pucho812

Jensen iso-Max transformers
« on: June 13, 2020, 03:28:36 PM »
Does anyone know what Jensen transformers are used in the iso Max and if there is a difference between. The input version and the output version?
I would imagine it’s just a 1:1 inbetween xlr connections. But what is the theory of operation. Aside from transformers block d.c.
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.


ruffrecords

Re: Jensen iso-Max transformers
« Reply #1 on: June 13, 2020, 03:54:05 PM »
I strongly suspect this is marketing by the new owners. I also suspect the transformers used are no different to the ones that have been available from Jensen for some time. I suspect the input one is very similar to the JT-11P range, They have a large range of output transformers so just pick the quoted level and pick one that fits.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

pucho812

Re: Jensen iso-Max transformers
« Reply #2 on: June 13, 2020, 04:37:14 PM »
Well the  iso max pre-made units have schematics on them, so would be easy to copy and build but what I am curious is to how much they work or don't work  and what they are doing to actually remove hum and or buzz. I am sure there is some marketing speak involved. They have been around for some time. My need for them is for our plates at the studio. Even in great working order, there is still some hum  and or buzz and  I am wondering if these would tame it.

Schematic #1
https://www.parts-express.com/jensen-iso-max-po-2xx-dual-channel-xlr-line-output-isolator-for-high-level-signals--246-0126?gclid=EAIaIQobChMI24_B3s__6QIVQxx9Ch3yuw2YEAQYASABEgJ7gvD_BwE

Schematic #2
https://www.parts-express.com/jensen-iso-max-pb-2xx-dual-channel-xlr-line-input-isolator-for-long-runs--246-0125?gclid=EAIaIQobChMI24_B3s__6QIVQxx9Ch3yuw2YEAQYBSABEgIFtPD_BwE
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

ruffrecords

Re: Jensen iso-Max transformers
« Reply #3 on: June 13, 2020, 05:54:28 PM »
The basic premise is that balanced floating transformer outputs successfully galvanically isolate the two pieces of equipment connected together so there cannot be a hum loop. The reason is that, unlike electronically balanced inputs and outputs, transformers do not need a 0V reference. In the good old days, when everything was transformer balanced floating, the screen of a twin screened cable was connected to chassis because it is really a screen and not a signal carrying or reference conductor. It was when electronically balanced inputs and outputs appeared that 'designers' forgot this and because their 'balanced' inputs and outputs were referenced to 0V analogue they connected the screens to 0V and created hum loops.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

pucho812

Re: Jensen iso-Max transformers
« Reply #4 on: June 13, 2020, 05:59:56 PM »
The basic premise is that balanced floating transformer outputs successfully galvanically isolate the two pieces of equipment connected together so there cannot be a hum loop. The reason is that, unlike electronically balanced inputs and outputs, transformers do not need a 0V reference. In the good old days, when everything was transformer balanced floating, the screen of a twin screened cable was connected to chassis because it is really a screen and not a signal carrying or reference conductor. It was when electronically balanced inputs and outputs appeared that 'designers' forgot this and because their 'balanced' inputs and outputs were referenced to 0V analogue they connected the screens to 0V and created hum loops.

Cheers

Ian

Thanks IAN, that was fab...  :) You sir are a delight...
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

ruffrecords

Re: Jensen iso-Max transformers
« Reply #5 on: June 13, 2020, 06:10:27 PM »
Thanks IAN, that was fab...  :) You sir are a delight...
Nice of you to say so.

Of course, I am sure you realise this became known as the Pin 1 problem.

I have been watching a lot of The Big Bang Theory just lately and I am trying my best not to start sounding like Sheldon.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

pucho812

Re: Jensen iso-Max transformers
« Reply #6 on: June 13, 2020, 07:14:40 PM »
Nice of you to say so.

Of course, I am sure you realise this became known as the Pin 1 problem.

I have been watching a lot of The Big Bang Theory just lately and I am trying my best not to start sounding like Sheldon.

