NewYorkDave Mila Dual Tube Preamp Help Thread
- Thread starter Stagefright13
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Help Support GroupDIY Audio Forum:
jaygunn
Active member
The Zobels I have seen on transformer secondaries place a cap and resistor between the two secondary leads. So, if you replace them with a jumper, you'll be shorting the secondary and you'll get...silence.
Check your schematic and see if I'm right. Admittedly I'm a newbie, and I don't have the MILA schematic handy...but check!
Check your schematic and see if I'm right. Admittedly I'm a newbie, and I don't have the MILA schematic handy...but check!
pstamler
Well-known member
Yep -- replacing the Zobel with a jumper means the secondary of the transformer is shorted, and there'll be no signal tonight. Cut the jumper.
Peace,
Paul
Peace,
Paul
MasonAtom
Well-known member
Yup... I'm a dumba$$.
Thanks a lot for putting up with my stupid questions guys! Can't believe I didn't realize that I was sending my signal to ground. Clipped the jumper and sure enough, the XLR started to work.
Sound is great, but unlike the DI, I'm getting some noise. I'm measuring about -35 to -40 dB on my meters in Tracktion (my recording program). I looked at the spectrum with Nichols Inspector VST and there is a little bit of jitter in the high end between about 2 kHz and 12 kHz, but most of the noise is low end from 150 Hz down, with a bit of a peak at around 60 Hz. I don't have the black wire (Faraday shield) of my traffo connected right now, so I'm guessing that's part of the problem. The noise seemed to be about the same regardless of whether I had the +48V engaged or not.
I can't thank Dave enough for sharing this design. The preamp sounds delicious. I recorded some acoustic guitar with a JoeMeek JM37 condenser and a Sennheiser e609. The JoeMeek gave a really lush and rich sound, the preamp does a great job at extracting all of the highs with great clarity, you can hear the snap of the strings like they are jumping out of the monitors. I didn't like the e609 as much, but then again I don't seem to like it on anything, so I'm not surprised. The e609 sounded a bit too "clinical" for me, like a direct capture with no character.
One thing I'm going to have to get used to is that the MILA captures "everything" so it is very unforgiving. With my Onyx pres, I can get away with a little sloppiness and it doesn't come through. The MILA is so detailed that if you have a slight slip-up or stutter on a string, it sticks out like a sore thumb.
I'll post some sound clips within the next few days, once I sort out my noise problem.
Mason
Thanks a lot for putting up with my stupid questions guys! Can't believe I didn't realize that I was sending my signal to ground. Clipped the jumper and sure enough, the XLR started to work.
Sound is great, but unlike the DI, I'm getting some noise. I'm measuring about -35 to -40 dB on my meters in Tracktion (my recording program). I looked at the spectrum with Nichols Inspector VST and there is a little bit of jitter in the high end between about 2 kHz and 12 kHz, but most of the noise is low end from 150 Hz down, with a bit of a peak at around 60 Hz. I don't have the black wire (Faraday shield) of my traffo connected right now, so I'm guessing that's part of the problem. The noise seemed to be about the same regardless of whether I had the +48V engaged or not.
I can't thank Dave enough for sharing this design. The preamp sounds delicious. I recorded some acoustic guitar with a JoeMeek JM37 condenser and a Sennheiser e609. The JoeMeek gave a really lush and rich sound, the preamp does a great job at extracting all of the highs with great clarity, you can hear the snap of the strings like they are jumping out of the monitors. I didn't like the e609 as much, but then again I don't seem to like it on anything, so I'm not surprised. The e609 sounded a bit too "clinical" for me, like a direct capture with no character.
One thing I'm going to have to get used to is that the MILA captures "everything" so it is very unforgiving. With my Onyx pres, I can get away with a little sloppiness and it doesn't come through. The MILA is so detailed that if you have a slight slip-up or stutter on a string, it sticks out like a sore thumb.
I'll post some sound clips within the next few days, once I sort out my noise problem.
