OPEN SOURCE DIY Mic Project - ORS 87 - Stripped Down u87

[micolas]

Ok, just for comparison, u87ai and ORS 87 with that Ali T-13 and generic, possibly Transound capsule.
View attachment 127344

My opinion is that for what it costs, the clone sounds very good compared to the U87ai.

 

[Migs 31]

You had a good experience with the Neutrik 10/3 haven’t you?

Hi there,

Just chippin'in. I have worked on a version of a U87/U87Ai, I made my own PCB's.
I used the Neutrik 10/3 in most of them. They sound really good compared to a genuine Neumann U87Ai. Hard to beat the real Neumann Capsule sound though. So +1 vote for Neutrik.

What baffles me a bit in this open source U87, is the need to add so much capacitance at C3-C4-C5-C6 (C110-1uF/50V on original Neumann). But hey! Tweak along and have fun guys.

PS: sadly I can already see the "Stripped Down U87 PCB's" adds for sale on the net (vultures).

M

 

[Khron]

What baffles me a bit in this open source U87, is the need to add so much capacitance at C3-C4-C5-C6 (C110-1uF/50V on original Neumann). But hey! Tweak along and have fun guys.

That's there rather for footprint options, rather than increasing capacitance. Up to 600-1000V rated caps might fit, at a cursory glance...

 

[Papa Tango Charly]

JLI's TSC-2 appears to actually be Takstar's CTS-2, and is found in the AKG Perception Series 420 and P420. Possibly the best Chinese k67 capsule available, closest to the original.
The single-sided capsule appears to be the one from the 220 model

https://en.takstar.com/product/type/75.html

http://recordinghacks.com/microphones/AKG-Acoustics/P220

Ok transound, you mean Taskar CTS! Yes there are the best! CTS have a yellow wire thought....

 

[Wordsushi]

My opinion is that for what it costs, the clone sounds very good compared to the U87ai.

Yeah... It was a lot closer to spitting distance than I expected and I suspect the difference can be cut even more with a good capsule.

This one is in an HL-77 body which has a really good replica headbasket size and geometry. Things I have come to see as a big variable towards getting that real 87 sound.

One note: The HL-77 body is notorious for having a resonance around 100 hz and it has been noticeable in other mics I’ve built into them. However, this ORS87 build has the Ali T-13 in it, which seems to have a slightly light low end. It seems that the body resonance is adding something positive here to that area. I suppose the sum of these flaws ends up working together somehow.

The experiment continues!

 

[OneRoomStudio]

For what it's worth, the JLI TSC-2 (Takstar CTS-2) is probably the ideal capsule for this project. Cheap, and close enough to a Neumann capsule that you'd have to spend at least 5x to get anything better. If I were going to build this project up for myself (and didn't already have parts laying around), this is what I'd do:

-Chinese HL-95 body
-UTM transformer (yes you can get cheaper, but this is already very good and very affordable)
-JLI TSC-2 capsule
-Regular quality components (i.e. "normal" metal film resistors, standard C0G and polypropylene caps of reasonable voltages (i.e., 63v)

If you go that way, you'd be spending less than $200 total, and you'd end up with a mic that would easily stand up next to just about anything out there.

No need to get esoteric with the parts on this.

 

[micolas]

For what it's worth, the JLI TSC-2 (Takstar CTS-2) is probably the ideal capsule for this project. Cheap, and close enough to a Neumann capsule that you'd have to spend at least 5x to get anything better. If I were going to build this project up for myself (and didn't already have parts paying around) and wanted to keep it affordable, this is what I'd do:

-Chinese HL-95 body
-UTM transformer (yes you can get cheaper, but this is already very good and very affordable)
-JLI TSC-2 capsule
-Regular quality components (i.e. "normal" metal film resistors, standard C0G and polypropylene caps of reasonable voltages (i.e., 63v)

If you go that way, you'd be spending less than $200 total, and you'd end up with a mic that would easily stand up next to just about anything out there.

No need to get esoteric with the parts on this.

Correct.
And if you think it sounds too clean, use a gzt-87 transformer.

 

[Thane Snipes]

For what it's worth, the JLI TSC-2 (Takstar CTS-2) is probably the ideal capsule for this project.

I'm under the impression that the TSC-1 is identical, save for being single membrane, cardioid only. Could save a few bucks there unless I'm mistaken? Also, are the frequency response graphs on JLI reliable? The RK47 and JLI-86U have identical graphs across the board if you look at the spec sheets, which sure seems like a mistake. The reason I ask is because the graphs for the TSC-2 and TSC-1 don't look much like what I'd expect from a K67 derivative capsule.

Also, if anybody is interested, I already have a TSC-2 in my possession, amongst an RK47 and a CK12, all from JLI, and I intend to capsule swap my Behringer B2 Pros, so I could do some comparisons once everything is in place. I'm particularly interested to hear the TSC-2 in comparison to the stock 797 K67 capsule for reasons outlined above.

Cheers, following this project with bated breath.

 

[micolas]

I'm under the impression that the TSC-1 is identical, save for being single membrane, cardioid only. Could save a few bucks there unless I'm mistaken? Also, are the frequency response graphs on JLI reliable? The RK47 and JLI-86U have identical graphs across the board if you look at the spec sheets, which sure seems like a mistake. The reason I ask is because the graphs for the TSC-2 and TSC-1 don't look much like what I'd expect from a K67 derivative capsule.

