rafafredd
Well-known member
I think you could use that 60Hz Lars Lundahl method. Very simple. Do you remenber this?
Calrec PQ 1061
- Thread starter BuzAllen
- Start date
Help Support GroupDIY Audio Forum:
I had not looked at this thread until I talked to Dave the other day.
Here are some ideas from me.
lets decide what size case. 1U 2U 3U 4U etc one or two channels and what size switches and knobs
Make the PCBs two PCB One with the gain stages on the board and not modules. I dislike modules and try not to ever use sockets sockets suck! I have > than 20 years in repair of all kinds of stuff. sockets suck learn to desolder. I am one of the people trying to build the 81s
Also make multable pads for the caps so different types and sizes can be used.
Make the other PCB a board for the solder mounting of the switches and pots.
decide on the depth of the case for the total size of the board.
design the PCB for radial electros.
Some of this is in the above threads posted by others I think.
Here are some ideas from me.
lets decide what size case. 1U 2U 3U 4U etc one or two channels and what size switches and knobs
Make the PCBs two PCB One with the gain stages on the board and not modules. I dislike modules and try not to ever use sockets sockets suck! I have > than 20 years in repair of all kinds of stuff. sockets suck learn to desolder. I am one of the people trying to build the 81s
Also make multable pads for the caps so different types and sizes can be used.
Make the other PCB a board for the solder mounting of the switches and pots.
decide on the depth of the case for the total size of the board.
design the PCB for radial electros.
Some of this is in the above threads posted by others I think.
TomWaterman
Well-known member
Hey,
sorry I've been a bit busy with sessions recently and have not sorted out the gain module layout to post up....I think we really need to decide the best way to do this, I see a 50/50 split concerning the use of plugin modules, PCB mount switches etc.
Shall we make a poll / vote?
Raf, what is the 60Hz Lundahl method?
Brian, do you still have the inductor out? It would be really great if we could measure it but I know nothing about measuring inductance....CJ?
Brian Sowter will make it if we can measure it, Brent Averill has not got back to me RE the inductor....I guess we need to measure the inductance at the taps plus DC resistance? How can we figure out the number of turns without hacking one apart ala the good Dr.hacksaw!!?
Got some really good info from Brian Last @ Sowter, here's a cut and past from the email:
"I have been investigating the history of type 3553 and find that
Calrec made three modifications to the original.
3553 was originally a transformer for 10kohm source and turns ratio
of 1:1 with primary tapped for 1.2kohm (0.288:1 ratio). Then they
increased ratio 1:1.035, presumably to adjust for transmission
loss. Then they upped the turns of the 1.2kohm taps an extra 2.4%
and finally increased the taps again by a further 3.5%. At this point
we re-numbered the design to type 2318 and changed a couple of
colours to differentiate.
2318 was the transformer that Calrec purchased over many years
and we would suggest this is probably what you want.
Primary colours were....
Yellow and violet for 10kohm.
White and grey for 1.2kohm.
Red and Blue would be joined together to form the primary centre
tap.
Orange and green are the secondary.
Black would be the electrostatic screen.
Earlier versions of 3553 had Brown and pink for the 1.2kohm tap. I
hope this is reasonably clear for you to ascertain which you want".
Prices as follows
42.85 pounds each
38.57 pounds each - 10% discount for 10+
36.42 pounds each - 15% discount for 20+
above prices not including 9.50 GBP carriage and VAT (17.5% for UK residents)
Hope this puts us a little closer....
Cheers Tom
sorry I've been a bit busy with sessions recently and have not sorted out the gain module layout to post up....I think we really need to decide the best way to do this, I see a 50/50 split concerning the use of plugin modules, PCB mount switches etc.
Shall we make a poll / vote?
Raf, what is the 60Hz Lundahl method?
Brian, do you still have the inductor out? It would be really great if we could measure it but I know nothing about measuring inductance....CJ?
Brian Sowter will make it if we can measure it, Brent Averill has not got back to me RE the inductor....I guess we need to measure the inductance at the taps plus DC resistance? How can we figure out the number of turns without hacking one apart ala the good Dr.hacksaw!!?
Got some really good info from Brian Last @ Sowter, here's a cut and past from the email:
"I have been investigating the history of type 3553 and find that
Calrec made three modifications to the original.
3553 was originally a transformer for 10kohm source and turns ratio
of 1:1 with primary tapped for 1.2kohm (0.288:1 ratio). Then they
increased ratio 1:1.035, presumably to adjust for transmission
loss. Then they upped the turns of the 1.2kohm taps an extra 2.4%
and finally increased the taps again by a further 3.5%. At this point
we re-numbered the design to type 2318 and changed a couple of
colours to differentiate.
2318 was the transformer that Calrec purchased over many years
and we would suggest this is probably what you want.
Primary colours were....
Yellow and violet for 10kohm.
White and grey for 1.2kohm.
Red and Blue would be joined together to form the primary centre
tap.
Orange and green are the secondary.
