tchgtr

Re: NT2 upgrades... which is better?
« Reply #20 on: June 04, 2019, 03:59:15 AM »
It's Henry Spragens page, its phenomenal.

I made this quick mod image for a friend, that is pretty much what i did with mine. You add the red components. You can go with or without the pot, or use a switch instead of it.


The Spragens site is interesting, and I've been looking it over since I found this thread. Thinking I might try this idea in a Nady SCM 1000 to tame the 67-style capsule .
However....it seems there is a bit of confusion with the schematic.
It calls for a 500k variable resistor, but in Spragens frequency plots, he gives values for resistance of R9 from 0 to 100K Ohms, and in the text refers to it as a 100k resistor.
Seems like 100k is the proper value. 500k would cause a very small frequency dip if his plots are accurate.
Thanks for the cool link!
Resistance is not futile. It is voltage divided by current.  (thanks, Bill)


Re: NT2 upgrades... which is better?
« Reply #21 on: June 04, 2019, 04:39:23 AM »
Frequency dip is achieved in full potential when pot is shorted, so when its set to zero ohms. I don't know how you came to that conclusion. You dont even have to use the pot.

tchgtr

Re: NT2 upgrades... which is better?
« Reply #22 on: June 04, 2019, 01:35:49 PM »
Frequency dip is achieved in full potential when pot is shorted, so when its set to zero ohms. I don't know how you came to that conclusion. You dont even have to use the pot.

Sure, but let's have it adjustable at first to see where we like the cut.
According to his frequency plots the dip would be so small if set at 500K Ohms as to be not worthwhile, and he doesn't show a plot for 500K, only 100K.
Look at the caption under the bottom plots. He does not reference a 500K Ohm figure, only 0, 5, 10, 25, and 100K.
Plus on Pt. 4 he shows a photo of a 100K pot and refers to the adjustment pot as 100K.
http://www.audioimprov.com/AudioImprov/Mics/Entries/2014/2/8_EQ_Pt.3_-_Transformerless_Mics.html
I think the 500K figure in his schematic is a misprint.
Resistance is not futile. It is voltage divided by current.  (thanks, Bill)

dp

Re: NT2 upgrades... which is better?
« Reply #23 on: June 04, 2019, 04:35:14 PM »
He may have chosen a larger value pot so that the taper is smoother and/or more finely adjustable?

I haven't ordered the parts yet... I got distracted by my DIYRE CP5 kit coming in the mail...  ;D

Re: NT2 upgrades... which is better?
« Reply #24 on: June 04, 2019, 04:57:30 PM »
Tchgtr, with all due respoct i am not sure you get what the pot is doing in the circuit. It can as well be 1meg.

If pot is set to 500k there would be no attenuation, at zero ohm it would give maximum attenuation.

As you can see HS's last diagram shows that at 100k there still is some HF attenuation (gray line) and if you want flat stock response you need something like 500k. 250k would probably work too.

I have posted my measures against u87 and if that is result that's required you dont need a pot, that is maximum hf attenuation, and pot value in that case is zero ohms-short.

tchgtr

Re: NT2 upgrades... which is better?
« Reply #25 on: June 04, 2019, 08:49:31 PM »
Tchgtr, with all due respoct i am not sure you get what the pot is doing in the circuit. It can as well be 1meg.

If pot is set to 500k there would be no attenuation, at zero ohm it would give maximum attenuation.

As you can see HS's last diagram shows that at 100k there still is some HF attenuation (gray line) and if you want flat stock response you need something like 500k. 250k would probably work too.

I have posted my measures against u87 and if that is result that's required you dont need a pot, that is maximum hf attenuation, and pot value in that case is zero ohms-short.

I see what you are saying. 500K would leave you with a flat (or nearly so) response.
I was just noting the discrepancy from the schemo to the photos, and observing that when he modded the mic in section 4 he used a 100K trimmer.
I may try the same in this Nady. It would  benefit from a bit trimmed off the top.
Very interesting site, and I like the way he justifies the use of this circuit. The whole site is interesting.
Thanks for your patient explanation, and linking it in the first place.
Resistance is not futile. It is voltage divided by current.  (thanks, Bill)

dp

Re: NT2 upgrades... which is better?
« Reply #26 on: June 05, 2019, 02:53:18 PM »

I have posted my measures against u87 and if that is result that's required you dont need a pot, that is maximum hf attenuation, and pot value in that case is zero ohms-short.


Ah... I was wondering about that. I may skip the pot altogether then.

So a switch instead of the pot would be a closer to stock sound off and closer to your curve on then?

Re: NT2 upgrades... which is better?
« Reply #27 on: June 06, 2019, 01:16:24 PM »
No, with a pot you get to tune attenuation to your taste. If you want u87 response you just set pot to zero ohms. In that case you can just use a switch, or a jumper instead of pot.


dp

Re: NT2 upgrades... which is better?
« Reply #28 on: June 07, 2019, 07:46:49 PM »
No, with a pot you get to tune attenuation to your taste. If you want u87 response you just set pot to zero ohms. In that case you can just use a switch, or a jumper instead of pot.

Yes, we are saying the same thing. I think  I may have just worded it funny. That's what I MEANT to say... thanks for clarifying!

dp

Re: NT2 upgrades... which is better?
« Reply #29 on: June 07, 2019, 07:53:14 PM »
So, with my Peavey VMP-2 I felt the stock  NT2 was a tad too bright. Not annoyingly so, but when my NTK was just too dark, I would swap it for the NT2 and it would add a little sparkle to it, and I would usually dial it out just a touch.

I just built a DIYRE CP5 and put the Louder Than Liftoff Royal Blue British Channel Module in it with the jumper set to a high shelf boost and holy cow... yeah the NT2 is CRAZY annoyingly WAY to bright with that.

So, the VMP-2 tames it quite a bit... the CP5 lets it shine in all of its annoying glory  ;D  SO I need to get on this mod ASAP!

The CP5 is also revealing that my NTK probably needs a cap job... getting some annoying noise with that, but that's a different story.


dp

Re: NT2 upgrades... which is better?
« Reply #30 on: June 08, 2019, 12:23:10 AM »
OK so I dug around my parts stash and found all the parts i need on-hand, so I dug into this mod tonight.

Holy cow wow... thank you so much for this idea! This mic is now amazing. I have no lust for a new mic now. What a difference. It's got a nice smooth top end now, no harshness. Just clear... that's all I can say to explain it.

I gave up on the idea of a daughter PCB... and I left out the pot and/or switch, I just connected the cap straight across instead. I had two of the real tiny 1/4-watt 1% MF resistors that I installed on the bottom of the board. I stuck one lead up through the hole where the "outside" lead of the C4/C5 cap was and soldered the other end to the bottom solder point of C2/C3. The leads that were now sticking up through the PCB became like turrets that I soldered each end of my 1nF cap to, and the PCB's existing traces took care of the rest of the connections. 

wow... thanks again! this thing sounds so much better now. This helped me make up my mind for my next project. It was either going to be a micparts mic kit or another diy 500-series preamp... Hairball audio has an order coming soon! Now I just need to decide if I want to go Lola or Copper...


 

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