the 1954 Limiter!!

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davemascera

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scott2000 said:
You're not the Dave from M>D> are you???

Umm I mean my band is called Moa Desert. I'm not sure if that's what you mean. We have like 20 fans or something and haven't released anything since 2015 and are going to call it quits after this upcoming album.
 

davemascera

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scott2000 said:
I thought so....
You guy's are crazy good!

That Seal cover is insane

thanks man... that drummer isn't the same one still in our band

hope you like our new stuff cause it's the last we're doing... gonna sell all the equipment we have after this too lol.

recorded a bit with this limiter to a track and it really couldn't fit better.. i'll post a clip next week.
 

opacheco

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DaveP said:
......A Fairchild for example has an output resistance of 100 ohms before its diodes, which enables its speed to get down to uS........

Dave, How I can get this figure from the Fairchild Schematics??

DaveP said:
I would try losing the 10k's and putting in two cathode followers from another tube to drive the 6AL5, this would take the source resistance down to around 250 ohms.

I thought the same, two catodes followers and a I Solid State Diodes Bridge instance the 6LA5 will give us a very low charging times value like the Fairchild configuration!!

Opacheco.
 

davemascera

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It's looking sorta uncertain that we're ever finishing this album so i'll just post a sample of when this compressor sounds like on a vocal chain, cause I always intended to once we finished...

https://drive.google.com/file/d/1y4UiBnp1ag0ePHMRVm6zvwlXkT65ayF8/view?usp=sharing

There's no EQ... just MK47 to this compressor onto some tape.
 

opacheco

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davemascera said:
It's looking sorta uncertain that we're ever finishing this album so i'll just post a sample of when this compressor sounds like on a vocal chain, cause I always intended to once we finished...

https://drive.google.com/file/d/1y4UiBnp1ag0ePHMRVm6zvwlXkT65ayF8/view?usp=sharing

There's no EQ... just MK47 to this compressor onto some tape.

Dave, it is really awesome!!....did you used the original 1964 schematic for?

opacheco
 

davemascera

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opacheco said:
Dave, it is really awesome!!....did you used the original 1964 schematic for?

opacheco

I used the one I posted. The biggest difference was that I changed the release/attack pots as suggested
 

Stevie342000

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I used the one I posted. The biggest difference was that I changed the release/attack pots as suggested
I have had the original magazine for many years, never got around to building it but it is on my to do list.

I recently discovered this thread and it has reignited my interest.

To save time could some one condense the changes that were made and why?
Is there a modified schematic?
What transformers were used?

Why were the changes made?
How does it improve on the original?
Thanks
 

mjrippe

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I have had the original magazine for many years, never got around to building it but it is on my to do list.

I recently discovered this thread and it has reignited my interest.

To save time could some one condense the changes that were made and why?
Is there a modified schematic?
What transformers were used?

Why were the changes made?
How does it improve on the original?
Thanks

I think that someone should be you, Stevie :). GroupDIY is an excellent place to read and learn. All your questions will be answered in the thread and the reasons behind them explained. "Saving time" may actually be against your best interests when it comes to building something from scratch.
 

Stevie342000

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I think that someone should be you, Stevie :). GroupDIY is an excellent place to read and learn. All your questions will be answered in the thread and the reasons behind them explained. "Saving time" may actually be against your best interests when it comes to building something from scratch.
Yes I have read it but unfortunately it is long and convoluted, what you are suggesting is the get out. The reason I suggested it is that if it could be condensed as to why those modifications were done it would save me time in having to re-read it for a 3rd time and anyone else that comes after me.

It may help to server others that follow that is why I suggested it, it was not the case of laziness on my part, I was hoping that if it could be done then it might help to consolidate the reasons in my mind, as I am not convinced of why the modifications were made and if or how they would benefit me.

When I get around to building it and do the modifications does that make it more flexible in the modern environment bearing in mind that I am going to be using it to cut records.

I have a mono AR Sugden (Connoisseur) cutting lathe well two actually one with the original head the other with a Presto 1=D.