Cheers

Ian

Yes it is.  I am working out the best way to remove the PIN 1 hum out of  one of our EMT plates at the studio. This has been an ongoing thing.   The one with original EMT electronics has more hum then then the other plate which has Martinsound  electronics.  So far it's a clear ground loop in the electrical because I can get more or less hum depending on which electrical circuit powers it.  So in the interest of trying to quiet them as much as possible, See what would be best here.
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

john12ax7

Re: Jensen iso-Max transformers
« Reply #7 on: June 13, 2020, 07:38:32 PM »
Do you have any old transformer lying around to test? Just hook it up and see if the problem goes away,  then can focus on buying an appropriate one.

Re: Jensen iso-Max transformers
« Reply #8 on: June 13, 2020, 09:05:53 PM »
I am working out the best way to remove the PIN 1 hum out of  one of our EMT plates at the studio. This has been an ongoing thing.   The one with original EMT electronics has more hum then then the other plate which has Martinsound  electronics.  So far it's a clear ground loop in the electrical because I can get more or less hum depending on which electrical circuit powers it.  So in the interest of trying to quiet them as much as possible, See what would be best here.
back on February 5 you wrote:
" The plate with EMT electronics has a light hum, and it can be heard if I crank  up the monitors to full. I assume this is normal for a plate that old that has seen little servicing. nothing that can't be addressed in time.
  The Martin sound electronics have large amount of hum.   I have swapped power   around with marginal success, meaning I ran a power extension cord from the control room power circuits  and connected to the plate with a reduction in buzz but still low frequency hum.  I have tried  running  audio cables directly from the control room to the plates and still had issues.   I have confirmed  the patchy connections are solid  and working as they should.
The Martin sound plate electronics had recently been serviced and given a clean bill of health by the manufacture. "

un-molested, original EMT 140 plates have very little hum, even when feeding long lines to and from control room.

and frankly never heard of a pin 1 problem with either V54 or type 162 electronics. 

if the send and return lines are not bundled together, there could be a large inductive  transformer loop.

if you really suspect electrical issues, power the plate from a isolation transformer, preferably an ultra-iso unit such as those made by Topaz.

not that it would fix your problem, but powering original EMT plates from 220 VAC is advantageous, it is "balanced power".

squarewave

Re: Jensen iso-Max transformers
« Reply #9 on: June 14, 2020, 10:39:44 AM »
Just to be clear, is it 60Hz / mains hum? Transducers will pickup electromagnetic interference so it's probably rather important that the plate be physically isolated from any nearby power lines (particularly ones with significant amounts of current running through them). If you have it along a wall and don't realize that there's a power cable in the wall, that could easily induce hum in the amp. I'm not a fan of just throwing parts at noise problems. I would try using a scope to diagnose first (taking into account that just attaching the ground clip of the scope probe can induce noise by itself).


Brian Roth

Re: Jensen iso-Max transformers
« Reply #10 on: June 14, 2020, 06:38:04 PM »
Around 20 years ago I was working with the crew of a live TV truck (they usually did NFL, etc. games for the TV networks) at a  convention.  We had set up some video monitors in the lobby for viewing of the feed being streamed and taped.  There were serious audio hum problems, so the chief engineer of the truck dug into his box of tricks.  He had a number of these which he had soldered various connectors in place of the RCA's:

https://www.amazon.com/dp/B002YGM5D8?tag=duckduckgo-ffab-20&linkCode=osi&th=1&psc=1

I thought it was a clever solution and bought more than a few over the years from Radio Shack stores (remember those?) for solving hum problems.  The transformers inside the shell tested out pretty well on the bench.  I would replace the RCAs with whatever connectors the task required.

If nothing else, they are an inexpensive go/no go method to see if an expensive transformer solution is warranted.

I've seen the same gizmos sold by other vendors but can't recall where.....probably someone who sells parts for car stereo installs.

Bri
Brian Roth Technical Services
Salina Kansas, home of the best vinyl on the planet!

http://www.BrianRoth.com
recordingservicesandsupply.com/
www.qualityrecordpressings.com/
store.acousticsounds.com

PRR

Re: Jensen iso-Max transformers
« Reply #11 on: June 14, 2020, 07:42:42 PM »
> He had a number of these

I was going to say that but I thought you fancy-audio experts would shout me down.

