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Messages - Jazz P Bass

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1
The Newcomer's Forum / Re: Hello
« on: September 15, 2021, 11:25:45 AM »
Welcome to the sight.
It sounds like you are on a roll!

2
Amplifier Discussion / Re: Fender London Reverb
« on: September 09, 2021, 12:22:57 AM »
What does the supply read for the power amp stage?
+33Vdc & -33Vdc is stated.

 The 15 Vdc supply is for the opamps.
A 3 volt drop will not hurt.
As long as they are both the same. (+ & -)

 The 18 Vdc supply is for the reverb & effects.
Again. No biggy as long as they are both the same.

 Have you checked for Vac ripple?


3
The Newcomer's Forum / Re: Greetings from a new member
« on: September 04, 2021, 01:34:16 AM »
Hello, Andre.
Welcome to the Forum.

4
The Newcomer's Forum / Re: Which replacement power cord?
« on: August 06, 2021, 12:08:21 AM »
Ohms Law
I=P/V
375W /120V = 3.12Amps

What you should look for is a cord that is the proper length for how you plan to use the amp.

At home a 5 or 6 ft cord will be fine.

On a stage you may want a 10 footer.

5
Amplifier Discussion / Re: Roland JC120 - Split Line Out for Stereo?
« on: July 29, 2021, 12:00:44 PM »
I am simply going by Roland's recommended values.
Leaving out the ground resistor defeats the divider circuit.

Play with the values if you like.
https://ohmslawcalculator.com/voltage-divider-calculator

6
Amplifier Discussion / Re: Roland JC120 - Split Line Out for Stereo?
« on: July 29, 2021, 12:57:51 AM »
"What would happen if I leave it out?"

You will not have a proper 'voltage divider' circuit.

7
Honey Amp / Re: Thoughts on my new Honey Amp
« on: July 28, 2021, 11:45:33 AM »
" No power switch, but I can understand the omission, since this is supposed to be highly customizable. I have to pop the battery connectors to power down, but my enclosure choice makes that easy enough"

You could try a 3 prong switching jack that disconnects the battery ground when no cord is inserted.

Like pedals use.

8
Amplifier Discussion / Re: Roland JC120 - Split Line Out for Stereo?
« on: July 28, 2021, 11:28:34 AM »
The Line Out circuit uses 2 47K and 1 100ohm resistors for the summing network.
You can disconnect R155 and add a 100 ohm resistor to ground to get a separate feed.

9
The Newcomer's Forum / Re: Just joined...
« on: July 07, 2021, 12:44:00 AM »
Welcome to the place.

10
Amplifier Discussion / Re: Unicord Power Plus 2X12 amp plus horn
« on: July 06, 2021, 12:06:06 PM »
A little side note on the 'PEC' tone control module.

Interesting reading: 
https://thedhtsstore.com/blogs/news/35901185-vintage-components-the-pec-a-k-a-couplate-or-bulplate

https://hackaday.com/2018/09/12/whats-a-couplate-the-stepping-stone-to-integrated-circuits/

They are available but without a datasheet you can't tell what they include internally.
https://www.bing.com/images/search?q=vintage%20PEC%20module&qs=n&form=QBIR&sp=-1&pq=vintage%20pec%20module&sc=0-18&cvid=32AEF5EA2B4D4AC78A3DEBF5456076FE&first=1&tsc=ImageBasicHover

Interesting how Sprague refers to them as a "Couplate PEC BulPlate Coupler Module ".

Centalab also made them:https://www.bing.com/images/search?q=%20Couplate%20Info&qs=n&form=QBIR&sp=-1&pq=couplate%20info&sc=1-13&cvid=7DA336B3F1BF4308ADE01C1119A853F7&first=1&tsc=ImageBasicHover

11
Amplifier Discussion / Re: Pedal Hiss?
« on: June 21, 2021, 12:54:48 PM »
I would not think that it's the battery's fault.
More likely it's the dc to dc converter.
Do you have access to a scope to find what frequency the hiss is?

12
Amplifier Discussion / Re: Pedal Hiss?
« on: June 20, 2021, 09:48:21 AM »
Oh.
But the converter is what is making the pedals hiss?
Not the amp? (with the pedals powered from the converter)

13
Amplifier Discussion / Re: Pedal Hiss?
« on: June 18, 2021, 07:53:23 PM »
https://www.vakits.com/14-watt-single-channel-audio-amplifier-kit-1344
Stupid question: why did you knock down the 12Vdc battery to 9Vdc?

14
Amplifier Discussion / Re: VOX Mini 3.. No speaker output
« on: June 16, 2021, 12:52:11 AM »
To replace the ic properly the balls on the pcb have to be reflowed.
They make sheets of teflon with the correct spacing holes in them & you simply lay the sheet over the flattened balls apply flux and reflow the them.

15
Amplifier Discussion / Re: VOX Mini 3.. No speaker output
« on: June 15, 2021, 11:42:49 AM »
What in the heck were they thinking when they chose that IC ?>>>?
Great for a cell phone but a guitar amplifier?
Come on !
Good job midibob!!

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