Does that help to make it clearer the reason I am asking is does it fit my needs modified or unmodified.
As the other option is Nu Federal 864U which I have read more than once as well.

Why do I want to cut disk because I can and it has been a passion that I have wished to follow since my teenage years. Plus I have a cutting studio within 0.5 miles of my home.

I have after years narrowed after years of research what system I can afford to build and I understand how each part works, it has been a mammoth task.

The other option is Fairchild 604 Conax Limiter which was designed for cutting disk or limiting in FM broadcasting and is what we would call de-esser these days.

So could somebody condense it for me, as the other option is for me to use it for its original design to cut those pesky adverts on my Living Room System when watching TV where to hear the program you have to have the volume to then get blasted out by the adverts and not in the Man Cutting Cave system.
 

davemascera

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Yes I have read it but unfortunately it is long and convoluted, what you are suggesting is the get out. The reason I suggested it is that if it could be condensed as to why those modifications were done it would save me time in having to re-read it for a 3rd time and anyone else that comes after me.

It may help to server others that follow that is why I suggested it, it was not the case of laziness on my part, I was hoping that if it could be done then it might help to consolidate the reasons in my mind, as I am not convinced of why the modifications were made and if or how they would benefit me.

When I get around to building it and do the modifications does that make it more flexible in the modern environment bearing in mind that I am going to be using it to cut records.

I have a mono AR Sugden (Connoisseur) cutting lathe well two actually one with the original head the other with a Presto 1=D.

Does that help to make it clearer the reason I am asking is does it fit my needs modified or unmodified.
As the other option is Nu Federal 864U which I have read more than once as well.

Why do I want to cut disk because I can and it has been a passion that I have wished to follow since my teenage years. Plus I have a cutting studio within 0.5 miles of my home.

I have after years narrowed after years of research what system I can afford to build and I understand how each part works, it has been a mammoth task.

The other option is Fairchild 604 Conax Limiter which was designed for cutting disk or limiting in FM broadcasting and is what we would call de-esser these days.

So could somebody condense it for me, as the other option is for me to use it for its original design to cut those pesky adverts on my Living Room System when watching TV where to hear the program you have to have the volume to then get blasted out by the adverts and not in the Man Cutting Cave system.
The attack circuit and release circuit were added to give the user the ability to modify how long it takes for the compression effect to entirely engage and disengage. There is a second release included in the original schematic which a switch was added to to give the user the option to eliminate.

An output section is necessary for this circuit because it is rather quiet, esp after compression reduces output. The Federal AM864 output stage was strapped on to the end of this circuit in the modified schematic (and in a couple cases it almost still doesn't produce a loud enough signal). Cathode and grid resistor modifications were done for biasing purposes. Exact values will vary entirely depending upon the specific tube you plug in, but in some cases (such as the push-pull output) a pot was used to make it easier to balance the output for cancellation.

The T-Pad at the end of the circuit was obviously included to reduce volume if necessary while retaining the correct impedance. The pad at the beginning of the circuit serves the same purpose.

Because there was an output stage added I used the A18 interstage transformer instead of the one in the original circuit. This may be unnecessary, but seemed like a pretty easy way to guarantee the modification would work. One of the more experienced members can clarify. Edcors were used on input and output. The exact models are listed in the modified schematic.

There is now a meter strapped to the cathodes of the vari-mu tubes. That modification was made because it's beneficial to see how hard the compressor is working, obviously. This is switched so you can use it while testing levels and then switch it off during actual use in case you are paranoid of distortion.

Lastly, the regulator tube had a bad value in the original schematic and a heat tolerant resistor of higher value needed to be used in order for other measurements to make sense.

The power supply I included in the modified schematic was my own design. In retrospect, I would not choke it if you are going to use edcors, but I was able to find a layout that worked.

A lot of my modifications were done using spare parts to save money and this project totaled out to about 300 dollars.

It works wonderfully on individual tracks in recording, but I would not use it on a master track as it is not fast enough. You'd need to implement the cathode follower circuit suggested by the other (more important) Dave in order to gain enough speed.

