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Mixer mod
Old 26th February 2019
  #31
Lives for gear
 
Brian M. Boykin's Avatar
Quote:
Originally Posted by Transmutant View Post
Maybe it's a complete waste of time. Maybe it's not.
Chalk it up to education no matter the results and then it’s not a waist of time. And once you own a piece of gear it’s yours to do with as you please. This idea we should not try to improve on a design is foreign to me. Manufacturers have revised versions of most of the gear I’ve purchased and played with so even they saw room for improvement. Good luck and keep us posted.

Brian
Old 26th February 2019
  #32
Gear Maniac
 
Bart Nettle's Avatar
Awesome project! That it is possible to upgrade older mixers and you have the skill is a good reason to do it! Should make it a more musical sounding mixer!
PSU upgrade is a big plus for using all channels cleaning up the headroom. But 8 channels of summing shouldn't be too much of a current draw.
Looking forward to your success with it.
Old 26th February 2019
  #33
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ruffrecords's Avatar
Quote:
Originally Posted by Transmutant View Post
Ok, I ordered 2x A187A11C transformers. They were 87€ including shipping. Not the cheapest but the price drops 5€/per transformer when buying more than 10pcs + free shipping over 100€ pucrhases. I did a quick summary (schematic) based on Ians great help. This what I'm starting with and will see how it goes. Maybe it's a complete waste of time. Maybe it's not.
87 Euros for two good mic transformer is relatively cheap. I just purchased 4 Jensen mic transformers and total cost inducing shipping and import duty came to £300 which is £75 per transformer.

Your schematic is basically right except the capacitors should be on the secondary side. They are not needed on the primary side because the phantom power should be fed via precision resistors so there will be no voltage across the primary even when a phantom powered mic is in use. However, the bias current into each input of the op amp could vary by an unknown amount so there could be dc voltage across the secondary winding so that is where you need the capacitors.

Cheers

Ian
Old 26th February 2019
  #34
Gear Maniac
Quote:
Originally Posted by ruffrecords View Post
87 Euros for two good mic transformer is relatively cheap. I just purchased 4 Jensen mic transformers and total cost inducing shipping and import duty came to £300 which is £75 per transformer.

Your schematic is basically right except the capacitors should be on the secondary side. They are not needed on the primary side because the phantom power should be fed via precision resistors so there will be no voltage across the primary even when a phantom powered mic is in use. However, the bias current into each input of the op amp could vary by an unknown amount so there could be dc voltage across the secondary winding so that is where you need the capacitors.

Cheers

Ian
You are right and it still goes to show are they any good.

Ok, I will move the caps on the secondary side. I will actually use the original 47uf caps, just move them on the additional board with the transformer. I gather they will still be part of a LC cirquit with the secondary coils but what I calculated the combination of 2x 2.82 with 23.5uf bipolar is 13Hz, should not be audible.

I'll add a bypass switch so the transformer can be taken out for the initial tests for true same channel A/B testing.

Thanks!
Old 26th February 2019
  #35
Gear Maniac
Ok, that was pretty fast. RS package just arrived with the 2 I ordered yesterday evening. I also got these vintage Lundahl transformers. I will be using the 1:1 mainly for the stem tracks coming from PC but they could work as insertable tone modules when recording mono tracks. Would the 30k:30k also work for line level colouring?
Attached Thumbnails
Mixer mod-img_20190226_170424__01.jpg  
Old 26th February 2019
  #36
Lives for gear
 
Brian M. Boykin's Avatar
I’m gonna suggest you start a build thread titled “Soundtracs (insert model #) build thread.” I did this with mine and it helps others find the thread rather than it being buried in this one. I have found lots of useful info about other gear buried in threads but it’s not an ideal way to find it. This is useful information for anyone wanting to learn and apply it to their own builds.

Brian
Old 26th February 2019
  #37
Gear Maniac
Quote:
Originally Posted by Brian M. Boykin View Post
I’m gonna suggest you start a build thread titled “Soundtracs (insert model #) build thread.” I did this with mine and it helps others find the thread rather than it being buried in this one. I have found lots of useful info about other gear buried in threads but it’s not an ideal way to find it. This is useful information for anyone wanting to learn and apply it to their own builds.

