Hi guys, i hope you can help me.
I have a Realistic 10 bands Equalizer type 31-9081.
I have this Equalizer for almost 20 years, but now there where some problems with it. When i put it on, on the first minute in a cold situation it sounds not very well, so i will replace all capacitors with new good one from Panasonic or Nichicon.
Are there people who have any service manual for me.🙂
I will also change the 3 op-amps njm4558D with OPA2134. But the biggest problem is, It sounds noisy when there is no sound. I think the power supply is a little bit weak. Do you have any sugestions for me to make this Equalizer sounds beatiful with a minimum of noise and good components.
Regards Rick...😀
I have a Realistic 10 bands Equalizer type 31-9081.
An externally hosted image should be here but it was not working when we last tested it.
I have this Equalizer for almost 20 years, but now there where some problems with it. When i put it on, on the first minute in a cold situation it sounds not very well, so i will replace all capacitors with new good one from Panasonic or Nichicon.
Are there people who have any service manual for me.🙂
I will also change the 3 op-amps njm4558D with OPA2134. But the biggest problem is, It sounds noisy when there is no sound. I think the power supply is a little bit weak. Do you have any sugestions for me to make this Equalizer sounds beatiful with a minimum of noise and good components.
Regards Rick...😀
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Do it in stages. The capacitors will most likely want replacement. You may also want to consider cleaning the sliders and switches with contact cleaner.
I would not recommend changing the 4558s for the 2134. The 2134 is a much faster opamp with FET inputs, and will probably oscillate in the circuit. NE5532's would be a good safe bet though.
What are those 16 pin DIP devices on the right?
I would not recommend changing the 4558s for the 2134. The 2134 is a much faster opamp with FET inputs, and will probably oscillate in the circuit. NE5532's would be a good safe bet though.
What are those 16 pin DIP devices on the right?
Replacing the op amps by JFET ones may reduce noise floor sometimes but not always. RC4558 has the same noise voltage level as OPA2134, the difference is lower noise current, so it will depend on circuit impedances.
What is usually worn out in such an equalizer are the faders. Measuring frequency response with a computer may help.
What is usually worn out in such an equalizer are the faders. Measuring frequency response with a computer may help.
Wow, i haven't seen one of those for about 20 years 😀 No tone controls in my system nowadays...
If i remember correctly i have the original user manual for that graphic (having owned one) & realistic (tandy) kindly gave a full circuit diagram with their manuals. I'll have a look about, no guarantees as i'm a terrible hoarder & it could be anywhere. It's something i'm not likely to have gotten rid of, but i'll be looking for a needle in a haystack so to speak.
Good luck with the service & i'll do my best in locating the circuit diagram 🙂
Hi guys, thanks for all so far, The biggest thing with this equalizer is to bring back the noise to a minimum and a better sound. So the first step wil be to replace the op-amps with opa2134.
So even when i recap the whole equalizer is there any guarantee
that it will help to bring the noise back to a minimum level. Also is it a good option to replace resistors with metal films???
They also use a Low Power Quad Operational Amplifier LM324N. Is there a beter replacement for this one?
The graphic equalizer ic`s are a 4X MC14066BCP. Cap`s in the power supply will be 470UF, is it better to replace it with ???? 1000UF.
Sorry for my bad englisch.
Regards Rick...
So even when i recap the whole equalizer is there any guarantee
that it will help to bring the noise back to a minimum level. Also is it a good option to replace resistors with metal films???
They also use a Low Power Quad Operational Amplifier LM324N. Is there a beter replacement for this one?
The graphic equalizer ic`s are a 4X MC14066BCP. Cap`s in the power supply will be 470UF, is it better to replace it with ???? 1000UF.
Sorry for my bad englisch.
Regards Rick...
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Aha - i suspected there would be some 4066's in there ! Try replacing those. They can often get damaged by static from the input sockets (they are very rarely protected by clamp diodes).
Recapping is always a good idea on older equipment. It will definitely help improve sound quality.
