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Make DIY inline preamp like Triton Fethead?
Old 1st February 2021
  #31
Here for the gear
 
Here's a pic of the finished board.
Attached Thumbnails
Make DIY inline preamp like Triton Fethead?-20210201_153424.jpg  
Old 4th February 2021 | Show parent
  #32
Lives for gear
 
🎧 10 years
You might want to base your prototype on the best possible performance model of this type of device...how do the Triton specs compare with the measurements of the sE or similar devices....see below ?

https://www.soundonsound.com/reviews...s-dm1-dynamite

https://www.soundonsound.com/reviews...-labs-dbooster

https://www.soundonsound.com/reviews...preamp-booster

https://www.soundonsound.com/reviews...s-cloudlifters

Last edited by studer58; 4th February 2021 at 12:02 PM..
Old 5th February 2021 | Show parent
  #33
Here for the gear
 
If you can find internal pictures of the other devices I'll gladly do so. I'm not about to shell out 150 quid for a cloudlifter.
Old 5th February 2021
  #34
Gear Guru
I'll sell mine for $75. You pay shipping.
Old 5th February 2021 | Show parent
  #35
Here for the gear
 
Quote:
Originally Posted by Jim Williams ➡️
I'll sell mine for $75. You pay shipping.
No, I can't justify buying it. Sorry. But if you can open it up and send good quality internal pics that would be great.
Old 10th February 2021 | Show parent
  #36
Gear Head
Quote:
Originally Posted by neppert ➡️
Here's a pic of the finished board.
Does it work as supposed?
Old 10th February 2021 | Show parent
  #37
Gear Nut
 
As I wrote in another thread I was just curious about the fethead phantom but didn't want to spend 160 euros for two of them, so I decided to trust an ebay diy guy who was selling a bunch of these devices ( both "standard" and phantom version) for half the price; he answered me that he was using the same components as the fethead so a bought a pair. Kinda works, have to say, with no wonders expected but still not a bad result.
Old 11th February 2021 | Show parent
  #38
Here for the gear
 
Quote:
Originally Posted by TormyVanCool ➡️
Does it work as supposed?
Yes, I posted a link to an audio sample if you scroll back. I also designed a 3D printable casing. I'll upload it to oshwlab soon.
Old 13th February 2021 | Show parent
  #39
Here for the gear
 
Quote:
Originally Posted by neppert ➡️
No, I can't justify buying it. Sorry. But if you can open it up and send good quality internal pics that would be great.
Took mine apart. How are those pics?

I actually was interested in building one as well, however, I am not as knowledgeable in circuitry. Could use a referral to some books to learn more about the electronics in our audio gear.

Already built a mic and preamp, but those were kits
Attached Thumbnails
Make DIY inline preamp like Triton Fethead?-img_3646.jpg   Make DIY inline preamp like Triton Fethead?-img_3645.jpg   Make DIY inline preamp like Triton Fethead?-img_3644.jpg   Make DIY inline preamp like Triton Fethead?-img_3643.jpg   Make DIY inline preamp like Triton Fethead?-img_3641.jpg  

Make DIY inline preamp like Triton Fethead?-img_3642.jpg  
Old 13th February 2021 | Show parent
  #40
Here for the gear
 
Thanks for the pics. However, I can't read the IC markings. Could you post them or provide a better picture?

Also are the male/female markings in the attached picture correct?
Attached Thumbnails
Make DIY inline preamp like Triton Fethead?-img_3641.png  
Old 15th February 2021 | Show parent
  #41
Here for the gear
Nice work on this guys

I was following the old Cloudlifter/Alctron schematics, and made a tiny "Ghetto-FET on a budget", just waiting for some matched 2SK170's to stick in and see if it will cram into a microphone shell
Attached Thumbnails
Make DIY inline preamp like Triton Fethead?-image5534.jpg   Make DIY inline preamp like Triton Fethead?-cloudlifterschematic.jpg   Make DIY inline preamp like Triton Fethead?-altron-ma-1-mic-booster-scheme.jpg  
Old 18th February 2021 | Show parent
  #42
Gear Head
My PCBs were delivered today.
They work as I designed!!

I'm very glad :-D

I put it into a RB-500. I received 5 of them.