Brian
Thanks for the tip. I will try to read what you did to yours. Should the new thread be under geekslutz?
Old 26th February 2019
  #38
Old 26th February 2019
  #39
Lives for gear
 
Brian M. Boykin's Avatar
Quote:
Originally Posted by Transmutant View Post
Thanks for the tip. I will try to read what you did to yours. Should the new thread be under geekslutz?
I did mine under Gearslutz. “Soundcraft 400b Build” is the title if I remember correctly. It didn’t get a lot of attention but that wasn’t the goal. Just wanted to leave an accessible reference to others.

Brian
Old 26th February 2019
  #40
Lives for gear
 
Brian M. Boykin's Avatar
Quote:
Originally Posted by Jim Williams View Post
Got test gear?
I’m pretty sure you know the answer to this. I think an oscope, a multimeter and software analyzers is what you can expect from us amatures. An Audio Precision is not practible. Like I’ve said many times, I send my gear off to you when I want it to go from a Volkswagen to a Top Fuel Dragster. I have another Aphex 651 that’s gonna visit you as well as a Compellor and two more Symetrix sx202’s. Not sure when, but they will make it your way.

Brian
Old 26th February 2019
  #41
Gear Maniac
Quote:
Originally Posted by Jim Williams View Post
Got test gear?
I got the basics: analog oscilloscope, multimeter and pc SW. I can borrow freq generator and a digital 4 channel oscilloscope, but nothing more.

What kind of setup should I have?
Old 26th February 2019
  #42
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Radardoug's Avatar
 

Transmutant, if you really want to learn you should go away and spend the next year studying transformers. People like Deane Jensen and Brian Sowter have devoted most of their lives to studying them. I get the feeling you know very little about them, and are relying on the usual Gearslutz misinformation to arrive at your conclusions. I'm not trying to be nasty, just suggesting a course of action that will produce results.
And I note you completely dismissed my suggestion that the source is the most important thing in recording.
Old 26th February 2019
  #43
Lives for gear
 
Brian M. Boykin's Avatar
Quote:
Originally Posted by Radardoug View Post
And I note you completely dismissed my suggestion that the source is the most important thing in recording.
This IS the most important part and why I’ve gone the transparency route. It’s my job to capture the performance as the artist gives it. When my gear ruins it or colors it I have a problem. When people describe gear as “neutral and does it’s job and you don’t know it’s there” I get interested. If a piece adds anything it better be depth and texture, not sonic color. You only need enough transparent gear to get the job done, not endless pieces of gear to achieve this or that sound. That’s the job of the musician and their gear/voice.

See, we agree on something. I’m liking you more and more.

Peace,

Brian
Old 26th February 2019
  #44
Gear Maniac
Quote:
Originally Posted by Radardoug View Post
And what you should bear in mind is:
If your source is good, your recording is good. If your source is crap, your recording is crap. The sound of the source is THE MOST important part of this equation. Gear is secondary.
You have a point here, but I feel the comment falls into the same category with the "there shouldn't be anything between an electric guitar and amp". Some people do not need anything, some people everything. I believe there's room for everyone. Or maybe not in Gearslutz?

I've been recording over 25years and I feel I am in a point in my life I want something other than what I have been hearing with the gear I have or have had. Funny you have a case against my postings. Am I taking room from other posts? Is there a level of professionalism required to be valid for participating?

I think all this slashing out is a cliche, ask yourself why you have to push your dogmas on other. Why only use what you got? "Shut up and make the best with what you got, why slice cabinet speakers to get distortion, why use tubes when transistors are better..."

Why do I need to go away for a year? So I do not ask anything? If everyone knew everything no one would have to ask anything... Or am I just asking the wrong questions? I don't want to dedicate my life solely to transformers like someone else has done and start a company that produces transformers. I just want to mod some gear. Why is it bugging you so much?
Old 26th February 2019
  #45
Lives for gear
 
Radardoug's Avatar
 

Actually, I'm not lashing out at you, I am trying to educate you. You dont have to go away for a year, you need to spend the time studying transformers so you can understand what they do. By all means stay on Gearslutz. I would not attempt to be a brain surgeon without studying in depth. This is the same thing. It fascinates me that many Slutz think they can easily improve designs that some designer spent years on, and they can do it in 10 minutes.
Old 26th February 2019
  #46
Gear Maniac
Quote:
Originally Posted by Brian M. Boykin View Post
This IS the most important part and why I’ve gone the transparency route. It’s my job to capture the performance as the artist gives it. When my gear ruins it or colors it I have a problem. When people describe gear as “neutral and does it’s job and you don’t know it’s there” I get interested. If a piece adds anything it better be depth and texture, not sonic color. You only need enough transparent gear to get the job done, not endless pieces of gear to achieve this or that sound. That’s the job of the musician and their gear/voice.

