[Now powdercoated] My very own Gyraf G7 build thread

[Harpo]

And this is the regulator

au.element14.com/jsp/search/productdetail.jsp?SKU=1609393

Wrong part. This is a LM317LZ, a max.100mA regulator in a TO-92 case.
You want a LM317T, a >=1.5A regulator in a TO-220 case, something like http://au.element14.com/fairchild-semiconductor/lm317t/reg-linear-1-2v-to-37v-adj-3to220/dp/2102581

 

[Enchilada]

Would one of these be OK? It would be cheaper to buy one of these from my local Jaycar shop because I wouldn't have to pay shipping.

http://www.jaycar.com.au/productView.asp?ID=ZV1615

 

[Enchilada]

Went to Jaycar, got the new part, voltages are now perfect. Thanks Harpo! ;D

I did have some problems with amazing loud noises when changing the pattern. I wired my rotary as per the diagram although I think my patterns might be a bit off. The voltages seem a bit low under load but should be OK. Cardioid reads 68V, omni reads 0V and figure 8 reads 140V. However, figure 8 is at least 2-3dB louder than cardioid and in omni the mic pics up basically nothing. If I pump the gain I can hear a little but not much. Any ideas?

UPDATE: Figure 8 has the back side louder than the front, Cardioid has the back side loud and the front much quieter but still audible. Omni has both sides basically silent. I'm using an edge terminated C12 style capsule from microphone-parts.com

I got my power supply running nicely in an old biscuit tin. Grounding is sorted now so it doesn't hum. Just having the issue with omni mode. Any suggestions to things I could check? I double checked I had wired my capsule correctly and I pretty sure it's not the issue.

 

[Enchilada]

Photo with my Quality Street tin power supply  ;D

 

[dmp]

I did have some problems with amazing loud noises when changing the pattern. I wired my rotary as per the diagram although I think my patterns might be a bit off. The voltages seem a bit low under load but should be OK. Cardioid reads 68V, omni reads 0V and figure 8 reads 140V. However, figure 8 is at least 2-3dB louder than cardioid and in omni the mic pics up basically nothing. If I pump the gain I can hear a little but not much. Any ideas?

UPDATE: Figure 8 has the back side louder than the front, Cardioid has the back side loud and the front much quieter but still audible. Omni has both sides basically silent. I'm using an edge terminated C12 style capsule from microphone-parts.com

These voltages might be a bit high for the capsule. If the voltage is too high, the capsule membrane gets pulled all the way in and basically stops working. When you shut off the psu, does the mic start working after a couple seconds?
With a stepped switch you will get loud pops when you flip the pattern switch.

 

[Enchilada]

Tried turning it off in all three modes to see if it would kick in and no, it didn't.

 

[Enchilada]

I'm still having issues with my G7 build. Could the way I've wired my transformer in be affecting which side of the capsule is working? I'm pretty sure I wired it correctly. I'm using a Cinemag CM 2480. My Tim Campbell CT-12 capsule arrived today and has been installed so I really want to get this mic happening  ;D. Voltages are all perfect and I've checked and re-checked my wiring 1000 times. I'm 100% confident that it's not an issue with the power supply as all voltages are fine.

Symptoms (with the CT12 capsule installed)

• Cardioid mode still picks up a little from the front but mostly picks up from the back.
• Omni mode has very little output that can barely be heard with very high gain from my preamp
• Figure 8 mode seems to almost work as omni, not much in the way of side rejection and the back side is still much more sensitive than the front.

Solution:
The 1uF Polystyrene cap was damaged. Replaced it and now I'm good to go.

 

[gyraf]

- Check capsule-to-pcb wireing
- Make sure to connect both backplate tabs together on the CT12 capsule (if it's the version with separate backplates)

Jakob E.

 

[Enchilada]

- Check capsule-to-pcb wireing
- Make sure to connect both backplate tabs together on the CT12 capsule (if it's the version with separate backplates)

Jakob E.

My knowledge of capsules is limited but from what I do know the backplate is the part behind the diaphragm and the tabs you're talking about are on the side of the capsule. Is that correct?

I did connect those connected them together with a small wire and connected that to the "centre(s)" connection (third contact from the top on the capsule side of the PCB). I then connected the tab on the front of the capsule to the "front" connection (first contact from the top on the capsule side of the PCB). The back of the capsule is then connected to the "back" connection (second contact from the top on the capsule side of the PCB).

Is this correct?

 

[Enchilada]

I'm thinking I might etch another PCB and start again with the mic. All the voltages in the PCB are good so that can't be the problem. Maybe I damaged the polystyrene caps while soldering, could that be the cause? I tried to be quick when soldering them.

