Apex 460 capacitor change?

[PhilGood]

I'm getting close to hammer time.

Last question(s) before I order my caps.
I will stay with 1uf - but if I go higher will the bass also increase? - or is it already maxed out?
Also: I have been told that I can lower the VDC with no ill effect. The cap installed is 450v when there is only about half needed. Where Im going with this is getting the smallest size while improving the sound the most.
Sound being #1- I will hammer it in if I must.

Thank you
Bobby

The cap just acts as a high-pass filter. You won't increase the bass response, but you will extend it. If it cuts off at 30hz you mught change it to 15hz by using a larger value cap.

The voltage rating is the capacitors MAXIMUM voltage. If its rated at 450v, that means it can't handle anything higher than that. I would go with a 250v. That's what I used in mine. I had to lay it flat nest to the tube socket and work the leads around other parts.

 

[PhilGood]

No doubt the C12 is a good circuit.
I just pointed out that to turn the 460 into half of C24 type of the circuit would be quite an easy task, without getting into complications of complete rewiring of the PCB and PSU.
BTW, apart from some voltages and part values, aforementioned half of C24 and Ela M250 circuits look similar, so you could use existing 460 PCB for Ela M250 type of circuit, as well.

Then I may have to try this. Didn't you or Gus do this once?

 

[Marik]

Then I may have to try this. Didn't you or Gus do this once?

IIRC, Gus did something else. I did the half of the C24, with higher grid leak resistor (1G).

 

[PhilGood]

IIRC, Gus did something else. I did the half of the C24, with higher grid leak resistor (1G).

So how does it sound???? Why are you holding out???

 

[Marik]

So how does it sound???? Why are you holding out???

I posted about it here... maybe a year ago, with listening impressions of a happy customer. Make a search on 1050 (or Nady) with my name as a poster.

 

[EdgeGuy]

The hammer falls

The cap just acts as a high-pass filter. You won't increase the bass response, but you will extend it. If it cuts off at 30hz you mught change it to 15hz by using a larger value cap.

The voltage rating is the capacitors MAXIMUM voltage. If its rated at 450v, that means it can't handle anything higher than that. I would go with a 250v. That's what I used in mine. I had to lay it flat nest to the tube socket and work the leads around other parts.

That's it!
Who's cap did you use?

Just a fun question. I've been looking at the schamatic and wondered what a 1km resistor (R10) is doing hanging off the capsule's ground?

Also What would happen if I lowered the value or complietly removed (C2).

Thanks guys, I will post my result's.

Bobby.

 

[EdgeGuy]

Hello PhilGood

Im getting frustrated trying to find the right parts. Can you help me out?
Black Gate is out of buisness, and I don't know exactly what cap to get for
(C8) that will fit. Also does it have to be polorized? I think it does but I don't know.
This is my first attempt at upgrading a mic. I'm learning to read schamatics on this project.
In the past Gus used to do that for me but I've moved and don't see him any more.

Thanks again.

Bobby.

 

[PhilGood]

Im getting frustrated trying to find the right parts. Can you help me out?
Black Gate is out of buisness, and I don't know exactly what cap to get for
(C8) that will fit. Also does it have to be polorized? I think it does but I don't know.
This is my first attempt at upgrading a mic. I'm learning to read schamatics on this project.
In the past Gus used to do that for me but I've moved and don't see him any more.

Thanks again.

Bobby.

No! It does not have to be polarized. Metal film/Mylar caps can run either direction. Here's what i think you should get:

http://www.mouser.com/index.cfm?han...oductid=628189&e_categoryid=5&e_pcodeid=53912

 

[PhilGood]

Just a fun question. I've been looking at the schamatic and wondered what a 1km resistor (R10) is doing hanging off the capsule's ground?

Also What would happen if I lowered the value or complietly removed (C2).

Marik, (Mark)

I've been looking back on this question and think it's a good one. Is R10 (1G) doing the biasing for the grid, or is R6 (200M)? My guess would be R6. In the C24 mod did you change C6 to 1Gohm?