See, we agree on something. I’m liking you more and more.

Peace,

Brian
I believe some gear to be musical and others not so much. My Soundtracs is not a musical mixer as is. It's not because the instruments are not good sounding, not because the people I play with do not know how to play, not because I have poor microphones, not because the songs are not exiting. It's just plain sounding, it does not reproduce the instruments in a flatteting way. Everything sound a bit down scaled and less vivid. This is why it was retired. I felt it was not doing the music justice and I was not serving other people well with that piece of gear. Now I want it to have another chance, that's all.
Old 26th February 2019
  #47
Gear Maniac
Quote:
Originally Posted by Radardoug View Post
Actually, I'm not lashing out at you, I am trying to educate you. You dont have to go away for a year, you need to spend the time studying transformers so you can understand what they do. By all means stay on Gearslutz. I would not attempt to be a brain surgeon without studying in depth. This is the same thing. It fascinates me that many Slutz think they can easily improve designs that some designer spent years on, and they can do it in 10 minutes.
I don't believe I can improve it in 10 minutes. I believe it's a long and rocky road but I feel it's worth it because I have a gut feeling there's something to it... I am willing to admit it was a waste of time and I was wrong, but I have to test it first and have something as a result.

Like the house I live in, I have been renovating it from 2010. Done most work myself, lots of blood and sweat. Somethings two times to get it right. There were times I hated the house, it was taking all my time and money.

Now I love the house. Have given it a new life and in return it has taught me so much. Yes I was naive going in to it and yes it would have been easier and sometimes cheaper to build one from scratch. But is that what life is about?
Old 26th February 2019
  #48
Lives for gear
 
Brian M. Boykin's Avatar
Quote:
Originally Posted by Transmutant View Post
I believe some gear to be musical and others not so much. My Soundtracs is not a musical mixer as is. It's not because the instruments are not good sounding, not because the people I play with do not know how to play, not because I have poor microphones, not because the songs are not exiting. It's just plain sounding, it does not reproduce the instruments in a flatteting way. Everything sound a bit down scaled and less vivid. This is why it was retired. I felt it was not doing the music justice and I was not serving other people well with that piece of gear. Now I want it to have another chance, that's all.
I get this and I’m with you 100%. I have a Soundcraft and they get no love on these pages. We’re at a point in recording that to be “analog worthy” it has to be a Neve, MCI, SSL, API, etc.... otherwise, it’s better to be ITB. Meanwhile, I had a band here at my “home studio” auditioning me for a reunion album. They were blown away at how good the recordings sounded. The drummer straight up told me before the session, “I’m considering this a demo session.” After he heard the first recording played back his mood totally changed and he was excited. He couldn’t believe how good his kit sounded. He’s recorded many albums with several different bands in both Austin and San Antonio Tx. One album in LA in the early 90’s. They ultimately didn’t go with me and I never got the reason but everyone in the band considered my setup a serious contender. It’s all modded no love on Gearslutz gear. I do have what I call musical gear, but I believe it to add depth, texture and gives the music a 3D feel. You can picture the band on stage because of the sound stage. I see music as much as I hear it if that makes since. When I see that golden weathered hazy music thatbis vailed I want to clear it up into vibrant metallic iodized colors.

Long reply to say I get it,

Mod away brother,

Brian
Old 26th February 2019
  #49
Gear Maniac
Quote:
Originally Posted by Brian M. Boykin View Post
I get this and I’m with you 100%. I have a Soundcraft and they get no love on these pages. We’re at a point in recording that to be “analog worthy” it has to be a Neve, MCI, SSL, API, etc.... otherwise, it’s better to be ITB. Meanwhile, I had a band here at my “home studio” auditioning me for a reunion album. They were blown away at how good the recordings sounded. The drummer straight up told me before the session, “I’m considering this a demo session.” After he heard the first recording played back his mood totally changed and he was excited. He couldn’t believe how good his kit sounded. He’s recorded many albums with several different bands in both Austin and San Antonio Tx. One album in LA in the early 90’s. They ultimately didn’t go with me and I never got the reason but everyone in the band considered my setup a serious contender. It’s all modded no love on Gearslutz gear. I do have what I call musical gear, but I believe it to add depth, texture and gives the music a 3D feel. You can picture the band on stage because of the sound stage. I see music as much as I hear it if that makes since. When I see that golden weathered hazy music thatbis vailed I want to clear it up into vibrant metallic iodized colors.

