Amek Neve 9098/9098i Query
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SSLtech
Well-known member
[quote author="Samuel Groner"]
Now, can you tell me the advantage of this coil over a simple cap between the two inputs? Wouldn't that "pull everything into common mode" as well?[/quote]
...To a point. -The advantage of this is interesting though, -it works better than a cap. Firstly, the coils increase in series reactance, working like the 'L' in an 'LC' filter, and the mutual reinforcement/induction at RF actually creates a cancelling waveform. Add that to the cap that IS present -C1- and you have a very efficient RF killer indeed.
It's such a neat trick that you'll find similar things on the front end of just about every switch-mode PSU that you open up. (they won't be optimised for this task however, -before anyone rushes off and pops open that VCR that got hit by lightning and hasn't worked since 3 years ago!) In the SMPS case, it's to try and limit the RF leakage back onto the power line, after the incomong 110V gets chopped up like a maniacal sushi chef on speed... every time the rectifying diodes go into conduction, the RF generated is connected back to the power line, so these things usually appear with a couple of small caps nearby, to try and 'snuff' the RF before it gets to the power cable... which makes a useful antenna!!!
Using the cap means that a lot of RF gets rejected before it gets into amplification... if you just allow it to pass into the preamp, you will -in this design- depend on common mode rejection later in the process, since the signal stays differential through the input stage, which has a lot of gain!
A couple of other points about this version of the 9098i mic pre... it is missing some fairly important pieces. The transformer balanced driver stage for one... The 'low/high CMRR trims' are not necessary if you look further down the line, at what happens next. The second stage of the mic pre is the 9098 line stage, which has a variable ±6dB trim. The mic stage goes into this, and the differential output shown here as going to the male XLR was NEVER intended to be the final output. This is merely an interim stage in case something absolutely has to be inserted, but the standard signal path then goes to two further stages: a differential-input/unbalanced output line stage, and the 'pumpkin' toroid balancing stage, which uses a tertiary winding for load correction, and some fairly large-scrotum drive transistors into the primary winding!
The output stage in particular is a very vital part of the 9098 design, and if you build the design as shown here, you'll be missing a big part of it. I have done a lot of research into this design and I have a "working" version on the bench... but I also have 184 9098i mic pres installed here to compare things to, (and three complete spare modules on my bench) and it's not right yet. the drive stage as shown should really not be used, since it is not cross-coupled, or unbalanced-friendly. In fact it's not needed at all, since the next stage (the front of the line amp) has a CMRR trim... if you build that as shown, you'll have 3 seperate and interactive CMRR trims to worry about...
I think I've been working on this for about 8 or 9 months... -not solidly I'll grant you, since I've had a lot else to do- but I built that stage first, and I can assure you that there's a lot more to it. -If you build that part, you'll end up with a variation on the green pre, nothing more... probably not worth the hassle, since it basically is just the green pre, (that you'll end up doing your own layout for!) You need the rest to make it a 9098.
Keith
Now, can you tell me the advantage of this coil over a simple cap between the two inputs? Wouldn't that "pull everything into common mode" as well?[/quote]
...To a point. -The advantage of this is interesting though, -it works better than a cap. Firstly, the coils increase in series reactance, working like the 'L' in an 'LC' filter, and the mutual reinforcement/induction at RF actually creates a cancelling waveform. Add that to the cap that IS present -C1- and you have a very efficient RF killer indeed.
It's such a neat trick that you'll find similar things on the front end of just about every switch-mode PSU that you open up. (they won't be optimised for this task however, -before anyone rushes off and pops open that VCR that got hit by lightning and hasn't worked since 3 years ago!) In the SMPS case, it's to try and limit the RF leakage back onto the power line, after the incomong 110V gets chopped up like a maniacal sushi chef on speed... every time the rectifying diodes go into conduction, the RF generated is connected back to the power line, so these things usually appear with a couple of small caps nearby, to try and 'snuff' the RF before it gets to the power cable... which makes a useful antenna!!!
Using the cap means that a lot of RF gets rejected before it gets into amplification... if you just allow it to pass into the preamp, you will -in this design- depend on common mode rejection later in the process, since the signal stays differential through the input stage, which has a lot of gain!