C2 and C1 are part of the circuit used to lower the impedance for the transformer, right? Are they just smoothing caps? What would be the result of a higher value or removing C2?

 

[Marik]

Marik, (Mark)

I've been looking back on this question and think it's a good one. Is R10 (1G) doing the biasing for the grid, or is R6 (200M)? My guess would be R6. In the C24 mod did you change C6 to 1Gohm?

C2 and C1 are part of the circuit used to lower the impedance for the transformer, right? Are they just smoothing caps? What would be the result of a higher value or removing C2?

The R10 is a capsule bias (BTW, it is not off the capsule ground), and R6 is a "grid leak" resistor. Looking back, now I remember I did not raise it, leaving 200M in there.

C1 and C2 are filter caps for B+ and capsule bias, respectively. The higher value would probably be better, but don't remove them.

If you don't have any problems with RF interference, then it is probably better to remove C9-C10.

 

[ittam]

Similiar

Well, this is GA TC-1, similiar to ADK Generis tube mic execpt it has pad and low cut. Can I make same cap chanches as with Apex 460? And could you show me what to change as I can`t see all the markings on the pcb. There is
one more component at the tube side but can`t see it either without dismantling. I have a NOS tube coming later this week and could change the most important ones at the same time. I´m tempted to put a Peluso capsule
here sometime in the future, which one?
Regards
Matti
P.S. sorry my amatourish approach

 

[EdgeGuy]

cap change update

Every time I make a change to this mic - I record my voice to check the changes in sound.

I replaced the mylar cap (C8) with an Ansar SPA 1uf 400. The differance is huge. I now really like this mic.
The grain in the mids are almost complietly gone.
The clouds in the mids and highs are gone.

I still have a few parts to replace and I will update (if anyone is reading this) again.

 

[PhilGood]

Is the Ansar SPA 1uf 400 much bigger than the mylar? Did you get it from Digikey?

 

[PhilGood]

Well, this is GA TC-1, similiar to ADK Generis tube mic execpt it has pad and low cut. Can I make same cap chanches as with Apex 460? And could you show me what to change as I can`t see all the markings on the pcb. There is
one more component at the tube side but can`t see it either without dismantling. I have a NOS tube coming later this week and could change the most important ones at the same time. I´m tempted to put a Peluso capsule
here sometime in the future, which one?
Regards
Matti
P.S. sorry my amatourish approach

Sorry, I don't know too much about this mic. A schematic might help.

 

[PhilGood]

I found the Ansar SPA 1uf 400 at tubestore. $15!

How much difference did the Ansar SPA 1uf 400 make in comparison to upgrading from the electrlytic to a mylar. I know that had to be an improvement from the electro. It was on mine. Is the Ansar a big leap or a minorly perceptible one?

 

[EdgeGuy]

next update

O.K. My 460 had a Mylar already in place. The new ones have updated electronics.
Still the difference between caps is dramatic.
The Anser just barely fit in the shell and I would have tried a Teflon cap but I knew it wouldn't fit.
That's why I bought the Anser (plus it was cheep).

I can clearly hear the difference after installing the Anser.

The biggest improvement was the Telefunken 12ax7.
The Tele 12ax7 isn't as hot as a modern 12ax7s (a good thing) but it is clean.
The noise floor dropped big time.

The next biggest improvement was the cap change.

After that was getting rid of the stupid inner layers of mesh.
I will use a pop filter for voice and nothing for instruments.

There is still work to be done.
I have tested the mic further and can describe the sound problems that remain very well.
S's have a quality a little like the way Sean Connery speaks.
I have more parts coming and will see what happens.

I suspect that the negative feedback is holding this mic back.
I do not think that the capsule is to blame.
I also do not want to replace the transformer.

This will be a cheap and easy mod for me (because I have a lot of Telefunken tubes) or nothing.
I might just as well just buy a better mic.

But for $230 and a willingness to heat solder - This is fun.
The mic is very useable right now.
It is already better than my old Rode classic for most things.

