Lowfreq
Well-known member
Hi all
Just wondering if anyone can help me with this. I've been putting togther a stereo green pre over the weekend, and seem to have run into a couple of things i'm a little stuck on. It's the older version using the power supply done by kev at this page.
http://www.diyfactory.com/projects/green/green.htm
Now I've been pretty good with my grounding (all at the same point etc) and for the most part the pre works great (got one going, just doin the rotary switch on the other one).
Anyways, here's the deal. When i use a dynamic mic (sm58), or have no mic and no phantom power, i seem to get a slight buzz (not as strong or deep sounding as and unearthed buzz). But when I plug a condensor in and switch on the phantom the buzz dissapears. If I have the phantom on while the sm58 is plugged in, I get the same buzz as when phantom is off.
Also if i'm using a condensor and switch the phantom off, everything goes dead silent for a few seconds, but then the condensor seems to come alive(well in a half ass kinda way) again, along with the familiar buzz :?
The other question I have (mainly for Kev, but anyone who knows) is to do with the power supply he designed. It's all working great, voltages are good, both of the 15v's and the 48v. There are seven terminals on the PSU, 2 for the LED, 2 for the +&-15v, 1 for ground, 1 for 48v.
The last one on the end next to the 48v, Whats that one for??? After trying to zoom in on some pics on kevs sight and also a couple of other peoples project pics, I can't seem to see clearly enough if anything is connected to it.
When testing with my meter, it seems work like another ground, but if i connect it anything else I get a lovely earth hum(apart from connecting it to the +48v, which i get a very pretty spark)
Is my curcuit not completed or something? I've been racking my brains all weekend over this one(still a newbie, not too smart :wink: ) and not had much luck. Did a search, and looked at the metas, found similar stuff, but not quite the same as my prob.
Anyways, I'm unsure if the phantom prob is to do with that last unused terminal on the PSU, or if i've got issues on the pre itself (i've checked everything with the meter a couple of times, and i'm sure componets are correct.)
If i was just gonna use condensors with the pre (as Matt is) then I prob wouldn't care, but I actually liked the sound of the sm58 on my voice through this thing (sounded clear & gritty at the same time :roll: hard to explain), and would be keen to rid myself of the buzz.
Any ideas or help would be soooooooooo apreciated as my limited knowledge has reached it's peak
regards
Steve
Just wondering if anyone can help me with this. I've been putting togther a stereo green pre over the weekend, and seem to have run into a couple of things i'm a little stuck on. It's the older version using the power supply done by kev at this page.
http://www.diyfactory.com/projects/green/green.htm
Now I've been pretty good with my grounding (all at the same point etc) and for the most part the pre works great (got one going, just doin the rotary switch on the other one).
Anyways, here's the deal. When i use a dynamic mic (sm58), or have no mic and no phantom power, i seem to get a slight buzz (not as strong or deep sounding as and unearthed buzz). But when I plug a condensor in and switch on the phantom the buzz dissapears. If I have the phantom on while the sm58 is plugged in, I get the same buzz as when phantom is off.
Also if i'm using a condensor and switch the phantom off, everything goes dead silent for a few seconds, but then the condensor seems to come alive(well in a half ass kinda way) again, along with the familiar buzz :?
The other question I have (mainly for Kev, but anyone who knows) is to do with the power supply he designed. It's all working great, voltages are good, both of the 15v's and the 48v. There are seven terminals on the PSU, 2 for the LED, 2 for the +&-15v, 1 for ground, 1 for 48v.
The last one on the end next to the 48v, Whats that one for??? After trying to zoom in on some pics on kevs sight and also a couple of other peoples project pics, I can't seem to see clearly enough if anything is connected to it.
When testing with my meter, it seems work like another ground, but if i connect it anything else I get a lovely earth hum(apart from connecting it to the +48v, which i get a very pretty spark)
Is my curcuit not completed or something? I've been racking my brains all weekend over this one(still a newbie, not too smart :wink: ) and not had much luck. Did a search, and looked at the metas, found similar stuff, but not quite the same as my prob.
Anyways, I'm unsure if the phantom prob is to do with that last unused terminal on the PSU, or if i've got issues on the pre itself (i've checked everything with the meter a couple of times, and i'm sure componets are correct.)
If i was just gonna use condensors with the pre (as Matt is) then I prob wouldn't care, but I actually liked the sound of the sm58 on my voice through this thing (sounded clear & gritty at the same time :roll: hard to explain), and would be keen to rid myself of the buzz.
Any ideas or help would be soooooooooo apreciated as my limited knowledge has reached it's peak
regards
Steve