Also, if anybody is interested, I already have a TSC-2 in my possession, amongst an RK47 and a CK12, all from JLI, and I intend to capsule swap my Behringer B2 Pros, so I could do some comparisons once everything is in place. I'm particularly interested to hear the TSC-2 in comparison to the stock 797 K67 capsule for reasons outlined above.

Cheers, following this project with bated breath.

The graphics published by the manufacturers are not real.

In B2-pro there are different capsules:
In the old one with through-hole parts it is 797 CY037
In the new one with SMD it is
797 CY002

 

[micolas]

@Thane Snipes
Kingkorg did the 797 CY002 vs Takstar CTS-2/TSC-2 measurements.
They have the same sound profile, only the 797 is a little brighter, it requires more de-emphasis.
But both, in the right circuit, take you to the U87 area.

 

[OneRoomStudio]

I'm under the impression that the TSC-1 is identical, save for being single membrane, cardioid only. Could save a few bucks there unless I'm mistaken? Also, are the frequency response graphs on JLI reliable? The RK47 and JLI-86U have identical graphs across the board if you look at the spec sheets, which sure seems like a mistake. The reason I ask is because the graphs for the TSC-2 and TSC-1 don't look much like what I'd expect from a K67 derivative capsule.

To quote @soliloqueen from another thread:

Another note is to beware inaccurate information from resellers, especially if they got their capsules from trading companies rather than directly from factories. For instance, JLI says that their tsc-1 and 2 capsules are from transound, but the tsc-1 is from aym and the 2 is from TakStar.

If this is true, then the TSC-1 is not a single-membraned version of the TSC-2, but a different capsule from another manufacturer entirely. They might end up being fairly similar since they're both based on K67's, but TakStar has a much better reputation for QA and consistency.

 

[Thane Snipes]

The graphics published by the manufacturers are not real.

In B2-pro there are different capsules:
In the old one with through-hole parts it is 797 CY037
In the new one with SMD it is
797 CY002

Interestingly, all four of my B2 Pros have the old logo, 3 of them have a mix of SMD and through hole components, 1 has all through hole and the detachable head basket, but I checked the capsule in one of the SMD ones I have, and it's got flathead screws on the clamping ring. Perhaps these old logo, SMD B2 Pros are an intermediate step between the oldest version and the current ones, where the capsule is still a CY037.

 

[Barry Hufker]

It is interesting to see frequency response plotted for comparison, but does anyone ever check impulse response?

 

[micolas]

Interestingly, all four of my B2 Pros have the old logo, 3 of them have a mix of SMD and through hole components, 1 has all through hole and the detachable head basket, but I checked the capsule in one of the SMD ones I have, and it's got flathead screws on the clamping ring. Perhaps these old logo, SMD B2 Pros are an intermediate step between the oldest version and the current ones, where the capsule is still a CY037.

Capsules from B2-PRO:
Left - old model with removable head and through-hole components, old logo
Right - new model with smd components, new logo

 

[Thane Snipes]

Capsules from B2-PRO:
Left - old model with removable head and through-hole components, old logo
Right - new model with smd components, new logo

I found this post of yours in another thread, which was very helpful in identifying my B2 Pros. I've attached some photos so you can see what I mean. None of them have the new logo, and the PCBs are different, but they both appear to have the same (old) capsule, judging from the flathead screws.

 

[Wordsushi]

Alrighty, who's ready for some straight-up blasphemy?

THEORETICALLY, how much of this circuit could be replaced with surface mount in order to shrink the footprint down as much as possible?

I'd keep c5/c6 as through hole for tuning, but what else could be SMD without too much compromise?

 

[Khron]

Alrighty, who's ready for some straight-up blasphemy?

THEORETICALLY, how much of this circuit could be replaced with surface mount in order to shrink the footprint down as much as possible?

Don't tempt me - the thought of shrinking down a U67 circuit had already crossed my mind, the other week...

 

[Wordsushi]

Don't tempt me - the thought of shrinking down a U67 circuit had already crossed my mind, the other week...

Do it!
At this point, when you've built the same stuff again and again, I just want to see what else is on the theoretical edge. I don't need another clone of a classic mic, but I'm really interested in what can be made by taking these old circuits as inspiration for the imagination.

My opinion is that for what it costs, the clone sounds very good compared to the U87ai.

It's crazy how much in the neighborhood you can get with just $100 in parts. I wouldn't call it "myth-busting", but overall I think the current urban legend that you can "Build a U87" for $500 is now yesterday's news. And honestly, I get these comments from time to time from people who live in parts of the world where $500 is an awful lot of money, so this idea that perhaps someone with a lot less expendable income and a decent amount of know-how and gumption, can create a recording tool that will be logarithmically better than anything they could buy in that price range. And you know the next step will be more people making PCB's, so it'll be an even easier build.

I do understand that my enthusiasm for this project may seem extremely high, but a lot of it is how I view this project as something that can make mic DIY much more accessible to a lot of people. And when you end up with something that sounds as reasonably good as the ones I've built with generic parts, it's really a joy. Pretty much everyone who gets into mic DIY wants to build a u87. It's the reason I got into DIY to begin with a decade ago.

 

[Wordsushi]

And the last thought of the day... Couldn't you build a more "u89-inspired" mic by not installing the de-emphasis and using Arienne's flat 47 capsule?
I know it's a different capsule, but her flat 47 is just so nice sounding on its own. And those smaller 87-style bodies on Ali are about u89 size.

 

[kingkorg]

It is interesting to see frequency response plotted for comparison, but does anyone ever check impulse response?

Yup, the method i use, uses impulse response to determine frequency response among other things.