 

[Enchilada]

Crisis over!!! I had damaged the polystyrene 1nF cap while soldering. I've now replaced it with another NOS 1nF 100V polystyrene I had lying around. I figured that as long as the mic is in cardioid or omni it should be OK for now. I'll have to order another 160V one.

The patterns seem to be working OK now although I can't use figure 8 because I'll blow the 1nF 100V cap. It does seem to be lacking the wow factor I was expecting after all the reading I did about the G7 with Tim's capsule and a NOS Mullard EF86 tube. I assumed the mic would be magical although after listening to the test I recorded tonight, it kind of seems lifeless.

Here's a test recording with my G7
http://soundcloud.com/kris-osullivan/gyraf-g7-vocal-test

And for comparison purposes, here's a song I recorded with a Studio Projects C1
http://soundcloud.com/kris-osullivan/what-a-wonderful-world

Any thoughts? Is this how a G7 is supposed to sound?

 

[tskguy]

Glad you figured out your issue. Its hard to really judge the difference having the source be so different. Can you solo the g7 track and post it? The female vocal sounds nice but its difficult to compare.
Eric

 

[Enchilada]

The second link was more to give an idea of the results I've had previously, not so much to use as a direct comparison. I'm not trying to find out which mic you prefer, just if my G7 is sounding as it should.

I'll solo the G7 vocal next time I'm in the studio.

I used copper tube for the mic body, could that have negatively affected the sound? perhaps I should line the copper tube with rubber to try and deaden any mic body resonance.

EDIT: I found another song I recorded with the same guy but with a different mic. This song has massive reverb on the vocals though because I was testing out my DIY plate reverb.
http://soundcloud.com/kris-osullivan/sheldon-wash-away

 

[dmp]

Here's a test recording with my G7
http://soundcloud.com/kris-osullivan/gyraf-g7-vocal-test

I don't hear any problems with the vocal track to think the mic isn't sounding like a G7 should. 
A mic is a just a tool - and it might not be the right mic for the style you are doing. You may want to try a shure sm7b for heavier vocals.

For reference - all the vocals for this project were recorded with my G7.
http://www.youtube.com/watch?v=7sZRAjZrbJk
Different style of music, then compression, plate reverb, etc etc...

 

[Enchilada]

I don't hear any problems with the vocal track to think the mic isn't sounding like a G7 should.

That's exactly what I was hoping to hear, thanks  ;D

 

[dmp]

Are you using the C12 style capsule from the group buy?

 

[Enchilada]

Are you using the C12 style capsule from the group buy?

Nope, using Tim Campbell's CT-12 capsule. I do have one of those capsule though.

 

[dmp]

Nope, using Tim Campbell's CT-12 capsule. I do have one of those capsule though.

Another member dandeurloo posted some samples of different capsules and they were very different. You might want to switch your capsules and see what you like more in the mic.
The amplification of the G7 isn't going to color the sound as much as not mess up the signal coming from the capsule I think. 
I have 5840 tube mics with the group buy Ck12 capsules and a G7 with a Dale M7 capsule. The ck12s seem to have more high frequencies and I think the 'ssss' can be a bit of a problem. But the other mics you are comparing too in the other clips may have more of the high frequency stuff that can make a condensor mic sound both good and bad (harsh)

 

[pasarski]

Sounds right to me. Try it with breathy female vocals (like in the whatawonderfulworld you posted) and you just can't stop smiling. For male rock vocals you might need the Neumanesque (or Shuresque) mid bump and grit, if it's not in the singers voice.

One thing about G7 and CK12/CT12: G7 has flat electronics, C12 and ELA M has a built in low cut and low shelf. The huge proximity effect easily makes a track dull sounding masking the high frequency content.

 

[Enchilada]

As I said earlier, I think my ears are too used to Chinese mics with scooped mids and HF boosts  :.

As for the proximity effect, initially I did record with the singer around 12 inches from the mic but I wanted to test its proximity effect so I moved him to only 6-8 inches from the mic. I'll record from further away in future.

Dual sided capsule wise, I have an RK-12 and two 67 style ones. I also have two RK-47 and another two RK-12 capsules on the way. One of the RK-47 capsules will be going in my Studio Projects C1. The other capsules were going to go in an Alctron HST-11A (Apex 460) and the other two were going in two other Chinese tube mics.

My goal is to have a wide variety of quality vocal mics. So based on what you guys are saying, might I be better off using a CK-12 in the G7 and Tim's capsule in an Apex 460 with the circuit modded to a C12 or ELA M?


Thanks again everybody for your input.