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R/E/P => R/E/P Archives => Fletcher => Topic started by: Bubba#$%Kron on January 15, 2011, 09:01:05 AM

Title: anyone know the difference between a neve 1272 and a 1271??
Post by: Bubba#$%Kron on January 15, 2011, 09:01:05 AM
 anyone know the difference between a neve 1272 and a 1271??

and


has anyone ever successfully converted a 1272 to a 1290 ??

Thanks
Title: Re: anyone know the difference between a neve 1272 and a 1271??
Post by: pete andrews on January 15, 2011, 10:01:12 AM
Quote:

anyone know the difference between a neve 1272 and a 1271??


1?

-pete
Title: Re: anyone know the difference between a neve 1272 and a 1271??
Post by: Fletcher on January 15, 2011, 10:55:45 AM
The difference between a 1271 and a 1272 is that a 1271 is missing an amplifier stage found in the 1272.  All you need to do to convert a 1271 to a 1272 is either replace the B283 amplifier board with one that is fully populated, or find the component values [from the schematic] and the components and install them on the B283 board.

If I'm not mistaken the 1290 is a "1073 style" pre-amp that will fit into a 500 series frame.  If that is indeed the case it would be quite a pain in the ass to try to attempt as you would first need to figure out how to make a +24vdc circuit run on
Title: Re: anyone know the difference between a neve 1272 and a 1271??
Post by: Bubba#$%Kron on January 15, 2011, 11:15:07 AM
Thanks fletcher!!,   Good to hear from you!!    So, does a 1271 have enough gain on its own to be used as a passive summing bus amp??

the 1290 is a 1272 with the 3rd gain stage added, to truly make it a 1073 with no eq.  They sell kits to convert, its just a complex gain knob(i think) and goes for like $300.  The real 1290's came off the actual consoles and were there for extra preamps.  At least thats what Ive gathered from Geoffs posts here and there.

another neve question- why did they use a class ab 33415 on the sum buss of the 8078 and not a 1272 like the previous models.  I think I read its because they wanted to save money, I find that hard to believe though!!

Thanks

Fletcher wrote on Sat, 15 January 2011 07:55

The difference between a 1271 and a 1272 is that a 1271 is missing an amplifier stage found in the 1272.  All you need to do to convert a 1271 to a 1272 is either replace the B283 amplifier board with one that is fully populated, or find the component values [from the schematic] and the components and install them on the B283 board.

If I'm not mistaken the 1290 is a "1073 style" pre-amp that will fit into a 500 series frame.  If that is indeed the case it would be quite a pain in the ass to try to attempt as you would first need to figure out how to make a +24vdc circuit run on
Title: Re: anyone know the difference between a neve 1272 and a 1271??
Post by: Fletcher on January 15, 2011, 11:27:54 AM
A 1271 should have enough gain for use in a "gain makeup" situation for a passive summing network... but probably not enough for use as a mic pre unless you were using a mic with a really hot output like a Neumann M-149

$300 for that gain switch isn't a bad price -- the Elma switch [without all the resistors soldered on] is a pain in the ass to find and usually goes for $125 USD + ... unless you have all the resistors and are somewhat skilled at soldering, the time it will take you to populate the switch properly seems more than worth the added $175 [ish] expense [or at least it does to me - YMMV]

On the 8078 summing amps - I would guess they went to the BA440 output amplifier because its modular [like an API 2520] and would cut down on the necessary service time if one went out.  Don't forget that these desks were intended for real studios where "down time" was a very bad thing that messed with the ability of the facility to bill for time.  There may have been other considerations, but that would be my guess.
Title: Re: anyone know the difference between a neve 1272 and a 1271??
Post by: Bubba#$%Kron on January 15, 2011, 11:31:12 AM
sweet!!  Thanks man, you rock!!!
Title: Re: anyone know the difference between a neve 1272 and a 1271??
Post by: MagnetoSound on January 16, 2011, 01:15:52 PM
Fletcher wrote on Sat, 15 January 2011 15:55

All you need to do to convert a 1271 to a 1272 is either replace the B283 amplifier board with one that is fully populated, or find the component values [from the schematic] and the components and install them on the B283 board.



That is not all - there is quite some rewiring to be done as well, and the input transformer needs to be changed (or, on a shoestring, at least reversed and rewired).


Fletcher wrote on Sat, 15 January 2011 16:27

A 1271 should have enough gain for use in a "gain makeup" situation for a passive summing network...




Also a mistake. The 1271 not only lacks the required sensitivity for making up the 20-40dB gain lost on a summing buss, but the transformer is, again, not the best match for the low buss impedance.

(This is quite variable, of course, depending on how much summing is taking place, but the rule is firm, as a rule.)


1271 is designed for line in applications, such as post-insert returns or FX returns, where high impedance and moderate gain is the order of the day.


Bubba#$%Kron wrote on Sat, 15 January 2011 14:01

 has anyone ever successfully converted a 1272 to a 1290 ??



1272 was designed for summing buss make-up duties and non-critical mic amp duties such as talkback. With the '1073 - style' gain switch fitted it does, indeed, become a proper mic pre, but as Fletcher said this requires a further gain stage to be added if you want the full 80dB of gain to be available.


Title: Re: anyone know the difference between a neve 1272 and a 1271??
Post by: Bubba#$%Kron on January 16, 2011, 01:46:15 PM
MagnetoSound wrote on Sun, 16 January 2011 10:15



1272 was designed for summing buss make-up duties and non-critical mic amp duties such as talkback. With the '1073 - style' gain switch fitted it does, indeed, become a proper mic pre, but as Fletcher said this requires a further gain stage to be added if you want the full 80dB of gain to be available.





but a 1290 kit is not the ususal gain boosting technique - its actually adding the 3rd gain stage to make a 1073 with no eq.  Thanks for your responses to the other questions also! I could use the 1271 as Plate returns it seems then.

cheers
Title: Re: anyone know the difference between a neve 1272 and a 1271??
Post by: MagnetoSound on January 16, 2011, 02:11:04 PM
Bubba#$%Kron wrote on Sun, 16 January 2011 18:46

MagnetoSound wrote on Sun, 16 January 2011 10:15

1272 was designed for summing buss make-up duties and non-critical mic amp duties such as talkback. With the '1073 - style' gain switch fitted it does, indeed, become a proper mic pre, but as Fletcher said this requires a further gain stage to be added if you want the full 80dB of gain to be available.



but a 1290 kit is not the usual gain boosting technique - its actually adding the 3rd gain stage to make a 1073 with no eq.




Yes, 1290 is exactly that.


Bubba#$%Kron wrote on Sun, 16 January 2011 18:46

I could use the 1271 as Plate returns it seems then.



Most definitely.