[ACMP investiupgradifications] All things PREAMP

[MATTI]

There was a picture of Chameleon Labs trafos here with the same
1000pF on the input one

Matti

 

[TomWaterman]

Yeah I have that pic too. It's obviouly not a schematic error... so I'd guess these trafos needed controlling more so than the originals.

One place to investigate when they arrive...

 

[Svart]

another interesting thing is that the pic of the *possible* preamp that Gyraf found shows IC opamps while the schematic on this thread shows discretes..

I wonder which one of these designs these preamps will be.

Kinda makes me wish I had ordered some..

 

[MATTI]

This schematic doesn´t show any auxiliary circuits like
power supply or metering & leds ( for wich the opamps are used here ),
so I´d say these are the same 797 preamps, 81 in Gyraf´s pic.

Matti

 

[rodabod]

[quote author="TomWaterman"]
Whats up with the excessive damping capacitance on the mic trafo secondary. Standard 10468 requires 180pF not 1000pF.

Wonder if the chinese trafos have substantial ringing and overshoot?
[/quote]

Probably. When we get them, I can test them against the Carnhill equivalents and also see if they've got the best values chosen there. Also, I wasn't sure if the original transformers would have a 12K strapped across the secondary too.

I'm not going to get in the mode where I decide everything is likely to be rubbish and decide what's going to be changed already. I'll test out what's there and see if anything is really holding it back. Just wait until people start discussing coupling caps...

 

[Baltimore]

well, if these are similar to the chameleon labs stuff, and it looks like they are, they should sound pretty f'in good right out of the box. i've used the CL stuff in a few different rooms and can't complain...and i thought that stuff sounded excellent for the price...

 

[Svart]

This schematic doesn´t show any auxiliary circuits like
power supply or metering & leds ( for wich the opamps are used here ),
so I´d say these are the same 797 preamps, 81 in Gyraf´s pic.

Look at the cards, there are opamps on each board:

 

[MATTI]

Yes, there are but not in the AUDIO circuit

Cheers

Matti

 

[ioaudio]

overload/clip led for each stage. transistors in the back.

funny way of marking the caps in the schematics.

 

[rodabod]

From looking at the schematic, I thought they might have been a bit more subtle with their Neve-inspired preamp... Still, I'd rather have that than anything else I suppose.

 

[TomWaterman]

As said there are enough transistors in the photo to form the discrete amp stages and there are so many clip leds on this device. God knows why but that is what the IC's are.

I agree with Roddy, there's not much point deciding to rip them apart before they get here. Chameleons do sound really good, so I don't think these will sound bad at all.

Roddy mentioned coupling caps... I don't see many tantalums but must listen first before judging.

I'll try and organise a shoot out with some real Neve on a variety of sources when they get here. Maybe piano, drums, ac guitar and vocal.

-T

 

[gareth.h.rees]

[quote author="TomWaterman"]
I'll try and organise a shoot out with some real Neve on a variety of sources when they get here. Maybe piano, drums, ac guitar and vocal.
[/quote]

That would be amazing! Except it may make me wish I ordered more!

Cheers
Gareth

 

[Jim50hertz]

[quote author="TomWaterman"]I'll try and organise a shoot out with some real Neve on a variety of sources when they get here. Maybe piano, drums, ac guitar and vocal.

-T[/quote]

+1 on that. Tom, that's a fine offer and I think would be very useful to the folks who've bought these. Many thanks :thumb:

Cheers

Jim

 

[crazydoc]

Looks like 3Q3 got left hanging. Doesn't inspire a lot of confidence in the schematic.

 

[EEMO1]

[quote author="rodabod"]I'd just like to say, can we please leave the arguing over at Gearslutz and Homerecording? We don't need that here.[/quote]


2nd that.

 

[playboss]

2nd what?
anyway, tought I post this
http://tinyurl.com/46dfn7

:green:

 

[okgb]

2nd , not turning this into a bitchfest ............which i 3rd
how may i help

 

[clintrubber]

Been away for a week, amazed a bit by all the action here (and indeed lame to see all those other discussions 'elsewhere').

Cool the schematics popped up, thanks :thumb:
I guess it'd be safe to say now that the output-stage of the ACMP-81 is identical to the -73 & -84 (so class-A, '3055, gapped TX bla bla bla) or what do you guys think ?

Bye,

Peter

 

[rodabod]

[quote author="clintrubber"]
I guess it'd be safe to say now that the output-stage of the ACMP-81 is identical to the -73 & -84 (so class-A, '3055, gapped TX bla bla bla) or what do you guys think ?[/quote]

I reckon this is probably likely.

 

[W DeMarco]

edit/delete

sorry read the original thread Im up to speed now