A couple of other points about this version of the 9098i mic pre... it is missing some fairly important pieces. The transformer balanced driver stage for one... The 'low/high CMRR trims' are not necessary if you look further down the line, at what happens next. The second stage of the mic pre is the 9098 line stage, which has a variable ±6dB trim. The mic stage goes into this, and the differential output shown here as going to the male XLR was NEVER intended to be the final output. This is merely an interim stage in case something absolutely has to be inserted, but the standard signal path then goes to two further stages: a differential-input/unbalanced output line stage, and the 'pumpkin' toroid balancing stage, which uses a tertiary winding for load correction, and some fairly large-scrotum drive transistors into the primary winding!
The output stage in particular is a very vital part of the 9098 design, and if you build the design as shown here, you'll be missing a big part of it. I have done a lot of research into this design and I have a "working" version on the bench... but I also have 184 9098i mic pres installed here to compare things to, (and three complete spare modules on my bench) and it's not right yet. the drive stage as shown should really not be used, since it is not cross-coupled, or unbalanced-friendly. In fact it's not needed at all, since the next stage (the front of the line amp) has a CMRR trim... if you build that as shown, you'll have 3 seperate and interactive CMRR trims to worry about...
I think I've been working on this for about 8 or 9 months... -not solidly I'll grant you, since I've had a lot else to do- but I built that stage first, and I can assure you that there's a lot more to it. -If you build that part, you'll end up with a variation on the green pre, nothing more... probably not worth the hassle, since it basically is just the green pre, (that you'll end up doing your own layout for!) You need the rest to make it a 9098.
Keith
Thanks SSLtech,
I did mention earlier that the first schem I posted was only a quarter of the full circuit & that this is the taken from the "System 9098EQ" box; not from the 9098i console.
As you mentioned: >>"A couple of other points about this version of the 9098i mic pre... it is missing some fairly important pieces. The transformer balanced driver stage for one... "<<, so I wasn't sure.
Maybe I should amend the first schem to being 1/6 or 1/8?
Second stage?
I'm impressed that you have put so much time into your project.
May I be so bold as to ask what you are actually setting out to create in this "version" you are working on?
Danielle
I did mention earlier that the first schem I posted was only a quarter of the full circuit & that this is the taken from the "System 9098EQ" box; not from the 9098i console.
As you mentioned: >>"A couple of other points about this version of the 9098i mic pre... it is missing some fairly important pieces. The transformer balanced driver stage for one... "<<, so I wasn't sure.
Maybe I should amend the first schem to being 1/6 or 1/8?
Second stage?
I'm impressed that you have put so much time into your project.
May I be so bold as to ask what you are actually setting out to create in this "version" you are working on?
Danielle
Samuel Groner
Well-known member
Thanks, Keith, for your explanation. Any chance of you posting the complete schemo?
Samuel
Samuel
SSLtech
Well-known member
I have to be careful about not offending some good friends at Amek, so I can't really post anything...
Rogy's post shows stage 2, but not the balanced output /tertiary feedback stage... also, the EQ stage is just for the midranges... the HF/LF with Rupert's 'mysterious' "Glow" and "Sheen" buttons is not there either... it does however show the cut-only "notch" switch for the two midranges.
Keith
Rogy's post shows stage 2, but not the balanced output /tertiary feedback stage... also, the EQ stage is just for the midranges... the HF/LF with Rupert's 'mysterious' "Glow" and "Sheen" buttons is not there either... it does however show the cut-only "notch" switch for the two midranges.
Keith
SSLtech
Well-known member
[quote author="danielle"]May I be so bold as to ask what you are actually setting out to create in this "version" you are working on?[/quote]
Sure... Scenaria and I are big fans of the 9098i... (in case you hadn't guessed!) -I must've installed and/or worked on about seven of them... anyhow, We wanted to try and develop a DIY version, but there are a few things which are very component-specific, and without proper parts, it 'works' in that it passes signal, and someone who doesn't have a point of reference to compare it to, might think it's okay, but nothing to get worked up about...
I don't know if you see what I mean, but I hope I'm describing it clearly.
