Apex 460

[haysonics]

If PT1 means Plate 1 then i want to connect Pin 6 to ground. So one end of my capacitor goes on Pin 6. Where do i attach the other end ? Where do i ground it ?

 

[Khron]

1 or 2 are rather irrelevant. You already have the schematic in that first link i posted, and which pin is what number and from what perspective, in the second link. And nevermind that i already mentioned that

How about pin 1 or 7, and pin 9 respectively?

(Hint: look at the schematic, and read this tip i self-quoted)

 

[haysonics]

OK, well Pin 9 goes to the edge of the schematic.

 

[Khron]

OK, will Pin 9 goes to the edge of the scematic

And what's on the lower edge of the schematic, right "south" of the transformer's primary winding?

 

[haysonics]

Ground, so that bottom line, that edge connects to ground.

 

[haysonics]

I should connect Pin 6 to a ground point (either Pin 9 or a ground point on the PCB) ?

 

[Khron]

I should connect Pin 6 to a ground point (either Pin 9 or a ground point on the PCB) ?

Why would you?

 

[MidnightArrakis]

Is that some polystyrene smoke I smell here??? (kidding!!! heh.....heh.....heh.....heh.....heh.....).

/

 

[haysonics]

I am sorry I don’t understand. Dave Thomas mentioned you can connect a capacitor from the plate of the first triode to ground to roll off some of the HF of a AK-12 capsule (his copy of the CEK-12).

I just want to know which pin corresponds to the plate of the first triode. You helped me with a diagram that states Pin 6 = PT1 which i assume means Plate 1. You also helped me by leading me to see on the schematic that Pin 9 goes to ground. And that there are various ground positions on the PCB.

That’s what i have figured out so far.

 

[haysonics]

And now someone else has chimed in and says doing that would burn out my 250v styrene cap.

So i am not sure whether i am being educated or trolled at this point.

 

[MidnightArrakis]

And now someone else has chimed in and says doing that would burn out my 250v styrene cap.

So i am not sure whether i am being educated or trolled at this point.

[i am not sure whether i am being educated or trolled at this point] -- Calm down!!! It's just some light humor!!! (sniff.....sniff.....sniff).

 

[haysonics]

The jokes obviously on me. Maybe someone else can help me ?

 

[MidnightArrakis]

The jokes obviously on me. Maybe someone else can help me ?

From what I have read and seen in this thread so far, it appears to me as though "Khron" as provided you with everything that you need so far. I am only guessing that with you being a "Beginner/Newbie" that you don't know enough yet to know where to either begin and/or possibly what to do. So.....let's start at some basic beginning level, OK???.....

1) As you are looking at the 12AX7 pinout sheet.....do you understand what it is that you are looking at? What don't you understand?

2) Do you know how to read, decipher and understand electronic schematics and their symbols?

3) What is it that you are attempting to accomplish?

4) Do you have the proper tools to properly accomplish this with?

5) Are you personally skilled enough to perform what is necessary to do?

6) Have you ever done anything like this before?

7) What is it that you currently -- DON'T KNOW -- that you believe that you -- NEED TO KNOW -- before you begin to heat-up your soldering iron??? Ask away.....OK???

8) Learn to accept and recognize "offbeat" humor!!! I'm "full-of-it"!!!.....

And, just for your "reference".....here is a piece of equipment that I had personally "hand-built" about 25-years ago:



/

 

[Khron]

I just want to know which pin corresponds to the plate of the first triode.

The "first" is relative. You have the schematic, do you not? That, i thought, pretty clearly shows the "first" triode's plate (aka anode) is pin 1, which is also connected to pin 7, is it not?

How about pin 1 or 7, and pin 9 respectively?

Oh ! I just place the capacitor between 2 pins on the tube socket to create the LPF ?

Isn't that precisely what you asked?

Dave Thomas mentioned you can connect a capacitor from the plate of the first triode to ground to roll off some of the HF of a AK-12 capsule (his copy of the CEK-12).

 

[haysonics]

The "first" is relative. You have the schematic, do you not? That, i thought, pretty clearly shows the "first" triode's plate (aka anode) is pin 1

OK, looking at this the plates are Pin 1 and 6. I understand I can choose which triode will be the first stage and which will be the cathode follower stage. So it is relative.



I suppose I allowed myself to be mislead by this diagram which shows Pin 1 = Plate 2 when in fact it can be either Plate 2 or Plate 1 depending on the circuit configuration.

, which is also connected to pin 7, is it not?

