[sdiy] BA6110 OTAs

[Tony Allgood]

> The BA6110 has been discontinued - I got the last samples from Rohm UK
over a year ago.

Alas this is true. But plenty of stocks left in many of the 'import'
suppliers.

The BA6110 is not a drop in replacement for the BA662. It is not pin
compatible or as well spec'd offset wise.

The 3080 can cope with a larger Iabc than the BA6110, but has no input
'lineariser' as does the BA6110. The BA6110 is closer to the CA3280 in
input circuitry, but maximum Iabc is far far lower.

The BA662 Iabc pin 'looks' like a CA3080. But the BA6110's Iabc pin is
one diode drop higher than the other two. Have a look at the internal
schematics on the data sheets.

The BA662 devices I have tested appear to have better offset specs than
either the BA6110 or 3080. See the SH101 VCA circuit where the PCB
layout depicts offset adjustment but no trimmer is fitted.

However, Roland selected BA662 for Gm in many of their cascaded filter
applications. Red and yellow dots are to be found on many ICs. They may
have also selected for offset too. There are BA662 and BA662A devices
around too. The A grade may depict better spec devices as in the CA3280A
and CA3280.

You may be able to use selected 3080 with follower and offset adjust in
many of the applications for BA662s.

> I know of at least two people as well as myself who have successfully
replaced the BA662 with CA3080...

Within the TB303's VCA circuit? The MAM MB33 does just this. Different
input resistors though, presumably to get the same soft clipping
effects??

Regards,

Tony Allgood                       Penrith, Cumbria, England

Oakley Sound Systems                     www.oakleysound.com
Modular projects            www.oakleysound.com/projects.htm