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Messages - Tassieviking

#1
Amplifier Discussion / Re: 12w Marshall
January 24, 2023, 12:17:06 PM
Guzzies3, have you considered trying to build some of BajaMans Pre-Amp pedals from https://www.freestompboxes.org ?
Some of those can work well in front of an amp I believe.
He has made Amp sims for several different amps as well as speaker sims etc.
They all have vero board layouts for them.
I made up some of them as PCB's but I havent had time to make any yet.

As far as hijacking a thread goes, I don't think Joecool85 minds it happening, at least I hope he doesn't.
As long as it is in a friendly manner and it keeps this site as a friendly forum where like-minded people can have a chat and share ideas and stuff.

Michael


#2
Amplifier Discussion / Re: Add effect loop to jc120
January 23, 2023, 10:24:26 AM
Enzo was a great man, he was always helpful AND informative.

Most of the time when Enzo gave you an answer he also explained it so you learnt something.

He always made me think of the old saying:
Give a man a fish and you feed him for the day.
Teach a man to fish and he has food for a lifetime. (or something like that)
#3
Amplifier Discussion / Re: 12w Marshall
January 23, 2023, 10:13:33 AM
Guzzis3, where are you getting the Hotone Boogie Siva for $72 from ?
I might be interested at that price.

I am not worried if this topic has drifted a tiny bit of topic, and I started it.
As long as I find out new things I'm happy.

I am especially happy now since I have found out about the Hotone Nano series.

Michael.  :)
#4
Amplifier Discussion / Re: Add effect loop to jc120
January 22, 2023, 08:17:23 PM
Thanks Phil for pointing out the JC models page, I have just finished reading it for the second time and it was very informative.
I have also re-named the JC-100 84 file to head only single channel.

I would do what Phil said regarding the effects loop, ignore what I said. :) 
#5
Amplifier Discussion / Re: Add effect loop to jc120
January 21, 2023, 09:52:50 PM
Phil, unfortunately Enzo passed away in August last year.

https://music-electronics-forum.com/forum/music-electronics/967156-rip-enzo
#6
Amplifier Discussion / Re: Add effect loop to jc120
January 21, 2023, 04:14:00 AM
I had a look through my files and found a 84 JC120 schematic with an effects loop,
if you compare the circuit after the return jack you will understand what I meant above.

Never mind, that's a single channel head only.  (Thanks Phil)
#7
Amplifier Discussion / Re: Add effect loop to jc120
January 21, 2023, 03:48:34 AM
You can also remove those resistors and use the holes for wires to run to the send/return jacks, just replace the resistor along the wires so it goes back in the circuit.
I would solder the resistor to the send jack and then add the wire to the resistor.
If it works ok then put a bit of heat-shrink tubing over the resistor.

I would have thought that the place to insert the send/return would be at C26/C126, or just before C26/C126.
I think it looks like the circuit between R19 and C26 is where the effects and distortion might enter into the circuit.
I might be wrong as I am not familiar with this amp.
#8
Amplifier Discussion / Re: 12w Marshall
January 19, 2023, 08:34:25 PM
G'day guzzis3, welcome to the forum.
I often drop in on the Marshall forum as well.
I don't own a Marshall, but one day....
I can't afford one on a disability pension.
I sent you a PM for your mailing information.
Well se what happens next time I go into town.
#9
It looks good, but.........not for me, if I can't make one myself from TH parts :-\ .
However.....If someone wants to give me one I would be one happy chappy. :)  :)  :)
(Happy Chappy is an old English saying and so is gay blade, both means a happy social person)
Just don't call a bloke in a pub a gay blade unless he was around in the 1930's.

#10
Amplifier Discussion / Re: Fender Stage 112 SE
December 30, 2022, 02:14:02 PM
Be very careful when tampering with the ground wires in this amp, they might be critical to the amp.
The amplifier is a "Flying Rails Amplifier"
Way beyond my experience, but the +45 -45V supply to the power amp has no earth on the center tap like conventional amplifiers.
The center tap is the output from the amp to the speaker, along with the chassis earth.
The +45 -45 voltage rails are moving up/down in relation to the chassis earth as the amplifier is working.
The center tap of the +45v -45v does not stay at zero volts in relation to the chassis, it moves up/down up to +45v and -45v.
This can make the +45v rail look like 0v to +90v, and the -45v rail can be at 0v and down to -90v during operation in relation to the earth on the chassis.

I'm confused just trying to explain it.
#11
Amplifier Discussion / Re: Fender Stage 112 SE
December 29, 2022, 08:53:27 PM
Schematic
#12
Amplifier Discussion / Re: 12w Marshall
December 24, 2022, 04:10:41 AM
The 50VA Toroidal I had ordered lasted 1 minute before the primary went O/C, I went to a local shop and grabbed a 20VA 30V CT transformer yesterday and tried again, all seems good so far.
I tried it with the 12 watt reverb circuit and mostly ok, when I tap the box I get reverb noise even with reverb pot on zero, possibly feedback through the final OP amp ?
Anyway, it sounded good through a Celestion V-type 70watt speaker I had on hand.
I built this one using 2N3904, 2N3906, TIP142 and TIP147 transistors in the power amp.
I borrowed the reverb from a Marshall G15RCD someone gave me earlier in the year, not the correct reverb tank but close enough for trying out.
At least it worked first time so I'm happy.
Now I just have to get some ply and make a cab for it, and a speaker and reverb tank.
I am also making a 12watt Bass version at the moment so I will have to see how that goes, I might have to modify it as I think the Bass version has some HP filters that are a bit too high for my liking.
I might make the cabs slightly larger then original because the original Bass cab was open back the same size as the lead cabs.
I might make the bass cab a lot deeper but the same front size as the lead and reverb cabs I am going to make for these.
Here is the Gerber file I sent to JLCPCB to make the PCB's, and the latest revision of the BOM.
I have noticed one fault with the BOM already, C24 on the 30W Bass 5503 list should be 220nF and not 22nF.
The schematic is a combination of all the 12watt schematics I found, and the power amp section is a mix of all the 12 and 30 watt schematics I found.
Just use the right combination of components and it should be ok.
#13
I think the Lab Series schematic explains it.You cannot view this attachment.
#14
Amplifier Discussion / Re: Jordan Two/01 Repair
December 08, 2022, 05:14:43 AM
That power amp PCB could do with some flux remover.
It would be a fun amp to trace out the schematic from the PCB's.
If you take a photo of the PCB with a bright light on the opposite side it should not be too hard.
#15
There are some amps where the high and the low inputs are opposite to most normal amps, I can't remember which ones they are.

I think the most important thing to remember when choosing low or high input is to use the one that makes you smile, end of story.