Yes, Pins 1 and 7 connect to a resistor. As 1 and 7 share a connection, thus are the 2 pins connected to each other. So "PT2" can be connected to ground by connecting "GT1" to ground.

Assuming this is correct, where on the schematic would I see which plate is designated the 1st stage in the 460's circuit ? That Pins 1 and 7 are connected to a resistor is not much help for a beginner.



And Pin 6 leads to another resistor. If the signals from each Plate don't meet too much resistance then they both lead to a common capacitor which is grounded.

Still nothing shouting out 1st or 2nd stage.

 

[Accelerator]

@haysonics

If I can give you same real, honest, wiseful & helpful advice to you as a "Beginner/Newbie", I can tell you that this whole Chin-o-Canadian (Peluso – Brian Fox - Dave Thomas) “Cinderella” or named it as you like marketing “model”, it is just a crap…

The Apex 460 and the whole Chinese “family” aka Nady TCM-1150, Carvin CM100, Alctron HST-11A etc… it is what it is, just a crap, because the Chinese electronic designers of Apex 460 took the DC Cathode Follower design that Leo Fender used firstly to Bassman 5F6-A (1958) Bass Guitar amplifier and then Jim Marshall used it to Marshall JTM-45 (1963) guitar amplifier and the whole Marshall JTM / JMP / JCM800 / JCM900 guitar and bass guitar amplifiers and then from there on the DC Cathode Follower design there is nearly (exept Hiwatt amps.) in any guitar amplifier (take a look at V2 pre-amp. tube circuit layout of Metroamp '62 Bluesbreaker) and they tried to modified it to a microphone, ignoring that the “reasons” that a DC CF circuit it is “so good” in a guitar amplifier circuit, it is just in opposite way "so worst" in a microphone circuit, but they didn’t and they do not care about it as they followed what Merlin Blencowe wrote to his article:

The DC Coupled Cathode Follower

https://www.valvewizard.co.uk/dccf.html

Worst yet, they put into this flat circuit their crappie Chinese 67-87 pre-emphasis capsules, the ECC83-12AX7 “guitar amp. tube”, the APEX 460 stock transformer, their 200 DC Voltage, in any other words, they do everything to make a crappie microphone as crappie as we all know that the APEX 460 that is …

Then the whole Chin-o-Canadian (Peluso – Brian Fox - Dave Thomas) “Cinderella” or named it as you like marketing “model” of “polish the tad” or “Chocolate covering the shit” comes in to the “play” and they say to you:

“No matter that your Chinese Apex 460 and the whole Chinese “family” aka Nady TCM-1150, Carvin CM100, Alctron HST-11A etc… is a crap, we can transforming it like a “Cinderella” to a decent “C-12”, ELA-M 251E, U-47, U-67 microphone if you pay us this summary of your (extra) money for our Chin-o-Canadian products and for our Canadian services…”

Take a look at Apex 460 Mods.pdf

https://gearspace.com/board/attachm...1235602544-apex-460-mod-u47-apex-460-mods.pdf

In the end of the line, if you will pay this whole summary of your (extra) hard-earnest money for these Chin-o-Canadian products and for all these Canadian mod. Services, you will end up with a modified Chinese Apex 460 microphone crap that will have to cost you an arm, a leg, a kidney, a whola-lotta of money and it will not be in any way a decent “C-12”, ELA-M 251E, U-47, U-67 microphone, while in the same time there are too many decent microphone producers like Stam Audio to buy a decent U-47, U-67 microphone in the right price and too many decent microphone kits like:

Vintage Microphone PCB

https://vintagemicrophonepcbkit.com/

Studio 939

https://store.studio939.com/

SK49 Multi-patern Tube Microphone

https://www.soundskulptor.com/en/microphones/23-65-sk49-multi-patern-tube-microphone.html

If you will to building a decent microphone kit(s) of your desire-ful microphone by your own…

 

[Khron]

I understand I can choose which triode will be the first stage and which will be the cathode follower stage.

Is the circuit not already connected the way that it is, inside the stock microphone? So no, you can't "choose which triode will be the first stage" - it's already wired the way that it is.

But, and i promise you I mean no offense or insult by saying this, it very much sounds to me like there's a good chance you shouldn't be poking around with a "firestick" (non-temperature-regulated mains-powered soldering iron) inside an arguably sensitive-ish piece of electronics like a microphone, especially not where you can (also) run the risk of getting a healthy zap - 120-180V DC is nothing to sneeze at. Well, not before you manage to learn at least a few of the basics.

