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Messages - phatt

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1
The Newcomer's Forum / Re: Fender bass cab questions
« on: January 17, 2019, 06:37:59 AM »
There are many ways to wire up speakers.
If the big one was 16 Ohm and the 2 smaller ones were 8 Ohm then yes that gives 8 Ohm load. After removing the wires Check the big speaker at the terminals you may find it is 16 Ohm.
Phil.

2
Preamps and Effects / Re: Aion lab series l5
« on: January 14, 2019, 07:04:16 AM »
Power down and read the resistance across that resistor,, it maybe open and read a much higher that stated.
Phil.

3
The Newcomer's Forum / Re: Gear Suggestions
« on: January 13, 2019, 10:54:20 PM »
Welcome Coolmic,

start with simple stuff;
You should be able to get a soldering iron that suits your needs for under $20 au.
Mine cost $18,, first one lasted 5years second is still going at 3 years.
Repaired many amps/pedals/guitars and built many projects including a couple of Vavle Amps.

Find it here; https://www.jaycar.com.au/20-130w-turbo-soldering-iron/p/TS1554

Multimeters; well take your pic if you are only working on low voltage pedals then you don't need to spend too much.

If you intend to work on mains stuff then you need a better meter.

Again this is what is around in Australia you place might be different;
https://www.jaycar.com.au/tools-test-equipment/multimeters/digital-multimeters/c/7AA?sort=popularity-desc&q

Oh and stay away from lead free solder,, ask for 60/40 solder.
Hope it helps,, Phil.
 

4
The Newcomer's Forum / Re: First real build. LM386.
« on: January 07, 2019, 12:39:44 PM »
Hey some nice blues riff there :tu:
BTW, looks like you are driving a hifi type speaker box,, if so then be aware they are woofers and generally have a low SPL,, a real guitar speaker will give a much bigger sound,, louder per watt of input.
Phil.
A friend has a 12" guitar speaker I can use. Time for a bit of joinery I think


Sent from my SM-G935F using Tapatalk
Works as a harmonica amp too. I made the mic using a headphone speaker. The black box on the right contains a Kemo preamp module, needed to overdrive the amp. A Danelectro overdrive pedal works too. https://flic.kr/p/22mhiVv

Sent from my SM-G935F using Tapatalk
Amp seems to have got more 'scratchy' since I first used it. Usually if I slightly overdrive it but its OK when I run it flat out (i.e. give it the full 0.75W !). Could some component have deteriorated  from being overdriven? or did I just not notice at the start?

Sent from my SM-G935F using Tapatalk
If you changed the speaker then you will hear different freq than you heard through other speakers. It was likely there you just did not notice it.
Phil.

5
The Newcomer's Forum / Re: First real build. LM386.
« on: January 07, 2019, 12:36:45 PM »
Hey some nice blues riff there :tu:
BTW, looks like you are driving a hifi type speaker box,, if so then be aware they are woofers and generally have a low SPL,, a real guitar speaker will give a much bigger sound,, louder per watt of input.
Phil.
A friend has a 12" guitar speaker I can use. Time for a bit of joinery I think


Sent from my SM-G935F using Tapatalk
Finally did the joinery ( takes me a while to do stuff!) I now have the amp and some pedals powered by a single PS in a case and going in to the 1x12. Plenty loud for home use and a great platform for bigger amp builds.
Speaker good for up tp 80w.
1w amp and pedals into 1x12 cab
 https://imgur.com/gallery/lKMg7CR

Sent from my SM-G935F using Tapatalk
Yes a real guitar speaker makes a much better sound. 8|
Phil.

6
The Newcomer's Forum / Re: First real build. LM386.
« on: January 07, 2019, 12:33:09 PM »
They are sometimes called 'Cliff style' but that is a brand name.  Maybe 'leaf' style?
Neutrik NMJ4HF-S would be an example.
I meant to ask about the switching part. I want it to switch off the speaker when a plug is plugged in. Is it just called a switched jack?


Sent from my SM-G935F using Tapatalk

Yes very common switched socket,, the plastic ones lift the connection when you insert a plug. there is a pic at top of page.
Phil.

