First of all, I don't see a section for preamps. Is this even the right place to discuss preamps?
Anyway, I am making a basic active mono system and have looked around and really haven't found what I want for my system. I'm no stranger to a soldering iron, so have decided to build what I want.
On further investigation, I think a nice simple preamp utilizing an NE5532x wuld be very satisfactory. I want defeatable tone controls. Power supply and inputs I can handle separately, but does anybody have a circuit?
This one is a nice start:
https://www.eleccircuit.com/wp-content/uploads/2012/09/circuit-of-pre-tone-control-stereo-bass-mid-range-treble-by-ne5532.jpg
...but I thought I would ask here in case anyone had anything they thought was better.
Thanks in advance!
Anyway, I am making a basic active mono system and have looked around and really haven't found what I want for my system. I'm no stranger to a soldering iron, so have decided to build what I want.
On further investigation, I think a nice simple preamp utilizing an NE5532x wuld be very satisfactory. I want defeatable tone controls. Power supply and inputs I can handle separately, but does anybody have a circuit?
This one is a nice start:
https://www.eleccircuit.com/wp-content/uploads/2012/09/circuit-of-pre-tone-control-stereo-bass-mid-range-treble-by-ne5532.jpg
...but I thought I would ask here in case anyone had anything they thought was better.
Thanks in advance!
The forum section for preamps is 'Analog Line Level'. Maybe a moderator will move this thread over for you.
For simple opamp based preamps, have a look at Rod Elliot's site: ESP Projects Pages - DIY Audio and Electronics
His project 97 is probably most relevant. You can mix and match the sections as you need. More or less what I did 35 years ago from magazine projects, and the damn thing is still in use! I've been thinking of doing a new one but have too many other projects in the way.
For simple opamp based preamps, have a look at Rod Elliot's site: ESP Projects Pages - DIY Audio and Electronics
His project 97 is probably most relevant. You can mix and match the sections as you need. More or less what I did 35 years ago from magazine projects, and the damn thing is still in use! I've been thinking of doing a new one but have too many other projects in the way.
you could have a look at apex TB3 tone control for an idea.
100W Ultimate Fidelity Amplifier
100W Ultimate Fidelity Amplifier
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The Balance and Volume pots interact awkwardly. With VOL at full or zero BAL can't do anything. At normal settings the effect of BAL varies with the setting of VOL. (We normally use BAL to compensate some static gain difference, and if VOL is a goog-gang pot, it won't change much with VOL; so interaction is unwanted.)
The VOL pot interacts very badly with the tone network. Tone nets start with 10K 3.9K 1.8K.... but they come from the 0 to 16K impedance of the VOL pot wiper. Really should be a buffer.
As drawn the circuit has no gain; did you want some?
The drawing shows no way to cut-out the EQ, which was one of your design goals.
With a volume pot at full and the balance control minimizing that side it would short the input. It's not good, but it's a thing.
I agree, but I wanted to use the circuit in mono, eliminating the balance circuit and the other amp entirely.
That's a good idea.
I think it appropriate to have the correct amount of gain for the input selected. Perhaps this could be done in the input buffer. Do you have any suggestions about how that might be done?
Also true. Again, do you have any idea how that might be done?
Do you want preamp as amp with gain or attenuator?
Maybe you will be happy with passive one?
Parametric EQ from any software player?
This will be an order better than most of line-level ones. Moreover, i’ll prefer one dedicated subwoofer level control than any of the super-duper-clever tone controls.
What I need in my system is a simple low noise mono preamp. Passive will not do, nor do I pretend to be such a purist. I want tone controls dedicated in my system, but I also want them defeatable.
My system will include a sub out to a powered sub with it's own DSP.
Give a chance for this one:
FS: PCB for Bruno Putzeys Balanced Preamp
See attached article, may be it answers your questions.
