Uuppsss!
This is not correct!
Thanks william for pointing that out!
I must have felt inverted some how.
It should have ben as the following:
The output caps (C101 and C102) passes through the higher inverted frequencies, and then they will be fed back through the resistors (R122 and R123) and then attenuate the noninverted input as much as the shunt resistors (R120 and R121) allows. But at some point on the frequensy scale, the cap (depending at the value) will begin to act as a resistor, the lower the frequensy the higher the resistance becomes, and hereby lowering the feedback acordingly. But when the NFB is lowered the gain at the drain rises, but again lowered some by the resistance of the outputcap, and thus the gaindevice keeps the gain close to constant within a wider band of frequencies. While the cap lowers the current flow through the feedbackresistors (R122 and R123) the gaindevice will compensate for the lack of gain because of the lower feedback, it will do so until the maximun gainlevel of the gaindevice is reached. From there the frequensy responce falls at the output.
Sorry for the confusion.
Regards
Henrik said:
This is not correct!
Thanks william for pointing that out!
I must have felt inverted some how.
It should have ben as the following:
The output caps (C101 and C102) passes through the higher inverted frequencies, and then they will be fed back through the resistors (R122 and R123) and then attenuate the noninverted input as much as the shunt resistors (R120 and R121) allows. But at some point on the frequensy scale, the cap (depending at the value) will begin to act as a resistor, the lower the frequensy the higher the resistance becomes, and hereby lowering the feedback acordingly. But when the NFB is lowered the gain at the drain rises, but again lowered some by the resistance of the outputcap, and thus the gaindevice keeps the gain close to constant within a wider band of frequencies. While the cap lowers the current flow through the feedbackresistors (R122 and R123) the gaindevice will compensate for the lack of gain because of the lower feedback, it will do so until the maximun gainlevel of the gaindevice is reached. From there the frequensy responce falls at the output.
Sorry for the confusion.
Regards
second test
Hi all,
yesterday I had another listen after modifiing the output caps / volume control.
There´s quite a change compared to the last time.
The soundstage has grown and is better defined now. The highs are not as grainy as before and bass level seems to be a bit louder.
The midrange sounds not quite as nice, tubelike (distortion?) as before but still very natural with good detail. The amp sounds very fast.
I only listened for a few hours and I´m a bit handicapped cause I´ve lent my modified P3-A to my father and this way (standard P3-A) CD doesn´t sound as good it could.
Switching to the ONO+X-BOSOZ gave the biggest difference (ONO unchanged). Now the soundstage is huge, VTA seems to be allright again and bass is very good. The difference with CD is quite a lot bigger than it was before
The difference compared to my previous phono stage is more speed / attack and a bit more depth to the soundstage. Bass is still a bit down but I will wait a few more days (burn in has only been 30 hours or so because the casing is still not finished and I don´t want my daughter to play with 80V DC)
Most of the listening was in balanced mode (Kimber PBJ) but I will try it unbalanced too.
Will be continued........
William
Hi all,
yesterday I had another listen after modifiing the output caps / volume control.
There´s quite a change compared to the last time.
The soundstage has grown and is better defined now. The highs are not as grainy as before and bass level seems to be a bit louder.
The midrange sounds not quite as nice, tubelike (distortion?) as before but still very natural with good detail. The amp sounds very fast.
I only listened for a few hours and I´m a bit handicapped cause I´ve lent my modified P3-A to my father and this way (standard P3-A) CD doesn´t sound as good it could.
Switching to the ONO+X-BOSOZ gave the biggest difference (ONO unchanged). Now the soundstage is huge, VTA seems to be allright again and bass is very good. The difference with CD is quite a lot bigger than it was before
The difference compared to my previous phono stage is more speed / attack and a bit more depth to the soundstage. Bass is still a bit down but I will wait a few more days (burn in has only been 30 hours or so because the casing is still not finished and I don´t want my daughter to play with 80V DC)
Most of the listening was in balanced mode (Kimber PBJ) but I will try it unbalanced too.
Will be continued........
William
You always have top notch information
Macka,
will try them (current sources) when everything else is ready and after Itried the cascoded version (without output caps). And maybe I will finish my Aleph-X first.........
Roddyama,
thanks for the compliment and yes, Peanut Butter and Jelly. In my opinion a cable with unbelievable value for money!
will try them (current sources) when everything else is ready and after Itried the cascoded version (without output caps). And maybe I will finish my Aleph-X first.........
Roddyama,
thanks for the compliment and yes, Peanut Butter and Jelly. In my opinion a cable with unbelievable value for money!
Mad_K, Taco,
I´m not shure about decreasing the output caps that much. There isn´t that much open loop gain to use as feedback. I wasn´t very happy with the sound of the 10muF I had (into 1k3).
Since the caps are in the feedback loop you could try normal 63V panasonic FC (50microF or so). They are biased with 32V so they will funktion well. All distortion will be cared for but you can always use a small (10-33nF) MKP in parallel.
william
I´m not shure about decreasing the output caps that much. There isn´t that much open loop gain to use as feedback. I wasn´t very happy with the sound of the 10muF I had (into 1k3).