Neverminding @Accelerator's view on the provenance of this particular circuit, that:

The DC Coupled Cathode Follower

https://www.valvewizard.co.uk/dccf.html

is a useful resource (and that website as a whole) of basic information about widely-used tube circuits, and the why's and how's.

Still nothing shouting out 1st or 2nd stage.

And that's part of the problem. While I would have no qualms about helping troubleshoot a phantom-powered mic, I'm less inclined about a circuit that could actually cause a bit of pain / harm.

Now, unless you can find someone local that could perform this mod for you, I'd recommend you use your patience, bide your time, and study some basics. I could point you towards

https://sound-au.com/articles/index.htm#begl
https://sound-au.com/articles/index.htm
https://sound-au.com/valves/index.html

 

[haysonics]

I have 2 Matador C12 mics :

One has a Heisermann HK12 from his first run with a 1950s era shallow dish and it is relatively flat up to 10kHz. Mods made to the circuit include the capsule being coupled to the tube and capacitors removed via using a diode bias similar to a C24. I couldn’t hear any HF roll-off with a 100 pF styrene cap placed between the plate and ground as I can't hear over 17kHz because of my age (but found it worthwhile to validate that ELAM tweak).

The other is more traditional in that I followed Matador’s circuit as is. I used a Beesneez BN-12 that sounds (to my ears) exactly like a 1960s era CK12 (allowing for variance between the aging CK12s).

As I have survived certain death with High Voltages I now wish to do 1 simple mod to a Stellar CM5. I kept the 10:5/1 Chinese transformer as it is excellent. Unlike my Matadors where I have early 1950s GE 6072 valves, I have an EH 6072a in the Stellar. This was the good one in the batch so a good match for this cheap mic.

What I am hearing with the AK-12 and RK-12 is that they don’t quickly roll off after 12 kHz like a CK12 so I want to place a 200 pF styrene cap from the plate of the first stage to ground. I do not know which triode the Chinese chose to use as the first stage. I figure I am either going to run the cap from Pin 1 or 6 or preferably between 2 points on the PCB itself.

That's all I am asking for here. I am a beginner as I can't figure it out from the schematic. If anyone actually knows the answer to the question I would be grateful. And don't worry about me, the iron I use is much safer than the one I was using in the 1970s. But that's a story for another day.

 

[Migs 31]

I have 2 Matador C12 mics :

One has a Heisermann HK12 from his first run with a 1950s era shallow dish and it is relatively flat up to 10kHz. Mods made to the circuit include the capsule being coupled to the tube and capacitors removed via using a diode bias similar to a C24. I couldn’t hear any HF roll-off with a 100 pF styrene cap placed between the plate and ground as I can't hear over 17kHz because of my age (but found it worthwhile to validate that ELAM tweak).

The other is more traditional in that I followed Matador’s circuit as is. I used a Beesneez BN-12 that sounds (to my ears) exactly like a 1960s era CK12 (allowing for variance between the aging CK12s).

As I have survived certain death with High Voltages I now wish to do 1 simple mod to a Stellar CM5. I kept the 10:5/1 Chinese transformer as it is excellent. Unlike my Matadors where I have early 1950s GE 6072 valves, I have an EH 6072a in the Stellar. This was the good one in the batch so a good match for this cheap mic.

What I am hearing with the AK-12 and RK-12 is that they don’t quickly roll off after 12 kHz like a CK12 so I want to place a 200 pF styrene cap from the plate of the first stage to ground. I do not know which triode the Chinese chose to use as the first stage. I figure I am either going to run the cap from Pin 1 or 6 or preferably between 2 points on the PCB itself.

That's all I am asking for here. I am a beginner as I can't figure it out from the schematic. If anyone actually knows the answer to the question I would be grateful. And don't worry about me, the iron I use is much safer than the one I was using in the 1970s. But that's a story for another day.

Ok,
A bit clearer now. Can you please post a pic. of the mic your are actually trying to mod (if not already done earlier on the thread).
Component side and traces side. And specially of the tube socket's bottom, so we can maybe help, as to what pins are what?
Is this a Stellar CM 5 you want to mod? Just to be extra clear.

I just moded a Thomann SCT800 last week and 270 pF styrene cap didn't make much difference to my ears, might need to go for bigger value. Venerable members (read older, more experienced/grumpy/extra crusty) here on this forum would advice to measure before and after (if you have the tools).

BTW. RK and AK 12's are not a CK12 never! I don't want to open an old can of worms but... every real CK12 will sound a bit different from one another...anyway. Depending on ageing, era etc etc. Fact!

Show us in detail what you got. Pictures can speak a thousand words, sometimes.

M

 

[haysonics]

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




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.