Black would be the electrostatic screen.
Earlier versions of 3553 had Brown and pink for the 1.2kohm tap. I
hope this is reasonably clear for you to ascertain which you want".
Prices as follows
42.85 pounds each
38.57 pounds each - 10% discount for 10+
36.42 pounds each - 15% discount for 20+
above prices not including 9.50 GBP carriage and VAT (17.5% for UK residents)
Hope this puts us a little closer....
Cheers Tom
rafafredd
Well-known member
\for 60Hz inductance test, have a look here:
http://www.groupdiy.com/index.php?topic=3209&start=0&postdays=0&postorder=asc&highlight=
http://www.groupdiy.com/index.php?topic=3209&start=0&postdays=0&postorder=asc&highlight=
plugins are good for manufacturers and good for consoles but I personally have never understood why people have brought this to their DIY projects. Its just another esoteric part that you have to find and specifically lay out a board for and then some guy in some corner of the earth cant get the connector, whats the advantage? How many times do you really plug and unplug these things? I dont really care either way, but it just seems so much simpler to just lay everything out on one board, less parts to have to source. Keep the newbies in mind. As for pcb mount switches (in the EQ section), this project is pointless to continue unless we get our heads around that idea, to wire everything point to point you might as well just buy one on ebay its not going to be any savings what so ever.
Good news on the transformer.
As for the stuff in gus' post, I think we can fit a single channel in a single height rack space, seems like lorlins will fit on the front panel easily enough.
dave
Good news on the transformer.
As for the stuff in gus' post, I think we can fit a single channel in a single height rack space, seems like lorlins will fit on the front panel easily enough.
dave
rafafredd
Well-known member
I think that the only advantage of the plugin is to keep the original layout. I don´t think it´s a very easy job to layout this board again. If the job is already done, and done nicely, why would we want to redo it? You know... Off coarse someone would have to draw it on cad again anyway, to output for gerber and have the boards made, but if you copy the original layout, it saves lots of thinking time. Also, maintaining the original layout, we are sure it will work the same way. A new layout can bring also new problems...
If someone can´t get the sockets or the pins, anyone can substitute it with some little solid core wire pieces and solder the plugins to the main PCB. The solid core wire will keep the plugins on their place...
I think this is really the way to go. Just scan the pcb on both sides and if there isn´t anyone else to do it, I will redraw the original layout for gerber...
If someone can´t get the sockets or the pins, anyone can substitute it with some little solid core wire pieces and solder the plugins to the main PCB. The solid core wire will keep the plugins on their place...
I think this is really the way to go. Just scan the pcb on both sides and if there isn´t anyone else to do it, I will redraw the original layout for gerber...
[quote author="rafafredd"]I think that the only advantage of the plugin is to keep the original layout. I don´t think it´s a very easy job to layout this board again. If the job is already done, and done nicely, why would we want to redo it?[/quote]
Well, considering that the ENTIRE thing has to be layed out from scratch, the idea of laying out the plugin opamp is hardly daunting in that light. Keep the original artwork if you wish, just incorporate it into the motherboard. Anyway you slice this project, SOMEONE is going to have to lay out the entire thing. Based on that, I cant see how original artwork is at all relevant, to do this RIGHT, we should be working from the schematic from a ground up approach. If I knew how to do this, Id be on it, this is getting frustrating...
Im not sure I at all understand the will to live in the past with some of this stuff. That thing was designed for a purpose, one which is much different than what we, or at least I am talking about. It is hard to imagine that the engineers at calrec would have used a layout that at all resembles what is in there if they were given the parameters and form factor we are discussing here.
At any rate, I shouldnt bitch because Im little help to see this thing through on any kind of technical level. Debating keeping some tiny piece of artwork when the other %98 of the artwork needs to be completely re-figured out from the ground up seems really irrelevant to me. With the intense changes that have been suggested (mostly by me), assuming we make them, whatever we wind up with in the end is going to be our mess, getting hung up over calrec's design just doesnt seem like it serves the project as we are going to have something that simply, is different. Beyond that, calrec's opamp art worked in the context of the rest of their artwork for the whole EQ. Its probably shortsighted to just assume that if we keep their plugin design, its just gonna work in whatever we whip up for a motherboard for it to plug into.
"inspired by" instead of "clone" is likely the better way to look at this.
dave
Well, considering that the ENTIRE thing has to be layed out from scratch, the idea of laying out the plugin opamp is hardly daunting in that light. Keep the original artwork if you wish, just incorporate it into the motherboard. Anyway you slice this project, SOMEONE is going to have to lay out the entire thing. Based on that, I cant see how original artwork is at all relevant, to do this RIGHT, we should be working from the schematic from a ground up approach. If I knew how to do this, Id be on it, this is getting frustrating...
Im not sure I at all understand the will to live in the past with some of this stuff. That thing was designed for a purpose, one which is much different than what we, or at least I am talking about. It is hard to imagine that the engineers at calrec would have used a layout that at all resembles what is in there if they were given the parameters and form factor we are discussing here.