The LM324 is probably used for the spectrum analyzer on the front. Don't bother changing it.
If you can fit 1000uF in the main supply, do so. Can you measure what voltages are used ?
Recapping is always a good idea on older equipment. It will definitely help improve sound quality.
The LM324 is probably used for the spectrum analyzer on the front. Don't bother changing it.
If you can fit 1000uF in the main supply, do so. Can you measure what voltages are used ?
no doubt that changing the 4558 for NE5532 will improve a lot
the thing. no possible comparison..the original op amps are just too bad..
the thing. no possible comparison..the original op amps are just too bad..
NJM4558 is a fairly low perf aop...
double the noise of the 5532, only 1V/uS slew rate ,
and so on..
That will not bring about a miracle improvement in sound quality here. Any improvement will be minimal and most likely inaudible.
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Joined 2002
right,if all settings are at 0 db...
and the listening level to 1W..
distorsion climb rapidly as soon that the gain
is more tHan unity in a tonality circuit using
feedback, as seems to be the case here..
no to mention the noise as many aop are used..
Seriously, it's almost criminal to encourage the OP to do something that will not make a difference - a waste of his time and money. The RC4558 are fine for this thing.
a NE5532 is 0.3 to 0.5 $...
and since he s reviwing the board because of
unwanted noises, it won t be more time and
money consuming..
but if the NJM4558 is enough, why not keep
its crappy sound well known by all guitarists
using old pedals..
NE5532 is intended to be fed from low source impedances, its input impedance is not very high and this will disturb frequency response of high impedance filters. Also, noise voltage is low, but noise current is high in these op-amps, and filters usually involve high impedances, so in the end noise is not likely to be lower than with 4558, and the driving capability of 5532 is not useful in high impedance circuits either.
Above 25k source impedance, the old TL072 can beat most bipolar op amps in noise performance due to its much lower noise current.
On the other hand, the purpose of an equalizer is quite obvious, I think. If you don't want to alter tonal balance of music on purpose, just don't use it.
Oh, and if there is no humm or buzz (other than from ground loops on wiring) don't bother with power supply, op amps only draw a few milliamperes with little dependency on signal.
btw: The 4066 always have internal protection diodes.
Above 25k source impedance, the old TL072 can beat most bipolar op amps in noise performance due to its much lower noise current.
On the other hand, the purpose of an equalizer is quite obvious, I think. If you don't want to alter tonal balance of music on purpose, just don't use it.
Oh, and if there is no humm or buzz (other than from ground loops on wiring) don't bother with power supply, op amps only draw a few milliamperes with little dependency on signal.
btw: The 4066 always have internal protection diodes.
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I had one of these, but in blackface 🙂
Got it for $10 at the thrift store, played wit it for a year, then ebay'd it for nearly $150 😱
Cheers!
Got it for $10 at the thrift store, played wit it for a year, then ebay'd it for nearly $150 😱
Cheers!
ok, so is it usefull to make changes right now??? I will try the ne5532, i have them here so it`s no any problem to try. I know it`s a bit creapy to make a whole redesign but i think there must be any option to make any sound improvements.
Old power suply cap`s are 470uf 35V, will change them with 1000UF/35V.
Also i will replace all caps with Panasonic or Nichicon.
Where do you think the noise is comming from??? Bad components, bad design???
Is it a good option to change the wiring with shielded ones.
Old power suply cap`s are 470uf 35V, will change them with 1000UF/35V.
Also i will replace all caps with Panasonic or Nichicon.
Where do you think the noise is comming from??? Bad components, bad design???
Is it a good option to change the wiring with shielded ones.
Quantum physics.
Op amps produce noise (a fixed component from voltage noise plus a source impedance dependent component due to current noise).Resistors produce noise proportionally to the square root of their value. Capacitors produce noise too.Carbon resistors exhibit excess noise while metal films are very close to the theoretical level. Capacitor noise depends mostly on value too.
I think a more important question is: Are the faders in good condition?