Where are you?
Hm...
Hi supernet,
I have not build this and will never do (I think) cause I don't like Opamp's.
That does not mean that it does not need to sound good.
I'll give you one example; I had a Burmester pre amp that some one asked me to take a look at and asked what he could do to improve the sound of it.
I first listen to the Preamp before opening the amp and said to the guy well, it sounds like an Opamp pre, and if this is the case I'll stop right now cause I don't like Opamp's. Afterwards I did some modifications and was flabergasted. The pre sounded better than manny other pre's I'v build and listend to. The mods where very simple, new transformer (bigger) Black Gate Caps, and sliver plated cable's. and new plugs and that's about it.
I don't have the schematics anymore but it's more or less the same as the Elektor one.
So if you like Opamp's, go for it, if you want something else, try the Pass pre's they sound much better (to my ears)
All the best and good luck,
Audiofanatic
I have not build this and will never do (I think) cause I don't like Opamp's.
That does not mean that it does not need to sound good.
I'll give you one example; I had a Burmester pre amp that some one asked me to take a look at and asked what he could do to improve the sound of it.
I first listen to the Preamp before opening the amp and said to the guy well, it sounds like an Opamp pre, and if this is the case I'll stop right now cause I don't like Opamp's. Afterwards I did some modifications and was flabergasted. The pre sounded better than manny other pre's I'v build and listend to. The mods where very simple, new transformer (bigger) Black Gate Caps, and sliver plated cable's. and new plugs and that's about it.
I don't have the schematics anymore but it's more or less the same as the Elektor one.
So if you like Opamp's, go for it, if you want something else, try the Pass pre's they sound much better (to my ears)
All the best and good luck,
Audiofanatic
Can't see anything wrong here, it's pretty rudimentary op-amp circuitry. A worthy note is the choice of op-amp, the opa627 is one of the best available and is widely used in some very highly rated designs - check-out the price of them too. Should make a very capable pre-amp.
Though like Audiofanatic I've a preference for discrete circuits, i've a couple of opa627's I'm going to use in a headphone amp.
I'd be curious to see the servo control circuit for operating the motor?
Though like Audiofanatic I've a preference for discrete circuits, i've a couple of opa627's I'm going to use in a headphone amp.
I'd be curious to see the servo control circuit for operating the motor?
If you are interested in building an op-amp based preamp, you can take a look at the esp site (http://sound.westhost.com/) There are various articles and projects about (pre)amplifier design on that site. I have built, but not tested yet, the P88 preamp.
active?
The name "active pot" is a bit misleading here. This is a regular circuit with a potmeter for vol control, except that you may use a motor driven pot, which I feel is only of advantage if you combine it with remote control. And if you do that, there is no reason why you can't use it in any other place where you have a vol control. So, if you don't like opamps, plug the motor pot in your favorite preamp and use the motor drive & remote control stuff.
I use a motor pot from ALPS in my preamp, driven from a PIC that receives & decodes RC5 IR commands. But this has nothing to do with the audio quality of the preamp. If there is interest, I can dig out the control circuit and the PIC software.
Jan Didden
The name "active pot" is a bit misleading here. This is a regular circuit with a potmeter for vol control, except that you may use a motor driven pot, which I feel is only of advantage if you combine it with remote control. And if you do that, there is no reason why you can't use it in any other place where you have a vol control. So, if you don't like opamps, plug the motor pot in your favorite preamp and use the motor drive & remote control stuff.
I use a motor pot from ALPS in my preamp, driven from a PIC that receives & decodes RC5 IR commands. But this has nothing to do with the audio quality of the preamp. If there is interest, I can dig out the control circuit and the PIC software.
Jan Didden
Super!!!
I use this simple circuit as a preamplifier matted with an input selector and a psu. It is a really super sounding pre I use as reference to test all my diy audio. It seriously outperforms any and I reapeat any, pre I have ever tried, including my aleph-L clone . There are some points need to change though, in order to perform super. First get tid of these 100nf and install directly on the coresponding 627 legs 47uf/25v elna starget or other good quality caps(silmic), needless to say we have to use carbon resistors hand matched to 1% and all other caps as well those in the power supplies should be of highest possible quality, prefer elna starget or silmic. The power supply should have the usual 317/337 setup with at least 60w of iron per channel and the power supplies should also be independed for each channel. Good idea is to use star ground system. You can also play with the ps voltage (13-16V)but for me the best sound comes with +-15,7 volts. Just try this pre and you will remember me one day! Have fun!!!
I use this simple circuit as a preamplifier matted with an input selector and a psu. It is a really super sounding pre I use as reference to test all my diy audio. It seriously outperforms any and I reapeat any, pre I have ever tried, including my aleph-L clone . There are some points need to change though, in order to perform super. First get tid of these 100nf and install directly on the coresponding 627 legs 47uf/25v elna starget or other good quality caps(silmic), needless to say we have to use carbon resistors hand matched to 1% and all other caps as well those in the power supplies should be of highest possible quality, prefer elna starget or silmic. The power supply should have the usual 317/337 setup with at least 60w of iron per channel and the power supplies should also be independed for each channel. Good idea is to use star ground system. You can also play with the ps voltage (13-16V)but for me the best sound comes with +-15,7 volts. Just try this pre and you will remember me one day! Have fun!!!
Re: active?
I am very interested in such a project, since I have too few time to start from scratch...
Cheers
Andrea
PS if you can't post on the forum here is my e-mail: andrea.pirovano@libero.it
janneman said:
I am very interested in such a project, since I have too few time to start from scratch...
Cheers
Andrea
PS if you can't post on the forum here is my e-mail: andrea.pirovano@libero.it
Maybe 60W seem a bit too much but definetely it is not! The more you use here the better it gets! I experimented a lot with that and I also tried my 680W transformer from my aleph. I really quarantee that the 680W is easily distinguished from the previous small (100W) version! However the difference does not justify the huge transformer. But 100W per channel is the perfect balance in my opinion, and 60W is o.k. Just try it. Do not forget to add fast rectifiers as the SBYV28-200 or similar as this pre is capable of great resolution and averything u use is heard easily as well as any change you perform to various components. An excellent test bed, its like a precise instrument!
No 100nf caps at all!
I do not use at all the 100n, I use instead 47uf elna stargate as burrbrown sugests. I verified this also soundwize and the use of decoupling capacitors directy tied to the legs(as close as possible) makes a huge difference compared with 100n. You could use 10uf-47uf with small differences, but 100n is out of the question, if you have any doubt on this, just try it and you will be convinced too.
I do not use at all the 100n, I use instead 47uf elna stargate as burrbrown sugests. I verified this also soundwize and the use of decoupling capacitors directy tied to the legs(as close as possible) makes a huge difference compared with 100n. You could use 10uf-47uf with small differences, but 100n is out of the question, if you have any doubt on this, just try it and you will be convinced too.
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