LL1521 for use in the 1176 compressor

Many included me are buying cheap LL1521 transformers from tommytones for use in 1176 compressors, but there is, so far, one known incompatibility.
The LL1521 doesn't have a ground pin, which the LL1540 has...

What to do?

hi ChrioN,
hmmm, that's strange. when i look at the pin-out info i have on the 1521 it says that pin 6 is shield (usually connected to GND). seems to connect to 0V on the mnats rev.H boards (which I'll be using my 1521 in).
BTW just FYI, it is tommytones who has offered these cheap, but quality alternatives.
cheers,
grant

Opps...mixed them up a little.

Hiya Chrion,

Just put 'em in - they sound the bollox :wink:

I've had no probs so far..........


Steve :thumb:

[quote author="Kid Squid"]Hiya Chrion,

Just put 'em in - they sound the bollox :wink:

I've had no probs so far..........


Steve :thumb:[/quote]

Oh no, there we have those bollox'n'danglers again. :? :roll:

Can we finally have samples of that... or at least some pics (that still comply with the forumrules) :thumb:

Hiya Clint,

Sorry for the wait, had to get it back off a mate :wink: , The other one will be finished this weekend.
Just got to finish off the front plate engraving :grin:

Going to make another two with the 1540's, and another two with opamp i/p's.

anywhoo -






:thumb:

Looks all neat'n'tidy, no messy danglers :thumb:

:grin:

:thumb:

Lookin' stellar! I'll finnish mine today, everything is done except to fire it up and see if it works :razz:

Well, looks like I spoke too soon :?

had a phonecall last night , when I was in work, aparently my G1176 #1, has stopped working correctly - distorting like mad, (but very nice distortion :wink: )


Just getting up, and I'd thought i'd put a post in !, I'm using the 1521's from Tom, and 1540 on O/P.
Get some nuclear strength caffeine in me, Pick it up, and i'll do some measuring.

Steve :thumb:

Thats wierd...have you done the R26 mod? I did this with a crappy trimpot that didn't track to well, so after a while the unit died too. It was the trimpot shorting I think because I changed the position of the wiper slightly and the problem was gone.

BTW, have you noticed any lack of bass with the 1521? Like very bass light compared to the material not going through the 1176.

Hiya Chrion,

Just got it back, i'm in process of opening her up :shock:

just curious about the r26 mod ?, been slowly going thru the 1176 posts as well - *&%^%$£$ 80 -odd pages :shock:

with regard to the lite bass, I didn't have it long enough to find out !, calibrated her up, and one of my mates called round, and asked if he could try it out 4 me (i been doing loads of stupid hours shifts!), I'll give him a call, but he never said anything about it .
aparently it was working a treat, then it started distorting, the distortion is common to the ammount of compression ??
I'm going to check the static d.c. volts as per the drawing on Jakob's page, first, and I'll get back as soon as I can.

Steve :thumb:

Hiya Chrion,

found the problem, crappy single turn presets - changed them all to 25 turn bourns trimmers, and works a treat :grin:

they sound great. going to build up another couple, with 1540 ins, and some electronic ins, just for comparing :wink:

Oh, also, i had a look at a friend's '76 clone, he couldn't get it working right.
found all signal amp transistor voltages were on, but first transistor in g.r. circuit, was oscillating - found he had wired (7) to (21) and vice versa on the main board -
works a treat now :grin:

I am going to put a trimmer in for the r26 mod when i get them back !

Steve :thumb:

:thumb: :green:

also , forgot to mention, the outputs, if you use mnats pcb, are out of phase on the silkscreen. swap 'em over. :grin: , and you might want to use a spare pole on the rotary, to disconnect the meter in 'slam' mode :wink:

here's a couple of pics, got to finish the front's off tho,



my daughter 'avin a go :grin:

Steve :thumb:

You have that St. Ives transformer color on your frontpanel right?
Looks awesome!

Great pic BTW....(the one with your daughter that is)

[quote author="Kid Squid"]....if you use mnats pcb, are out of phase on the silkscreen.[/quote]

What revision?

[quote author="Kid Squid"]also , forgot to mention, the outputs, if you use mnats pcb, are out of phase on the silkscreen. swap 'em over. :grin: [/quote]
This has come up before and I believe, in fact, that it is Jakob's Rev 7 boards that have the outputs marked in reverse - not my own. Here is a link to some images in the big 1176 post. I don't think anyone ever followed up with confirmation of an error on Jakob's design.

(Edited out false information)

The markings are correct if you use either the Lundahl or OEP on the input and all the other markings are correct for both the Lundahl and OEP output transformers. Just measure when you're done and swap hot and cold if there's a problem.

Ah, that explains it! The polarity of my signal was reversed coming out of the 1176. I thought I had made a mistake and swapped the wires......

hi mako,
looked over your G1176 Rev.H checkplot and it seems correct or am I missing something? is it the primaries or the secondaries of the LL1540 that are swapped on both yours and jakobs pcbs?


thanks,
grant