Since the caps are in the feedback loop you could try normal 63V panasonic FC (50microF or so). They are biased with 32V so they will funktion well. All distortion will be cared for but you can always use a small (10-33nF) MKP in parallel.
william
balanced v. unbalanced
yesterday I had the chance to do some further listening changing between balanced and pseudo balanced interconnects with just the flick of a switch.
I´ll try to explain:
To use my unbalanced outputs I´ve mounted a switch on the back of the preamp that connects -out to ground (after the series resistor of the balanced vol. pot). So it connects pin 1 and 3 on the XLR outputs and pin 1 and 3 on the Aleph XLR inputs. This is (very conveniently) just what you need to change the Aleph from balanced to unbalanced operation
A further bonus is that the 6dB extra gain of the balanced output are compensated for by the balanced volume control so you don´t have to change the volume when comparing (it took me a while to figure out why nothing went louder when changing from unbalanced to balanced........)
The pseudo balanced mode has the advantage that the common mode rejection is kept high. So the only thing that changes is the output from the preamp.
To make a long story short, no dramatical differences, no small differences and maybe some subtle differences but these will take a bit longer to find out.
I always thought that the X was only accomplished when using the X-BOSOZ balanced (out) or am I wrong?
William
yesterday I had the chance to do some further listening changing between balanced and pseudo balanced interconnects with just the flick of a switch.
I´ll try to explain:
To use my unbalanced outputs I´ve mounted a switch on the back of the preamp that connects -out to ground (after the series resistor of the balanced vol. pot). So it connects pin 1 and 3 on the XLR outputs and pin 1 and 3 on the Aleph XLR inputs. This is (very conveniently) just what you need to change the Aleph from balanced to unbalanced operation
A further bonus is that the 6dB extra gain of the balanced output are compensated for by the balanced volume control so you don´t have to change the volume when comparing (it took me a while to figure out why nothing went louder when changing from unbalanced to balanced........)
The pseudo balanced mode has the advantage that the common mode rejection is kept high. So the only thing that changes is the output from the preamp.
To make a long story short, no dramatical differences, no small differences and maybe some subtle differences but these will take a bit longer to find out.
I always thought that the X was only accomplished when using the X-BOSOZ balanced (out) or am I wrong?
William
Re: balanced v. unbalanced
Hi william!
I had almost the same expirience with my analog output stage in my CDP, which I made like an XBSOZ but with current sinks. The sound from this circiut is just great, but the difference between bal and un bal is subtle.
The case is, that I have never realy heard my xbsoz in unbal mode, becauce my xsoz sounds not so good when driven unbalanced and also the gain became too low. So this told me nothing about the X and non X sound from my xbsoz, only that my xsoz can´t be driven unbalanced.
You must bee right, we can´t have any X in unbalenced mode.
I have tried to understand your way of connecting the attenuator and your bal/unbal swich.
Is this the way?
Regards
Hi william!
wuffwaff said:
I had almost the same expirience with my analog output stage in my CDP, which I made like an XBSOZ but with current sinks. The sound from this circiut is just great, but the difference between bal and un bal is subtle.
The case is, that I have never realy heard my xbsoz in unbal mode, becauce my xsoz sounds not so good when driven unbalanced and also the gain became too low. So this told me nothing about the X and non X sound from my xbsoz, only that my xsoz can´t be driven unbalanced.
You must bee right, we can´t have any X in unbalenced mode.
I have tried to understand your way of connecting the attenuator and your bal/unbal swich.
Is this the way?
Regards
Attachments
Henrik,
you´ve got it right. I only think the Aleph has a lower balanced input impedance (standard Aleph330/60).
The volume pot is a switched type and for a typical volume setting has around 100 ohms. Unbalanced this means 100/(2200+100) attenuation and balanced it´s 100/(2200+100+2200) wich is almost half. This means the 6dB extra gain is lost when you don´t move the volume pot.
william
you´ve got it right. I only think the Aleph has a lower balanced input impedance (standard Aleph330/60).
The volume pot is a switched type and for a typical volume setting has around 100 ohms. Unbalanced this means 100/(2200+100) attenuation and balanced it´s 100/(2200+100+2200) wich is almost half. This means the 6dB extra gain is lost when you don´t move the volume pot.
william
more listening
after a few more days with the ONO / X-BOSOZ combination there was still this feeling that something was wrong. Level was still a bit too much in the highs, with almost too much detail. For example listening to Beasty Boys "Hello Nasty" was almost impossible cause I didn´t know where to listen first (there´s an unbelievable amount of little sounds and samples on this record).
I tried changing the gain (-10dB) because maybe the preamp was overdriven a bit but this didn´t help.
A short switch to my old phonostage (via X-BOSOZ) showed a simillar type of sound, very fast, very detailled and just a bit too much (like a Naim on steroids).
