MC step-up stage?
I want to modify my VSPS to be able to drive my AT-OC9 without transformer.
This will run only for a few month because I'm assembling a Pass ONO clone but this takes some time.
I built my VSPS using a OPA2134 and have about 10 of them laying around.
Can I simply put another OPA2134 before the input of the VSPS?
I assume removing R1, connecting the output of the new 2134 to the non inverting input of the existing one. Similar like this mini circuit from the WIKI
And put a 100ohm load resistor on the input of the new opamp?
and if so what resistors should i use for a 20 to 30db extra gain?
I want to modify my VSPS to be able to drive my AT-OC9 without transformer.
This will run only for a few month because I'm assembling a Pass ONO clone but this takes some time.
I built my VSPS using a OPA2134 and have about 10 of them laying around.
Can I simply put another OPA2134 before the input of the VSPS?
I assume removing R1, connecting the output of the new 2134 to the non inverting input of the existing one. Similar like this mini circuit from the WIKI
An externally hosted image should be here but it was not working when we last tested it.
And put a 100ohm load resistor on the input of the new opamp?
and if so what resistors should i use for a 20 to 30db extra gain?
upgrade
Hello again,
I just wanted to share the upgrade i did on my own VSPS.
I used cheap monacor mkp capacitors of 4.7uf for the output.
And the sound was so nice.
I could get my hands on Black gate non polarity 4.7uf capacitors.
Some of you wrote here on the forum that they sound very good.
So i removed the monacors and placed the black gates.
First listing impressions are very bad. :-(
No depth and the sound is very bright.
I know the capacitors have to run in.
Strange thing is that the monacor capacitors sounded nice when they where brand new.
The Black gates sure don't.
Hope they will improve in a couple days.
Hello again,
I just wanted to share the upgrade i did on my own VSPS.
I used cheap monacor mkp capacitors of 4.7uf for the output.
And the sound was so nice.
I could get my hands on Black gate non polarity 4.7uf capacitors.
Some of you wrote here on the forum that they sound very good.
So i removed the monacors and placed the black gates.
First listing impressions are very bad. :-(
No depth and the sound is very bright.
I know the capacitors have to run in.
Strange thing is that the monacor capacitors sounded nice when they where brand new.
The Black gates sure don't.
Hope they will improve in a couple days.
Well no one answered my question so I had to figure "something" out myself.
The board I used was too small to add another opamp.
So I halved the R2 to get some more gain (just enough)
But now I had a very thin sound, I figured this had to do with the input load resistance. Looking at some other schematic's I noticed that most opamp based MC head-amps (at least the simple ones I've seen) had no load resistance so I cut R1 (used to be 47k) from the board.
Now I have a reasonable sound, just enough to get me through the "Ono Clone" assebling period.
I tend to think this is all easier as I used to think before but It's probably better to think I've just been lucky.
The board I used was too small to add another opamp.
So I halved the R2 to get some more gain (just enough)
But now I had a very thin sound, I figured this had to do with the input load resistance. Looking at some other schematic's I noticed that most opamp based MC head-amps (at least the simple ones I've seen) had no load resistance so I cut R1 (used to be 47k) from the board.
Now I have a reasonable sound, just enough to get me through the "Ono Clone" assebling period.
I tend to think this is all easier as I used to think before but It's probably better to think I've just been lucky.
Re: upgrade
After listening a couple days, the sound improved allot.
Sound is more natural, depth came back and the highs are velvet like.
I prever the blackgates now.
And as a bonus the blackgates non polar capacitors are much smaller then any other good 4.7 uf capacitors.
So you can build a smaller amp.
http://again.at/bijma
Homepage is not ready yet but if you click on the button hobby, you'll find a photo gallery of my VSPS.
It's not most beautifull casing but it works for me.
ebijma said:Hello again,
I just wanted to share the upgrade i did on my own VSPS.
I used cheap monacor mkp capacitors of 4.7uf for the output.
And the sound was so nice.
I could get my hands on Black gate non polarity 4.7uf capacitors.
Some of you wrote here on the forum that they sound very good.
So i removed the monacors and placed the black gates.
First listing impressions are very bad. :-(
No depth and the sound is very bright.
I know the capacitors have to run in.
Strange thing is that the monacor capacitors sounded nice when they where brand new.