The modified schematic is in the thread, but not accurate to the final build. Luckily, all changes were written in text in the thread clearly and plainly.
 
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Stevie342000

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The attack circuit and release circuit were added to give the user the ability to modify how long it takes for the compression effect to entirely engage and disengage. There is a second release included in the original schematic which a switch was added to to give the user the option to eliminate.

An output section is necessary for this circuit because it is rather quiet, esp after compression reduces output. The Federal AM864 output stage was strapped on to the end of this circuit in the modified schematic (and in a couple cases it almost still doesn't produce a loud enough signal). Cathode and grid resistor modifications were done for biasing purposes. Exact values will vary entirely depending upon the specific tube you plug in, but in some cases (such as the push-pull output) a pot was used to make it easier to balance the output for cancellation.

The T-Pad at the end of the circuit was obviously included to reduce volume if necessary while retaining the correct impedance. The pad at the beginning of the circuit serves the same purpose.

Because there was an output stage added I used the A18 interstage transformer instead of the one in the original circuit. This may be unnecessary, but seemed like a pretty easy way to guarantee the modification would work. One of the more experienced members can clarify. Edcors were used on input and output. The exact models are listed in the modified schematic.

There is now a meter strapped to the cathodes of the vari-mu tubes. That modification was made because it's beneficial to see how hard the compressor is working, obviously. This is switched so you can use it while testing levels and then switch it off during actual use in case you are paranoid of distortion.

Lastly, the regulator tube had a bad value in the original schematic and a heat tolerant resistor of higher value needed to be used in order for other measurements to make sense.

The power supply I included in the modified schematic was my own design. In retrospect, I would not choke it if you are going to use edcors, but I was able to find a layout that worked.

A lot of my modifications were done using spare parts to save money and this project totaled out to about 300 dollars.

It works wonderfully on individual tracks in recording, but I would not use it on a master track as it is not fast enough. You'd need to implement the cathode follower circuit suggested by the other (more important) Dave in order to gain enough speed.

The modified schematic is in the thread, but not accurate to the final build. Luckily, all changes were written in text in the thread clearly and plainly.
thanks Dave I was memory checking to make sure that I had understood how all the mods came together and that nothing had changed much in the meantime that I had missed.
 

MidnightArrakis

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Here's a scheme. I drew it like a kindergartener because that's about where my drawing ability is at.

The scan cut off at the bottom so I had to photoshop in a chassis ground symbol. I also erased some of my mistakes.

Some things to note.. I don't know what the nominal secondary of my power transformer is... I'm guessing it's 300-and-something volts to each side.

Also, I haven't actually tested a .5 ma meter so keep that in mind. It just seems pretty likely it will work.

Last thing is that it's been brought up that my 'attack' adjustment doesn't make sense. It's the 250k dual gang pot near the 6AL5. It definitely does something but I have yet to verify that it actually slows the attack whilst allowing the eventual gain reduction to be expectedly sizable. It definitely reduces gain reduction at least a little. I know that much. I'll do some tests and figure it out.

I've been sick so I haven't gotten the chance to go back into the studio. But I'll get some A-B's in. If anyone has a preferred way to do it let me know. I'll probably just do what's easiest otherwise even if that means singing separate takes. I'm rather good at repeating.
I completely re-drew your "1954 Limiter" schematic using my CAD-design schematics program (CADENCE/OrCAD "PCB Editor" Release 17.4). Granted, my schematic version is much larger than your hand-drawn one, but that is because CAD-programs work by being on a grid and hand-drawn is a "whatever" grid!!! However, should you wish to do so.....you can use my CAD-generated schematic to also design a PCB of this limiter, which I think would be a really cool thing to do!!! NOTE: There are some areas of my schematic which are drawn differently than yours, but this was done either for clarification purposes or because the CAD schematic symbols come - fixed - as being a certain way and are simply "different" than how you had manually hand-drawn them.