At any rate, I shouldnt bitch because Im little help to see this thing through on any kind of technical level. Debating keeping some tiny piece of artwork when the other %98 of the artwork needs to be completely re-figured out from the ground up seems really irrelevant to me. With the intense changes that have been suggested (mostly by me), assuming we make them, whatever we wind up with in the end is going to be our mess, getting hung up over calrec's design just doesnt seem like it serves the project as we are going to have something that simply, is different. Beyond that, calrec's opamp art worked in the context of the rest of their artwork for the whole EQ. Its probably shortsighted to just assume that if we keep their plugin design, its just gonna work in whatever we whip up for a motherboard for it to plug into.
"inspired by" instead of "clone" is likely the better way to look at this.
dave
TomWaterman
Well-known member
Good points from both sides,
Dave, I'm really glad you're into this project, your ideas are very valid and you're not bitching, just fleshing ideas out...
You are very right when you mention that 98% of the design is going to have to be redone....so what difference will the gain blocks make?
Its a tough one, on one hand the gain block is the majority of active circuitry in the box and keeping a layout similar to the original may remove a small amount of 'hit or miss' syndrome when getting the thing working. Of course the orignal layout (component wise) could be kept but just placed on the main board instead of modules....
On the other hand, a completely new design may allow us to be more creative and produce a project that is improved over the Calrec module...
As you say, laying out the main board will take some time and I am wiling to have a stab at copying a scan but it needs considerable experience to design from the schematic, ground up.
Are any thread lurkers up for this, Fabio, Jakob????
There doesn't seem to be as many people interested in this as you would think...maybe everyone is watching quietly?
The one worry for me is that the plugin gain modules actually need to be a little over 1" high, by the time they are mounted on the motherboard, the vertical space may be a little tight in a 1U box. In fact this may mean it makes more sense to have them on the motherboards.....I'm considering modules in a schroff rack if this gets sorted.
However this micpre/EQ project really is a no-go unless we can measure the MF inductor. Thats the crux of the problem, the rest is just details that need to be organised.
Brian has the inductor to be measured, so in my mind thats where we should focus our interests for now.
Tom
Dave, I'm really glad you're into this project, your ideas are very valid and you're not bitching, just fleshing ideas out...
You are very right when you mention that 98% of the design is going to have to be redone....so what difference will the gain blocks make?
Its a tough one, on one hand the gain block is the majority of active circuitry in the box and keeping a layout similar to the original may remove a small amount of 'hit or miss' syndrome when getting the thing working. Of course the orignal layout (component wise) could be kept but just placed on the main board instead of modules....
On the other hand, a completely new design may allow us to be more creative and produce a project that is improved over the Calrec module...
As you say, laying out the main board will take some time and I am wiling to have a stab at copying a scan but it needs considerable experience to design from the schematic, ground up.
Are any thread lurkers up for this, Fabio, Jakob????
There doesn't seem to be as many people interested in this as you would think...maybe everyone is watching quietly?
The one worry for me is that the plugin gain modules actually need to be a little over 1" high, by the time they are mounted on the motherboard, the vertical space may be a little tight in a 1U box. In fact this may mean it makes more sense to have them on the motherboards.....I'm considering modules in a schroff rack if this gets sorted.
However this micpre/EQ project really is a no-go unless we can measure the MF inductor. Thats the crux of the problem, the rest is just details that need to be organised.
Brian has the inductor to be measured, so in my mind thats where we should focus our interests for now.
Tom
I have not done any PCB design stuff in almost 20 years. I do have a few ideas for the build. How DEEP a rack cab is OK???????
Some "problems" I see First one of the big ones is the microphone/line gain switch again it will be a >$50.00 USA one per channel, it looks like a 6 pole I think a 3 pole and a 4PDT relay could work fine. 2nd the inductors like posted by others the one in the mid section and the one in the HF filter.
What is the X, Y on the left side of the schematic from the wipers of the gain switch?
Next what type PET etc. and build style wound or stacked are the many filter caps?
Will builders be able to handle bending the transistor legs so BC or 2n EBC or 2sc ECB based transistors can be used etc................. I don't worry too much about Si transistor numbers I kind of think of them as small, med and large.
I don't know if cheap PCB switches will have enought contacts and poles for some of the spots.
internal or external PS?
What current PCB layout software has most of the footprints of switches etc or do you still have to make your own libary of footprints?
Some "problems" I see First one of the big ones is the microphone/line gain switch again it will be a >$50.00 USA one per channel, it looks like a 6 pole I think a 3 pole and a 4PDT relay could work fine. 2nd the inductors like posted by others the one in the mid section and the one in the HF filter.
What is the X, Y on the left side of the schematic from the wipers of the gain switch?
Next what type PET etc. and build style wound or stacked are the many filter caps?
Will builders be able to handle bending the transistor legs so BC or 2n EBC or 2sc ECB based transistors can be used etc................. I don't worry too much about Si transistor numbers I kind of think of them as small, med and large.
