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Messages - Jazz P Bass

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1
Amplifier Discussion / Re: First attempt to do upgrade
« on: October 10, 2021, 12:21:05 PM »
From the Web: "Made in the sixties for film editing, this little squawk box amp is all kinds of fuzzy fun. You can play straight into the amp through its rattly tiny speaker, or use the headphone jack to run it into another amp …"

2
The Newcomer's Forum / Re: Busking Amp for Bass & Vocals
« on: October 02, 2021, 08:57:08 PM »
Sounds like a fun project.
The real issues will be the cabinet & the recharge circuit.

Alesis has a 25 w/ 50 w peak amp for under 200 US.
https://www.sweetwater.com/store/detail/TransActW2--alesis-transactive-wireless-2

3
The Newcomer's Forum / Re: Warwick Xtreme 10.1
« on: September 27, 2021, 12:20:57 PM »
Here is the schematic if thqt helps.

4
Amplifier Discussion / Re: Fender M80 Issues
« on: September 27, 2021, 12:20:51 AM »
More likely than not there was a zener diode failure.
Cr 25 or CR26 on this drawing.

5
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!

6
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?


7
The Newcomer's Forum / Re: Greetings from a new member
« on: September 04, 2021, 01:34:16 AM »
Hello, Andre.
Welcome to the Forum.

8
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.

9
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

10
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.

11
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.

12
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.

13
The Newcomer's Forum / Re: Just joined...
« on: July 07, 2021, 12:44:00 AM »
Welcome to the place.

14
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

15
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?

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