Latest Microphone Mod Pictures (Gus)

Hi ,
I'm posting these pictures for Gus...

Firstly 3 tube modified mics (the black ones were MXL mics):



and some detail of the single point grounding...



And some pictures of a Fet Modified mic built into and MXL V67:








Finally a glose up of one of the capsules



Look good, don't they?
Gus will drop by and give us some details shortly.

Stewart
:thumb:

The silver one is a sam ash stageworks with a 6072 ela m 251 type circuit the transformer is a jensen 12:1

The 2001s are royer circuit with 1 gig grid to ground a cathode bypass cap 140V PS. Cathode R was changed to 1K. Jensen 12:1s

The capsule in the stageworks one is a strange design the blind hole volume seems to be replaced cut rings.

The pictures of the V67 are with a 2sk170 now it has a 2n3819.

The 10pf is the red wirewape wire in shrink I twisted and bent the wire using a sencore lc102 to measure the total cap. Wire wrap is teflon or teflize both are good dielectrics.

If you want to take a MXL capsule apart the two front screws at 12 and 6 o clock the two back screws at 3 and 9 o clock IIRC.

I don't think the PET is glued to the ring in the mxl brass ring capsule. It looks like no glue. The 797 capsules look like they are glued.

Hi Gus
Did you use same parts for ELA M clone like on original and how it sounds.
My friend from Slovenia will send me Haufe T14/1 and maybe I will use capsule from my AKG C414EB (original brass CK12). Also I have a new teflon CK12 2071Z0005 and SKE106. Shall I use excatly schematics?
Your opinion.
Thanks
Duka

Duka

I have not used a real ELA M251. there are 2 schematics on the web I know of One uses the 6072 and two different input grid to ground resistors 8 meg or 30meg if I remember correctly. There is also one with the AC701 tube.

The circuit I used was the one for the 6072 but I did not use a grid to ground resistor. Thats why I used the work type. type means close to the same but not the same as I use it here.

I used a jensen 12:1 the model used in the Royer circuit.

Some things to note.

The T14/1 is small. It is possable that the designers of the ELA M251 used 8meg or 30 meg grid to ground to remove more of the low freguences. This would help to not overload the small transformer.

I would build it with the new CK12 as a cardiod only. When the circuit is tested I would then change to the older CK12.

I think you will be building a better clone of the 251 than me.

Gus,
What would be the advantages and dissadvantages of building mods into Marshall V67 as opposed to the 2001 or 2003? It looks like the V67 has more room and is also inexpensive. Do the capsules compare?
Kelley

I may be wrong, but I´ve heard people saying that the V67 has a superior grill.

Where can I find circuits for these mods?

The 2001 and v67 use the same capsule and transformer. There is a difference in the circuit a few resistors are changed that
set the openloop gain. With stock grills I tend to like the sound of the v67 grill 3 layer, remember it is a taste thing.

The 2003 has a 797 3 micron capsule and a more open grill two layers with a good SS circuit. The mod I do is cap upgrades.


The china transformer was sent to Chris to check because I don't think the stock circuit of the MXL67 is a bad design however I believe it is limited buy the parts used. I have upgraded the parts in SS and tube china built microphones WITH the stock transformer in place and could not get them to sound good to my ears. When I placed other circuits with better transformers the microphones sound so much better.

I am thinking a lam upgrade and a few cap changes and circuit mods will make the 2001v67 into much better microphones.

You can try a 2001 grill on a v67 etc. Think of a grill as a EQ. The best way to find what works seems to be YOUR ear/brain and trying different things. I don't have enought infomation built up to give a GOOD answer yet.

There is a lot of info in the microphone metas.

http://www.geocities.com/SiliconValley/Peaks/5212/start.htm

Good Site

Gus, the capsule looks weird. Just out of curiosity, how deep these holes on the rim. Any idea, as for their purpose?

You can try a 2001 grill on a v67 etc. Think of a grill as a EQ.

Click to expand...

I remove two layers of internal mesh from 2001. It makes quite noticable difference and I prefer acoustically transparent grills.

Hi
What european transformers can work good in Royer MXL modification. Jensen is 12:1.
Thanks
Duka

I have found the Sowter 4935 to be a good output tranny for this. 1:7 ratio.

I would bet that one of the lundahl mic input xformers would also work (reversed), although I haven't tried this.

Hope that helps.

[quote author="zebra50"]I have found the Sowter 4935 to be a good output tranny for this. 1:7 ratio.

I would bet that one of the lundahl mic input xformers would also work (reversed), although I haven't tried this.

Hope that helps.[/quote]

Is it enought 7:1 for 5840 tube?
I have OEP 1:6,45 and Lundahl LL1577 1:7

Now it gets interesting for us europeans...
Would an OEP be sufficient? :shock:
Lundahl and sowter types were not discussed really for the royer / gus 251 mods 'til now, if my memory serves me right...BUT...i remember, i saw a LL1538 somewhere on a photo of a frankensteined mic - i just can't remember where... :?

This would be nice alternatives for us europeans to experiment with cheapo chinese mics and probably upgrade to a better / other / more expensive transformer if the circuit is generally working good...

Very valuable infos here, indeed. (Thanks, Gus, for the link to the 6072 ela ckt!) :thumb:

Kind regards

Martin

Ooops, last post was 1/2 year old :shock: