Hello !
I have a pair of AW 60 blocs that are configured for mono use and a EC 4 as a preamp and they have way too much gain, moving the volume only the slightest with a regular cd player gets my 66 studio monitors way too loud and they're no sensitive speakers at all.
EC actually put out several versions of the aw-60 and they had different gain values so I started by getting both blocs to match the lowest gain version they offered (I used one I worked on before as an example). This gives me a little improvement but it's still too much and I would like to reduce the gain of the preamp as well. As there are no schematics out there I'm in need of some guidance.
Does anyone have a schematic for the gain stage, or have any idea on which resistor values to play with in order to reduce the overall amplification ?
Thanks 🙂
I have a pair of AW 60 blocs that are configured for mono use and a EC 4 as a preamp and they have way too much gain, moving the volume only the slightest with a regular cd player gets my 66 studio monitors way too loud and they're no sensitive speakers at all.
EC actually put out several versions of the aw-60 and they had different gain values so I started by getting both blocs to match the lowest gain version they offered (I used one I worked on before as an example). This gives me a little improvement but it's still too much and I would like to reduce the gain of the preamp as well. As there are no schematics out there I'm in need of some guidance.
Does anyone have a schematic for the gain stage, or have any idea on which resistor values to play with in order to reduce the overall amplification ?
Thanks 🙂
Hi,
Yes I did think of that but it doesn't really make sense to amplify the signal at the preamp, than attenuate it again to re-amplify it at at the power stage... wouldn't that also introduce more noise ?
Yes I did think of that but it doesn't really make sense to amplify the signal at the preamp, than attenuate it again to re-amplify it at at the power stage... wouldn't that also introduce more noise ?
If you try it you will get the answers. It will cost you almost nothing and you will learn something🙂
Regards,
Regards,
I know how it works and could easily do it, sansui did this in some of their earlier amps, they attenuated each source input differently and than amplified them all the same amount through the phono stage while applying the riaa equalisation through the feedback loop, also connected to the source selector, only to the phono input.
Although I absolutely love the sansui AU-222 and 555 I don't think this would integrate well in the EC design. I would like to just be able to calm down the gain stage of the preamp somehow, by changing the feedback resistor for example, only I don't know which one it is as I don't have a schematic.
Although I absolutely love the sansui AU-222 and 555 I don't think this would integrate well in the EC design. I would like to just be able to calm down the gain stage of the preamp somehow, by changing the feedback resistor for example, only I don't know which one it is as I don't have a schematic.
I re read my message and found it to be a little bit blunt, sorry for that, this wasn't intentional !
Well, a little bit of patience and careful tracing always pays off 🙂.
I found the two feedback resistors for the inverted and none inverted amplification stages (R41 (141 for the other channel) and R42 (142) on the EC-4 for those that would like to do the same thing) and changed them from 8.2 to 3.3k, and I might even get down to 2.2k to reduce gain by almost 4. This should calm things down quite a bit !
I found the two feedback resistors for the inverted and none inverted amplification stages (R41 (141 for the other channel) and R42 (142) on the EC-4 for those that would like to do the same thing) and changed them from 8.2 to 3.3k, and I might even get down to 2.2k to reduce gain by almost 4. This should calm things down quite a bit !
If you found the right resistors changing their value will affect the gain and inevitably the sound...
Regards,
Regards,
Can you develop why this would change the sound ? That's not what I'm looking for, when I said calm things down I just meant that it wouldn't make my ears bleed with the volume up just one tiny bit 😛
Amount of feedback does affect gain but at the same time also output impedance, harmonic distribution, bandwidth...
Regards,
Regards,
Hmm I see. I tested for bandwidth between unmodified and modified channel, no changes whatsoever there but I don't have anything to test harmonics.
In your case the bandwidth change shouldn't have significant effect.
But who knows maybe you get the sound you will like more than you had with unmodified preamp🙂
Regards,
But who knows maybe you get the sound you will like more than you had with unmodified preamp🙂
Regards,
I loved the sound before and don't really want to change it. I just read some articles about it being also a probable cause for instability, maybe this wasn't such a great solution (although it seems stable to me).
You can still try to attenuate the signal at AW60 input. Listen to both solutions and decide which one you like best.
Regarding the oscillations: the problem is that in most cases you will not detect them by ear because they occur at high frequencies. Far beyond from what our ears can detect.
Regarding the oscillations: the problem is that in most cases you will not detect them by ear because they occur at high frequencies. Far beyond from what our ears can detect.
I checked for oscillations by scope on a square wave as well as on a very high frequency on a regular sine wave, they both look perfectly clear of any oscillation.