I don't know if cheap PCB switches will have enought contacts and poles for some of the spots.
internal or external PS?
What current PCB layout software has most of the footprints of switches etc or do you still have to make your own libary of footprints?
TomWaterman
Well-known member
I think we'll have to make PCB footprints for switches ourselves.
This is one reason why I would like to mount the switches off board and use standard molex headers. for P-to-P (just for the EQ switches etc).
I'm using the edu version of Eagle for the gain block but have access to Protel99SE. From the layout i'm working on, the transistor legs shouldn't need to be bent.....I can't see why they should need to be anywhere else (?)
As far as PSU's go, the schematic shows the requirement for both +/-22V and +/-24V...I'm not sure which it is but JLM powersupplies look good to go and are pretty cheap. I vote for leaving the PSU off the mainboard in case someone wants to mount 8 in a chassis...JLMs can be used internally in a 1U etc as well.
Tom
This is one reason why I would like to mount the switches off board and use standard molex headers. for P-to-P (just for the EQ switches etc).
I'm using the edu version of Eagle for the gain block but have access to Protel99SE. From the layout i'm working on, the transistor legs shouldn't need to be bent.....I can't see why they should need to be anywhere else (?)
As far as PSU's go, the schematic shows the requirement for both +/-22V and +/-24V...I'm not sure which it is but JLM powersupplies look good to go and are pretty cheap. I vote for leaving the PSU off the mainboard in case someone wants to mount 8 in a chassis...JLMs can be used internally in a 1U etc as well.
Tom
definitely an external powersupply. Id like to potentially build a mixer and dont need a power transformer in the box with my unshielded mix busses. Of course as mentioned you can mount the external supply inside the same box if you wish, Ive done this with many projects.
gus, the board should be able to fit in a par metal case, I think that gives us 7" orr 8" deep, Im not sitting near any gear to measure out...
the front end needs to be redesigned. We've got to make it work with a lorlin switch. If this means less gain steps and a wider fader swing between steps, so be it.
If the cheap lorlins dont offer enough contacts to do all the bands in the EQ, we are going to have to leave some off.
Here's the bottom line, I think this is worth saying again. For about $1k (or less) you can go, with due dilligence, and buy one of these modules, and for another $30 in cheap power supply and cable and connector, you've got a working unit which doesnt *need* racking (its in a cassette which can be set on top of your console). Not only that, but your investment is completely safe, the day you want to sell it, you should be able to without losing a dime.
Once we get a green light on the inductors, the way I look at this, in order for this tremendous amount of work to be worth doing at all is to bring this project in as inexpensively as possible. If this thing can't be designed with lorlin switches and (minus the iron) common and inexpensive parts, it quickly becomes nott the best use of our energy. You can use expensive switches if you want, but the boards should be layed out and the project should be based around the cheapest parts we can find. This after all is my reaction to the expense of the 1081 project and the amount of people who are abondoning it because of that. To save only $300 over what a real one would cost is not worth it to me. Id rather invest $1k into a vintage antique than $700 into my DIY of the same thing. Im not gonna be able to get my money out of the DIY if I need to...
I think we should really decide wether or not this is the direction the group would prefer to take this project in. I feel its importat to get this out in the open as we can go in circles debating things that wont be constructive if we are not all on the same page with the direction of this project.
Im thinking the whole thing needs to be built around lorlin switches that cost $2 each. No esoteric or expensive switches should be NEEDED (you can use whatever you want on yours). In order to achieve this, certain things, like the front end will need to be redesigned and the EQ is going to need to be entirely changed in its layout. I can still see not a single good reason to use satellite plugin amps (other than it looks cool which nobody concerned with the sound coming out of the speaker gives a F about), this just makes the project more complicated for newbies. There is no flexability to be gained by swapping other kinds of opamps in there, so really, whats the point? Just most contacts to go bad. We arent servicing a console here, most people will only be building one or two channels, certainly not an incredibly daunting thing to be faced with desoldering...
hey, maybe none of this will work and we'll be left with just the mic pre, which is where all this started and if thats the case, thats totally cool, I'll be excited to build a few. I think however, in order to consider this as the whole EQ project, we all need to be thinking together in the same direction otherwise we are going to go in circles. I also dont intend to be the all knowing dude on this, if anyone has any suggestions to take this in a different direction, please speak up. I think though that the relatively low cost of the original units (relatively low reflecting what it would cost s in parts alone to assemble a straight clone) needs to remain a corner stone of reflection when we weigh our options about what makes sense here.
dave
gus, the board should be able to fit in a par metal case, I think that gives us 7" orr 8" deep, Im not sitting near any gear to measure out...
the front end needs to be redesigned. We've got to make it work with a lorlin switch. If this means less gain steps and a wider fader swing between steps, so be it.
If the cheap lorlins dont offer enough contacts to do all the bands in the EQ, we are going to have to leave some off.