In any case.....please review my version of your schematic and see if I have everything in there that needs to be in there and that everything that is in there is also connected up correctly. There were a couple of areas that I found very difficult to read and/or decipher in your hand-drawn version, so let me know if everything that I have re-drawn is OK.....OK??? THANKS!!! You can reach me directly here, should you have any additional new information or updates: [email protected]

/
 

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opacheco

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I completely re-drew your "1954 Limiter" schematic using my CAD-design schematics program (CADENCE/OrCAD "PCB Editor" Release 17.4). Granted, my schematic version is much larger than your hand-drawn one, but that is because CAD-programs work by being on a grid and hand-drawn is a "whatever" grid!!! However, should you wish to do so.....you can use my CAD-generated schematic to also design a PCB of this limiter, which I think would be a really cool thing to do!!! NOTE: There are some areas of my schematic which are drawn differently than yours, but this was done either for clarification purposes or because the CAD schematic symbols come - fixed - as being a certain way and are simply "different" than how you had manually hand-drawn them.

In any case.....please review my version of your schematic and see if I have everything in there that needs to be in there and that everything that is in there is also connected up correctly. There were a couple of areas that I found very difficult to read and/or decipher in your hand-drawn version, so let me know if everything that I have re-drawn is OK.....OK??? THANKS!!! You can reach me directly here, should you have any additional new information or updates: [email protected]

/
I think we need to add one ground connection in the side chain tube rectifier/time network. Please check my attached pic.

opacheco
 

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opacheco

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Not sure if I am missing something but I could not see where Bal 1 & Bal 2 went either
It seems to me, without this ground connection, the control voltage processed by the timing network, doesn’t been referenced to ground (it will be like a floating voltage) and this don’t control the grid of the 6SK7 Mu valves.

Please check that!
opacheco
 

MidnightArrakis

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Opacheco & Stevie: "THANK YOU!!", Gentlemen.....for your valuable input. I really do appreciate it!!!

Opacheco -- I have added a "GND" connection symbol at the bottom of C14, taking that whole connection line to "GROUND"!!!

Stevie -- BAL1 & BAL2 located in the lower-left of the schematic is shown being connected to "BAL1 & BAL2" in the upper-right hand corner of the schematic on T2 and its third secondary of 6.3VAC. Perhaps to better understand this, look at the original hand-drawn schematic. The original schematic shows the 5Y3 tube and to its left is a transformer with 3 secondaries, the bottom one shows 6.3VAC with a hand-note saying "To balance circuit". Immediately above the GBU4005 Bridge-Rectifier are a couple of resistors with arrows pointing to the right, with a note that says, "To AC Heater 6.3V". Since the schematic itself isn't explicitly clear and since there weren't a whole lot of left-over options, I then - deduced - that these two points connected up together. If I'm wrong, just let me know how things are "supposed" to be and I will update the schematic. NOTE: Since I do not know you or your background and just in case you are not aware of how electronic schematics work.....the symbols I have used and their labels ( BAL1 BAL2 ), along with all of the vacuum tube heater connections ( HTR1 HTR2 ), are electrically connected - internally - within the software. However, when the data is generated for the PCB design, a physical "rats-nest" connection will be shown on-screen between all of these common-named points. That's how CAD schematic and PCB design programs work.

NOTE: As I have browsed through this thread I have seen that there have been several different modifications and updates to various points within this schematic overall. If someone could be so kind and provide me a consolidated list of - ALL - of the modifications and updates, I would appreciate it. Then, I will update the entire schematic will ALL of the changes all at one time. Sound like a plan???

Also, since this is a - limiter - circuit, I believe it is important that all of the pots are labeled with their "taper" (audio/linear/log). If someone can provide me with that information, I will then also include that information into the schematic.

So.....who's into wanting to actually build this circuit??? RAISE YOUR HANDS!!!

/
 

MidnightArrakis

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OOPS!!! I got a phone call while I was typing my previous response and I forgot to attach my updated schematic!!! Please find it here. THANKS!!!

/
 

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