Long reply to say I get it,

Mod away brother,

Brian
There is so much truth in what you say. When I started recording I did also think too many times "just a demo session". What you don't count for is the magic of the moment, the feel. Though done later with better gear will never have the same feel. Therefore all sessions should be tracked as they would be the real deal. That is why the gear you record it with has to be 'good enough', it does not have to be Neve or API. The difference between good and great is not so big it could not be used. It's harder to make poor sound good than good great.

This 3 dimensionality is also what I'm chasing. It's a feeling rather than a scientific list of specs and atributes. There are known elements that give that dimensionality. When I was studying music technology 15 years ago, the school studio had HUGE 48+ channel D&R desk and 24 track 'top of the line" tape machine. I loved the sound of that combination, but could never ever in my life get something like that for my small home studio. I can't afford those or even Anamod or Neve tape emulators. I have to chase the sound from more affordable solutions.

I'm just trying to achieve level of 'good enough' and focus on never having to settle for OK'ish because the gear was the weekest link.
Old 26th February 2019
  #50
Lives for gear
 
Brian M. Boykin's Avatar
I just bought an MCI JH16. A 1977. Has all the transformers. 16 and 24 track heads. Obviously this is not a transparency piece, but I’ve always wanted one and this one was in my ballpark. After I finish my console I’m starting in on it. It’s getting recapped. No intentions of swapping op amps. Just a complete restoration back to spec. It’s sole purpose is that 2” analog tape sound when I want it. No matter the end result, I’m gonna learn and I’ll be a better engineer because of it. I have an Otari MTR10 and an MCI JH110B. Based on what those do I think I’m gonna be happy with the end result.

Brian
Old 27th February 2019
  #51
Gear Maniac
[QUOTE=Radardoug;13834577]It fascinates me that many Slutz think they can easily improve designs that some designer spent years on/QUOTE]

I do not think this is the case most of the time, even with Soundtracs. I don't believe Soundtracs have thought this for years. It's fairly simple design, build around that SSM Chip. Transformers are costly, like we all know well, so that is why parts like that are usually dropped first and the design is take towards cheaper options.

There was a time (and still is) around the creation of this Topaz series desk that people thought 'the cleaner the better'. Now what this means to different people is how they see it. I also do not want smear of cut any frequency (high or low) because I had just put a tranny in the chain in hopes of sweet delight.

When playing back I never hear instruments as they were sounding in the room while recording. I think they do sound good on most occations on their own but when mixing I feel they are not gluing together and more ofther fighting against each other. This is now an open place to lash out that maybe I don't understand where to put the mics...

Why would people close mic guitar cabinets (mostly they do) or drums etc if they wanted to hear how it's sounding in the room? I believe it's because the sound of the room is not what they are after but actually the illusion of dimentionality and sense of presence when the image is mostly created with complicated phase shifting combined with stereo placement.

What is distance on a 2D canvas? Debth of field. That does not mean aqual sharpness, equal color amplitude etc. It's aberration, hazyness and color dilution. Now tell a painter they must only paint what they see? Maybe we all se different things, some even abstract... Words like 'realism' does not come to mind when I think of Jimis wersion of 'All along the watchtower'.

I read while back discussion about the NE5534 single op amps and how some people felt they were too realistics. What the hell is that? I have never heard anything that is too realistic.
Old 27th February 2019
  #52
Gear Maniac
Heres an example of my Soundtracs in action

YouTube

And here some recordings I did last summer with Tascam M520

Pimea vuodenaika by Mestari Laurentius on Spotify

I know both youtube and spotify are not really good sonicly but you get the idea. Both do the trick but Tascam has better lows.
Old 24th April 2019
  #53
Gear Maniac
Hi

I finally had time to do more experimentation on this. Since my last post I've spent many weekends just recording and mixing.

Meanwhile I bought a dual mono Behringer PreQ preamp (made in Germany) that has 2 of the same SSM2017 chips that are in my Soundtracs. I modded the other channel with the OEP A187A11C input transformer and Lundahl LL2801 on the output. The change is small, but there is a change.

I recorded few tracks of myself singing using two same condensers and two same ribbon mics. Most noticable change was in the high frequencies. I would not say the sound is any more coloured or 3 dimentional, just a little more gentle on the ears, just a fraction. The high-high end is still there but the sibilants are not as in-your-face and the mids feel to be tiny bit more 'THERE', that might be just because the attenuation of sibilants... I even switched the mics around to eliminate possible variance.

I did not change the 10Kohm load resistors on the input, seems like Behringer designers went and copied the datasheet example schematics and used the maximum value. Those are 1Kohm in Soundtracs and that is also right value for loading the input transformer. I will change those and see if it makes any difference. Maybe only for the noice floor.

Not sure if it's worth the money to be honest. Have to tinker more to see if I find a setup that has more of something. I might flip the 1+1+1 input tranny around and use the two output coils as parallel/series (low/high Z) to see if that gives more tonal options.
Attached Thumbnails
Mixer mod-img_20190424_200727.jpg   Mixer mod-img_20190423_151328__01.jpg  
Old 24th April 2019
  #54
Gear Maniac
Tested the reversed input transformer. No change to sound, still the same difference between channels. Few dB change in level when parallel connected. Next to change the load resistors and maybe some other stuff...
Old 25th April 2019
  #55
Gear Maniac
Boom!!

There was a connector fault yesterday in my reversed tranny test. Today it worked, the higher Z mode thinned out the frequency response, cut all the lows... BUT!

I started thinking the whole channel chain within the Behringer and took the signal to the output transformer direct from SSM2017 output & gnd pins (5 & 6) and returned the input transformer to the original wiring. Man!! This was the ticket. The tests that I did yesterday were all smeared up/trashed by whatever comes after the preamp low cut etc.

I did A/B channel tests and the sound quality between the two channels is now night and day. After listening to the channel where I have the OEP input transformer and the direct to Lundahl output the unmodified sounds trashy, cut lows, distorted mids and unwanted sibilant spikes.

I can post link to some files next week if anyone is interested... I'm happy camper. This gives me thought that the Soundtracs mod might be worth while after all.
Old 26th April 2019
  #56
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Brian M. Boykin's Avatar
I would be interested. I have an older globe emblem Ashly SC55 and it has lots of real estate inside if I want to add transformers. The input and output jacks are not PCB mount. There are wires running to the PCB. Output trannies would be easy and I could make them switchable. I’ve already recapped it and swapped in OPA2134’s and 134’s. It sound really good. I have 3 others that are later revisions and get used more so this one I’m wanting to experiment with.
Old 29th April 2019
  #57
Gear Maniac
I'll post some clips this week... Btw I bought and picked up yesterday 32pcs of those Lundahl LL2801 1:1 output transformers for 200€. I have now 42pcs of those all together. They were used as isolation and taken out of a Finnish public service broadcast company patch bay. Sweet!
Old 29th April 2019
  #58
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Brian M. Boykin's Avatar
Quote:
Originally Posted by Transmutant View Post
I'll post some clips this week... Btw I bought and picked up yesterday 32pcs of those Lundahl LL2801 1:1 output transformers for 200€. I have now 42pcs of those all together. They were used as isolation and taken out of a Finnish public service broadcast company patch bay. Sweet!
I would imagine they’re more transparent then not. Probably along the lines of what I’ll be looking for. I want to put this SC55 on a guitar subgroup and use it for parallel compression. Trannies will help catch any missed transient peaks.
Old 29th April 2019
  #59
Gear Maniac
Quote:
Originally Posted by Brian M. Boykin View Post
I would imagine they’re more transparent then not. Probably along the lines of what I’ll be looking for. I want to put this SC55 on a guitar subgroup and use it for parallel compression. Trannies will help catch any missed transient peaks.
Yes, you are right. They are quite transparent, but there is a slight change in sound. Just a tiny bit different feel on the top end, not so much to the bass end. I was reading online that you can boost the low end by placing a series capacitor on the output primary coil. The main fuction is to filter out sub sonic frequencies, but if calculating the size of the cap with the coil inductance a nice ramp can be achived... A bit like Pultec style high pass might work. This could be bypassable feature also...
Old 11th July 2019
  #60
Gear Maniac
I've been tinkering away without updating this thread. I've been comparing the Soundtracs & Behringer. Though both unit have almost identical signal path, the Behringer has more top end. In Behringer I took the signal straight from the SSM2017 output so it should be as Soubdtracs direct out.

The only difference I can find at the moment is that the Sountracs has 2pcs 1K2 ohm resistors in the input and Behringer has 2pcs of 10K as indicated in the SSM2017 datasheet example schematics. I'm thinking this is too low so I will change them to 10K and compare the results.
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