Here's the bottom line, I think this is worth saying again. For about $1k (or less) you can go, with due dilligence, and buy one of these modules, and for another $30 in cheap power supply and cable and connector, you've got a working unit which doesnt *need* racking (its in a cassette which can be set on top of your console). Not only that, but your investment is completely safe, the day you want to sell it, you should be able to without losing a dime.
Once we get a green light on the inductors, the way I look at this, in order for this tremendous amount of work to be worth doing at all is to bring this project in as inexpensively as possible. If this thing can't be designed with lorlin switches and (minus the iron) common and inexpensive parts, it quickly becomes nott the best use of our energy. You can use expensive switches if you want, but the boards should be layed out and the project should be based around the cheapest parts we can find. This after all is my reaction to the expense of the 1081 project and the amount of people who are abondoning it because of that. To save only $300 over what a real one would cost is not worth it to me. Id rather invest $1k into a vintage antique than $700 into my DIY of the same thing. Im not gonna be able to get my money out of the DIY if I need to...
I think we should really decide wether or not this is the direction the group would prefer to take this project in. I feel its importat to get this out in the open as we can go in circles debating things that wont be constructive if we are not all on the same page with the direction of this project.
Im thinking the whole thing needs to be built around lorlin switches that cost $2 each. No esoteric or expensive switches should be NEEDED (you can use whatever you want on yours). In order to achieve this, certain things, like the front end will need to be redesigned and the EQ is going to need to be entirely changed in its layout. I can still see not a single good reason to use satellite plugin amps (other than it looks cool which nobody concerned with the sound coming out of the speaker gives a F about), this just makes the project more complicated for newbies. There is no flexability to be gained by swapping other kinds of opamps in there, so really, whats the point? Just most contacts to go bad. We arent servicing a console here, most people will only be building one or two channels, certainly not an incredibly daunting thing to be faced with desoldering...
hey, maybe none of this will work and we'll be left with just the mic pre, which is where all this started and if thats the case, thats totally cool, I'll be excited to build a few. I think however, in order to consider this as the whole EQ project, we all need to be thinking together in the same direction otherwise we are going to go in circles. I also dont intend to be the all knowing dude on this, if anyone has any suggestions to take this in a different direction, please speak up. I think though that the relatively low cost of the original units (relatively low reflecting what it would cost s in parts alone to assemble a straight clone) needs to remain a corner stone of reflection when we weigh our options about what makes sense here.
dave
The mic pre does not look like anything special, I have not heard one that is a guess from the schematic. plus the gain switch costs alot. If people want to build it we need more information see below.
OK what if we make just an EQ? Drops a B202 and a B210 However and this a big however need to know about the connections at the left side.
ins ret
line switc
y
x
******note r44 connection to the LF filter section to the ins ret line**** this can be a BIG problem because we need more info on the unknown connections outside the schematic.
two of the gain wafers wipers go out X,Y????????
I have not made sense of the phase rev switching yet.
What line levels should it be designed for if built as an EQ?
Good thing I see is the pots are lin!!!!
switches, what I can find in the new Mouser cat. I picked shorting if I could find it. Is the stock unit shorting or nonshorting (I will guess nonshorting because of the 10meg resistors for pop control? on the switches) shorting will be less parts and PCB holes.
HF shelf 2P6T mouser 10WA345 PCB lorlin $3.17
mid 2P11T mouser 10wr212 solder term Alpha $3.17
(most connections switch from mouser in Lorlin PCB 2X6)
LF shelf 2P6T mouser 10WA345 PCB $3.17
LF filter 3P6T 690-C4D0312N-A 3p12t adjusted for 6 mouser Electroswitch non shorting $14.21 solder term
(most connections switch from mouser in Lorlin PCB 3X4)
HF filter 2P6T mouser 10WA345 PCB $3.17
PCB mounting of the switches looks like it is out
Do we need the eq in and out switch?
Except for the inductors and switches the rest of the parts look to be easy to get.
TO92s can pin out EBC or ECB
with the microphne pre section 8 gain stages with 5 transistors(40 total) lets GUESS on the high side $0.50 each $20.00 USA
above switches and transistors guess $47.00
1U case? par metal 10-19112x 19 x 1.74' x11" deep looks like about $46.00
lets call it $100 (02-27-2005) so far if I have good prices and my math is right then the knobs and other parts like caps and resistors and the next high cost items the gain switch, inductors and the power supply.
Please give feedback! This might not be worth building if one can find real modules.
OK what if we make just an EQ? Drops a B202 and a B210 However and this a big however need to know about the connections at the left side.
ins ret
line switc
y
x
******note r44 connection to the LF filter section to the ins ret line**** this can be a BIG problem because we need more info on the unknown connections outside the schematic.
two of the gain wafers wipers go out X,Y????????
I have not made sense of the phase rev switching yet.
What line levels should it be designed for if built as an EQ?
Good thing I see is the pots are lin!!!!
switches, what I can find in the new Mouser cat. I picked shorting if I could find it. Is the stock unit shorting or nonshorting (I will guess nonshorting because of the 10meg resistors for pop control? on the switches) shorting will be less parts and PCB holes.
