Hi All
Starting to build this PMsix61 vari-gm limiter.
Based on the venerable original and using some design features and modules from Analag/Silent Arts PM660 limiter offerings.
Intended to step further towards the original 'brute force' approach with higher powered signal and sidechain amps.
The cathode bias will use either of the traditional arrangement for a 660 as well as a version of the PM660's flexible cathode-clamping. This feature was in my opinion a point of merit in the PM660 and as far as I am aware, novel to Analag's design.
Still done relatively 'poor' style that I have happily used a number of times - point-point on the top tray and pcb modules and other components inside. Standard 2RU rack suffices and the whole construction is about keeping to easily available stuff.
As you see it in the first pic, it is around 1000usd including all the tubes and everything with 200 of that in shipping down heeer in Hobart at the bottom of Australia.
I am replacing the little edcor with a utc shortly. Mostly for aesthetics
but also because sometimes I long for the luxuries in a transformer.
-----
I like to use a mix of Edcor/Hammond transformers and some exotic old old stock signal transformers where I can.
Mounted on an inexpensive 2RU, it is a single channel unit only, making construction somewhat more robust.
Tubes are also relatively low cost. Labelling panels is pretty basic stuff using Sifam printable film.
So - here is the start of the build. I hope describing it here motivates me to make a reasonably quick build which I can then use and observe whiles I optimises it.
A lot Nearly all of the information I'm talking about here is out there in the Poorman 660 Support Thread, Pimp our Poorman 660 and the myriad of Vari-Mu threads in general.
Its all out there
--------
First pic of my layout which I am marking for drilling and all that.
Will take a few daysand then a week or so for the front panel. (I hate hand filing those meter slots to size )
My style of construction is .. hasty at best and massively messy at worst.
Here I am keeping it 'simple' without too many bells and whistles in order to get reasonably robust and stable.
I'll be using it as a instrument limiter/compressor after a tube preamp channel of Orange 86+eq+drive.
The sorts of figures I want to achieve are improvements such as few dBs better noise floor, a few dBs higher output, a percent and a half better THD and certainly doing something with the high IMD issues, as discussed by Kingston in some detail in his postings. Also, a few more dBs GR available. And hopefully, achieving a slightly smoother, less grainy audio quality.
I've used all these parts in other projects and they represent the best mix of performance, cost and character I can come up with.
Time will tell!
--------------------
My reason for doing this one is that I very much admire the Poorman 660 design as well as the predessor designs too.
Apart from improved construction values, I am trying to get a stronger level from the signal amp and a more brutish level out of the sidechain amp for the option of original-like constants as well as some more general constants.
It will be interesting to note the effect of the transformer choices too.
All that in a context of applying some tube matching spells as well as ironing out some build mismatches which bring down my original PM670 a little bit.
Lowering THD under GR and examining issues relating to IMD are relatively new a concern for me.
-------
All that IFF it works! ;D
Starting to build this PMsix61 vari-gm limiter.
Based on the venerable original and using some design features and modules from Analag/Silent Arts PM660 limiter offerings.
Intended to step further towards the original 'brute force' approach with higher powered signal and sidechain amps.
The cathode bias will use either of the traditional arrangement for a 660 as well as a version of the PM660's flexible cathode-clamping. This feature was in my opinion a point of merit in the PM660 and as far as I am aware, novel to Analag's design.
Still done relatively 'poor' style that I have happily used a number of times - point-point on the top tray and pcb modules and other components inside. Standard 2RU rack suffices and the whole construction is about keeping to easily available stuff.
As you see it in the first pic, it is around 1000usd including all the tubes and everything with 200 of that in shipping down heeer in Hobart at the bottom of Australia.
I am replacing the little edcor with a utc shortly. Mostly for aesthetics
but also because sometimes I long for the luxuries in a transformer. -----
I like to use a mix of Edcor/Hammond transformers and some exotic old old stock signal transformers where I can.
Mounted on an inexpensive 2RU, it is a single channel unit only, making construction somewhat more robust.
Tubes are also relatively low cost. Labelling panels is pretty basic stuff using Sifam printable film.
So - here is the start of the build. I hope describing it here motivates me to make a reasonably quick build which I can then use and observe whiles I optimises it.
Its all out there
--------
First pic of my layout which I am marking for drilling and all that.
Will take a few days
)My style of construction is .. hasty at best and massively messy at worst.
Here I am keeping it 'simple' without too many bells and whistles in order to get reasonably robust and stable.
I'll be using it as a instrument limiter/compressor after a tube preamp channel of Orange 86+eq+drive.
The sorts of figures I want to achieve are improvements such as few dBs better noise floor, a few dBs higher output, a percent and a half better THD and certainly doing something with the high IMD issues, as discussed by Kingston in some detail in his postings. Also, a few more dBs GR available. And hopefully, achieving a slightly smoother, less grainy audio quality.
I've used all these parts in other projects and they represent the best mix of performance, cost and character I can come up with.
Time will tell!
--------------------
My reason for doing this one is that I very much admire the Poorman 660 design as well as the predessor designs too.
Apart from improved construction values, I am trying to get a stronger level from the signal amp and a more brutish level out of the sidechain amp for the option of original-like constants as well as some more general constants.
It will be interesting to note the effect of the transformer choices too.
All that in a context of applying some tube matching spells as well as ironing out some build mismatches which bring down my original PM670 a little bit.
Lowering THD under GR and examining issues relating to IMD are relatively new a concern for me.
-------
All that IFF it works! ;D
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