need to try to keep circuit mods to a min as this is an existing amp board with built in crossover. I'd also like to shift the freq rang to a fixed 4K or change the range to something like 2-5K
AD8066 is very nice and not so expensive. AD8620 is another option. I've read many opinions that NE5532 is OK for audio but a little bit outdated. imho it makes sense use most recent ICs.
As a precaution hi speed opamps can oscillate easily especially if used as simple swap on browndog. That can be misinterpreted like "an artificial sounded" opamp.
As a precaution hi speed opamps can oscillate easily especially if used as simple swap on browndog. That can be misinterpreted like "an artificial sounded" opamp.
oops my bad
big OOPS.. I POSTED WRONG SCHEM!!..Ok here goes..
I have everything figured out (not really) in talking to amp manufacture. I have posted correct schems and am updating amp to current specs and upgrading opamps..why? because (2) 5532 had to be cut out to get to other ECO changes on the board. Ok on the input board they changed R247,245,271,269 from 4.75K to 4.22K ?? Why I dunno I'm not an EE. If you look at R240 and R239 there is a hole in the switchable gain structure>i need to fix this..(a huge part of my problem is the preamp puts out best signal and voltage right in this hole (the hole was confirmed by manufacturer).
Regarding Op amp discussions.. I try to be open minded and don't fallinto the flavor of the week. However I have noticed that people who like different opamps, reading many many forums, I find seem to think the OPA627 is the mac daddy, but in general, all op ams that are well liked by designers and listeners, have slew rates over 20V/uS, very low noise, and fast settling time( this may be the key here although the 627 is not terribly fast)
Remember I have to buy some op amps as 2 are missing, so this is not just a swap mod.
Ok to the amp. It appears I have 900ma to play with (Input board schems) for the op amps. I know the 2132/2134 can drop in for the TL072 without too much duress. what do I replace the 5532 with? based on what I have researched( slew rate, NOISE, Settling time) the LM4562 or LT1208xxx appear to be good choices. But I have also gathered they can easily oscilliate because of their speed! Any sparkys out there want to help out on this?? Oh yea and I bet I am pushing 16 V on the ps rails( not sure but It's a car amp with 14.4Vdc coming in.) thanks
OH YEA DUAL 627 OR 827 ON ADAPTERS?
big OOPS.. I POSTED WRONG SCHEM!!..Ok here goes..
I have everything figured out (not really) in talking to amp manufacture. I have posted correct schems and am updating amp to current specs and upgrading opamps..why? because (2) 5532 had to be cut out to get to other ECO changes on the board. Ok on the input board they changed R247,245,271,269 from 4.75K to 4.22K ?? Why I dunno I'm not an EE. If you look at R240 and R239 there is a hole in the switchable gain structure>i need to fix this..(a huge part of my problem is the preamp puts out best signal and voltage right in this hole (the hole was confirmed by manufacturer).
Regarding Op amp discussions.. I try to be open minded and don't fallinto the flavor of the week. However I have noticed that people who like different opamps, reading many many forums, I find seem to think the OPA627 is the mac daddy, but in general, all op ams that are well liked by designers and listeners, have slew rates over 20V/uS, very low noise, and fast settling time( this may be the key here although the 627 is not terribly fast)
Remember I have to buy some op amps as 2 are missing, so this is not just a swap mod.
Ok to the amp. It appears I have 900ma to play with (Input board schems) for the op amps. I know the 2132/2134 can drop in for the TL072 without too much duress. what do I replace the 5532 with? based on what I have researched( slew rate, NOISE, Settling time) the LM4562 or LT1208xxx appear to be good choices. But I have also gathered they can easily oscilliate because of their speed! Any sparkys out there want to help out on this?? Oh yea and I bet I am pushing 16 V on the ps rails( not sure but It's a car amp with 14.4Vdc coming in.) thanks
OH YEA DUAL 627 OR 827 ON ADAPTERS?
Last edited:
Ok do I expect to hear any difference..NO.. I mean there is a ton of stuff between that and the Bipolar output transistors, but If It cleans up the signal then great..Less noise cleaner sound is better usually. This is a "highend" car amp so it is worth doing up right. The bigest problem I have is all head units now use a digital gain control so and when you get into the upper volumes you get like 1.5-3db gain jumps. This is what started this whole debacle..the gain is wither not enough( hiss when i turn up amp gain) or too much( oops that nasty clipping sound). SO we are going to clean up the gain structure to match the head units.. The rest is just gravy....So anybody for some circuit help?
They are pretty good. The TL07x series etc are slightly lower noise than the TL08x series. A practical problem is that the maximum drive current is limited and about 2 to 3 k is as low an impedance as you would want to hang on the output for full rail to rail swing at low distortion.
Sonically in certain applications they better the 5532, particularly in DAC output stages and I/V conversion. The OPA604 is noticably more "coloured " I would say, but in a good way... and we are talking small degrees anyway.
hello.
I want to design a circuit with a amp. I have an alpine 9833 and the outputs are 4V. I want to boost them on 7-8V but without no noise, i mean clear sound! I mean a good chip. I have a power suplly +/- 30V, but i can reduce to a lower value ex +/- 15V. What opamp do you recomand for my aplication.
Thank you!
PS. Excuse me if i don't post where i must.
I want to design a circuit with a amp. I have an alpine 9833 and the outputs are 4V. I want to boost them on 7-8V but without no noise, i mean clear sound! I mean a good chip. I have a power suplly +/- 30V, but i can reduce to a lower value ex +/- 15V. What opamp do you recomand for my aplication.
Thank you!
PS. Excuse me if i don't post where i must.
Probably better to start a new thread really 
However any good opamp will perform what you ask, noise will be a non issue at these signal levels too. I take it you want to increase a 4v signal to around 8 volts. Keep the feedback resistor network in the 10 to 20k region for best performance.
The LM4562 (dual) is about as good as it gets, the TL072 (dual) or the NE5532 (dual) are also perfectly suited to something like this. There are dozens to choose from, all will perform well for something like this.
However any good opamp will perform what you ask, noise will be a non issue at these signal levels too. I take it you want to increase a 4v signal to around 8 volts. Keep the feedback resistor network in the 10 to 20k region for best performance.
The LM4562 (dual) is about as good as it gets, the TL072 (dual) or the NE5532 (dual) are also perfectly suited to something like this. There are dozens to choose from, all will perform well for something like this.
OPA1612. Excellent performance, cutting edge.
http://www.ti.com/lit/ds/symlink/opa1612.pdf
LME49990 is up next in absolute performance, but sadly there is no dual version available.
http://www.ti.com/lit/ds/symlink/opa1612.pdf
LME49990 is up next in absolute performance, but sadly there is no dual version available.