HELP ME ON NEVE BA283

[dhonny]

Hallo guys I'm Dhony, I'm actually new in electronic and stuff, long story short based on my curiosity I decide to build my very own mic pre-amp from Neve BA283 schematic. I knew here a lot of electronic genius hope some of you guys can help me.
first question :
what is N, U(I'm guessing this is where audio source coming in?),V (I aguess this is voltage source?),P, S, T stand for on schematic on the left and right side.

 

[Rob Flinn]

No, your guesses are wrong. The letters just refer to fingers on the edge connector of the BA283 card. You need to look at the BA283 card in context of being in a mic amp. Maybe search for a diagram for a Neve1290 mic amp which will make things clearer for you.

 

[dreamix]

My guess is N is the power rail, U is positive and V is Common

 

[dhonny]

No, your guesses are wrong. The letters just refer to fingers on the edge connector of the BA283 card. You need to look at the BA283 card in context of being in a mic amp. Maybe search for a diagram for a Neve1290 mic amp which will make things clearer for you.

ok thanks Rob,

 

[dhonny]

My guess is N is the power rail, U is positive and V is Common

thanks dreamix for you thoughts, actually I found new documents let's checkout together.

 

[dhonny]

ok thanks Rob,

I found new schematics from http://www.hausverwaltung-heger.de/al_leck_trick/Neve1073_Manual.pdf#
at least it says (U) from input right ? haha correct me if wrong again.

 

[dhonny]

I have I thought what if I experimenting with this schematics to make some simple (mic/guitar) amplifying system, is that wort to try?? anybody?

 

[dreamix]

Well, just guessing again but isnt this just a gainstage inside the i.e 1073, not sure you have any benefit from it using it as is

 

[ruffrecords]

PIn T is the gain set pin. Connect a resistor between here and ground to set the gain

Cheers

Ian

 

[dhonny]

Well, just guessing again but isnt this just a gainstage inside the i.e 1073, not sure you have any benefit from it using it as is

yes sir

 

[dhonny]

PIn T is the gain set pin. Connect a resistor between here and ground to set the gain

Cheers

Ian

Thanks Mr Ian. Big-fans of your works BTW, your tube consoles looks amazing.

 

[ruffrecords]

Well, just guessing again but isnt this just a gainstage inside the i.e 1073, not sure you have any benefit from it using it as is

It is indeed, but back in the micd70s when I worked at Neve, I built my second mixer with mic preamps based on exactly this circuit. When you rememeber that a typical internal signal level for the Neve can be around -15dBu, the this little preamp set to 30dB gain and with 6dB of gain from the mic input transformer, gives you a basic mic sensitivity of -51dBu which is plenty for most uses ( and I was recording rock bands at the time).

Cheers

Ian

 

[Whoops]

I have I thought what if I experimenting with this schematics to make some simple (mic/guitar) amplifying system, is that wort to try?? anybody?

Maybe you should explain better and be more clear about what you want to accomplish.
Probably then we would have a better understanding on how could we help you

The BA283 is an amplifier card used as a mic Preamps or Line amp,
I'm not seeing it much being useful for guitar...

 

[thomasdf]

Does anyone know how much a BA283 AM draws on a 24V rail, running 35dB of gain ? Thanks

 

[ruffrecords]

Does anyone know how much a BA283 AM draws on a 24V rail, running 35dB of gain ? Thanks

A correctly set up BA283 draws about 70 to 80mA irrespective of gain setting.

Cheers

Ian

 

[thomasdf]

Thanks Ian !

 

[thomasdf]

Hello

I am using a BA283AM as a makeup amp after a balanced passive EQ (Eckmiller W86). I have hooked up my circuit as follows :

• input → 1:1 Sowter isolation transformer → Passive EQ (34dB loss)
• passive EQ → 1:1 Cinemag isolation transformer → hot to (L), cold to ground (J) on the BA283AM
• BA283AM → VTB1148 : (M) to pin 1, (B) to pin 3
• Output Xfrmr : pin 5 to hot, pin 8 to cold.

Ground : input pin 1, output pin 1, SMPS V-, balanced cables shields and pin (J) on the BA283AM

VTB1148 pin 2 & 4 linked, pin 6 & 7 linked, resistor and cap between 5 & 8
24VDC from a Meanwell SMPS to (M)

My problem is, I have a PSU noise in the audio whereas normally the Meanwell SMPS are very quiet but for now on my circuit is not earthed, and more disturbing : I seem to lack some headroom ? I have set up the bias with my oscilloscope...
I am not familiar with the BA283AM so maybe the lack of headroom is normal when running 34dBs of gain ?
The EQ is capable of pretty broad boost in 6dBs increment for the low end, and when boosting by 6dB I can clearly hear distortion. The level is dropped by 34dBs after it, so I wonder what is clipping... ?

My best bet yet is some sort of impedance mismatch. What's the ideal impedance the BA283AM wants to see at its input ?

 

[Golgoth]

Hello

I am using a BA283AM as a makeup amp after a balanced passive EQ (Eckmiller W86). I have hooked up my circuit as follows :

• input → 1:1 Sowter isolation transformer → Passive EQ (34dB loss)
• passive EQ → 1:1 Cinemag isolation transformer → hot to (L), cold to ground (J) on the BA283AM
• BA283AM → VTB1148 : (M) to pin 1, (B) to pin 3
• Output Xfrmr : pin 5 to hot, pin 8 to cold.

Ground : input pin 1, output pin 1, SMPS V-, balanced cables shields and pin (J) on the BA283AM

VTB1148 pin 2 & 4 linked, pin 6 & 7 linked, resistor and cap between 5 & 8
24VDC from a Meanwell SMPS to (M)

My problem is, I have a PSU noise in the audio whereas normally the Meanwell SMPS are very quiet but for now on my circuit is not earthed, and more disturbing : I seem to lack some headroom ? I have set up the bias with my oscilloscope...
I am not familiar with the BA283AM so maybe the lack of headroom is normal when running 34dBs of gain ?
The EQ is capable of pretty broad boost in 6dBs increment for the low end, and when boosting by 6dB I can clearly hear distortion. The level is dropped by 34dBs after it, so I wonder what is clipping... ?

My best bet yet is some sort of impedance mismatch. What's the ideal impedance the BA283AM wants to see at its input ?

Hello Thomas,

I never had any luck with Meanwell switching PSUs and Neve circuits for some reason.. I tried on a 83046 and also had PSU noise in the audio path using a medical grade Meanwell. Grounding was okay tho (the PSU's metal casing is meant to be grounded). There are some good 24V linear PSU kits around, I might even have one unpopulated board in a box somewhere..

 

[thomasdf]

That's interesting. Maybe that's because of the single ended output ? But the noise from the PSU is not my main concern at this point. I've had luck using a regulator on a SMPS power rail in the past, haha

I have some Beyer peanut transformers I can wire 200 : 45K maybe that would solve my problem ? The EQ wants 200 ohms at its output ... I'll give it a shot one of these days, until I can figure the ideal signal impedance to feed the BA283AM.

 

[ruffrecords]

Do you have J and A connected?

Cheers

Ian