HF shelf 2P6T mouser 10WA345 PCB lorlin $3.17
mid 2P11T mouser 10wr212 solder term Alpha $3.17
(most connections switch from mouser in Lorlin PCB 2X6)
LF shelf 2P6T mouser 10WA345 PCB $3.17
LF filter 3P6T 690-C4D0312N-A 3p12t adjusted for 6 mouser Electroswitch non shorting $14.21 solder term
(most connections switch from mouser in Lorlin PCB 3X4)
HF filter 2P6T mouser 10WA345 PCB $3.17
PCB mounting of the switches looks like it is out
Do we need the eq in and out switch?
Except for the inductors and switches the rest of the parts look to be easy to get.
TO92s can pin out EBC or ECB
with the microphne pre section 8 gain stages with 5 transistors(40 total) lets GUESS on the high side $0.50 each $20.00 USA
above switches and transistors guess $47.00
1U case? par metal 10-19112x 19 x 1.74' x11" deep looks like about $46.00
lets call it $100 (02-27-2005) so far if I have good prices and my math is right then the knobs and other parts like caps and resistors and the next high cost items the gain switch, inductors and the power supply.
Please give feedback! This might not be worth building if one can find real modules.
TomWaterman
Well-known member
[quote author="soundguy"]definitely an external powersupply. Id like to potentially build a mixer and dont need a power transformer in the box with my unshielded mix busses.[/quote]
This is where I'm heading as well......just leave power headers on the main boards which can be fed from internal or external PSUs.
Although not all of us are based in the US and can get hold of Par-Metal cases. I'll get dimensions for a bunch of diff cases so we can find a size that fits all. I see nothing wrong with a pair of eurocards like Jakob's CalrecEQ.
Well, I sort of agree - I like Brians suggestions for the front end, 12 pos gain and trims....but I don't think we can make it work with Lorlins without severe simplification.
NSF also do modular switches which are cheap, available from Farnell and flexible.
I really don't see the point in PCB mounting Lorlins though, its only a 'little' bit of P-to-P and shouldn't add drastically to the cost. The gain switch is most probably going to need to be something other than a Lorlin as they dont offer enough contacts. The project would still be affordable if it was Grayhill gain and Lorlin everything else.
If the inductor issue isn't sorted we cannot go any further with this than a micpre and to be fair there are loads of good micpre project here already. The EQ is the interesting part for me.
As a project it should be much cheaper than the 1081. 1081 uses loads more iron, complex concentric switches and original knobs that are very expensive.
However, the 1061 even with input and output iron plus a custom run of MF inductor would still be a considerable investment @ approx $150 of iron per channel. I don't think you could build a channel for less than $500 anyway you slice it, so its still a large investment of sorts.
Again a good reason not to mount the switches. Leave some degree of flexibility, mount resistors and headers on the PCBs. Wire the swithces up, this allows for front panel spacing. Important if you want to mount these in things other than a 1U rack. For example a 6U vertical rack cassette for a small mixer.....
I'm with you - this is the direction this should go in. Simplify the input section, use standard switches for the EQ section. Lets simplfy or get rid of the cut filters, I could do with just a low-cut (HPF), two positions.....lets do it to use Lorlins but not PCB mount them. Leave PSUs and regulators off board, mount the filter caps and discrete amps on the mainboard without the need for plugin modules.....they may prove problematic concerning vertical space and its one more PCB to get manufactured and pay for.
We can still use the original amp layout pattern for the mainboards......
The one reason I can see would be testing new gain blocks for other channels in one complete channel. Ideal if your building a 8ch mixer with these for example......although less of a problem if your just doing a couple of channels in a standard rack.
Also, I can't see how it makes it harder for newbies (like myself). Smaller board to concentrate on, easier to handle and less chance of soldering components into the wrong place. It wouldn't require expensive sockets and pins like the 990 opamps. The pins Brian found are cheap, available and should not add to the complexity.
Plugin modules would however add to the cost due to the PCB fabrication and are a potential issue for mounting problems and vertical space etc....
So I guess I agree - no plugin modules but keep a layout similar to the original at least.
We should spend some time going through the schematic and looking for points where it can be simplified, what the original requirements for the switches were etc.
Then we can put together a specification for the revised version. By that time hopefully we are further forward with the one 'real' problem - the inductor.
The small value inductor could probably be a TOKO or Wilco or something......47mH.
So far, we know we have the input transformer sorted, the active stages can be made, its just a case of format / layout, finding good supply of the semis. The switches need simplifying, the inductors are a real issue. I like Brians suggestions for the input switching....we know we can find suitable output iron.
Cheers Tom
This is where I'm heading as well......just leave power headers on the main boards which can be fed from internal or external PSUs.
Although not all of us are based in the US and can get hold of Par-Metal cases. I'll get dimensions for a bunch of diff cases so we can find a size that fits all. I see nothing wrong with a pair of eurocards like Jakob's CalrecEQ.
