NewYorkDave Mila Dual Tube Preamp Help Thread

[poctop]

Thanks InsomniaClown for the Vumeter details,  well  small details make a big difference isnt "
Dan

 

[poctop]

Got it ,  if you do have a reall AC meter 100$ and more you can go ahead and to the 3.6 K tricks but if you have an internal rectified signal for DC reading (wich i do) you may have some thd 0.03 to 0.3 %,  i am just wandering how much of this is actually audible,  but remember if we have to do things we have to do it right,

Hope this clarifies the point,

Cheers ,
Dan,

 

[Rybow]

You're welcome Dan. Glad I could help.

As I understand it, the 3.6K resistor allows the VU meter to display +4dbu as its range. Increasing this resistor to 5.6k would display +8dbu. Thats how it is setup in the LA 4's that I built. I looked over the schematic, and the meter is just strapped across the outputs with the 3.6k resistor on the (-) wire of the meter. I don't hear any undo distortion, so it probably isn't that big of a deal. If you want to give it a go, that buffer circuit from JLM is only like $20. It would be interesting to hear if it makes an audible difference.

Did you read the part about strapping a 100uF cap on the back of the meter to slow it down? The article says this will get you closer to a true RMS reading. Looked interesting. I'll probably try that at some point. For now, I am just down with the sexy looks of VU meters!

Ryan

 

[poctop]

Thanks Man,  i finnaly realized that my meter would squash for no signal after i done the 3.6 K with a 5K pot,
i could tune em for +4 = 0db on the meter,

This was the last ongoing thing for this one,

your the man,

Many thanks,

Dany,

 

[who]

I started picking up all informations from this forum about N.Y. Daves Mila Preamp and sourced for parts.

I am going to buy some more for you so 8 Mono Milas total can i offer as kit. Please do a pre-order:
http://don-audio.com/NYD-Mila-Electronical-Parts-Kit (you need to register as diy-friend)

the Kit excludes i/o trafos, tubes and tube holders. I also have 250-0-250v trafos for european use.

I don´t know if i will offer those kits regular in the white marked in the future. So if these 8 are gone, there probably will not be planed a kit for the near future. The order will be placed on 17.04.2011, so the parts i have to portion /8 will arrive 2-3 weeks later.

let us awake this great project of Dave.
yours "who"

 

[etiefenthaler]

Hi,
try to find most parts at mouser. But mouser does not offer the grayhill switch.
Is this http://ch.mouser.com/Search/ProductDetail.aspx?R=MB05L1NCGDvirtualkey61170000virtualkey611-MB05L1NCGD
a useable equivalent?


Unfortunatly lots of helpful pics in this thread have been removed. 
Does someone have  pictures of correct wiring the range switch?

Thanks a lot

Erich

 

[buildafriend]

Do you mind if I ask, what is the range doing?

 

[ding]

Are people having good results with the power supply in the Mila updated schematics? I am aware that some people don't think it is very adequate for this preamp. I was going to go for the G9 spare PSU but I am not sure if that has enough juice plus it requires 2 PT's plus 1 more for phantom power. I am planning on using the Antek AS-1T250 PT. 100VA with [email protected] and 2x6.3v with the Mila PSU. Anyone got any better suggestions for a PSU? How many mA's does a dual Mila need? I imagine if I go with the Mila PSU that just one [email protected] should be enough for both channels.

here is that PT http://www.antekinc.com/details.php?p=671
here is the mila http://www.twin-x.com/groupdiy/albums/userpics/MILA1-Updated.pdf
here is a PSU that looks very similar to the G9 that I was considering http://diy-tubes.com/index.php?route=product/product&product_id=119

Thanks,
-Alain

 

[ding]

Is this correct and the best way to go with a PSU for a dual Mila? I will be supplying it with [email protected] and 6.3VAC@3A. I was looking at a schematic for a fixed biased pentode mode regulator but I think I want to keep it simple for now since this is my first turret board preamp. Here is the link http://diyaudioprojects.com/mirror/members.aol.com/sbench/reg1.html . Its the one at the very bottom.

I think to get good smoothing I need to increase the capacitor values but I am not sure how to calculate that. I know that for a simple full wave rectifier the formula is V=l/(f x C) but that is as far as I have gotten. Since this has 2 resistors and 2 capacitors I am not sure how to calculate the best values for a 200mA PT.

 

[Kingston]

Since you are going with VAC heaters this whole plan is accurate enough. Just check you have the cap/diode polarities perfect and you are good to go.

You don't need any calculators to increase CRC capacitor values. Increase the value and improve the PSU noise performance. You can simply go with what your wallet says. You can divide the resistor to half and come up with an even better CRCRC passive PSU. 100uF in place of those 22uF is just fine and will improve things - if only marginally. NYD was fond of the values from the sixties. We're not limited to that.

Try your current plan first and see if it gives you adequate noise floor. The ancients were happy with that, but us newcomers still have some say in this.

 

[ding]

I'm going to give it a go. If anything I will add an extra RC to clean it up. I made the first cap 100uf. I also added a phantom psu copied from mnats. For fun I am trying to keep pcb's to a minimum. I think I will go with this for phantom. http://www.antekinc.com/details.php?p=16

 

[ruffrecords]

@ding,

That's a good looking drawing. What did you use to create it?

Cheers

Ian

 

[ding]

Hey Ian,

I am using DIY Layout Creator. http://code.google.com/p/diy-layout-creator/ It has its limitations like they still havent added transformers to version 3 even though version 2 had them but for nice looking turret board design and schematics/PCB it does a pretty good job. BTW I was looking for your phantom power schematics but only found the pcb drawings so I ended up going with mnats schematic in the end.  I'm going to draw up the rest of the Mila as I go along so hopefully there will be a few good drawings for people to follow by the time I am done. I can also post the .diy files if anyone is interested.

-Alain

Edit: Here is a more correct version with appropriately sized components.

 

[ruffrecords]

I have no idea why there's no schematic for my phantom PCB - I'll chek that out.

By the way, there seems to be connections to only two of the three pins of the TL783 on your layout.

Cheers

Ian

 

[ding]

Oops, yeah I was moving components around and screwed the pooch on that. Fixed, thanks.
I was noticing some periods get blurred out but FYI those are 2k7 and 2k2 resistors.

 

[ruffrecords]

I have no idea why there's no schematic for my phantom PCB - I'll chek that out.

By the way, there seems to be connections to only two of the three pins of the TL783 on your layout.

Cheers

Ian

Here's a link to the phantom PCB schematic:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/power/Phantompsu.png

It was in the original thread but I had not up loaded it to my web site.

Cheers

Ian

 

[ding]

So here is my 1st attempt at drawing out the wiring for my build. I am sure there are a mountain of mistakes so if anyone catches any of them don't be shy.  I am not really sure about the VU or the HPF. Also, I think I got the DI and the heaters right but...?

 

[madriaanse]

I really like the Mila's sound - very open. In fact, I liked it so much I ended up doing this.

Test bench pic:

.094 FR4, 2oz Copper, 100-150mil traces.  ;D

M.

 

[ding]

Very nice!!!! I want to give this p2p a go but for future endeavors do you have the files to that pcb?

 

[audiophreak]

That's Sweet      I'm starting a quad of these - torn between Turret or perf board. One of these days I'll be able to doPCB layouts and etch my own.