Anyhow... I started with all good intentions of making this another DIY project like the 9k preamp, for everyone to source and make themselves... however, there has been much else to do (LA-2a's, the Bloo Series 2 project, the 1176's and so forth) that this took a bit of a back burner, since it is built and passes signal... however, I think that this might be a tough project for people to reliably source and build with a good chance of actually getting it to sound like the real thing... I don;t know why that is, but there's definately some mojo somewhere in this thing.
Rupert Neve himself commented to me that the PCB layout was critical and Andrew (the main system designer over at Amek, I had a sit down with him when I went back and spent some time at the factory on my last trip back to the UK) was pretty critically important in getting the layout and component selection/specification nailed down...
This really might be better for everyone -in terms of a consistent result- if it was produced as a kit... That way stability, (the first tries tended to oscillate like mad things!) performance and consistency are all the same from unit to unit.
To this end, Scenaria and I have had some discussions about the possibility of making a kit, which would comprise a rack frame, and plug-in modules. That way the whole thing could become something like a 7th-Circle type of project, but rather less expensive. The metalwork would obviously be first-rate, (ask anyone who has received the Bloo kits for the LA-2a type comressors) and in this case they would be absolutely complete kits... otherwise the consistency issue would be completely out the window and the whole purpose of the kit is defeated.
Scenaria is still working hard on the optical tube compressors, and his time and cash is largely tied up in that for the time being. I've got some preliminary specs for the unit, and they're pretty good at the moment, but we're still trying to nail it down, make it sound like the real thing, and keep it affordable and stable.
Bear in mind that the rack-mount outboard version of the 9098 mic preamp does not sound quite like the 'real thing'... that should tell you something!!! :shock: Even Amek were struggling a little with this for a while.
Okay, nobody send me PMs saying "When will the kits be ready?" -If I don;t get this thing to sound right, there will never be a kit. There'll be no point in making a kit for something that doesn't sound like the wonderful, beautiful, excellent real thing. If I ever get this thing to sing like bird however, there will be the opportunity to either:
a) Make this a DIY project for everyone, (if we find out that all you need is mettalised poly, or whatever)
b) make a complete kit, which will make more sense if it has to be a very specific collection of components, some of which might come in minimum order quantities.
Time will tell.
Oh and yes... I have the front end RF filter in the circuit... it's soldered right on the XLR terminals!!! :green:
Keith
Sure... Scenaria and I are big fans of the 9098i... (in case you hadn't guessed!) -I must've installed and/or worked on about seven of them... anyhow, We wanted to try and develop a DIY version, but there are a few things which are very component-specific, and without proper parts, it 'works' in that it passes signal, and someone who doesn't have a point of reference to compare it to, might think it's okay, but nothing to get worked up about...
I don't know if you see what I mean, but I hope I'm describing it clearly.
Anyhow... I started with all good intentions of making this another DIY project like the 9k preamp, for everyone to source and make themselves... however, there has been much else to do (LA-2a's, the Bloo Series 2 project, the 1176's and so forth) that this took a bit of a back burner, since it is built and passes signal... however, I think that this might be a tough project for people to reliably source and build with a good chance of actually getting it to sound like the real thing... I don;t know why that is, but there's definately some mojo somewhere in this thing.
Rupert Neve himself commented to me that the PCB layout was critical and Andrew (the main system designer over at Amek, I had a sit down with him when I went back and spent some time at the factory on my last trip back to the UK) was pretty critically important in getting the layout and component selection/specification nailed down...
This really might be better for everyone -in terms of a consistent result- if it was produced as a kit... That way stability, (the first tries tended to oscillate like mad things!) performance and consistency are all the same from unit to unit.
To this end, Scenaria and I have had some discussions about the possibility of making a kit, which would comprise a rack frame, and plug-in modules. That way the whole thing could become something like a 7th-Circle type of project, but rather less expensive. The metalwork would obviously be first-rate, (ask anyone who has received the Bloo kits for the LA-2a type comressors) and in this case they would be absolutely complete kits... otherwise the consistency issue would be completely out the window and the whole purpose of the kit is defeated.
Scenaria is still working hard on the optical tube compressors, and his time and cash is largely tied up in that for the time being. I've got some preliminary specs for the unit, and they're pretty good at the moment, but we're still trying to nail it down, make it sound like the real thing, and keep it affordable and stable.
Bear in mind that the rack-mount outboard version of the 9098 mic preamp does not sound quite like the 'real thing'... that should tell you something!!! :shock: Even Amek were struggling a little with this for a while.