7
The Newcomer's Forum / Re: Update on Londoner L100A amp
« on: January 07, 2019, 12:28:36 PM »
If the original switch can't be found you may need to look at mounting a different type of switch.
I assume the original is a round hole mount with metal toggle.
There are plenty of 10Amp plastic package rocker switches around now but they are mostly square cutout type.


Re the speaker socket.
Who knows why,, without seeing the unit I have no idea but a lot of amps do have a switching setup so that when the external speaker jack is used it turns off the internal speakers.
This avoids the low ohms issue that can often burn out the power amp.
If the parametric EQ pot is stuffed that will cause wacky sounds, the amp may even oscillate and squeal like a pig. :o
In my experience, the can of cleaner will only be a temporary fix and likely cost more than a new pot. 8|
Phil.

8
The Newcomer's Forum / Re: Update on Londoner L100A amp
« on: January 07, 2019, 07:26:52 AM »
Yes 50k pot is the same thing.
i.e. when a schematic calls a resistor 5k you use a 4k7 resistor.
Except for maybe the bias it's rare in these circuits to need exact values.

To find out if the pots are linear or log just use your meter to measure end to end,, jot that down ,, now turn the knob to halfway and measure from wiper tab (Centre) to one end then the other.
If it's a linear pot it should read close to half the total value from both ends.
If Log,, it will read about 10~20% from bottom to centre and 80~90% from centre to top tab.

The burn marks are a common result as they are power resistors and do get very hot. Would be better to mount them on insulated stand offs but amps are made to a cost. If the heat is extreme the board can burn up and it can de laminate the copper tracks underneath but yours looks ok.

So Q?
Is the amp working?
if so don't replace parts willy nilly as you may cause a new problem.
Fix the pots first then see how it sounds.
Phil

9
The Newcomer's Forum / Re: Update on Londoner L100A amp
« on: January 04, 2019, 09:35:47 PM »
Need more info,,
Is it a resistor?  a Capacitor? what does it look like?
Try and take a pic of the part.
Phil.

10
Amplifier Discussion / Re: Etching your own boards
« on: January 04, 2019, 06:13:58 AM »
Oh I now see what you are trying to do,,
Don't put your self through hell,, go get software and learn how it works. :tu:

http://diy-fever.com/software/diylc/

It's freeware it's not bad for small stuff like fx pedal circuits.
I did try it long age when it was basic but It has been greatly improved.
The learning curve will not be as hard as some of the higher end CaD programs.

I use Kicad (Also free) but that is vastly more complex and a steep learning curve. xP

If you do want to hand draw,, use a lead pencil to do a draft of the tracks,
you can easy rub out mistakes.
Then when it's right you just follow the pencil lines with a Dalo pen.
Dalo pens are designed for the specific purpose of making PCB's, ask at you local electronics store. They might be called some other name where you live.
Marker pens used to be all Oil based but hard to find now.

If you want to DIY your own circuits my advice is bread board everything first.
And test and re test it to make sure it's going to work *With Your Gear* before you go off make pcb's.
Tiss all to easy to get impatient and just assume that your build is going to sound as good as the utube demo,, often played through $$$$ amps giving a false impression of how it sounds.
Phil.

11
Amplifier Discussion / Re: Grounding techniques
« on: January 03, 2019, 08:01:37 AM »
Maybe post some pictures of what you have and that might help us to work out the issue. :tu:
Phil.

12
Amplifier Discussion / Re: Grounding techniques
« on: January 02, 2019, 08:53:23 AM »
I believe that you are missing the point of the Earth connection.

"Wall Wart" power supplies are typically rated as 'Double Insulated'.

Therefore there is no need for a connection to Earth Ground.

If you are having noise issues with the amplifier, I would look into why.

The power pack itself may be the issue, noise wise.
Agree,, If one or both plugpaks are Switchmode type that can present problems with circuit grounding.
The older Iron/copper transformer Plugpaks were less prone to this.
Phil.

13
Amplifier Discussion / Re: Etching your own boards
« on: January 02, 2019, 08:27:29 AM »
+1 what *galaxiex* posted. :dbtu:

I'm doing a pedal PCB right now so I'll try to get some pics of the process in the next week or so.

Adding my experience,
I found my wife's house and garden magazines are made of thin but Glossy paper. whatever you use the surface has to be glossy.
I started by using expensive photo paper but it takes hours to soak the paper off. Magazine paper rolls off in warm water in less than 5 min.