It seems that the character of the X-BOSOZ is less forgiving than that of the OPA627 based preamp showing shortcommings of the previous stages a lot better.
So the only thing that helped was changing the VTA and leaning the cartridge a bit more to the back (this was what I suspected in the first place ) This way everything sounds a lot more relaxed so now I can listen again.
I´ve finished the top of the preamp case (needed some ventilation holes) so now I only have to do the power supply (also needs holes) and the fronts. I hope I will be finished next weekend.
William
after a few more days with the ONO / X-BOSOZ combination there was still this feeling that something was wrong. Level was still a bit too much in the highs, with almost too much detail. For example listening to Beasty Boys "Hello Nasty" was almost impossible cause I didn´t know where to listen first (there´s an unbelievable amount of little sounds and samples on this record).
I tried changing the gain (-10dB) because maybe the preamp was overdriven a bit but this didn´t help.
A short switch to my old phonostage (via X-BOSOZ) showed a simillar type of sound, very fast, very detailled and just a bit too much (like a Naim on steroids).
It seems that the character of the X-BOSOZ is less forgiving than that of the OPA627 based preamp showing shortcommings of the previous stages a lot better.
So the only thing that helped was changing the VTA and leaning the cartridge a bit more to the back (this was what I suspected in the first place
) This way everything sounds a lot more relaxed so now I can listen again.I´ve finished the top of the preamp case (needed some ventilation holes) so now I only have to do the power supply (also needs holes) and the fronts. I hope I will be finished next weekend.
William
wuffwaff-
I have started to tackle the "x-soz" thread to hopefully find the definitive information on mating Suzy and Bosoz... However the "condensed" text is at 100 full pages, with no graphics. So before I finish my reading, here is a quick question: is there a "known-good" / "known-stable" x-bosoz design that currently exists? Is this the one that you used? Where do I turn for THE schematic, or is there not one and I just have to experiment. What if someone has built the BOSOZ using one of the available PCBs..... can they add the Suzy, without taking the whole thing apart? Thanks for the insight!
I have started to tackle the "x-soz" thread to hopefully find the definitive information on mating Suzy and Bosoz... However the "condensed" text is at 100 full pages, with no graphics. So before I finish my reading, here is a quick question: is there a "known-good" / "known-stable" x-bosoz design that currently exists? Is this the one that you used? Where do I turn for THE schematic, or is there not one and I just have to experiment. What if someone has built the BOSOZ using one of the available PCBs..... can they add the Suzy, without taking the whole thing apart? Thanks for the insight!
Amo,
look for the x-bosoz thread. Here you´ll find henriks schematic wich is the one I use (with some minor changes at the in- and output).
It is very easy to make a X out of an existing BOSOZ and visa versa. It are four additional resistors and one jumper between the two fet sources.
I think the schematic is also somewhere in this (not so long) thread.
william
look for the x-bosoz thread. Here you´ll find henriks schematic wich is the one I use (with some minor changes at the in- and output).
It is very easy to make a X out of an existing BOSOZ and visa versa. It are four additional resistors and one jumper between the two fet sources.
I think the schematic is also somewhere in this (not so long) thread.
william
Here is a link to my xbosoz and xsoz.
http://www.diyaudio.com/forums/showthread.php?postid=67322#post67322
In the xbsoz scematic I forgot to draw C3 and C4 from the original circiut, they are most certainly needed.
http://www.diyaudio.com/forums/showthread.php?postid=67322#post67322
In the xbsoz scematic I forgot to draw C3 and C4 from the original circiut, they are most certainly needed.
Hello Henrik,
Is there any particular reason that you use the attenuator at the input (P1-P2) for you X-BSOZ? Why not put it at the output (P3-P4)?
Does the X require a fixed output impedance (in order to operate optimally)? I know that output impedance will vary if P3-P4 changed.... so I guess you're avoiding the impedance variation.
Is that correct?
Cheers,
Is there any particular reason that you use the attenuator at the input (P1-P2) for you X-BSOZ? Why not put it at the output (P3-P4)?
Does the X require a fixed output impedance (in order to operate optimally)? I know that output impedance will vary if P3-P4 changed.... so I guess you're avoiding the impedance variation.
Is that correct?
Cheers,
Hi sianturi
Yes, the attenuator is placed at the input of the xbsoz to keep the outputimpedance of the xbsoz as low as possible. This becauce my xsoz has a very low inputimpedance at 120 Ohm. Any variation in the driving sources (xbsoz) impedance will cause variation in the amount of x-feedback in the xsoz and also some change in the frequensy responce.
The attenuators are the standard to ground.
I am working on a new and better attenuator for the input of the xbsoz.
Yes, the attenuator is placed at the input of the xbsoz to keep the outputimpedance of the xbsoz as low as possible. This becauce my xsoz has a very low inputimpedance at 120 Ohm. Any variation in the driving sources (xbsoz) impedance will cause variation in the amount of x-feedback in the xsoz and also some change in the frequensy responce.
The attenuators are the standard to ground.
I am working on a new and better attenuator for the input of the xbsoz.
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