gear porn inside (ml-1 tube pre)

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pucho812

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o.k. so this came through the other day.... made by the mastering lab, it's an all tube mic pre... It used 2 tubes a 5751 and an e188cc

(The Front)
SAM_0168.jpg


(shot of the power transformer) Covered in a metal box for shielding
SAM_0170.jpg


(Power Supply Board)
SAM_0171.jpg


(Tube Board)
SAM_0172.jpg


(The Board other side)
SAM_0172.jpg


(Tube board back side)
SAM_0175.jpg
 

tv

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Looks nice, but I really dislike the big blue elco mounted "under" the pcb. The way it is mounted, it looks like it could break the traces if some pressure is applied the wrong way.
 

pucho812

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tv said:
Looks nice, but I really dislike the big blue elco mounted "under" the pcb. The way it is mounted, it looks like it could break the traces if some pressure is applied the wrong way.

you mean on the tube board? The cap is tied down and the board securely mounted... I don't see that as a potential problem.

I do see the price of an e188cc tube to be costly... Any cheaper alternatives?
 

Matthew Jacobs

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I like the L shaped brackets that secure the PCB to the chassis. That's just the idea I needed for a project I'll be working on someday... a 1U tube distortion unit...

J

 

strangeandbouncy

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Hi Pucho,


  I am not sure if I am correct, but I think e188cc is ultimate lo noise/long life version of the 6922/e88cc 6dj8 etc. I needed something similar for an Innertube u87 retrofit, and tried quite a few different types, including Telefunken and Siemens e88cc, and Mullard e188cc. I even borrowed a genuine telefunken CCa. I found some NOS ex-Nato spares(listed as ex-nuclear submarine!), and finally some National CCa, i believe made for spanish telephones. . . . . . National CCA won hands down in every test! they were quite cheap too . . . . I have also tried them in a Redd-type preamp, and they rocked there too!


    worth a punt, I reckon . . . .



          ANdyP
 

rotation

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I used E188CC instead of E88CC and it worked well. I'm pretty sure you can use E88CC in your preamp without problems, but check datasheet first.
NOS Tesla E88CC are still pretty cheap, i like older versions (had problems with late 80's production).

Miha
 

jamesfei

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Thanks for the pictures. What's the input transformer (assuming there is one)? Any idea about the topology?

Best,

James

 

pucho812

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jamesfei said:
Thanks for the pictures. What's the input transformer (assuming there is one)? Any idea about the topology?

Best,

James
the unit has an input transformer but unblanced outputs. The outputs come up on 2 XLR jacks one wired pin 2 hot and one wired pin 3 hot... The input transformer is mounted inside it's own little metal cylinder off to the side and IMO is either a cinemag or a jensen. I have yet to do any real detective work on a unit as the two units came in for a quick recap job. I have read nothing but great things about how good it sounds and one of the local studios has 32 of them for tracking purposes, bill schnee studio IIRC.

It is a tube mic pre.

Maybe I can get a schematic from the mastering lab?
 

pucho812

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MHanson said:
pucho812 said:
Maybe I can get a schematic from the mastering lab?

Anything come of this idea????

I love these pre's.

Michael

No nothing yet... they are fairly simple.. Shouldn't be too difficult to reverse and get a schematic but setting time aside is not in the near future. I almost want to stick a 1:1 output transformer in these just so they are balanced out but that is said to not be a real issue.
 

pucho812

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Old thread for sure.  I sold those pre's long ago. They were outstanding but I was made an offer I couldn't refuse. Schematics?  hmmmmm never got around to it but they are fairly simple and nothing that isn't text book tube stuff.
 

AusTex64

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Thanks for your response. Agreed, old thread. Thought I might get lucky! Next up - rent one and check it out.
 

sami1501

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Feb 20, 2016
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Hi guys!

I have 4 of theese preamps but I broke one one of them. Someone connect to 220V and the pre was set to 110V.  I've opened the pre and I have found this...

1.jpg


2.jpg


3.jpg


4.jpg



Only 4 capacitors (brown), 1 capacitor 450v 33uF (Blue), 1 resistor (dark green) and the 5751 valve are broken.

My problem is that I don't know the value of the parts (specially the 4 capacitors and resistor) and the resistor.

HELP!!!!!! SCHEMATICS!!!!!!

;D ;D ;D
 

pucho812

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if you truly have 4 of these pre's, then you have 3 you can look at to fix the four. If you can't read resistor color codes you can use a color code calculator on the internet ;)
 

sami1501

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Hi again,

I have done what you said to me. I opened one of the other three and I have all the parts that I need.

Thanks

@pucho812, here are my other three preamps:
5.JPG
 

pucho812

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oh I hope I didn't sound like I was trying to insult you, or call you out or whatever. I was just saying if you had the other 3 which you do, then you can use them to reference.
I had a pair at one point, I wish I still had them and such. But gear  was revolving at the time, and the unbalanced out's were no bueno for that period.
 

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