Find pages with only print avoid pages with lots of dark print pictures as some of the solid colour will transfer and muck up the result. plain printed words only.

Yes you will need to experiment with paper and also the printer settings.
Your printer settings should allow you to print at full ink density, you want as much ink as possible. Beware of cheap refills as the ink may not be up to the task.
Other setting might be, Improve fine line resolution.
In my case I also set for *Thin paper*

The pcb is cut to size and all edges filed so that there are no burrs on any edges. the copper is then scrubbed with kitchen scour, not new ones they are too aggressive. Dry the board ,, then wipe with Acetone.

I then sellotape the printout down on the Blank,, tape the corners down hard onto a clean laminated particle board.
With iron on high Gently slide the iron across the surface until it starts to stick. once it starts to stick then I carefully lay the iron down flat and press hard for 30sec,, lift and turn, press again. Keep turning the iron as mine has the element in the middle so the heat is not even. So I have to move it around. if the pcb is large you may have to do this a lot to get all the ink to melt and adhere to the copper.

A 70x30mm PCb will need about 3~4 minutes to melt the ink well.
Iron on hottest setting, Linen.

Then drop it in cold water so the ink will set hard,, now dunk in warm or hot water and the paper will start to wrinkle and you will then see the track through the paper.
After about 3min you can gently lift the paper.
Some times it just rolls off but do it slowly and keep dunking as you do.

Some paper will stay on the pcb so you will need to gently rub it off ,DON"T use your fingernails roll it off with the flesh of you finger/thumb.

Next step is touchup any missing bits with oil based ink pen (Dalo pen)
Then you etch,,
when done Acetone off all the ink.
Now if you are hand drilling I lightly centre pop all the holes before drilling with Dremmel or similar.

I use a 1mm drill (you can go down to .8mm but they break real easy).
Tape down on flat board and drill holes.
to de-burr all the holes after drilling I just scrape a steel rule across all the holes, work a treat.

Just one more thing about the software side,,,
If it's diy at home build find global setting in you CAD program and setup the track widths and pad sizes.

Most of these programs are *Assuming* we are all building mother boards and preset pads and tracks are tiny. Don't even think about trying to home build with tracks thinner than say .5mm as you will fail.
avoid ground fills as this can lead to problems if the ink gets so hot it spreads a little and any track that is close by will get bridged.

Anyway If I think of anything else I'll add later,, got to go to bed sometime.
Phil.

14
Amplifier Discussion / Re: Grounding techniques
« on: December 31, 2018, 07:40:27 PM »
Maybe what was meant is;
He is using a plugpak/wallwart so there is no mains to the amp?

"IF" so and there is hum/buzz then the Q is valid but confusing. :loco

@ Flester;
The term *Ground* can have many meanings.
Mains ground (EARTH) although related is quite different to the Ground or *Common* in your circuit.

If your Amplifier is as above, no mains in the chassis and powered via an external double insulated supply then you have have a local circuit ground issue.
Grounding back to mains EARTH probably won't solve much if you have a circuit problem causing hum/noise.

If it's hum, You most likely have a bad connection in the amplifier circuit common path somewhere.
If the circuit is very buzzy then likely there is too much gain somewhere with bad shielding.

Be aware that a lot of amps for modern higain thrash will all buzz when the distortion pots are maxed out and at bedroom volume it quite pronounced.
At gig level you would hardly notice it until you stop playing. 8|
And yes,,, as *DrGonz* mentioned give us more info and clarify the problem so we can help. :tu:
Phil.

15
Amplifier Discussion / Re: More gain from Crate 120
« on: December 27, 2018, 07:04:17 AM »
You could try;  R43 around IC3A is 22k,, try 47k.
Keep in mind that will also raise the output level of the high Gain Channel as well.  Worth a try.

To raise the Volume level of *Odrive only* you will have to tweak around the ODrive level pot. Try bridging R72 with a wire link and if not enough volume lift you could temporarily lift one end of R76 (10k) as well, though that will alter the tone a bit which may or may not be good but suck it and see how it sounds.

Be careful with de-soldering parts as some of the PCB's have very tiny solder pads and very thin tracks that are easy to wreck.  :'(
Phil.

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