Especially on a reverb! But I've never been real ashamed to use it on Program.

CJ

Re: Jensen iso-Max transformers
« Reply #12 on: June 14, 2020, 09:51:58 PM »
Jensen sells those iso-max  for video also?   supposedly that is what is keeping them in business, OEM accounts for cable tv and stuff.



If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page: www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar Amps: http://bmamps.com/Tech_sch.html

pucho812

Re: Jensen iso-Max transformers
« Reply #13 on: June 15, 2020, 03:37:54 AM »
back on February 5 you wrote:
" The plate with EMT electronics has a light hum, and it can be heard if I crank  up the monitors to full. I assume this is normal for a plate that old that has seen little servicing. nothing that can't be addressed in time.
  The Martin sound electronics have large amount of hum.   I have swapped power   around with marginal success, meaning I ran a power extension cord from the control room power circuits  and connected to the plate with a reduction in buzz but still low frequency hum.  I have tried  running  audio cables directly from the control room to the plates and still had issues.   I have confirmed  the patchy connections are solid  and working as they should.
The Martin sound plate electronics had recently been serviced and given a clean bill of health by the manufacture. "

un-molested, original EMT 140 plates have very little hum, even when feeding long lines to and from control room.

and frankly never heard of a pin 1 problem with either V54 or type 162 electronics. 

if the send and return lines are not bundled together, there could be a large inductive  transformer loop.

if you really suspect electrical issues, power the plate from a isolation transformer, preferably an ultra-iso unit such as those made by Topaz.

not that it would fix your problem, but powering original EMT plates from 220 VAC is advantageous, it is "balanced power".

I did. Then the Martinsound blew up and got a complete rebuild. It’s ok now. But the emt hums and it’s noticeable.  So yes still working on this months later as we were shut down from covid.
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

Re: Jensen iso-Max transformers
« Reply #14 on: June 15, 2020, 09:36:04 PM »
Jensen sells those iso-max  for video also?   supposedly that is what is keeping them in business, OEM accounts for cable tv and stuff.

Jensen was bought by Radial some years ago, Radial uses Jensen transformers in their DI boxes, apparently they used to buy so many that it was cheaper to just buy Jensen, so I'm guessing that those Radial boxes are whats keeping Jensen in business.

From Jensen's webpage:

"But Radial’s demand had outpaced Jensen’s ability to deliver. The company needed more equipment, inventory and staff. Over the years, Radial President Peter Janis had expressed an interest investing Jensen Transformers and eventually an agreement was signed on April 14th, 2014 . . . coincidentally Bill Whitlock’s 70th birthday.

Since Peter’s involvement, Jensen has already purchased two more Meteor Winders, significantly increased inventory, added extra assembly workers and is currently evaluating production methods. Computer software has been updated to manage production flow, sales and marketing initiatives have also been put in place. Bill has agreed to stay on-board as a consultant for new product development and technical support for the next few years. The Jensen legacy will continue."

Re: Jensen iso-Max transformers
« Reply #15 on: June 15, 2020, 10:06:10 PM »
Jensen was bought by Radial some years ago, Radial uses Jensen transformers in their DI boxes, apparently they used to buy so many that it was cheaper to just buy Jensen, so I'm guessing that those Radial boxes are whats keeping Jensen in business.
not always prudent to guess.
owned by Ultimate Support Systems.  if you are not familiar, they fabricate microphone stands.

Brian Roth

Brian Roth Technical Services
Salina Kansas, home of the best vinyl on the planet!

http://www.BrianRoth.com
recordingservicesandsupply.com/
www.qualityrecordpressings.com/
store.acousticsounds.com

Re: Jensen iso-Max transformers
« Reply #17 on: June 16, 2020, 01:06:37 AM »
not always prudent to guess.
owned by Ultimate Support Systems.  if you are not familiar, they fabricate microphone stands.

Either way you can still assume the DI boxes are the main Jensen customer, I don't think that microphone stands need transformers, do they?


 

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