Okay, nobody send me PMs saying "When will the kits be ready?" -If I don;t get this thing to sound right, there will never be a kit. There'll be no point in making a kit for something that doesn't sound like the wonderful, beautiful, excellent real thing. If I ever get this thing to sing like bird however, there will be the opportunity to either:
a) Make this a DIY project for everyone, (if we find out that all you need is mettalised poly, or whatever)
b) make a complete kit, which will make more sense if it has to be a very specific collection of components, some of which might come in minimum order quantities.
Time will tell.
Oh and yes... I have the front end RF filter in the circuit... it's soldered right on the XLR terminals!!! :green:
Keith
Thanks Keith,
:shock: hoowee; a 9098i strip in a toaster rack!
Now I see why you've been working at it for 8 to 9 months off & on.
Not much I can say really as you've anticipated the obvious questions that would be thrown at you & answered them already!
I like the way Joe has set up his JLM99V deals:
http://www.jlmaudio.com/JLM99V.htm
DIY components or full kit.
As a matter of fact I like the idea so much I'm starting on a JLM99V when my world settles down after the xmas/new year madness.
Thanks & regards,
Danielle
:shock: hoowee; a 9098i strip in a toaster rack!
Now I see why you've been working at it for 8 to 9 months off & on.
Not much I can say really as you've anticipated the obvious questions that would be thrown at you & answered them already!
I like the way Joe has set up his JLM99V deals:
http://www.jlmaudio.com/JLM99V.htm
DIY components or full kit.
As a matter of fact I like the idea so much I'm starting on a JLM99V when my world settles down after the xmas/new year madness.
Who's a lucky boy then hey? :twisted:
Thanks & regards,
Danielle
Zee1usa
Well-known member
Bump..
Keith,
xmas is coming. any progress on this one.
Z :guinness: :razz:
Keith,
xmas is coming. any progress on this one.
Z :guinness: :razz:
Hi Keith,
I know this thread is really old, just would like to ask you if you ever got the chance to finalize your version of the system 9098?
thank you
I don't know if you see what I mean, but I hope I'm describing it clearly.
Anyhow... I started with all good intentions of making this another DIY project like the 9k preamp, for everyone to source and make themselves... however, there has been much else to do (LA-2a's, the Bloo Series 2 project, the 1176's and so forth) that this took a bit of a back burner, since it is built and passes signal... however, I think that this might be a tough project for people to reliably source and build with a good chance of actually getting it to sound like the real thing... I don;t know why that is, but there's definately some mojo somewhere in this thing.
Rupert Neve himself commented to me that the PCB layout was critical and Andrew (the main system designer over at Amek, I had a sit down with him when I went back and spent some time at the factory on my last trip back to the UK) was pretty critically important in getting the layout and component selection/specification nailed down...
This really might be better for everyone -in terms of a consistent result- if it was produced as a kit... That way stability, (the first tries tended to oscillate like mad things!) performance and consistency are all the same from unit to unit.
To this end, Scenaria and I have had some discussions about the possibility of making a kit, which would comprise a rack frame, and plug-in modules. That way the whole thing could become something like a 7th-Circle type of project, but rather less expensive. The metalwork would obviously be first-rate, (ask anyone who has received the Bloo kits for the LA-2a type comressors) and in this case they would be absolutely complete kits... otherwise the consistency issue would be completely out the window and the whole purpose of the kit is defeated.
Scenaria is still working hard on the optical tube compressors, and his time and cash is largely tied up in that for the time being. I've got some preliminary specs for the unit, and they're pretty good at the moment, but we're still trying to nail it down, make it sound like the real thing, and keep it affordable and stable.
Bear in mind that the rack-mount outboard version of the 9098 mic preamp does not sound quite like the 'real thing'... that should tell you something!!! :shock: Even Amek were struggling a little with this for a while.
Okay, nobody send me PMs saying "When will the kits be ready?" -If I don;t get this thing to sound right, there will never be a kit. There'll be no point in making a kit for something that doesn't sound like the wonderful, beautiful, excellent real thing. If I ever get this thing to sing like bird however, there will be the opportunity to either:
a) Make this a DIY project for everyone, (if we find out that all you need is mettalised poly, or whatever)
b) make a complete kit, which will make more sense if it has to be a very specific collection of components, some of which might come in minimum order quantities.