Mason
pstamler
Well-known member
[quote author="MasonAtom"]Sound is great, but unlike the DI, I'm getting some noise. I'm measuring about -35 to -40 dB on my meters in Tracktion (my recording program). I looked at the spectrum with Nichols Inspector VST and there is a little bit of jitter in the high end between about 2 kHz and 12 kHz, but most of the noise is low end from 150 Hz down, with a bit of a peak at around 60 Hz. I don't have the black wire (Faraday shield) of my traffo connected right now, so I'm guessing that's part of the problem. The noise seemed to be about the same regardless of whether I had the +48V engaged or not.[/quote]
Are your filaments floating up around +75V? That cuts down hum leakage from the filaments to the cathode pretty effectively.
Peace,
Paul
Are your filaments floating up around +75V? That cuts down hum leakage from the filaments to the cathode pretty effectively.
Peace,
Paul
MasonAtom
Well-known member
[quote author="pstamler"][quote author="MasonAtom"]Sound is great, but unlike the DI, I'm getting some noise. I'm measuring about -35 to -40 dB on my meters in Tracktion (my recording program). I looked at the spectrum with Nichols Inspector VST and there is a little bit of jitter in the high end between about 2 kHz and 12 kHz, but most of the noise is low end from 150 Hz down, with a bit of a peak at around 60 Hz. I don't have the black wire (Faraday shield) of my traffo connected right now, so I'm guessing that's part of the problem. The noise seemed to be about the same regardless of whether I had the +48V engaged or not.[/quote]
Are your filaments floating up around +75V? That cuts down hum leakage from the filaments to the cathode pretty effectively.
Peace,
Paul[/quote]
Not sure I understand what you're saying?
+75V on pins 4/5 of the tubes?
I'm measuring 5.91V on the filaments from my DC-filtered supply.
Mason
Are your filaments floating up around +75V? That cuts down hum leakage from the filaments to the cathode pretty effectively.
Peace,
Paul[/quote]
Not sure I understand what you're saying?
+75V on pins 4/5 of the tubes?
I'm measuring 5.91V on the filaments from my DC-filtered supply.
Mason
pstamler
Well-known member
Ah, that's a different issue. I thought you were driving the filaments with AC. It's often a good idea to "float" the filament winding by connecting its center-tap to about +75Vdc. This cuts down on hum radiation from the filament to the cathode.
In the case of DC, hum radiation isn't usually a problem -- and if that was the issue, the hum would be 120Hz rather than 60Hz.
Peace,
Paul
Stagefright13
Well-known member
Not the "A" list my friend. 
You just need to ask a question someone may know the answer to. I can't help you with that question. I don't know transformers so well. But am learning.
For the record I am building my second Mila this weekend. (Mine) And my son called me again yesterday to tell me how much he LOVES the one I gave him for Christmas. He's never had a good preamp before. He is one happy camper. Besides using it with a mic he constantly uses the DI with his guitar.
You just need to ask a question someone may know the answer to. I can't help you with that question. I don't know transformers so well. But am learning.For the record I am building my second Mila this weekend. (Mine) And my son called me again yesterday to tell me how much he LOVES the one I gave him for Christmas. He's never had a good preamp before. He is one happy camper. Besides using it with a mic he constantly uses the DI with his guitar.
MasonAtom
Well-known member
[quote author="maxwall"]Anyone have any opinion on using Altec transformers for the MILA
I have these and would like to use them for this project
Altec 4722 150/50K ( 1:16 )
Altec 15095A 150-600 /15K ( 1:10 or 1:4 )
I'll keep posting till I get some help here
( seems you need to be on the A list to get help around here - sucks )[/quote]
I used a 150:50K Cinemag in mine and it sounds very good, so I don't see why a similar rated Altec wouldn't. I know a guy who used the 4722 in a dual 6SN7 preamp and he says he loved the transformer.
Mason
I have these and would like to use them for this project
Altec 4722 150/50K ( 1:16 )
Altec 15095A 150-600 /15K ( 1:10 or 1:4 )
I'll keep posting till I get some help here
( seems you need to be on the A list to get help around here - sucks )[/quote]
I used a 150:50K Cinemag in mine and it sounds very good, so I don't see why a similar rated Altec wouldn't. I know a guy who used the 4722 in a dual 6SN7 preamp and he says he loved the transformer.
