MS, Pultec, 1/2-BA283 boards support thread!

[MatthisD]

I haven't built this exact project. I have my makeup gain (not using M/S) set to a fixed amount. Do you have DC voltage on the case of the 2n3055?

 

[jandoste]

yep, 2n3055 is 23V

I haven't built this exact project. I have my makeup gain (not using M/S) set to a fixed amount. Do you have DC voltage on the case of the 2n3055?

 

[jandoste]

I got some strange bug! Now the 9046 has right connexion! but that what I have a bit strange! 
- Open the Unit,
- 5 minute later it's not sounding itself! I hear any sound!
- Attached a picture with the new number of vtb9046
Any idea?
Thanks

 

[Igor]

Best trouble shooter than me: oscillator, scope, trace the signal.

I got some questions about inductor's pinout. Here it is.

 

[Sylvain D.]

Need help :-\

Anyone figure-out what values for R1, R5, R6 (TBD)?

 

[Igor]

R1 is the load for input trannie. Depends on inp trannie you use.
R5/6: resistors on makeup switch. See:
http://ij-audio.com/downloads/BA283_MKUP.zip

 

[Sylvain D.]

Thanks Igor.

 

[muffy1975]

um,

if i were to use a pair of BA283 for an output to an active summing mixer, which dual stereo put should I use for an output control?

Would I correct in presuming 10k log dual?

thanks guys. after all, this is the BA283 support thread too.

Michael

 

[Igor]

um,

if i were to use a pair of BA283 for an output to an active summing mixer, which dual stereo put should I use for an output control?

Would I correct in presuming 10k log dual?

thanks guys. after all, this is the BA283 support thread too.

Michael

Depending on gain you need to restore after summing bus.
I'd use dual revlog 10k at the place "gain" resistor/switch between J and K, in series with 51R resistor.
Should give 16-40db gain range, which is fine for most apps. As well, if you going to use input transformer here,
be sure to load/terminate it proper way.

ba283_op_stage_info.pdf
http://ij-audio.com/downloads/BA283_MKUP.zip

 

[muffy1975]

igor,

if you have a minute.

I am summing 16 channels of my reverse engineered Phoenix Audio Active Input blip.

The summing network involves a 68k resistor either side of the 16  pan knobs.

There is naturally alot of level when these 16 channels are summed.

Should I use a dual 10k log pot to connected to earth to have a variable volume control 'before your BA283 summing stage'.?

This is what they seems to do but then they use a virtual earth too.

Or.....Should i use a transformer to drop the level of the 16 channels before the BA283.? Phoenix don't do this!



Thanks for any help

Michael

ps i'm new ish at this game. I have reverse engineered Phoenix Audio's famed input channel but my knowledge ends there.


Also I'm gonna strap the TG compressor of yours across the bus in my new console. Gonna be awesome.

 

[alexc]

I'm doing something similar with the 1/2 BA283 board too

- a summing bus feeding an input transformer to the 1/2 ba283 using the variable gain switching arrangement described in Igor's docs.

Does anyone know what impedance the 1/2 BA283 likes to have connected to it?

I'm trying to figure out what impedance to make the summing bus/input transformer combo.

Any opinion would be welcome.  I'm thinking it might like to see a few Kohms impedance connected?

Cheers

 

[area8]

Thanks, Igor, for making these boards available - I am waiting on a pair of 1/2 BA283 boards just now.

I was getting ready to order some parts, and (forgive me if I missed it, but I looked) I'm looking for which case type the output transistor is.

I've found the 2N3055 in both TO-3 and TO-204 cans, and, while I'm guessing it is TO-3, I'm not positive which to order. I'm guessing the ON Semi part is good.

Also, are the NTE199 an acceptable substitute for the BC184C? Do these sound OK, or are folks using something they like better? Is there still a source for the originals at a decent price (or does it make a difference)?

Thanks,
Frank
Area8

 

[area8]

OK - I think I've at least partially answered my own questions, after finding the referenced NeveInfo2.pdf document online, and Geoff Tanner's comments in there. Just in case it might help anyone else, I'll post what I found:

According to Mr. Tanner, I can use a BC550 as a substitute for the BC184, and I already have plenty of those (and have found them to generally sound "good"). As always, if anyone objects or has better suggestions, I'm all ears.

If Igor's board matches the original BA283 layout (I have no idea), the output xsistor case is a TO-3.

I'll try to stick to the original types and values of caps, as I've certainly found they can change the sound significantly (see Steve Bench's classic Sound of Capacitors article as great reference).

All suggestions still welcome - good luck to all my fellow DIYers.

Frank
Area8

 

[Igor]

Hi Frank!

Output transistor is TO-3 case, 2n3055.

BC550 can be used instead of 184C, but beware "original parts" guys - they probably will call it heretic.
Double check the pinout. It written on silkscreen.

muffy1975: mmm.... Why not active summing with discrete opamp, 5...10 k resistors and than use BA283 after the master fader as booster as a "color thing"...
Possible to sum with 68 k resistors, too. I prefer lower resistor values.

I working now on active summer using "zero input field" input trafo like German oldies and  Neve'ish output stage after the master fader.
Got really nice results with LL7101 (they claimed as line input transformers but work great for summing). well... another project to do,
wery curious to listen the sound - for sure I will claim it as too much color but nice, most of studio geeks will call it woa, "punchy crispy etc
More I freaking with sound electronics more become tired of too much coloration. The prob is this is most of you dudes want!

 

[area8]

Thank you, Mr. Kapelevich!

Are your boards basically the same as the BA283/AV circuit?

I'm eagerly awaiting two of the 1/2 BA283 boards, and also a Rackit, which I'm looking forward to using. I'm finally getting my other parts ordered to get ready for them.

Thank you once again for making all these wonderful toys available.

Frank
Area8

 

[area8]

Also - one more thing:

I was planning on using Ed Anderson's EA1166-500 smaller gapped output transformer (as used in Hairball Audio Lola) - any problems with this?
Anyone have any objections to this one? Any love for this one?

Thanks,
Frank

 

[Axelerator]

regarding the Lorlins, shorting or unshorting ?  or doesn´t care ?
thanks as always
axel

 

[pacemaker]

Hi Guys !
i'm struggling searching for the correct value of R1 ,
the loading resistor on front panel PCB for the 10468 input transformer.
I looked at transformers datasheet, other schematics using 10468 etc,etc...
and didn't found any "clear" answer.

Reading these topics i found some posts talking about loading 10468 with 5k-6k  :
http://www.groupdiy.com/index.php?topic=21341.msg251363#msg251363

http://www.groupdiy.com/index.php?topic=7126.msg87245#msg87245

http://www.groupdiy.com/index.php?topic=6576.msg77210#msg77210

but in this application, 10468 reversed, this post indicate 600R loading :
http://www.groupdiy.com/index.php?topic=34207.msg418603#msg418603

can anybody help me to find the correct answer please ?
regards,
Francois

 

[Axelerator]

bumpedi bump
as i have shortening lorlins and unshorting lorlins i would like to know if  i could use each ones for the nevtec ?

greets
axel

 

[Axelerator]

and bump again, cannot find specs for the lorlins anywhere. have shorting and unshorting ones.
can i take both in this projekt ? what have you guys used ?
thank you !
axel