The Black gates sure don't.
Hope they will improve in a couple days.
After listening a couple days, the sound improved allot.
Sound is more natural, depth came back and the highs are velvet like.
I prever the blackgates now.
And as a bonus the blackgates non polar capacitors are much smaller then any other good 4.7 uf capacitors.
So you can build a smaller amp.
http://again.at/bijma
Homepage is not ready yet but if you click on the button hobby, you'll find a photo gallery of my VSPS.
It's not most beautifull casing but it works for me.
I am making a single sided PCB for this design that uses 2x OPA637.....but I am having trouble knowing what capacitors to choose.
Mine will be high-Z so:
C1 - 330p
C2 - 1.0n
but I dont know what types to get. I can see from the photos on http://www.geocities.com/rjm003.geo/rjmaudio/diy_pho5.html that they look kind of like green caps (Metallised Polyester) but then in ebijma's pics they look like box caps which are MKT (polyester) ???
does it matter?
Can someone point me in the right direction?
I will be using http://www.jaycar.co.nz/ as a source for components
Mine will be high-Z so:
C1 - 330p
C2 - 1.0n
but I dont know what types to get. I can see from the photos on http://www.geocities.com/rjm003.geo/rjmaudio/diy_pho5.html that they look kind of like green caps (Metallised Polyester) but then in ebijma's pics they look like box caps which are MKT (polyester) ???
does it matter?
Can someone point me in the right direction?
I will be using http://www.jaycar.co.nz/ as a source for components
maxw said:I am making a single sided PCB for this design that uses 2x OPA637.....but I am having trouble knowing what capacitors to choose.
Mine will be high-Z so:
C1 - 330p
C2 - 1.0n
but I dont know what types to get. I can see from the photos on http://www.geocities.com/rjm003.geo/rjmaudio/diy_pho5.html that they look kind of like green caps (Metallised Polyester) but then in ebijma's pics they look like box caps which are MKT (polyester) ???
does it matter?
Can someone point me in the right direction?
I will be using http://www.jaycar.co.nz/ as a source for components
I didn't use the best caps for the RIAA and i use a input cap of 1uf.
I need the in input cap because the turntable i have uses a cd 4066 to turn of the sound when the arm is traveling. I could hear hard pop when the circuit is activated. With a input cap there's no pop.
And i didn't us regulators because with this transformer the rail voltage is +/- 12,4 volts.
But i did use snubbers in the power supply.
It's not the best config for the sound, but it sure sounds great.
maxw said:
What you should use is totaly up to you.
For the RIAA i used MKT folie ones ( don't know the brand ), for the input 1uf MKT wima and for the output Blackgate 4.7uf non polar.
And i build the lo-z version.
I also put one 100nf wima on each power rail close to the chip.
Hope this answers your question.
I am thinking about making this my first electronic DIY project. I would like to build the high Z version. The needles I will be using are these.
http://www.needlz.com/cartridges/m44g.asp
On the site it says that the load should be "47 kilohms in parallel with 450pf " does this mean I should hook up a 450pf cap in parallel with the R1?
I plan on building one for practice then I might build two in an enclosure to use with my Vinyl DJ setup.
Before I go and order parts is there anything I should be aware of?
http://www.needlz.com/cartridges/m44g.asp
On the site it says that the load should be "47 kilohms in parallel with 450pf " does this mean I should hook up a 450pf cap in parallel with the R1?
I plan on building one for practice then I might build two in an enclosure to use with my Vinyl DJ setup.
Before I go and order parts is there anything I should be aware of?
If you ask for help, then you shouldn't assume that someone is insulting you when they try to help you. Sometimes its hard to tell what background people have.
DJNUBZ said:
Dude chill out
Just trying to help. I dont want you to build it and then find out you have to sacrifice an input from a CD to use it DJNUBZ said:
Depends what mixer you have. Why dont you open it and see whats inside? You will probably find its based on dip8 opamps just like this design so maybe you could upgrade them to higher quality ones like in most CD players....(although my vestax wasn't like this).
maxw said:
Got them today....I think I was thrown by the size of the ones in the pics but that is in the low-Z version which has bigger values so they are bigger (I think). I could only get ceremic caps in as low as 330p. If no one see any prob with these caps then I will design the PCB tonight.
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