Mason
skipwave
Well-known member
I'm using a 15095A on the output of Dave's 6SN7 design. Works great.
maxwall
Well-known member
- Joined
- Nov 17, 2004
- Messages
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Good news and thanks for the replies
Stagefright - Hey thats really great that your giving your kid a mic pre
thats something that stays with you for life. I discovered this stuff in my early 20's ( before internet days) - glad I did, no one around but a close studio friend /musician who turned me on recording arts and now DIY.
Altec transformers - I thought I was on the right track ,but was'nt 100% sure.
Can some one post a link to the 6SN7 design details here , I have'nt seen that one yet ? I'd like to look it over.
Stagefright - Hey thats really great that your giving your kid a mic pre
thats something that stays with you for life. I discovered this stuff in my early 20's ( before internet days) - glad I did, no one around but a close studio friend /musician who turned me on recording arts and now DIY.
Altec transformers - I thought I was on the right track ,but was'nt 100% sure.
Can some one post a link to the 6SN7 design details here , I have'nt seen that one yet ? I'd like to look it over.
Stagefright13
Well-known member
Yeah wish someone gave me a Marshall when I was his age lol! I woulda got famous much sooner! And I can't overemphasize more how much better a good preamp when combined with a good microphone can sound! Don't forget a good quality mic. Dynamic such as SM7 or 57 or a good LDC. If you don't have alot of money a MCA SP-1 sounds great into the Mila. NewYork Dave designed this pre and hit the high end of tube preamp sound. Thanks NYD! You rule!!!!
Gonna post pic next of my Mila #2 need to get it rolling... I have some of it done but need to finish it. Been busy for a while...
And I can't overemphasize more how much better a good preamp when combined with a good microphone can sound! Don't forget a good quality mic. Dynamic such as SM7 or 57 or a good LDC. If you don't have alot of money a MCA SP-1 sounds great into the Mila. NewYork Dave designed this pre and hit the high end of tube preamp sound. Thanks NYD! You rule!!!!Gonna post pic next of my Mila #2 need to get it rolling... I have some of it done but need to finish it. Been busy for a while...
Stagefright13
Well-known member
Here it is so far on my antique 1960's kitchen table I got for free. So my girlfriend will let me build stuff on it:
abby normal
Well-known member
Hey what are you all using as the power transformer for dual MILA's in one unit? Or what would you suggest using? The specs on the suggested Stancor come up about .8 mA short on the 6.3V secondary for two channels.
MasonAtom
Well-known member
I would guess that a Hammond 269JX would do the trick. You can pick one up for about $35 at Angela Instruments. These supply 2.5 A on the 6.3V tap and 250-0-250 for your secondary, make sure you ground the center tap.
Stagefright13
Well-known member
Oh sorry I didn't post in a while but Mila2 is built! For a while now. My digi camera crashed or I would show you pic. Is the same as the Christmas Mila for my son. Except I put the tubes slightly closer to the input on the turret board. Otherwise is exactly the same.
Has a powerful sound! Very clear and punchy in a tube way. Hard to explain. Not an API sound but fantastic on vocals and gentler instruments such as acoustic guitar and louder instruments like horns, sax etc.
If ya built any 312/512 stuff this is a welcome addition. I use it constantly and makes a formidable DI. I sold one of my UA610's because It sounds just like it or better in some things.
Has a powerful sound! Very clear and punchy in a tube way. Hard to explain. Not an API sound but fantastic on vocals and gentler instruments such as acoustic guitar and louder instruments like horns, sax etc.
If ya built any 312/512 stuff this is a welcome addition. I use it constantly and makes a formidable DI. I sold one of my UA610's because It sounds just like it or better in some things.
Stagefright13
Well-known member
Anyone know how to mod the Mila slightly so I can use as a DI and also send the input to a guitar or bass amp?
pstamler
Well-known member
If you don't mind the instrument being loaded by both the 1M of the MILA's instrument input and whatever the input Z of the amp is, then a non-shorting jack in parallel with the Inst. input jack would work fine. Wire its tip terminal to the Inst In tip terminal
Peace,
Paul
Peace,
Paul
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