Ok. But try this passive one:
It provides four dicrete LF settings and smooth HF regulation.
build a passive tone stack and drive it with a 1/2 of 5532 gain of 7 to drive tone stack.
place bypass switch at input of other half of 5532 used to buffer tone stack output.
use resistor network ( 15k // 1.5k) to match levels at buffer output
adjust buffer gain ( 1 to 5 ) to match amp
repeat for other channel.
use relay or CD4066 to switch tone on / off
I used a 6922 twin triode to drive mine and then tweaked the values slightly to be ruler flat at the center position of both controls
place bypass switch at input of other half of 5532 used to buffer tone stack output.
use resistor network ( 15k // 1.5k) to match levels at buffer output
adjust buffer gain ( 1 to 5 ) to match amp
repeat for other channel.
use relay or CD4066 to switch tone on / off
I used a 6922 twin triode to drive mine and then tweaked the values slightly to be ruler flat at the center position of both controls
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That looks like a very nice preamp - but is not what I am looking for. I have nothing balanced that will be connecting to it, and it will be connected straight to a MiniDSP. I will not be connecting anything with long runs. The preamp will be in it's own shielded case with it's own dedicated supply. I don't need to launch the shuttle, nor will that degree of precision be anywhere necessary.
I appreciate suggestions and input, but I would appreciate more suggestions and input about what I am asking for. If I want a simple preamp why would I want a balanced one? If I want tone controls why would I settle for "HF regulation"?
Again, thanks for the suggestions - but I am afraid they are just not what I am looking for.
Those sound like good suggestions, but honestly if I could do what you are asking I wouldn't need to come here in the first place.
Can you point to a diagram or other reference illustrating what that is? That would be very much appreciated.
BesPav, interesting passive circuit. Do you by any chance have the fr response curves which correspond to 4 particular settings? Link to original article?
There are some much parameters than simplicity, aren't it?
Balanced Putzeys preamp will work with any unbalanced source, but provides 2-3 orders better CMRR.
CMRR itself means nothing straight until it influences differential mode error, and i must be fair - it makes it's best for influencing straightly this way.
Don't get opposed, but there are a tons of preamps and tone control kits on ebay. Be sure, all of them are ugly. After founding bad sounding and trying right ways you could understand how much ugly they're.
So why use ugly if you can simply and firstly build best of the best for yourself?
It provides comprehensive and sophisticated filtering, are you sure you need something after?
There are other factors of error in the input opamp. It is noninverting and its common mode error are nonlinear with its common mode itself.
Why doing so if we could put first opamp inverting in both channels.
FR at lower and higher positions attached. Mid are somewhere inbetween.
Keep in mind -20 dB attenuation. If you need i will draw them in LtSpice.
Original article in Russian and PDF'ed, i suppose it couldn't help.
Attachments
Elliot's Sound Products is a wonderful resource with many great DIY projects. His project 97 is pretty close to what I want, though the tone defeat doesn't exactly defeat, and though released free to the DIY community he puts strict restrictions on any other use. Once I have my circuit, I would like to keep my options open on any future use.
I honestly thought my hopes were pretty modest, that somewhere would be a generic preamp with tone controls that was simple and just quietly did it's job, out in the public domain. It appears my hopes were just wishful thinking.
I find it interesting that there are SO many artists making music these days, but so very few artists making the devices we depend on to listen to music. Yes there is a fairly robust DIY community, but by definition they are pretty much doing it just for themselves.
And to be clear, I'm not averse to busting out the calculator and figuring this out for myself - I just didn't think something so relatively simple would be so hard to find. My time is limited, but if I have to, I will.
Many, for sure - however I realize that anything more complex than what is required is simply unnecessary overkill.
I'm sure it is a very nice preamp, and if I was building a reference stereo system from the ground up I would jump on it - but I'm not. Realizing this, I realize your preamp isn't a good fit for my needs.
I think I have been very clear of what my needs are. Again, I appreciate the input, but I would think the first time I said "This does not fit my needs" (whether it's spec'd too high or too low) one might make another suggestion. I have to admit I find it inexplicable that on a site dedicated to audio that some people would be such terrible listeners - no offense.
Wow - that's a nice circuit! Very close to what I am looking for. I love that he included the phase plots as well. I will have to tweak the adj. levels up a bit for the bass, and I still have to figure out the defeat, but very good.
Thanks!
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