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just finishing off the front panel design for my SSL but have noticed on many of the pics on here of peoples units that their threshold goes from -15db to 15db and gain is from 0 to 15.

my pdf of the PCB shows these figures as being -20 to 20 and 0-20 respectively.

am i missing something or are the differing PCB designs carrying different values here?
 
Hi Everyone

I'm another newbie who's started building the GSSL clone, with
a few questions. I have had a quick look through the META's, but
it would be really appreciated if someone could point me in the
right direction/link etc

I have just finshed soldering most of the components onto the
board and everything seems to be progressing quite nicely. :grin:
I'm about to place an order for my vca's and while i'm waiting for
them to arrive i want to start looking at getting my power transformer
up and running.

Now for the questions
1. Should I use the Farnell 976635(2x 18v, 4.5VA 0.13A)
as written on the Gyraf Board,
or the RS 201-7038(2 x 15v, 6VA, 0.2A)
as i think Kev used on his instruction page? Do they have any
effect on performance, or none that i'd notice?
2. I know that the farnell unit is the bare minimum and i wont have
enough juice to run a meter light, is the 0.2A RS unit gonna be the
same? or will it have enough xtra to spare.
3. If i go for the RS unit which has an external PCB, what sort of PCB
do i go for? Do i have to etch my own? Or use a different
type of PCB?
I understand the theory behind the series/parallel idea for
110/220v, but have had no luck finding out about the PCB itself.

Any help is greatly appreciated. I've got my head around most of it,
just those little things stump be sometimes.

Cheers
Steve
 
Hi Steve,

Welcome to The Lab..

If you use on-board transformers, you won't have spare power for a meter light. This is why most people build this unit with power transformer mounted off-board.

The easiest and most quiet will be a toroid power transformer - you'll need 2x15V or 2x18V secondary at some 10-20VA. Then you'll have a couple of watts or so for meter illumination without annoying the important parts.

Jakob E.
 
Hi All...

Posted this querry over on tube jay's "ssl north american parts" thread, so forgive the repetition, but am in need of advice badly on the Lorlin Switch choices...there seem to be conflicting suggestions about which ones to use.

I am using Gustav's board and have gathered all the other parts described on the lists with the exception of these switches :sad:

Can anyone help?

Greg's Mouser List suggest:

-10WA137 (4X3)and 10WA135(2X6)... are both listed at mouser as "NON SHORTING (brake before make)" variety and both with "p.c. terminals" and "D shaft"
-10WA167(4X3)... is listed the same, but with "solder terminals"


Others Parts Lists here suggest;

-10WA367(4X3) and 10WA365 (2X6)....both listed at mouser as being "SHORTING (make before brake) variety and both with solder terminals and "flat shaft"

ARE THESE DIFFERENCES SIGNIFICANT?

MOUSER IS CURRENTLY OUT OF STOCK OF THE 10WA135.

COULD 10WA365 SUBSTITUTE FOR 135?

any clarity appreciated
t. :shock:
 
man you're fast, jakob ... do you get tired of folks telling you how thankful they are all the time?
too bad.
:wink:
thanks.
very much.
 
Hello, After reading the various posts, I see that there are two different models of Sifam meters being used for the GSSL:
The AL19WF and the PPM 14.

Are there any advantages to either?

Does the PPM 14 have better ballistics since it's a peak meter? Which is cheaper? I haven't been able to locate a dealer in north america who has either one of these. Any suggestions?

thanks---Ron
 
Ron,

As mentioned several times, you need a standard, linear-scale meter, 1mA FSD sensitivity. The actual type has little or no significance. I think the original used a sifam presentor 19wf. in us, try meterdistributor.

Jakob E.
 
I have a problem where the threshold is not working, it has no effect at all...

I measure correct voltages on the wiper legs, and my rails are ok and stable..., also...any kind of input hammers the meter to full scale and it only moves slightly with the input from there. Any ideas ?
 
could be controlboard-to-mainboard connection. check that voltage on pot viper reflects on TL072 output voltage (pin no's in schematic are switched between the two halves)

Jakob E.
 
Jacob,

Im not sure how to count which pins are which on a IC. Heres how I explain what I found:

Top and bottom viperrs on threshold pot stable at 11.8V

MIddle viper swinging from -11.73V to +11.8V, seems ok there, yet threshold has no effect.

Then I turned the PCB over, now im looking at TL072, from the perspective of the bigger PS caps being closest to me. on the TL072 I have:

pin bottom right 11.8V (dosent vary with threshold)

next pin up -1.17V

next pin up 0.00V

top pin 0.00

moving to left hand side of TL072...

bottom pin from -2.95V to +2.95V verying with threshold

next pin up 0.00V

next pin up 0.00V

top pin up -11.73 V not varying with threeshold


Sorry for the unknowledgable crap description, just learning :0) thanks again
 
Figures looks right - but the pin with varying voltage vs. threshold turn should also carry a DC voltage following input level.

look up the TL072 data sheet for information and an example of opamp pinout. This is important stuff to know!!!!

check circuit around sidechain VCA and between TL072 and sc vca.

Jakob E.
 
Ok im looking at the datasheet and have the pins sorted out. the pin I mentioned with varying DC on threshold seems to be the output, pin 1.

It does indeed vary with input level too. up to about 3.5V DC at max input, the fgures I quoted in my other post are at 0db input....

going to check sidechain now.
 
ok, I found a short near the VCA, right where on of the poly caps. I forgot that last time I used it (a while ago) I had to replace this cap ,long unecessary story.

Anyway fixed short, solved problem. Sorry to put you through that Jacob, but thanks anyway, much appreciated. :grin: :guinness: :guinness:
 
One other thing, not a problem in terms of operation, but annoying...

As you increase compression right up with increasing threshold...

As soon as you come back the other way, my meter drops slowly but consistantly back down to zero. While its dropping threshold has no effect. Got to wait for it to get back to zero, or switch bypass out and then back in.

I think I remember reading this can be due to voltage reg's latching up? Is this right? Couldnt find anything in the meta...

thanks again.
 
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