1176 REV A on ebay - UNIQUE MOD??!

[Darkhyrys]

Hi man,
So? Is it solved?
Where are the exact diferences?

 

[dreamix]

Hi man,
So? Is it solved?
Where are the exact diferences?

You will hear it first here!

The biggest difference in sound and what the "miswire" is, is in the input knob where they mixed 2 resistors up (R2 and R3 620ohm in original) and are connected to chassi ground, i can make a small schematic of this miswire, but this leads to a excited kinda sound, if anyone is interested in the whole theory and what BLA did i can make a short video. R2 from + to chassi ground, move R3 to common - and chassi ground.

The "excited" sound is static and is not affected by the input knob, if you turn the input all the way down, you will still but only hear the miswire therefore BLA is mixing some direct sound in through resistors so there will always be a bit signal mixed together up to i.e 36, idk if this is to make it more useful or to cover up the "secret" abit, but its not needed if you intendent to run it around 30 as the mix engineer it is something BLA added to their units.

But its easy, you can do this mod in 5 min, and its great

 

[Darkhyrys]

thanks man.
What about the added RC and CR filters in the preamp and amp section seen on your schematics (other thread) ?

 

[dreamix]

thanks man.
What about the added RC and CR filters in the preamp and amp section seen on your schematics (other thread) ?

Ye, Im not sure why these are added, if there is a solution to get it closer to original in sound to compensate for the reproduction transformers etc... but these components is not in the circuit they replicated, Ive seen photos of it and they are nowhere to be seen there so I didnt bother to much about them. Like the reason they didnt felt it had the same "shine" as the original so they added the SSL routing part to it.

Also... if you measure the input transformer in the replica, it is I think closer to 30ohm between the 2 input pins than in original unit that is closer to 40ohm? On a original transformer has more options, its wired with 1,5 but to get it closer I measured and used 2 other pins which gave me 30ohm but cant remeber which, I dont think this is very crucial but it gives a little more boost into the circuit. They had their input transformer custom made for their unit so I figured they must have done their own measuring in the original unit and tried to match these values so probably the pins used in the original unit also doesnt match the schematic. If you get what Im saying.

 

[Darkhyrys]

Ye, Im not sure why these are added, if there is a solution to get it closer to original in sound to compensate for the reproduction transformers etc... but these components is not in the circuit they replicated, Ive seen photos of it and they are nowhere to be seen there so I didnt bother to much about them. Like the reason they didnt felt it had the same "shine" as the original so they added the SSL routing part to it.

Also... if you measure the input transformer in the replica, it is I think closer to 30ohm between the 2 input pins than in original unit that is closer to 40ohm? On a original transformer has more options, its wired with 1,5 but to get it closer I measured and used 2 other pins which gave me 30ohm but cant remeber which, I dont think this is very crucial but it gives a little more boost into the circuit. They had their input transformer custom made for their unit so I figured they must have done their own measuring in the original unit and tried to match these values so probably the pins used in the original unit also doesnt match the schematic. If you get what Im saying.

So no changes, only those 2 resistors on the Input knob ...

 

[dreamix]

So no changes, only those 2 resistors on the Input knob ...

Ye, thats the miswire "secret"... you will hear the difference for sure, I couldnt find anything else, except maybe if you want to mess around with using other pins on the input transformer to reach closer to 30ohm, which generally just give some boost.

There is also a difference in the metering, where CLA´s unit probably has the trimpot seen in pictures all the way down (GR meter driver Amp) in the replica this trimpot is replaced with a 10ohm resistor so (R44)... its pretty fast reacting/releasing, and by doing the "miswire" will also effect the attack/release and metering.

 

[dreamix]

Here is a compare first is the miswire, second without, it was an early test before calibration... but easy to spot nonetheless

bluey mod.mp3

 

[Darkhyrys]

fantastic
"i can make a short video" please go ahead

 

[Darkhyrys]

BTW, the 2 resistors are still 620 ohms in the mod?

 

[Darkhyrys]

can I writte a small schematic actually?

 

[dreamix]

BTW, the 2 resistors are still 620 ohms in the mod?

No they are actually I think 330ohm, I tried using 620ohm since I figured if it indeed was a miswire those resistors would have been 620ohm, but I changed to 330 since it fits better to my ears and this was in the BLA aswell

 

[Darkhyrys]

I've tried that (Pics), It sounds good too:

 

[dreamix]

I've tried that (Pics), It sounds good too:

Interesting, When (If) I find another 1176 bluestripe cabinet, I will build another unit and def will include these other "mods" and see what happens.

 

[Darkhyrys]

So with the Bluey, when the input is set to "0" there still a signal in the output?

About the input resistors, you mean : 2 resistor (420 each) come from the chassi to: * one to the oin2 xlr input * other one to the transformer (lead 1 on UTC O12) and (lead 4 on ALTRAN C-3837-1) ?

 

[Darkhyrys]

"Ye, thats the miswire "secret"... you will hear the difference for sure" :
I hear a diference but not as obvious as your vocal clip

 

[dreamix]

"Ye, thats the miswire "secret"... you will hear the difference for sure" :
I hear a diference but not as obvious as your vocal clip

This unit in the video is with only original parts (...or in fact switched out some to what I thought I saw in CLA`s unit) in the circuit and true REV B design if that would matter Idk, but you can see when input is all the way down, there is loads of signal in, I guess this mod acts like a HF sidechain injecting it back into the circuit after the input transformer

1176 miswire mod.mp4

 

[Darkhyrys]

yes , great ...
btw, the RC and CR filter mods are psychological lol. After an "inverted phase" test ... they're axactely the same

 

[dreamix]

yes , great ...
btw, the RC and CR filter mods are psychological lol. After an "inverted phase" test ... they're axactely the same

Did you try it? seems like Im the only one thats been messing with this so would be cool to hear what others says about it, I think its sooo nice

 

[Darkhyrys]

View attachment 102520

This unit in the video is with only original parts (...or in fact switched out some to what I thought I saw in CLA`s unit) in the circuit and true REV B design if that would matter Idk, but you can see when input is all the way down, there is loads of signal in, I guess this mod acts like a HF sidechain injecting it back into the circuit after the input transformer

1176 miswire mod.mp4

making exactly this wiring, make no more signal at input 0 ... Are you sure about that?