Chameleon 7602 Input Transformer Mod
Chameleon 7602 Input Transformer Mod
Howdy Y'all,
Here's my first post, please be gentle.
I'd like to put a different input tranny on my 7602. I'm looking at Lundahl--LL1538XL, LL1550, or LL1576--because they are in the price range I'm shooting for.
Anybody done a mod of this type and have some suggestions?
Thanks!
Here's my first post, please be gentle.
I'd like to put a different input tranny on my 7602. I'm looking at Lundahl--LL1538XL, LL1550, or LL1576--because they are in the price range I'm shooting for.
Anybody done a mod of this type and have some suggestions?
Thanks!
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Don't have the Chameleon unit, but I'd use a Carnhill vtb9045, which is what is used in Neve clones (and the new Neves I believe) today. You can get them at Audio Maintenence Limited (you can also get an output transformer, and inductors for the EQ).
The Lundahls are nice but I think would give a cleaner sound, which may be what you want.
Craig
The Lundahls are nice but I think would give a cleaner sound, which may be what you want.
Craig
I have to second the Carnhill recommendation. The Lundahls will impart a different sound. Plus, the Carhill will be the same pinout format, which means you should be able to just drop it in place where the existing one is. The Lundahls would require some kind of daughtercard and hand wiring to connect it to the Chameleon board since the transformer pinout is different from the Lundahl format, I believe.
Please do!
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I've got the tranny and am starting the mod. I'm not exactly a genius with regard to electronics so I'm trying to figure out the odd little circuit board on the top of the Chameleon's tranny.
It looks like there's a capacitor and a resistor between pins 9 and 6 with pins 7 and 8 and 2 and 3 bridged.
Does that look correct to anybody else?
Also, does anybody have a suggestion for the kind of cap I shout use on the Carnhill or if I need to at all?
It looks like there's a capacitor and a resistor between pins 9 and 6 with pins 7 and 8 and 2 and 3 bridged.
Does that look correct to anybody else?
Also, does anybody have a suggestion for the kind of cap I shout use on the Carnhill or if I need to at all?
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Yeah, what should he expect to hear? Or not hear?Secular_Tool wrote:I installed the tranny without the cap and it sounds pretty good. It sounds great actually.
I fried the cap trying to get it off the circuit board and don't have a local source but I have a variety of caps ordered.
What should I expect to hear with the addition of the cap?
I am guessing it cleans up the tonality in the upper range, but what upper range? 10k and up?
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Pinout for Canrhill upgrade 9045
http://www.audiomaintenance.com/downloa ... _guide.pdf
scroll down. Just helping out since i had trouble finding the details.
Also my engineer drew this for me:
http://mindfart.com/pic/?carnhill
scroll down. Just helping out since i had trouble finding the details.
Also my engineer drew this for me:
http://mindfart.com/pic/?carnhill
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The zobel is going to stop the rigging, that may be inaudible to your ears. rumor has it if it's left off it allows for some extra high end, but it's pretty much standard to have it. I would keep the 180pf (Silver Mica, Film) in the circuit
http://www.ams-neve.com/Sites/8/Files/D ... Issue5.pdf
Page 22 of 46 shows the schematic, locate the Mic input transformer (upper left) and the pin out's (which should be the same on the Carnhill) Depending on if any impedance switching happens for the High and low Z function you would set you input ratio by soldering jumpers to make that connection or a switch. I believe the secondaries are depicted in series as it's shown as an single coil where the primary is shown as two that are in parallel (low Z) or in series (High Z).
Primary imp in low = 300 ohm Z
Primary Imp in High = 1.2K ohm Z
Series Secondary = 4.8K Ohm Z
from this chart http://www.technicalaudio.com/reading/n ... o7113.html
http://www.ams-neve.com/Sites/8/Files/D ... Issue5.pdf
Page 22 of 46 shows the schematic, locate the Mic input transformer (upper left) and the pin out's (which should be the same on the Carnhill) Depending on if any impedance switching happens for the High and low Z function you would set you input ratio by soldering jumpers to make that connection or a switch. I believe the secondaries are depicted in series as it's shown as an single coil where the primary is shown as two that are in parallel (low Z) or in series (High Z).
Primary imp in low = 300 ohm Z
Primary Imp in High = 1.2K ohm Z
Series Secondary = 4.8K Ohm Z
from this chart http://www.technicalaudio.com/reading/n ... o7113.html
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