Oktava MKL2500 schematic
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Marik
Well-known member
[quote author="adrianh"]
With the DC through the primary this may be an issue.
I was going to use amphorous core Lundahls.[/quote]
From the pics it seems that the trafo is pretty small. Hmm, it's ought to be gapped. Stewart, do you have any means of checking it's inductance?
With the DC through the primary this may be an issue.
I was going to use amphorous core Lundahls.[/quote]
From the pics it seems that the trafo is pretty small. Hmm, it's ought to be gapped. Stewart, do you have any means of checking it's inductance?
microx
Well-known member
I cant see the point in making drastic changes to the circuit like converting it to plate load. I like this circuit, better quality caps etc by all means and a good PSU for 120/6.3 is easy. No need to re-invent the wheel just make it rounder.
Steve
Steve
microx
Well-known member
Well said!
I guess a tranny cold be checked by injecting a signal into the primary, scoping the secondary and then adding some DC (Battery and a pot with a meter in circuit) and seeing at what point the wave form changes. This would be the saturation point.
Thoughts?
Steve
I guess a tranny cold be checked by injecting a signal into the primary, scoping the secondary and then adding some DC (Battery and a pot with a meter in circuit) and seeing at what point the wave form changes. This would be the saturation point.
Thoughts?
Steve
The reasons I posted about converting it to a plate out. A CF tends not to have a sound of its own compared to a plate out. I have built a LD using a 219 capsule and a SF.
I think to get a good sound out of that capsule you might want a plate out. Use a PET cap for some extra DA to get some "warmth" and play with the bias point.
I went and looked at some web pages that sell the 2500. I misunderstood the use of the term power block with added 3th distortion. I thought at first it was a SS output.
A powerblock with added 3th distortion might be an ungapped too small output transformer with DC affecting the output! Marketing can come up with some good terms!
I think to get a good sound out of that capsule you might want a plate out. Use a PET cap for some extra DA to get some "warmth" and play with the bias point.
I went and looked at some web pages that sell the 2500. I misunderstood the use of the term power block with added 3th distortion. I thought at first it was a SS output.
A powerblock with added 3th distortion might be an ungapped too small output transformer with DC affecting the output! Marketing can come up with some good terms!
Well it seems like the later models of this mic have a different circuit. A friend has just bought one and sent me a picture:
There is a trimmer pot in this mic and the caps values are 22uF/16V and 1uF/250V. I'm thinking that this is consistent with a plate follower type circuit. Perhaps the trimmer is for a feedback circuit or for bias adjustment. We're trying to get schematics from Oktava & the UK importers.
There is a trimmer pot in this mic and the caps values are 22uF/16V and 1uF/250V. I'm thinking that this is consistent with a plate follower type circuit. Perhaps the trimmer is for a feedback circuit or for bias adjustment. We're trying to get schematics from Oktava & the UK importers.
[quote author="Marik"]
From the pics it seems that the trafo is pretty small. Hmm, it's ought to be gapped. Stewart, do you have any means of checking it's inductance?[/quote]
Splashed out on a meter that does inductance too so finally got some figures on the transformer:
Primary (i.e. mic side)
DC resistance: 217ohms, Inductance: 6.05H
Secondary (i.e. output side)
DC res. 60ohms, Inductance: 3.275H
Volts Ratio: 1.49:1
From the pics it seems that the trafo is pretty small. Hmm, it's ought to be gapped. Stewart, do you have any means of checking it's inductance?[/quote]
Splashed out on a meter that does inductance too so finally got some figures on the transformer:
Primary (i.e. mic side)
DC resistance: 217ohms, Inductance: 6.05H
Secondary (i.e. output side)
DC res. 60ohms, Inductance: 3.275H
Volts Ratio: 1.49:1
evil grill
Well-known member
i know this thread might be getting old but i´d like you all to see this suggestion for a mkl2500 mod.
http://www.geocities.com/evilgrill/mkl2500mod.jpg
anyone got some thoughts? i propably wont do it myself since i´m gonna use the mike quite alot and there´s not enough time for eventual mishappenings.
christr
http://www.geocities.com/evilgrill/mkl2500mod.jpg
anyone got some thoughts? i propably wont do it myself since i´m gonna use the mike quite alot and there´s not enough time for eventual mishappenings.
christr
Well that's a much more standard cathode follower design. It'll work, but I guess you'd need to try it to see if it sounds better. You might want a higher ratio on the transformer ..... 2:1. Depends what you're going to be driving into.
We're still waiting to hear from Oktava about why there are two totally different circuits for this mic.
We're still waiting to hear from Oktava about why there are two totally different circuits for this mic.
robomatique
Well-known member
The MKL2500 sells for EURO 330 in sweden, strangely enough even cheaper in swedish kronor...
http://www.studiosolutions.se/english/index.html
Robert
http://www.studiosolutions.se/english/index.html
Robert
I just picked up one of these over the weekend, have a feeling Oktava mics are going to be in shorter supply...not that they were plenteous...
I have to say as my first Cathode follower mic I really like the sound of this...there is a pretty low level hum which I'm hoping changing out the capacitors in the PSU will help...its not really all that bad and it IS a tube device...I tried using a grounding jumper with the psu open to see if it helps but it isn't there until it has warmed up for a while...its actually not worth getting worked up about.
According to my internot sleuthing this is an actual Russian version, the PSU is a newer one than all the pics I've and found my voltages are right on...
Anyway I like it, its a shame whats happening to our audio bros all over the world.
I have to say as my first Cathode follower mic I really like the sound of this...there is a pretty low level hum which I'm hoping changing out the capacitors in the PSU will help...its not really all that bad and it IS a tube device...I tried using a grounding jumper with the psu open to see if it helps but it isn't there until it has warmed up for a while...its actually not worth getting worked up about.
According to my internot sleuthing this is an actual Russian version, the PSU is a newer one than all the pics I've and found my voltages are right on...
Anyway I like it, its a shame whats happening to our audio bros all over the world.
