mikeyB

Re: Roger Mayer RM57 build?
« Reply #320 on: February 02, 2019, 11:20:26 AM »
Do the FETs have to be matched? That is the audio FET and the meter FET.
Great sounding unit by the way
making better music!


RuudNL

Re: Roger Mayer RM57 build?
« Reply #321 on: February 03, 2019, 04:12:42 AM »
Yes, to obtain good stereo tracking, you should match the Fets. (Since there is no way to adjust the tracking.)
In my case, tracking is better than 0.5 dB over 20 dB gain reduction.
I found two pairs out of 20 Fets.
The meter tracking circuit should use Fets that have the same characterictic as the attenuator Fets.
So in an ideal case a 'matched quad'.  (Although a small difference isn't that critical in the meter circuit, but try to match them as good as you can.)
There is a solution for every problem!

http://www.vansteenisaudio.nl

mikeyB

Re: Roger Mayer RM57 build?
« Reply #322 on: February 03, 2019, 04:27:10 PM »
Thanks RuudNL
making better music!

RuudNL

Re: Roger Mayer RM57 build?
« Reply #323 on: February 04, 2019, 03:24:10 PM »
If there is a small tracking error, you can cheat a little and vary the value of R1 (18K) a little.
This way you can optimize small tracking errors!
There is a solution for every problem!

http://www.vansteenisaudio.nl

mikeyB

Re: Roger Mayer RM57 build?
« Reply #324 on: February 09, 2019, 10:44:35 AM »
Thankyou,
Probably my next project - I've got an albums worth of drums to squash!
making better music!

dmp

Re: Roger Mayer RM57 build?
« Reply #325 on: March 08, 2019, 11:12:53 AM »
Pcb print attached, happy new year yall!!!

Hi Spencer
Can you post the final schematic you used that corresponds to this layout?
I'd like a build an RM57... heard about it in a song exploder this morning with Butch Vig.

Any thought of making this into a 500 series version?

Spencerleehorton

Re: Roger Mayer RM57 build?
« Reply #326 on: March 08, 2019, 12:41:05 PM »
Hi DMP,

yeah this could easily be worked into a 500 series, I think RuulNL's version would be better as its a smaller footprint on the PCB.
I haven't printed out Ruul's version yet but will do it next week, just need to design the meter for it.
The schematic is per the original and I think I shared all info?
Let me know any help you need.
website: www.mohawkstudios.co.uk
email: [email protected]

If it hisses its probably the wrong impedance!!!
Or a snake!!!

dmp

Re: Roger Mayer RM57 build?
« Reply #327 on: March 08, 2019, 01:38:23 PM »
Yeah, but you posted several schematics so I wasn't sure which one was the final. the layout says V5 but I never saw a schematic with that in the name. If the last one was the final? "Schematic_RM58-Clone.sch_Sheet-1_20181123115959.pdf"

Not sure I followed everything but RuulNL's was a different "inspired from" design using opamps instead of discrete transistors

iampoor1

Re: Roger Mayer RM57 build?
« Reply #328 on: March 08, 2019, 05:48:14 PM »
Yeah, but you posted several schematics so I wasn't sure which one was the final. the layout says V5 but I never saw a schematic with that in the name. If the last one was the final? "Schematic_RM58-Clone.sch_Sheet-1_20181123115959.pdf"

Not sure I followed everything but RuulNL's was a different "inspired from" design using opamps instead of discrete transistors

+1

Im having a hrd time finding the verified working schematic. Can someone repost it, or link to the post its in? My brain is just not cooperating today.  ;D

Spencerleehorton

Re: Roger Mayer RM57 build?
« Reply #329 on: March 09, 2019, 12:46:30 PM »
I’ll sort this Monday for you.
website: www.mohawkstudios.co.uk
email: [email protected]

If it hisses its probably the wrong impedance!!!
Or a snake!!!


iampoor1

Re: Roger Mayer RM57 build?
« Reply #330 on: March 09, 2019, 12:47:24 PM »
I’ll sort this Monday for you.

Thanks! Super excited to buy one of these for 20$.....sure beats 8500$  ;D 8)

Spencerleehorton

Re: Roger Mayer RM57 build?
« Reply #331 on: March 09, 2019, 04:35:31 PM »
That’s exactly why I built it!!!
Easy enough to make the pcb, the design I’ve done could easily be made better, I was just in a rush so drew it out quickly, and at the time we weren’t sure it was correct.
I’ll put up all details of Psu as well.
website: www.mohawkstudios.co.uk
email: [email protected]

If it hisses its probably the wrong impedance!!!
Or a snake!!!

iampoor1

Re: Roger Mayer RM57 build?
« Reply #332 on: March 11, 2019, 07:40:49 AM »
That’s exactly why I built it!!!
Easy enough to make the pcb, the design I’ve done could easily be made better, I was just in a rush so drew it out quickly, and at the time we weren’t sure it was correct.
I’ll put up all details of Psu as well.

Great!

Spencerleehorton

Re: Roger Mayer RM57 build?
« Reply #333 on: March 12, 2019, 05:24:27 AM »
This is the schematic I did and used, transistor wise it didn't matter what i used i got the same result, BC550C, BC550B, 2N3391 or 2N5088.

For Q1 use PNP BC560c and for the FET's use the 2N3820, match them if you can.

The 4.7uf I used 6.8uf didn't seem to matter, everything else was as per original schematic.

Hope this helps and clears up any confusion, happy building.
website: www.mohawkstudios.co.uk
email: [email protected]

If it hisses its probably the wrong impedance!!!
Or a snake!!!

dmp

Re: Roger Mayer RM57 build?
« Reply #334 on: March 12, 2019, 10:11:45 AM »
Cool - thanks Spencer

Hummingwire

Re: Roger Mayer RM57 build?
« Reply #335 on: June 05, 2019, 06:15:53 AM »
I would be very interested in building a 500 version (either RM57 or RM58) as well!

Spencerleehorton

Re: Roger Mayer RM57 build?
« Reply #336 on: June 09, 2019, 04:32:02 AM »
Go for it and show us your build!!
website: www.mohawkstudios.co.uk
email: [email protected]

If it hisses its probably the wrong impedance!!!
Or a snake!!!

diggy fresh

Re: Roger Mayer RM57 build?
« Reply #337 on: June 20, 2019, 08:20:58 AM »
Hi Spencer,  thanks alot for the redrawn schematic. I want to try a layout but i'm a bit confused about how it goes together because nothing is labeled on your schematic.

Can you update it or tell us what the connection points are? That would be very appreciated. thanks
English is my second language, apologies

Autodidact audio geek, constantly learning.

Very interested in old technology, i mostly learn from the info you guys share on here, so thanks!

Fuzz Face

Re: Roger Mayer RM57 build?
« Reply #338 on: June 20, 2019, 08:47:18 AM »
Hi Spencer,  thanks alot for the redrawn schematic. I want to try a layout but i'm a bit confused about how it goes together because nothing is labeled on your schematic.

Can you update it or tell us what the connection points are? That would be very appreciated. thanks

I was trying to use that schem as well and all of the pots are shown wired as (fixed) resistors. I guess the wipers are supposed to tie to one of the outer lugs?

Spencerleehorton

Re: Roger Mayer RM57 build?
« Reply #339 on: June 25, 2019, 01:09:23 PM »
had a quick look, this should help, if it doesnt just look at the docs on the first few pages, you should be able to work it all out, I did!!
website: www.mohawkstudios.co.uk
email: [email protected]

If it hisses its probably the wrong impedance!!!
Or a snake!!!


 

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