Please here the Audio on SoundCloud

Attached Thumbnails
Make DIY inline preamp like Triton Fethead?-4.jpg  
Old 18th February 2021 | Show parent
  #43
Gear Head
Quote:
Originally Posted by neppert ➡️
Yes, I posted a link to an audio sample if you scroll back. I also designed a 3D printable casing. I'll upload it to oshwlab soon.
I tried to check for it and I can't find it :-/ I see many links but not audio ones :-/
Old 19th February 2021
  #44
Gear Nut
 
1 Review written
🎧 15 years
This is completely awesome! Sounds pretty good too. How could i score a pcb?
Old 20th February 2021 | Show parent
  #45
Here for the gear
 
Quote:
Originally Posted by TormyVanCool ➡️
I tried to check for it and I can't find it :-/ I see many links but not audio ones :-/
Here: https://dl.dropboxusercontent.com/s/...20fethead.flac
Old 21st February 2021 | Show parent
  #46
Gear Head
Excellent :-) Thank you!
Old 24th February 2021
  #47
Here for the gear
 
I got the new PCB and added photos, as well as 3D printing files for an enclosure: https://oshwlab.com/zipdox/fethead
Old 25th February 2021 | Show parent
  #48
Here for the gear
 
Quote:
Originally Posted by neppert ➡️
Thanks for the pics. However, I can't read the IC markings. Could you post them or provide a better picture?

Also are the male/female markings in the attached picture correct?
Sorry for the late reply, but yes, the Male/Female Markings are correct.

And the IC markings are both: LSK389F 1649 C
Old 27th February 2021 | Show parent
  #49
Gear Head
Quote:
Originally Posted by neppert ➡️
I got the new PCB and added photos, as well as 3D printing files for an enclosure: https://oshwlab.com/zipdox/fethead
Great job, dude ;-)
Old 1st March 2021 | Show parent
  #50
Here for the gear
 
Quote:
Originally Posted by neppert ➡️
I got the new PCB and added photos, as well as 3D printing files for an enclosure: https://oshwlab.com/zipdox/fethead
I just ordered your board and the parts, I'll let you know how it works out. I have the proper soldering equipment for surface mount work.
Old 2nd March 2021 | Show parent
  #51
Here for the gear
 
I must inform you that for some reason some XLR cables will not work with it on the Mic side. I don't have a clue why, I'm trying to figure that out myself. Maybe it has something to do with cable capacitance or impedance??? Anyway, if you run into problems, try different cables. I'll update you if I find out the reason.
Old 2nd March 2021 | Show parent
  #52
Here for the gear
 
Quote:
Originally Posted by vincefedor ➡️
Sorry for the late reply, but yes, the Male/Female Markings are correct.

And the IC markings are both: LSK389F 1649 C
I'm having trouble reading the resistors too. I'll post a schematic once I figure out the PCB.
Old 7th March 2021 | Show parent
  #53
Gear Head
 
🎧 5 years
Hi, wonder if someone can help with a few questions - looking at the Cloudlifter circuit for instance, it looks like that 3k resistor could be swapped for a potentiometer to allow variable input Z, is this correct?

Also, what is the output impedance of a cloudlifter type device - is it different to the input? - is it anything to do with the 22k resistors?

The reason I ask is that I have been playing with different resistors/pots in parallel with my ribbon mic (around 50-75 ohms output), and it makes a huge difference to the character of the sound, so the trick of using a potentiometer in parallel with XLR connections 2 and 3 in a box could work for me - but then I got thinking about combining this with a booster (pretty much like the Cloudlifter Z).

I thinking of just taking a fethead board and putting it in a box with a pot wired instead of the resistor, but if I just use a potentiometer in a box I wonder if this is going to sound different to putting this before a mic booster.
Or preferably, I could just leave the fethead as is and make my impedance box, but then surely I'd have a confusing mix of the impedence box plus the 3k of the mic booster, and then whatever the output impedance of that is!

I am using an old ampex tube preamp so the input impedance of that might not be standard (I first came across this when I rewired the 30-50 ohm input transformer of the preamp into its 150-200 configuration and got a big difference in the bass response - I am not sure if it is actually 30-50 ohm as I don't understand impedance that well, without the transformer the pre amp is supposedly 10kohm impedance, so perhaps the terminology was just different in the 60s, I don't know).

(...as an aside, some of these devices such as cloudlifter, alctron etc. seem to be able to half the output, but how is this done? Is it just a switch using only 2 out of 4 of the fets? - not sure where to put the switch exactly but seems like that might be it?