Time will tell.
Oh and yes... I have the front end RF filter in the circuit... it's soldered right on the XLR terminals!!! :green:
Keith
[/quote]
I know this thread is really old, just would like to ask you if you ever got the chance to finalize your version of the system 9098?
thank you
Sure... Scenaria and I are big fans of the 9098i... (in case you hadn't guessed!) -I must've installed and/or worked on about seven of them... anyhow, We wanted to try and develop a DIY version, but there are a few things which are very component-specific, and without proper parts, it 'works' in that it passes signal, and someone who doesn't have a point of reference to compare it to, might think it's okay, but nothing to get worked up about...SSLtech said:
I don't know if you see what I mean, but I hope I'm describing it clearly.
Anyhow... I started with all good intentions of making this another DIY project like the 9k preamp, for everyone to source and make themselves... however, there has been much else to do (LA-2a's, the Bloo Series 2 project, the 1176's and so forth) that this took a bit of a back burner, since it is built and passes signal... however, I think that this might be a tough project for people to reliably source and build with a good chance of actually getting it to sound like the real thing... I don;t know why that is, but there's definately some mojo somewhere in this thing.
Rupert Neve himself commented to me that the PCB layout was critical and Andrew (the main system designer over at Amek, I had a sit down with him when I went back and spent some time at the factory on my last trip back to the UK) was pretty critically important in getting the layout and component selection/specification nailed down...
This really might be better for everyone -in terms of a consistent result- if it was produced as a kit... That way stability, (the first tries tended to oscillate like mad things!) performance and consistency are all the same from unit to unit.
To this end, Scenaria and I have had some discussions about the possibility of making a kit, which would comprise a rack frame, and plug-in modules. That way the whole thing could become something like a 7th-Circle type of project, but rather less expensive. The metalwork would obviously be first-rate, (ask anyone who has received the Bloo kits for the LA-2a type comressors) and in this case they would be absolutely complete kits... otherwise the consistency issue would be completely out the window and the whole purpose of the kit is defeated.
Scenaria is still working hard on the optical tube compressors, and his time and cash is largely tied up in that for the time being. I've got some preliminary specs for the unit, and they're pretty good at the moment, but we're still trying to nail it down, make it sound like the real thing, and keep it affordable and stable.
Bear in mind that the rack-mount outboard version of the 9098 mic preamp does not sound quite like the 'real thing'... that should tell you something!!! :shock: Even Amek were struggling a little with this for a while.
Okay, nobody send me PMs saying "When will the kits be ready?" -If I don;t get this thing to sound right, there will never be a kit. There'll be no point in making a kit for something that doesn't sound like the wonderful, beautiful, excellent real thing. If I ever get this thing to sing like bird however, there will be the opportunity to either:
a) Make this a DIY project for everyone, (if we find out that all you need is mettalised poly, or whatever)
b) make a complete kit, which will make more sense if it has to be a very specific collection of components, some of which might come in minimum order quantities.
Time will tell.
Oh and yes... I have the front end RF filter in the circuit... it's soldered right on the XLR terminals!!! :green:
Keith
[/quote]
Post here so I don't have to explain again and not add another post to our sea of posts...
this part could work as VT30972?
http://dx.com/es/p/uu9-8-10mh-common-mode-inductor-line-filter-black-copper-20-piece-pack-142436
Should I use it in a transformerless mic pre or I just use nothing or a couple of 10Ω resistors?
Thanks
JS
this part could work as VT30972?
http://dx.com/es/p/uu9-8-10mh-common-mode-inductor-line-filter-black-copper-20-piece-pack-142436
Should I use it in a transformerless mic pre or I just use nothing or a couple of 10Ω resistors?
Thanks
JS
kato
Well-known member
Thanks Kato
Which are exactly those? I've never know... are them those that has 6 holes on a cylindric core or could I use just the radio choke resistor-like shape? how many turns or inductance we expect?
JS
kato said:
Which are exactly those? I've never know... are them those that has 6 holes on a cylindric core or could I use just the radio choke resistor-like shape? how many turns or inductance we expect?
JS
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