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NE5534 circuit. I need more bass. Help!!
NE5534 circuit. I need more bass. Help!!
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Old 13th February 2018, 04:52 PM   #91
dj_holmes is offline dj_holmes  United Kingdom
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Wow lots of input!

1, Ok I tried 4.7uf bipolar on the 2.2uf input had little effect
2, the 1pf changed to anything higher than a 5pf sounds muffled. i.e no treble and sounds hollow the higher the capacitance
3, I have to trace the circuit to find where the + supply for the opamp is coming from but currently can only find 1 22uf power cap.
4, the DC offset was only high when the 30k input resister was changed to 100k otherwise DC offset is normal
5, the opamp is dual power so I have been told 100nf from each power supply to ground is recommended.
6, tried changing the 220pf for something slightly higher and has little effect with high frequency.

I know the Ne5534 is a good opamp so changing that is really last resort.

Love reading the suggestions!!!
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Old 13th February 2018, 07:11 PM   #92
anatech is offline anatech  Canada
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NE5534 circuit. I need more bass. Help!!
Hi rmaudio,
That is stunningly clear, I was only addressing concerns that dj_holmes had brought up earlier. Your input wasn't very helpful. Try to bring some information to the conversation in future, rather than poke away at someone. After all, what I said was true.

Hi dj_holmes,
Replacing the 5534 will only bring you another op amp with soldered leads. I hope you aren't using a socket.
1.) That was expected
2.) Lower the resistance and use a higher value feedback capacitor. Limit the gain to something more reasonable as I think you are trying to get more from one stage than you should. Stray capacitance from the board could be causing some of your problems too.
3.) Who made the board, or are you using a prototyping plug in strip?
4.) Okay, that is expected as well.
5.) Yes, but the world won't end unless there are no filters on the negative rail.
6.) Yes, that is determined by the impedance of the device sending the signal as well as your own component values.

Why not try cutting your feedback resistors by 10, so a 22K feedback resistor with the leg to signal common at 4K3? That will also allow you to use normal values of capacitance for your feedback compensation cap (now 1 pF).

-Chris
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Old 13th February 2018, 07:31 PM   #93
dj_holmes is offline dj_holmes  United Kingdom
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Hi Chris,

the amp is already built! I didn't build it. My buddy acquired it and it was unbranded (probably brand rubbed off) case is a bit tatty.

Sorry which resistor should I cut back? Can you possibly refer to original value?

The amp is stored away but I'm hoping to fish it out tomorrow or day after and try all possible solutions offered here
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Old 13th February 2018, 08:33 PM   #94
anatech is offline anatech  Canada
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NE5534 circuit. I need more bass. Help!!
Hi dj_holmes,
Was this commercially made, or a home brew amplifier? There is a different approach for each situation. Commercial equipment can be assumed to have worked at some point in time. Home-made things do not have any guarantees that at one time they functioned properly.

Before doing anything, can you take a picture of the area and confirm whether it was made in a factory or a garage?

-Chris
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Old 13th February 2018, 09:56 PM   #95
dj_holmes is offline dj_holmes  United Kingdom
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The parts are high quality nothing is failed, everything is working perfectly fine just needs more bass less treble not even by much!

This is not home made looks commercial.. I can only take pics once I start work on it this is why I need the info. I need to drop it to my mates house too as not only does he need it but its actually for him!
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Old 13th February 2018, 10:26 PM   #96
anatech is offline anatech  Canada
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NE5534 circuit. I need more bass. Help!!
Hi dj_holmes,
I'm at a loss as to why it is light in the bass department. It shouldn't be. Do you have access to an oscilloscope? I want to make sure it isn't oscillating above your range of hearing. What would be nice right about now is an oscillator and an AC meter to confirm it is low in bass output and at what frequency the drop-off begins (-3 dB point).

-Chris
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Old 14th February 2018, 02:13 AM   #97
dj_holmes is offline dj_holmes  United Kingdom
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Quote:
Originally Posted by anatech View Post
Hi dj_holmes,
I'm at a loss as to why it is light in the bass department. It shouldn't be. Do you have access to an oscilloscope? I want to make sure it isn't oscillating above your range of hearing. What would be nice right about now is an oscillator and an AC meter to confirm it is low in bass output and at what frequency the drop-off begins (-3 dB point).

-Chris
I do actually have a kit version I built but dont know how to use it. To be honest I do understand what you are saying but I just dont have that time to spend on it. Changing a few caps or resistors with advice is great but getting scopes out etc I'm lost and it seems to much work to please a friend. I'm going to hell for that last comment aint I?
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Old 14th February 2018, 03:35 AM   #98
anatech is offline anatech  Canada
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NE5534 circuit. I need more bass. Help!!
Hi dj_holmes,
The instruments will save you a great deal of time.

If it were me, I would change the feedback components. But, I also would have looked at the thing with instruments already. You can't change things without knowing where you where and where you are afterwards. It's a commercial product (not well designed), and so you have to assume it worked at some point. If it was cheap, it may not have worked well, but it worked in some fashion. You may be fighting against the design of the thing.

Anyway, at least connect some scope leads in there and see if it's oscillating. It would be easy to see if the bass frequencies were really cut off or not. A bunch of answers in a short time if you would only use your equipment. Plus, you are gaining experience, there is a benefit here for you. Take the opportunity and learn.

-Chris
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Old 14th February 2018, 09:17 AM   #99
rmaudio is offline rmaudio  United Kingdom
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Quote:
Originally Posted by anatech View Post
Hi rmaudio,
That is stunningly clear, I was only addressing concerns that dj_holmes had brought up earlier. Your input wasn't very helpful. Try to bring some information to the conversation in future, rather than poke away at someone. After all, what I said was true.

-Chris
Well what I said was true too. Big Deal.
The point is that the OP risks being distracted from a solution to his actual or perceived problem. And the comment re Offset was not especially targeted at your input - there was a suggestion of balancing the impedances seen by the op amp inputs to reduce offset. This is correct but there's a noise penalty for no real audio benefit.

Don't presume to tell me what to do "in future". Understand ?

FWIW I agree that the high resistor values and 1pF hf feedback cap are an issue.
If 1pF to 5pF is giving a problem then there's likely to be layout / stray capacitance problems. Plus resistor noise for no benefit.
Plus , yes, needs to check for instability / oscillation.
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Old 14th February 2018, 10:49 PM   #100
dj_holmes is offline dj_holmes  United Kingdom
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The circuit looks so simple honestly can I not just copy a preamp circuit that already works so good??

Also what is Oscillation. I kinda know what it means but how can I tell because it sounds perfectly fine!
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