zachs
Well-known member
Just want to say this thread/project is still 100/100. So impressive.
8 Channel, 3U NEVE 1073 completed
- Thread starter madriaanse
- Start date
Help Support GroupDIY Audio Forum:
Hey there ! I'm working on a variation of this project and wanted to do the modification of the Decoupling & Output capacitor value increase as well.
Could anyone guide me as to which were the original values and to what they were increased to?
Is there any further adjustment that's gonna be needed if I increase those capacitor values?
Thank you !
Could anyone guide me as to which were the original values and to what they were increased to?
Is there any further adjustment that's gonna be needed if I increase those capacitor values?
Thank you !
MidnightArrakis
Well-known member
>> Why is -- R6 -- shown as being a capacitor? Is this an "OOPS"??? Or, some kind of "secret MOJO" modification???.....
/
MathCantin
Member
This is a big oops on the silkscreen! This is C7 and R6 is the resistor just behind
The trace appears to be the same as an usual B283 allergies.for.all
Member
Look amazing!
I run into some issues with sound passing but very low level and distorted. I have to max out the gain to even get a bit of signal
I've tried reflowing all solder joints and checked values / cap orientation for any obvious mistakes but everything seems to be correct.
2N3055 biased to 22.66V
I've taken some measurements from the transistors and it seems that 2 transistors don't match the reference measurements in the guide.
I've replaced TR4 to see if it would make a difference but still get the same readings.
Any suggestions on how to methodically troubleshoot the unit so I can pin point the issue?
Thank you!
I've tried reflowing all solder joints and checked values / cap orientation for any obvious mistakes but everything seems to be correct.
2N3055 biased to 22.66V
I've taken some measurements from the transistors and it seems that 2 transistors don't match the reference measurements in the guide.
I've replaced TR4 to see if it would make a difference but still get the same readings.
Any suggestions on how to methodically troubleshoot the unit so I can pin point the issue?
Thank you!
Potato Cakes
Well-known member
Inject signal at the input. Take a multimeter and find where the signal stops.
Thanks!
Paul
Thanks!
Paul
I just realized I've ordered a 1/4 270R resistor when the BOM states it should be 1W , is there going to be an issue if I keep the 1/4w? The only ones I could find in 1W are carbon film but I'm not sure if it might increase noise/distortion ( never used them before and I keep reading about how noisy they are )
Thank you
Thank you
I just checked Mouser, and they have several 1W 270R in metal film, from Yageo, TE, and Vishay. I wouldn’t use 1/4W where a 1W is specified.
Appreciate the feedback! Do you think if I use carbon film , there is going to be a difference in noise? It's gonna be a bit expensive to order just 1 resistor from mouser
Thank you!
If the BOM says "1W" then that's exactly what you should use, the BOM exists to you don't have to second guess, you just have to follow it.
If you start changing components from the specs in the BOM at you own will then it's normal in the end that you don't have the proper voltages or have problems in your build
For sure, no problems with that.
"Carbon Film" are very good, just "carbon composition" have pretty low specs and many problems
Original Neve cards used Carbon Film
No.
The difference will not be even measurable with test gear
MidnightArrakis
Well-known member
[I'll get the carbon film 1w!] -- "Metal-Film" will be even better and there is basically no price difference than that of "Carbon-Film". Metal-Film resistors will have even lower noise.
Carbon-Film: Mouser #: 660-SPR1CT52R271J = $0.32 each
Metal-Film: Mouser #: 594-PR01000102700FA5 = $0.46 each
/
I seem to be battling with this project for while.. any help would be INSANELY appreciated .
All my transistor values are extremely close to the build guide reference except TR1 emitter. I get 350mv instead of 0.4v
The unit is working , I get sound and nothing weird seems to be happening. What might be the reason for the TR1 emitter voltage being that low?
I tried reflowing that part of the circuit but nothing changed. Checked all resistor values and capacitor orientation and they seem to be correct
I'm completely lost!
All my transistor values are extremely close to the build guide reference except TR1 emitter. I get 350mv instead of 0.4v
The unit is working , I get sound and nothing weird seems to be happening. What might be the reason for the TR1 emitter voltage being that low?
I tried reflowing that part of the circuit but nothing changed. Checked all resistor values and capacitor orientation and they seem to be correct
I'm completely lost!
0.4v is 400mV, so if you're measuring 350mV it seems to me it's pretty close and in the ballpark.
remember the notes in the transistor voltage chart:
"Notes:
Voltages were measured with the rail adjusted to +24.05VActual voltages may vary from unit to unit, BUT:
Collector should always be most positive
Base voltage should always be .5 to.6V higher than Emitter"
Wanted to share a few pics of the finished unit! Would like to thank everyone who contributed to this project , such an amazing sounding preamp!
This project was one of the easiest yet hardest ones I've built ; allowing tolerances is your friend when mounting components in cases!
First time building in a 1U case and every inch mattered! ( insert adult joke here )
Onto the next one
This project was one of the easiest yet hardest ones I've built ; allowing tolerances is your friend when mounting components in cases!
First time building in a 1U case and every inch mattered! ( insert adult joke here )
Onto the next one
Hello everybody! I'm a DIY newbie, I've been reading this forum for a long time and I really appreciate the patience and knowledge you give to newbies like me. EZ1290 isn't my first project but probably the most challenging I've tried.
I finished my 2 channel unit, with trim, line input (with fixed pad), impedance selector and a board I specifically designed to support Alps spun pushbutton for +48, phase and pad. I couldn't find a PCB-mount grayhill switch in stock so I did it with panel mount ones that made the cabling a little bit more messy (photo of the inside attached).
The unit works fine and sound great until I set the gain to the last two positions (70 and 75 dB). Here the noise become unacceptable, I measured the output (+ to gnd) with the scope and found out that I got 23V on 70dB setting and almost 50V on 75dB setting. This problem is the same on both channels. I read a lot of posts on this thread and already doubled checked the resistor's values, caps orientation and the transistor voltages are close enough to the tab on the assembly guide.
Can anyone please help me to figure out what can be the cause of this issue?
Thank you!!
(please be kind with my english, this is my first post)
I finished my 2 channel unit, with trim, line input (with fixed pad), impedance selector and a board I specifically designed to support Alps spun pushbutton for +48, phase and pad. I couldn't find a PCB-mount grayhill switch in stock so I did it with panel mount ones that made the cabling a little bit more messy (photo of the inside attached).
The unit works fine and sound great until I set the gain to the last two positions (70 and 75 dB). Here the noise become unacceptable, I measured the output (+ to gnd) with the scope and found out that I got 23V on 70dB setting and almost 50V on 75dB setting. This problem is the same on both channels. I read a lot of posts on this thread and already doubled checked the resistor's values, caps orientation and the transistor voltages are close enough to the tab on the assembly guide.
Can anyone please help me to figure out what can be the cause of this issue?
Thank you!!
(please be kind with my english, this is my first post)
Attachments
Just to make sure I understand, with no signal going in, phantom power off, you turn up the gain and measure 50VDC on the output xlr pins + and gnd?
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