I will update as I go.
I'm glad some people are interested.
I ordered two of every part because I will get another 460 and update it.
I like this mic.

See you again after I record a vocal on Sunday.

 

[PhilGood]

I guess cheap is a relative term. I bought the mylar cap for a buck-seventy five and it was a big upgrade from the electrolytic. I guess I will have the shell out $30 for two Ansers. (I already have two mics)

If you figure out what to do about the negative feedback let me know what you did. In the meantime, I am going to try Marik's C24 suggestions!

After I get done with a few other projects, of course...

Also, I think changing the transformer would be a good thing. There are some phase problems that some folks have blamed the on the transformer.

 

[EdgeGuy]

I guess cheap is a relative term. I bought the mylar cap for a buck-seventy five and it was a big upgrade from the electrolytic. I guess I will have the shell out $30 for two Ansers. (I already have two mics)

If you figure out what to do about the negative feedback let me know what you did. In the meantime, I am going to try Marik's C24 suggestions!

After I get done with a few other projects, of course...

Also, I think changing the transformer would be a good thing. There are some phase problems that some folks have blamed the on the transformer.

I don't hear any phase problems with this mic. I'm using my ears and not a scope.
Shell out the $30 bucks for the Ansers.
They will fit but you will need too expand the holes a bit to except the wire leads.
I thought I lost some bass with these caps but it was really that the high end opened up. Would you consider trying a slightly higher value - i.e.:1.2uf to compensate? Let me explain. The high end opened up and the bass remained the same. I think a higher value would also open up the bass. Not volume but extention.
It's your money and I'm an electrical moron. I would like to see some more extension in the bass. It might be that I am no longer looking at the high end and the low end just showed up as an issue.
I am getting a Black Gate for the negative feedback (C6) and will see.
I suspect that I will have to reduce the NF. Not sure how to do that.
Can you tell me -in advance- what I would need to do to "reduce" the NF in this mic.

You will love the new caps.

 

[PhilGood]

I don't hear any phase problems with this mic. I'm using my ears and not a scope.
Shell out the $30 bucks for the Ansers.
They will fit but you will need too expand the holes a bit to except the wire leads.
I thought I lost some bass with these caps but it was really that the high end opened up. Would you consider trying a slightly higher value - i.e.:1.2uf to compensate? Let me explain. The high end opened up and the bass remained the same. I think a higher value would also open up the bass. Not volume but extention.
It's your money and I'm an electrical moron. I would like to see some more extension in the bass. It might be that I am no longer looking at the high end and the low end just showed up as an issue.
I am getting a Black Gate for the negative feedback (C6) and will see.
I suspect that I will have to reduce the NF. Not sure how to do that.
Can you tell me -in advance- what I would need to do to "reduce" the NF in this mic.

You will love the new caps.

The phase problems are only shown on the graph. Can't remember where that link is, but I'll find it.

If I would go for a higher value Ansar, it would be a 3.3uf 400v CPA, which is a lesser performance cap than the SPA, but about the same size. That would extend the bass a bit. Probably down to 20hz easily. Too bad we couldn't find a paper in oil that would fit! That would be the best!

Marik or Flatpicker or mshilarious could tell you how to alter the negative feedback, if it exists. I've always heard that negative feedback can actually correct renagade spikes. Wish Gus would comment! Haven't seen him here in a while.

Did you try a better coupler cap for C4? If we could find a suitable polystyrene, that would KILL and solve alot of problems. It would have to be a suitable voltage. I've used 1000pF 50v on SS mics and it makes a HUGE difference!

BTW, I am using Telefunken 12AT7 for the tube, and found it seems to be the best suited for the circuit. Tried a 6072A, but found it to be too soft sounding.

 

[Gus]

Is that you Bobby S? If so the I lost your number and message on my machine because I replaced the phone. give me a call.
I have a better circuit for that microphone. People are missing a circuit I posted in the past. Also people are missing some problems with the power supply. Still have the mxl603?

Do you check "the Lab"