Well, I sort of agree - I like Brians suggestions for the front end, 12 pos gain and trims....but I don't think we can make it work with Lorlins without severe simplification.
NSF also do modular switches which are cheap, available from Farnell and flexible.
I really don't see the point in PCB mounting Lorlins though, its only a 'little' bit of P-to-P and shouldn't add drastically to the cost. The gain switch is most probably going to need to be something other than a Lorlin as they dont offer enough contacts. The project would still be affordable if it was Grayhill gain and Lorlin everything else.
If the inductor issue isn't sorted we cannot go any further with this than a micpre and to be fair there are loads of good micpre project here already. The EQ is the interesting part for me.
As a project it should be much cheaper than the 1081. 1081 uses loads more iron, complex concentric switches and original knobs that are very expensive.
However, the 1061 even with input and output iron plus a custom run of MF inductor would still be a considerable investment @ approx $150 of iron per channel. I don't think you could build a channel for less than $500 anyway you slice it, so its still a large investment of sorts.
Again a good reason not to mount the switches. Leave some degree of flexibility, mount resistors and headers on the PCBs. Wire the swithces up, this allows for front panel spacing. Important if you want to mount these in things other than a 1U rack. For example a 6U vertical rack cassette for a small mixer.....
I'm with you - this is the direction this should go in. Simplify the input section, use standard switches for the EQ section. Lets simplfy or get rid of the cut filters, I could do with just a low-cut (HPF), two positions.....lets do it to use Lorlins but not PCB mount them. Leave PSUs and regulators off board, mount the filter caps and discrete amps on the mainboard without the need for plugin modules.....they may prove problematic concerning vertical space and its one more PCB to get manufactured and pay for.
We can still use the original amp layout pattern for the mainboards......
The one reason I can see would be testing new gain blocks for other channels in one complete channel. Ideal if your building a 8ch mixer with these for example......although less of a problem if your just doing a couple of channels in a standard rack.
Also, I can't see how it makes it harder for newbies (like myself). Smaller board to concentrate on, easier to handle and less chance of soldering components into the wrong place. It wouldn't require expensive sockets and pins like the 990 opamps. The pins Brian found are cheap, available and should not add to the complexity.
Plugin modules would however add to the cost due to the PCB fabrication and are a potential issue for mounting problems and vertical space etc....
So I guess I agree - no plugin modules but keep a layout similar to the original at least.
We should spend some time going through the schematic and looking for points where it can be simplified, what the original requirements for the switches were etc.
Then we can put together a specification for the revised version. By that time hopefully we are further forward with the one 'real' problem - the inductor.
The small value inductor could probably be a TOKO or Wilco or something......47mH.
So far, we know we have the input transformer sorted, the active stages can be made, its just a case of format / layout, finding good supply of the semis. The switches need simplifying, the inductors are a real issue. I like Brians suggestions for the input switching....we know we can find suitable output iron.
Cheers Tom
ok, thats a lot to digest...
Gus, Im in the process of getting my hands on a real 1061 right now, if I wind up getting one, maybe we can trace it out together or something. This will be a lot easier to think about with the thing physically in front of us I think.
I would be well into making just the EQ but Im sure that you and me are probably the only people here to think like that. My approach to this is more of a line thing for mixing much more than as a mic pre. I dont want to distract the discussion too much with that though, Im pretty sure everyone interested would want to mic amp as well or instead of the EQ all together.
It would be nice to keep the EQ in/out switch, I actually use that all the time, easier than resetting everything...
I think if we do this right we could put two channels in a two space box for under $700. Thats a good point to shoot for at least. I think its possible if we are smart about it. At a price close to that all in, its very much worth doing IMO (assuming we can get it to sound good...)
dave
Gus, Im in the process of getting my hands on a real 1061 right now, if I wind up getting one, maybe we can trace it out together or something. This will be a lot easier to think about with the thing physically in front of us I think.
I would be well into making just the EQ but Im sure that you and me are probably the only people here to think like that. My approach to this is more of a line thing for mixing much more than as a mic pre. I dont want to distract the discussion too much with that though, Im pretty sure everyone interested would want to mic amp as well or instead of the EQ all together.
It would be nice to keep the EQ in/out switch, I actually use that all the time, easier than resetting everything...
I think if we do this right we could put two channels in a two space box for under $700. Thats a good point to shoot for at least. I think its possible if we are smart about it. At a price close to that all in, its very much worth doing IMO (assuming we can get it to sound good...)
dave
If running wire from the switch to the boards is OK. The cheap switches I found at mouser should work well.
Here is a big question, will it still have the enought of same sound with a different microphone pre section if we change it?
If EQ only do we want a 10K:10K input transformer?
Still need the to know what is going on on the other side of the connections noted above.
A 1u PCB idea is forming in my brain with no modules. I am even debating buying a PCB layout program.
How about a regulated supply on board with just the transformer mounted in another box, or a box with the transformer and diodes and first filter
cap stage so only dc comes to the unit?