...further still the Radial McBoost allows variable gain (see https://www.radialeng.com/wp-content...am-768x273.jpg) (I am guessing this possibly affects the sound as it also has a switch for just half/full - not sure how to wire the "differential gain control" or if it's worth it?)

Thanks
Old 7th March 2021
  #54
Gear Head
 
🎧 5 years
Oh wait, those are 22 ohm resistors, anyway TLDR: can a pot go in place of the 3k resistor? - what is the output impedance? - and where would a half output switch go? Cheers
Old 10th March 2021 | Show parent
  #55
Here for the gear
 
On the input there's a header that selects the input impedance. It selects either 150 or 3k ohms. You could replace it with a potentiometer yes. I'm still working on the output impedence.
Old 10th March 2021 | Show parent
  #56
Gear Head
 
🎧 5 years
Thanks, great, will try a pot, curious to know how the output impedance is determined, Radial clearly state the output impedance for the Radial McBoost as 220 Ohm, but it doesn't seem to be stated for the others.

I just wonder how this ultimately affects the interplay between the Mic and preamp. I see that a lot of mics are around 200 ohms output impedance. But obviously these devices are largely designed to help with ribbons and dynamics - at least the two ribbons I have are more like 50-75 Ohm.
As I say with my preamp I notice a big difference in sound when changing the impedance, so while the Cloudlifter Z type thing of adding a potentiometer sounds interesting, I wonder if the output is stuck at 200, whether it affects the sound, and if there is some mod so that this output impedance can be selected also.

I guess it won't be 50 to whatever preamp impedance is, it will be 200 to that, so the ratio is different. Then again, I might be totally misunderstanding things if the difference is sound I am experiencing is totally dependent on what the mic sees.
Old 10th March 2021 | Show parent
  #57
Gear Head
Quote:
Originally Posted by jomaco2 ➡️
Thanks, great, will try a pot, curious to know how the output impedance is determined, Radial clearly state the output impedance for the Radial McBoost as 220 Ohm, but it doesn't seem to be stated for the others.

I just wonder how this ultimately affects the interplay between the Mic and preamp. I see that a lot of mics are around 200 ohms output impedance. But obviously these devices are largely designed to help with ribbons and dynamics - at least the two ribbons I have are more like 50-75 Ohm.
As I say with my preamp I notice a big difference in sound when changing the impedance, so while the Cloudlifter Z type thing of adding a potentiometer sounds interesting, I wonder if the output is stuck at 200, whether it affects the sound, and if there is some mod so that this output impedance can be selected also.

I guess it won't be 50 to whatever preamp impedance is, it will be 200 to that, so the ratio is different. Then again, I might be totally misunderstanding things if the difference is sound I am experiencing is totally dependent on what the mic sees.
get this rule of thumb: the input impedance of the preamplifier, should be >= 10 times the output impedance of the source (the mic, in this case).

The circuit I've made is exactly what Triton did. With a cost that is more than 1 order of magnitude less expensive. I have not any issue at the moment.
Old 10th March 2021
  #58
Here for the gear
 
I suggest you all take a look at the patent for the Cloudlifer: https://patents.google.com/patent/US9668045B1/
Old 18th March 2021 | Show parent
  #59
Gear Head
Quote:
Originally Posted by neppert ➡️
I suggest you all take a look at the patent for the Cloudlifer: https://patents.google.com/patent/US9668045B1/
Interesting to see no one of the diagrams (schematics) above, are the real circuit used into the Lifter.
Not only: that patent could also be contested it seems, because they are using a normal double cascode which is the same circuit already used in many other mics, much early than this. I.E. AKG414 ...................... and not only them :-D tones of other preamps, are using the same configuration.

So, I have not clue where you want to go with. Certainly: this is not what they did into the CloudLifter

ALTHOUGH is a valuable/valid solution. I'm wondering how they could patent something there was forever ... since the TUBES, as architecture. There is nothing new on it
Old 18th March 2021 | Show parent
  #60
Here for the gear
 
Quote:
Originally Posted by neppert ➡️
I got the new PCB and added photos, as well as 3D printing files for an enclosure: https://oshwlab.com/zipdox/fethead

Got my copies of your board and parts. Soldered up in about 15 minutes, and works fabulously. Stands up to an INA217 based preamp. Nice work, painless to acquire.
Attached Thumbnails
Make DIY inline preamp like Triton Fethead?-img_20210318_162304139_hdr.jpg  
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