Tube Mic Royer Mod Build Thread

[dmp]

I bought a punch set and it didn't work well at all. Granted it was cheap from harbor freight I think. It would deform the metal and the holes weren't very clean.
I now use step drill bits and they work great for XLRs.

 

[sr1200]

+1 on the stepped bits, works awesome, just gotta keep em lubed up

 

[tchgtr]

Thx,
Will they work with a hand drill, or do you need a press?
Price is much better...

 

[tchgtr]

I've been tempted to see if there was any interest in a group buy for OEM mics to mod either tube (like the HST-11a) or FET (like the myriad U87 style). There seems to be a current interest in mic modding, so it might be a good time to organize something like that.

I've been keeping an eye out for a used HST11A-style mic. Don't care if it doesn't work, as I will rebuild most of it. Something like this would interest me, but only if it were a very good deal.

 

[sr1200]

Gettin a bit off topic kinda but, yeah, i would recommend a press for the stepped bits since they work best if you can gradually increase pressure on them to go through, if you try to just push it through, you may get kick back or you may wind up stripping the bit.

 

[sr1200]

im using the jensen db-e(u) transformer, according to the schemo red/brown go to pin 1/2, yellow goes to C2, orange goes to common, then theres black and grey.

not quite sure where to go with these, do they get tied together, for a DI application, black and orange get tied together and grey goes to pin 1 of the XLR.  Do they just hang out by themselves like the creepy guy at the local pub...

 

[dmp]

I think they are case shielding - so I would connect them to the chassis ground.
Royer used the uncased version so I would assume it didn't have those???

 

[sr1200]

I thought the (u) was un cased.  Theres basically yellow tape around it.

 

[phillockwood]

I just got my boards today from Blue Jinn (thank you!).  I've found a BOM BigUgly posted for his boards, but I'm wondering - is anyone doing the Royer mod with these boards, and if so, do you have a Mouser project or parts list?  I've been assembling one in Mouser, but it'd be great to have a fully loaded project.  Otherwise, I'll post mine when it's done.

Also, the BigUgly boards:

1) What are people using for CONN-H5 (connector h5?)
2) What transformers are needed?  I've heard reference of two transformers.  Why?  One for power supply, is a second needed?
3) Any power constraints on the resistors needed on the power supply?  I've heard R1 is a 5 watt.

Thank you!  Sorry for the 20 questions, I've been reading across threads all day!

 

[dmp]

1) What are people using for CONN-H5 (connector h5?)

I soldered the wires directly.

2) What transformers are needed?  I've heard reference of two transformers.  Why?  One for power supply, is a second needed?

There is a output transformer as well as the psu transformer.  Reading the article is a great way to understand the project better. Tape Op NO. 25, Sept/Oct 2001. You can order a copy only for a few bucks - it is well worth it.

3) Any power constraints on the resistors needed on the power supply?  I've heard R1 is a 5 watt.

First off, I used a 10k resistor instead of the 330 ohm.  Earlier in the thread there is a post by PRR about how this increases the filtering effect. It also drops the B+ voltage which may be necessary depending on your psu transformer. Second, you want to select a resistor that has a higher rating than the power dissipation it will see.  Say the mic will draw roughly 1 mA. You can use that to estimate the power dissipation in the resistor. Power = V*I. Ohm's law: V=I*R. So Power=I^2*R.

 

[dmp]

I thought the (u) was un cased.  Theres basically yellow tape around it.

Maybe they are connected to the core then? I'm not sure if it is better to connect the core to audio ground or chassis ground. I would guess audio ground.

 

[tchgtr]

1) What are people using for CONN-H5 (connector h5?)
2) What transformers are needed?  I've heard reference of two transformers.  Why?  One for power supply, is a second needed?
3) Any power constraints on the resistors needed on the power supply?  I've heard R1 is a 5 watt.

Thank you!  Sorry for the 20 questions, I've been reading across threads all day!

It might help if you understand that BigUgly combined parts of the Royer circuit with the Gyraf G7 mic circuit, to essentially make a multi-pattern Royer mic. Or a Royer-ized G7, if you prefer.
If you haven't looked at the Gyraf PSU, you might want to do that. He uses two AC transformers to supply what shows up as the 9v and 100v AC inputs on the BigUgly schemo.
If you look at the Gyraf head amp schemo, you will see what parts BU took from that to multi-pattern the Royer.
Something that has also been confusing people all along is the mistaken AC input voltage of 190V on the BigUgly schemo posted at the beginning of this thread.
Add to that the need for an output transformer from the mic to your preamp input, there is a possibility of three transformer in this build.
However, someone posted above a link to a nice toroid AC transformer that seemed to supply all the voltages.
I'm going to try a US voltage version of Gyrafs brilliant two-transformer idea on my upcoming PSU build.
If you are just building a single-pattern Royer mic, it doesn't need to be so complex. The basic Royer circuit is quite easy and educational.

 

[phillockwood]

Thanks guys.  These are the tips I needed.  I'll look over the G7, BigUgly, and Royer, and figure out the changes between the 3.

