Apex 460

[MidnightArrakis]

>> You could possibly run a pair of 24-AWG wires from the tube-socket pins over to the PCB area and then connect them to your capacitor that you have -- hot-glued -- down to the PCB somewhere it will easily fit. Just a thought.....

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[haysonics]

Thanks, I am contemplating that as there is plenty of space on the PCB. Maybe enough for a PIO cap. I think I will start by adding a socket so I can try various styrene's with values from 180 pF upwards.

 

[Migs 31]

Thanks. Its too late over here for me to contemplate the small screws so its just component pics for now :
View attachment 131701
View attachment 131702
View attachment 131703

I want to shrink-wrap those pins sticking out the bottom of the tube socket so unless you see obvious solder points on the PCB I think I'll run the cap between 2 of the pins.

Note: The CM5 has the Dave Thomas circuit mods and is essentially a first edition Advanced Audio CM12 (but with the stock 10:5/1 transformer). I have seen various HST11A boards over the years (this is a Shuaiyin SYT1100) but I just refer to that series as an APEX 460 as that's the brand-model most known.

Ahhh the plot thickens!

So it is really NOT an Apex 460.
It really is a Stellar Pro Mics (Peter Bloch ?)
Originally Made by Shuaiyin in China.
And with a AA - Dave Thomas mod kit ?

No wonder it sounds too bright!

Thanks for the pics. Take more- like the valve socket - when you can.

M

 

[haysonics]

Will do !

Yes, Peter and Dave’s mics were made by Shuaiyin and both utilise Dave’s modified circuit and capsule. They also use 6072a tubes and different transformers from the Apex 460.

The capsule can be 90% of the sound of a mic. The Stellar circuit, transformer and tube are all flat response. It is the AK12 which is the issue. It’s a copy of the CEK-12. The Chinese overtighten membranes which increases the resonance. It’s why their K67 is 6dB brighter at 10 kHz than one made by Neumann. They won’t change their ways as “this is what sells”. I blame the C800G for that.

 

[Migs 31]

The capsule can be 90% of the sound of a mic. The Stellar circuit, transformer and tube are all flat response. There will be greater 2nd order harmonics with a plate follower of course. But it is the AK12 which is the issue. It’s a copy of the CEK-12. The Chinese overtighten membranes which increases the resonance. It’s why their K67 is 6dB brighter at 10 kHz than one made by Neumann. They won’t change their ways as “this is what sells”. I blame the C800G for that.

"AK12 which is the issue"
Isn't that AK12 an Audio Advanced "made" capsule, with 6 micron Mylar from Deutschland?

Quote AA Europe site:
"This edge fed capsule is skinned with 6 micron German Mylar.
This capsule has a response with 1.5db of the average venerable old AKG CK12 capsule."

Surely Dave from AA must have some sort of say or check on his product, tension etc?
So Chinese made capsule, German Mylar, packed by Canadian virgins (rare to find, unless an incel )?
Is this only marketing bla bla or can we all here believe their (companies) talk?
Peter Bloch and Dave T. are supposed to know a bit more than you and I.
What's going on here (honest question)?

M

 

[haysonics]

The mylar is German but tensioned, sputtered, and added to the capsule in China. The comment about the response being within 1.5dB of a CK12 is copied from Peluso. Verner (John's partner) got their CEK-12 within 1.5dB of their CK12. The AK12 is a copy of the CEK12.

Although Dave doesn't mention tensioning, I think he happens to like bright mics. He took a badly implemented cathode follower stage, fixed it, and then made a successful business out of it. Apparently his C800G copy sounds like the real deal (too bright for me).

 

[haysonics]

I am pleased to report that I tested Dave Thomas' statement that you can add a capacitor (working as a LPF) between the plate of the first stage/triode in a Apex 460 (or similar) and ground. It works ! Please see attached pics and sound files of a shootout between:
a special order clone of a 1950's CK-12 (Heisermann)
a clone of a 1960's CK-12 (Beesneez)
a low pass filtered (270pF) AK-12/CEK-12 clone of a 1960's CK-12.

