LA-4 Help Thread!

[dirtyhanfri]

Sorry, I said 15k, that was 150K

Don´t worry about couldn´t help me finishing this, you helped me a lot in the build, so thanks!

I´ll try the cap between the terminals, and report what happens.

Must be distressing being waiting for you gear, hope your move was ok!

I´m gonna make the calibration this weekend.

Thanks!

 

[dirtyhanfri]

Hi everyone, Merry Christmas!

After a long time I got time to get back in this project, I´m gonna try the cap between meter terminals (Thanks InsomniaClown) and if it don´t work, I´ll try to install 4 germanium diodes.

I´m thinking in a bypass too. Simple thing, I´ll change the Stereo Link Switch and make it Bypass. I will use a dpdt switch, with the input jack, the output jack and the circuit input wired to it. I´d like to avoid pops`n`clicks when switching it, I´ve read about "true bypass" with a pair of 1M Resistors on the input cap leads. I´ll look the schem to locate the caps, but I´d like to not mess to much around in the pcb. Must I solder the resistors directly to the caps? o could I solder them in the wire going to the circuit input?

Also I´ve seen Bypass pcb´s around in the market, what are real advantages using one of them? Also, if you guys know another (easy and relatively cheap) way to implement the bypass, I´ll be pleased to know.

Thanks, I´ll post some pictures of my finished unit soon

 

[dirtyhanfri]

Finally I solved the meter issue

I`ve installed the cap, still don´t measuring output level.... I soldered 4 Germanium diodes, with or without cap it did`t measure GR, then I soldered the 4 diodes before switch, in the wires coming from PCB points 29 & 30, and the cap between the meter terminals , everything looks right now, I got to calibrate it properly, but looks fine.

Working in the meter made me think in add a pair of positions; one relative to my converters, for check tracking levels (I`ll mess around with some resistor values for that) And I was thinking in add a Input level mode, maybe just taking the signal from the input connector (with 4 diodes too)?

I´ll work on the bypass now.

 

[dirtyhanfri]

Finally I did the bypass switch just with a DPDT, switching between the output of the circuit and the input jack to the output jack, no clicks or pops, so useful for my workflow.

Worked a lot this months with this compressor, tracking voices, I enjoy it, but looks like it doesn fit the job like I'd like to, so maybe i'm gonna build a 1176 soon, and use the la-4 for basses.

 

[dirtyhanfri]

My (finally) finished unit

 

[sage]

Hi Luny

I am waiting for the PCB boards, gonna try to build 2 units and fit them into an old MCI JH-110 2 rack unit, so I will have meters and xlr in/out...

Do you happen to have a link made with BOM/part numbers at mouser or digikey - I could swear at one point I saw that somewhere but I just can't trace it -

Thank you,

sage

 

[sage]

Hey Luny I tried to post before but I might made a mistake I think... anyhow I was curios if you have a BOM link to Mouser as a project, I could swear I saw it once, it went straight to the shopping cart of Mouser with all the correct part numbers...

Is there such a thing?

sage

 

[sage]

Actually doesn't have to be Mouser, could be Digikey or any other US company - ordering from Europe might just be too expensive, it doesn't make sense - I am new to DIY so having certain parts # would prevent beginners from buying the wrong Tranformers or parts....

sage

 

[dirtyhanfri]

Just an advice, try to roll your own Bom's, It will help you understanding basic concepts actually, and if you are not sure about some parts you will get help from the forum.

 

[sage]

Yes You are right - I started and I have been compiling info - as you know there are so many different variations of components as far as volts, watts, amp..... so it helped a lot to at least see the Farnell list and reference to the specs of each component and then find that in the digikey web store.
So far so good - perhaps some questions about the transformer but I might have sorted that out too - I will keep on this forum and definitely seek help when needed -
thank you

sage

 

[sage]

Hi

so I have spent several hours and I have almost all the parts figured out and in a cart at DIGIKEY - eventually I will make a BOM out of that, i have omitted a bunch of resistors that I already have so it won't a super complete list...

Anyhow here is the question:

WHAT does MODUL mean?

I see in the CER. CAPACITOR 4.7pF 1 MODUL

I cannot find that parameter anywhere in Digikey, the 100 pF are 2 MODUL... again I am a little lost... can someone point me in the right direction ?

Thank you,

sage

 

[culteousness1]

WHAT does MODUL mean?

This was already asked in reply #68...

 

[sage]

Well Thank you - I did a search and It did not produce results even inside the thread - obviously I must have done something wrong - anyway for people that would like a direct answer rather than searching for answer #68 (which by the way on my browser the answers are not numbered - are they on yours?) the correct answer is :

LEAD SPACING:
1 MODUL = 2.54mm
2 MODUL = 5.08mm



None of the US websites such as Digikey or Mouser list that parameter - once i am done with this BOM for digikey i will make it public on this forum if that is OK with everyone -
Also I should add that voltage doesn't matter on those caps - that I have gathered from this Thread - there are many options when you go buy but you can overlook that, any will do.

sage

 

[sage]

One more "probably silly" question - for a dual unit do i need 2 Power Transformer or just 1 ?

Again I read thru the posts and I think there's one member that tried with one but did it work?

I have nothing against putting 2 transformers in the unit but just wanna make sure it is the right thing to do ....

thanx

sage

 

[culteousness1]

Well Thank you - I did a search and It did not produce results even inside the thread - obviously I must have done something wrong - anyway for people that would like a direct answer rather than searching for answer #68 (which by the way on my browser the answers are not numbered - are they on yours?)

This is what it looks like on Firefox 11:

One more "probably silly" question - for a dual unit do i need 2 Power Transformer or just 1 ?

Again I read thru the posts and I think there's one member that tried with one but did it work?

Regarding your transformer question. I think the answer is in the thread as well.
Great tool to find such things:
Print function of the board + search function of your browser (CRTL + F in Firefox).

I am using a 2x18V/30VA transformer with a single PSU for two boards by the way.

Best,
Carsten

 

[sage]

Hi there

so I have finally finished my order and I would like to share this BOM from Digikey, this is not complete, I had to get some parts from Mouser and a couple from Newark (which by the way had great prices), I also omitted a bunch of resistors because I already had them. Obviuosly this is a starting point and it should always be compared to Luny's list.
This is for a STEREO or DUAL MONO unit and I also should say that I cannot guarantee that I picked all the right parts althought I did spend a significant amount of time comparing the parts on the BOM from Farrel I found in this forum form the ones available on Digi-key and I have tried to pick the ones with the right specks.

As far as the resitor I could not tell how many watts so I eneded picking 1/2 when available or 1 but I realized I picked a couple of 2 watts - which might be too much? Not sure if that matters.

Anyway here it is in PDF format for download:

sage

 

[sage]

sorry here it is:

 

[sage]

Hi there

I started the stuffing of the PCB, cool thing - I HAVE A QUESTION about the capacitor 1000 uf /50V that is what is in the BOM - but the PCB indicate 40V - is that a print mistake ? Am i OK with the 1000 at 50V ?

Also a suggestion to anyone interested in starting this project - the resistor should all be 1/2 watt or 1 watt maximum because the 2 Watts are too big for the PCB, the legs do not go thru properly and they stick out....

So if anyone is taking my BOM from Digikey make sure to know that some of the resistors that I put in are 2 watts and they are too big - only a couple of them luckily all the others i got where 1/2 or 1 W.

sage

 

[dirtyhanfri]

Hi there

I started the stuffing of the PCB, cool thing - I HAVE A QUESTION about the capacitor 1000 uf /50V that is what is in the BOM - but the PCB indicate 40V - is that a print mistake ? Am i OK with the 1000 at 50V ?

You're OK with 50V.

The V of the caps tells you about the maxium voltage it will stand, so, if you put a 50V cap in there, it should be ok.

Good Luck with the project

 

[sage]

Thank you very very much !!

sage