EDIT the unit uses Si transistors. Hfe and power rating is all we basically need if we want to use other transistors. you have your high gain low noise ones like the MPSA18s and 2n5088 and lower gain higher Ic ones like the 2n4401s and 2n4403s etc.
I think getting the right film caps is going to be a big part of the sound.
Dave if you get one I will take a ride to look at it. Maybe even pull a few transistors and measure the gains.
FWIW the one thing that seems to matter in some Si transistor circuits is hfe and the Hfe vs Ic curves. Some transistors have flatter hfe Vs Ic curves than others and simple designs like the gain stages of this unit might be affected by it.
Here is a big question, will it still have the enought of same sound with a different microphone pre section if we change it?
If EQ only do we want a 10K:10K input transformer?
Still need the to know what is going on on the other side of the connections noted above.
A 1u PCB idea is forming in my brain with no modules. I am even debating buying a PCB layout program.
How about a regulated supply on board with just the transformer mounted in another box, or a box with the transformer and diodes and first filter
cap stage so only dc comes to the unit?
EDIT the unit uses Si transistors. Hfe and power rating is all we basically need if we want to use other transistors. you have your high gain low noise ones like the MPSA18s and 2n5088 and lower gain higher Ic ones like the 2n4401s and 2n4403s etc.
I think getting the right film caps is going to be a big part of the sound.
Dave if you get one I will take a ride to look at it. Maybe even pull a few transistors and measure the gains.
FWIW the one thing that seems to matter in some Si transistor circuits is hfe and the Hfe vs Ic curves. Some transistors have flatter hfe Vs Ic curves than others and simple designs like the gain stages of this unit might be affected by it.
TomWaterman
Well-known member
I would guess that the input TX is a big part of the sound and as Sowter can remake it, it seems sensible to use it.
So I guess keeping the micpre the same makes sense.
Forgive me if I understand this wrong but the TX can be wired for 1200ohm input and 10k input. I guess that way you have your line input sorted with this TX anyway?
Do you think you could just build a line input EQ (at the insert input point) with the same TX input?
Gus, really good to have your knowledge on this - I didn't realise the transistors could be replaced, do we need to do that for availability issues?
As for the external connections - maybe when Brian is less busy, he has some time to check his module out??
I like the idea of local PSU regulation onboard - like tommytones forssell opto boards...it might also make more sense if you were to try and build a small mixer out of these.
Does anyone know the brand of film caps used - the silver ones?
$700 for two in a box is a great price point - plus if enough people are interested, a group buy of the iron from sowter would reduce the costs. I wonder if there is a greater discount for 30+ 2318 TXs etc.
Cheers Tom
So I guess keeping the micpre the same makes sense.
Forgive me if I understand this wrong but the TX can be wired for 1200ohm input and 10k input. I guess that way you have your line input sorted with this TX anyway?
Do you think you could just build a line input EQ (at the insert input point) with the same TX input?
Gus, really good to have your knowledge on this - I didn't realise the transistors could be replaced, do we need to do that for availability issues?
As for the external connections - maybe when Brian is less busy, he has some time to check his module out??
I like the idea of local PSU regulation onboard - like tommytones forssell opto boards...it might also make more sense if you were to try and build a small mixer out of these.
Does anyone know the brand of film caps used - the silver ones?
$700 for two in a box is a great price point - plus if enough people are interested, a group buy of the iron from sowter would reduce the costs. I wonder if there is a greater discount for 30+ 2318 TXs etc.
Cheers Tom
gang of elk
Well-known member
speak o th' devil. there's a nice looking pr on ebay for a good price..
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=23792&item=7304386165&rd=1&ssPageName=WDVW
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=23792&item=7304386165&rd=1&ssPageName=WDVW
About that inductor, with work taking some unexpected turns I am out of the DIY loop for a bit. But if there is someone in the LA area I'll be over there working for the next forseeable future. If you have the test equipment to diagnose this inductor give me a hollar and we can measure this guy. If so give me a PM.
Gus, the x and y are connected to common. This completes the gain setting circuit. Why there on the edge connector I'm not sure.
Brian
Gus, the x and y are connected to common. This completes the gain setting circuit. Why there on the edge connector I'm not sure.
Brian
cannikin
Well-known member
I'm with Dave on this. I actually would like to build 8 or 12 channels of these Pres and EQ with external power supply.
Eventually I would love to adapt this into a summing mixer too, so it could be front end DAW and back end too. But I'm not thinking too hard about that now, I just want to get to a place with everyone else in the group so we can build these Units, Easily/Cost effectively without too much compromise of the sonic characters (I would like it to resemble the Calrec 1061).
Eventually I would love to adapt this into a summing mixer too, so it could be front end DAW and back end too. But I'm not thinking too hard about that now, I just want to get to a place with everyone else in the group so we can build these Units, Easily/Cost effectively without too much compromise of the sonic characters (I would like it to resemble the Calrec 1061).
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