The Beesneez and Heisermann capsules are in Matador C12 mics.



View attachment HK-12.wav
View attachment BN-12.wav
View attachment AK-12.wav

 

[haysonics]

Fixed the audio so you can hear it !

If you listen on a phone or PC the audio is almost identical between the 2nd and 3rd files but when listening on good monitors or headphones you can hear a difference (mainly the AK-12 does not have the enhanced low end of the proper CK-12 clones).

And that's really the thing that differentiates all capsules. Nothing has the enhanced bass of a properly made or cloned CK-12. No M7, K47 or K67/K87 boosts the bass like that. You would need to revert to a ribbon to get that enhanced bass response. That is why the ELAM 251 circuit cuts bass. An ELAM corrects bass - bringing it back to reality. And the ELAM's 2nd layer in its head basket reigns in some of the 1960s era CK12 added top end.

But, if you have modded an APEX 460 to the extent that its not really a APEX 460 anymore, BUT you used an RK-12 or AK-12 and are still finding it too bright, I suggest just spending 5 minutes and soldering in a one dollar 270pF cap between pin 1 and 9 on the tube pins.

 

[MagnetoSound]

The first file is markedly darker than the other two. It sounds as though there is a high-end roll-off extending well down into the upper mids.

Very ribbon-like, but too scooped sounding and not particularly what I associate with the CK12s I’ve used, although I did once have a pair of C12A that were quite soft in the upper register, but even those had a little more top than I’m hearing here. Is this the Heiserman?

Listening on DT250s.

 

[haysonics]

Yes, but that Heisermann CK-12 is his first production capsule so has the shallow dish/chamber of an early 1950s era CK-12. Not many have heard one of those. It is certainly not what folk associate with a CK-12. BUT, you could imagine Telefunken hearing it and thinking that would be an ideal replacement for the U47.

It wasn't until 1978 and the c414EB that AKG engineers took the opportunity to correct the overly bright 1960s capsule (the bean counters had ordered them to produce a cheaper capsule) and thus was born the Teflon CK-12. And then they made the BULS more linear ! And then the marketing department stepped in and demanded a bright CK-12 again. And the TLII was born. Back and forth, neutral, bright, neutral, bright, etc.

 

[jeremynothman]

Yes, but that Heisermann CK-12 is his first production capsule so has the shallow dish/chamber of an early 1950s era CK-12. Not many have heard one of those. It is certainly not what folk associate with a CK-12. BUT, you may imagine Telefunken hearing it and thinking that would be an ideal replacement for the U47.

It wasn't until 1978 and the c414EB that AKG engineers took the opportunity to correct the overly bright 1960s capsule (the bean counters had ordered them to produce a cheaper capsule) and thus was born the Teflon CK-12. And then they made the BULS more linear ! And then the marketing department stepped in and demanded a bright CK-12 again. And the TLII was born. Back and forth, neutral, bright, neutral, bright, etc.

Really? I mean, maybe i'd need to hear it in a U47, but that doesn't really sound anything like any M7 or K47 (or SM204, for that matter) I've heard. I think I'd be left questioning the thoroughness of the copy by Heiserman, rather than thinking that's how it should sound.
Does it sound better when you're more distant? I hear this and don't really know where/what instrument I'd want to stick this on. Maybe a trombone or trumpet?

 

[haysonics]

I am not suggesting an early CK-12 sounded the same as a M7. This CK-12 is relatively flat up to 10kHz (it lifts up from there). I use it in shootouts as a yardstick for neutral frequency response. It works really well for hearing how bright other capsules are. And in this shootout, how close the other 2 capsules are to each other (with the 270pF offset added to the AK-12).

A Teflon CK-12 is remarkably close to it. It might sound dark (and maybe even useless) compared to the other 2 capsules but feed it into a V72 or REDD47 preamp and it becomes my favourite mic (beating a U47 clone fed into a neutral preamp).

Its also similar to a special ribbon mic I own that has a flat frequency response except the CK-12 has air (via its boost above 10kHz).