SE Z5600 a

[spottydog10]

I used to run a small studio in the local school but left a couple of years ago.
The school kindly gave me some stuff recently as the studio was being closed down, including an SE Z5600 ii a.
When testing it, it appears to have lost a bit of bottom end and some low mids so I changed the valve to a 6072A/12AY7-ELECTRO HARMONIX
as the easiest option to try and resolve this but this made no difference.

Any thoughts on what to try next? I would have had a look at the capsule to check if there was any dirt on it but I cant see an an obvious way of
getting to it.
Any advice gratefully received.
Cheers

 

[Barry Hufker]

OK, I know this falls into the obvious but I believe in making no assumptions, so forgive me this isn't meant as an insult. You've checked that the bass roll-off isn't on or the switch is broken. I mean this only as a first step towards helping.

 

[spottydog10]

Hi Barry, I've tested with the bass switch on and off and it works fine, there's a definite change in bass response

 

[Khron]

it appears to have lost a bit of bottom end and some low mids

... Compared to what / when?

 

[spottydog10]

... Compared to what / when?

I remembered the mic having a much more robust bottom end to it.
Granted, that could be subjective but comparing against a Rode nt1a, a studio works condenser and an se pencil mic there is a definite lack in the lower frequencies. Thanks.

 

[Khron]

Meant no offense, but as i'm sure we all know, the easiest person to fool is yourself - (TM) AvE

Internal photos?

 

[RoadrunnerOZ]

Has the mic been modded perhaps?? Capsule replacement maybe. Worth a look inside and posting some pics as Khron suggested……

 

[Drosselmeier]

My clone M251 lost low frequencies (sharp drop after 1000 Hz) due to the poor quality of the Chinese cable - 10 meters.

 

[Khron]

My clone M251 lost low frequencies (sharp drop after 1000 Hz) due to the poor quality of the Chinese cable - 10 meters.

LOW frequencies? How???

 

[spottydog10]

The cable is the original cable so must be over 10 years old, I had a quick look online and they seem to be expensive (over £100)
so I cant just cable swap to test.

I'm happy to post pics but I have no idea how to open up where the capsule is. I did notice when I changed the tube that all seemed pretty clean and tidy in there. It's unlikely that the capsule has been changed - they weren't technically minded in that school!

 

[Khron]

Internal photos?

I'm happy to post pics but I have no idea how to open up where the capsule is.

I'm not sure i'm reading "show us the capsule" anywhere...?

Of course, you could've also (already) snapped a photo or two of the underside of the headbasket, so we can point out where some screws might be hiding...

May very well be where that kinda-Z-shaped metal tongue is visible just in front of the tube socket, and likely another one on the opposite side.

(Later edit) And you could have considered perhaps putting the (complete) name of the ACTUAL mic we're talking about (Z5600a vs. Z5600a ***II***). Just sayin'...

 

[spottydog10]

Don't know if these pics are sharp enough but here goes.
You can see that there is a dent in the basket - looks like it may have been dropped at some point.
SE Z5600a ll is written on the mic.

 

[Khron]

Anything looking relevant in the fourth photo, wink-wink?

 

[spottydog10]

Yes and my guitar allen key fits.
If I unscrew them
a: how careful will I need to be?
b; is it easy to get them back in?
c: what should I be looking for regarding the capsule and surrounds?
Cheers

 

[Khron]

I'm still a bit uncertain what exactly you hope / expect to find upon removing the headbasket, but "you do you", i guess.

That being said, depending on the age of the thing, replacing those electrolytics might not be the worst idea. Loss of capacitance could lead to lacking low-end response, depending on the role within the circuit, plus they seem to be some no-name far-eastern ones, ie. not-trustable to begin with...

 

[spottydog10]

I suppose just to see if there is any obvious grime on the capsule that could explain the lack of low end.
"Replacing the electrolytics" is well over my head I'm afraid

 

[RoadrunnerOZ]

When testing it, it appears to have lost a bit of bottom end and some low mids so I changed the valve to a 6072A/12AY7-ELECTRO HARMONIX

ECC83A is a low noise, low microphony better shielded version of the ECC83/12AX7 tube and has a mu of 60 IIRC
12AY7 is a lower gain tube again - (40 vs 100 for 12AX7/ECC83 vs 60 for ECC83A) and may not be the best alternative for this mic. The tube already in the mic may have aged??
Caps may have dried out from heat - there is a lifespan for electrolytics which reduces exponentially with increase in ambient operating temperature so if replacing try to use high temp, high grade ones.
Do not use any solvent or hard brush or any pressure to clean a capsule diaphragm, you’ll either wipe off the gold film coating or dent/deform the diaphragm. Gentle wipe with a soft (like sable) artists brush and a light blow from a distance- side on NOT direct into the face with an air duster. The old style camera lens soft brush with the rubber squeeze blower is a good tool.

 

[spottydog10]

I'll take a better pic with a camera tomorrow but here is the capsule

 

[RoadrunnerOZ]

Plastic mount has cracked at the base of the capsule - looks like it was dropped. Little bits of dust/grit on the diaphragm surface - a light brush and blow should get rid of those, but nothing there to suggest lack of performance due to dirt/grime - buildup usually tends to lower high frequency performance mostly and not much at the bottom end anyway, as the diaphragm just gets heavier. No sign of the gold having been wiped off either - looks ok. The shock of dropping may have damaged the capsule frame and it may be slightly distorted causing a drop in performance but I’d first be looking at getting the correct tube (in a heavy hit a tube’s internal metalwork can be displaced even though the glass hasn’t broken although age is a likely culprit - eroded cathode) as the one in there is probably the original by the look as it has SE printed on it.

 

[spottydog10]

I have changed the valve to a 6072A/12AY7-ELECTRO HARMONIX but it made no discernible difference.