 

[sr1200]

OK, so i finished my project over the weekend. Had a few issues with grounding on the mic itself (the original schematic was REALLY small and i missed the little note of putting ground (common) to chassis ground on the connector.  The power supply i built from scratch, point to point on perf board from RS, works amazing!  Only other issues I had were with me making a a bad bridge from the back of the little teflon pin thing to the back, (connected it to the wrong solder pad... but schematic reference sorted that right out)

I gotta say the mic sounds pretty sweet.  Not quite as warm as my R0de NTK, but it's a HUGE improvement over what the mic sounded like before the mod.  Thanks for the help with everything and the mic board, fun project!

 

[SteveB]

Hi,

Thanks for all the helpful info and detailed progress on this mic mod.  I have spent the last month reading and rereading... cool community here.

I recently completed  the Royer Tube LDC and psu on perfboard, using the layout detailed on this forum, only with a RK-47 capsule and a cinemag 2480, all housed in an old  CAD GXL 2200 i had on hand. The mic is spectacular tone wise.. the best I have compared to the original CAD, and even a huge improvement over another Chinese Tube "bottle style" Mic I have.

I am having that ominous noise trouble detailed in this and other threads.  Having tried a few different PSU enclosures and arrangements, the most success in reducing noise came from using the Cad's standoff to connect the grid to capsule.  However, there is still a bit of noise there... loud at power on, then nearly disappears  as the tubes heat up.

I am linking  a 10 sec recording of the noise... here http://snd.sc/xaH1Ip recorded much louder than normal level to emphasize the noise there  (ignore noisy NYC apartment life in the background)

I realize there are quite a few variables to noise/hum, grounding issues..but perhaps someone else here with more experience can help lead me in the right direction, trouble shooting-wise, given this clip.  Thanks for your time and advice.


EDIT:
found this thread at tape-op,  similar discussion with a "Trace Mod".  http://messageboard.tapeop.com/viewtopic.php?t=49624&postdays=0&postorder=asc&&start=75

going to play with the grounding so more and pwr xfrm placement....but still open to ideas.. (and i realize that posting a generic hum is a little silly... but, you know,  i am a "newbie").

 

[Blue Jinn]

Couple of questions/comments:

you used plain perf or the perf w/ small little solder pads? if the latter, gyraf has some comments about htat in another thread.

if the noise dies down after the tube warms up, why is it a problem? (not trying to be smarmy here, but I find my build has to warm up for a few minutes to settle in, also, I let it originally "burn in" for about 5-6 hours and that made a considerable improvement as well for whatever reason.)

clean up all the flux you can.

instead of a teflon standoff try connecting the grid direct to the capsule, which is how it is done in the orig Royer mod ("mid air") the teflon are for the bigugly PCB version

also, take a look at the grounding scheme you use. look at marktokach's recent G7 grounding threads (there is more than one) there is a lot of info there and some good links.

 

[SteveB]

Thanks!

Indeed I did use boards with solder pads. I ll probably start fresh on perf board. I also suspect the grounding... Though it seems correct, I am sure I will find something.
I did burn in the tube overnight and most of the day....

I will read those posts you referenced and re- retrace this grounding.

I will move the power transformer... As is, I have it across from the board in the ammo case....
Also my audio transformer is uncased in the mic... Thoughts on this?

Also,  may I ask what to do with the center tap on the Power Transformer? Currently I have it unconnected and  taped off.  My power connector is two prong as well, if this provides any clues.

Thanks so much for the direction....

 

[tchgtr]

Also my audio transformer is uncased in the mic... Thoughts on this?

Thanks so much for the direction....

The Cinemag doesn't need any shielding. It most likely is not your problem. The positioning of the power transformer might be causing the problem. If it's easy to move around, try that, and see if the noise changes in any way.
The suggestion to clean any extra flux is a good one.
There is a small chance it's the tube, but obviously this is the last thing to try, since it is difficult to de-solder.
Good luck. So far, this is the best circuit I have found for the cheaper U67-type capsules.

 

[SteveB]

Success!!!

So I did a few things, not a very scientific process, but the noise is eliminated.

Here were my steps:

1.  Relocated Power Transformer parallel to Circuit. Scraped ammo can paint off where the xfrm contacts the can.

2.  Removed all jumpers I had leading to a ground point  in the PSU. Replaced them with an L shaped  ground rail,  attempting to replicate the royer ground plane on the PCB.

3.  Scraped the paint off the contact point of the the pin XLR and ammo can.  Made the "chassis ground connection" at the ground lug of this xlr.

4. Cleaned and shortened connections in the PSU

Mic is functioning with no hum or buzz and very little self noise.  A lot of variables here, but anything sound familiar ? any obvious missteps or misunderstandings? 

Thanks for the help!

 

[tchgtr]

Congratulations. It's a nice feeling to solve these problems, especially when you are just starting out, and unsure.
Sounds like it was a ground problem.
About ready to do my own 2nd Royer circuit, and am excited about having multiple patterns. I'm a bit off the beaten path with this, but will feel like I learned something if it is successful, as I am using parts I already have, and making it up as I go.