2181lb for GSSL, have I confused myself again?

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StrayCat

Well-known member
Joined
Jun 7, 2004
Messages
83
Location
Nova Scotia
I made a large Error on a post a while back about the 2181xx series VCA. I grouped it together with the 2180xx pre trimmed VCA. :? This is incorrect, the 2181xx requires trimming. The 2181xx is supposed to be able to achieve a better distortion spec after trimming but you still have to trim it as per the design spec. After checking out the design notes on the 2181xx when substituting for the 2151 I noticed the statement that R2 in the trimming circuit should be removed since the 2181xx has an internal 27 Ohm resistor, which resistor in the GSSL would represent the R2 resistor? Is all of this necessary in the GSSL? Is trimming a must? OK I sound (and feel) desperate. :cry: I may have to learn how to use a distortion analizer. HELP. Here is the design note page for anyone looking for the information on the 2181xx substitution.

http://207.36.153.49/datashts/dn137.pdf

the design note number is 137

I read somewhere that the 2181 has the same specs but does it require trimming as per a 2151? Any and all help on this would be appreciated.
 
just go for the 2180 ... it sounds great !!

you don't hav eto trim anything..


the first ssl comp I build with 2150 and a trimmer, but when I turned the thd trimpot I couldn't recognize any audible change in sound... so i think it's not really important... and a 2180la for example has thd at 0,01% without a trimmer, a 2150 has 0,05 % thd when it's trimmed to its best setting...

mat
 
Thanks matthias, I already have 2181LB's so it looks like the trimming will have to happen unless someone has some input or experience with the 2181xx series VCA in the GSSL.
 
Yes you might be trimming eventually.
BUT
just put it all together and it is likely that it will sound fine.
As matthias says, the dist untrimmed for the 2180la is 0,01%
you shouldn't be far from that with the trims centred.
 

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