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Author Topic: 18w minimalist  (Read 13385 times)

guitarfreak666

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18w minimalist
« on: February 08, 2012, 10:29:40 AM »
hi everyone,

i have some questions:
1
id like to build a 18w minimalist, but with a preamp volume. is the schematic alright or do i have to make some changes(i havent changed any values but i just adden a 1m pot in front of the first tube.

2
i live in belgium and i have a tranny with 230 on primary, do i have to get another fuse value?

thanks

gr guitarfreak


mensur

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Re: 18w minimalist
« Reply #1 on: February 08, 2012, 11:18:03 AM »
hi everyone,

i have some questions:
1
id like to build a 18w minimalist, but with a preamp volume. is the schematic alright or do i have to make some changes(i havent changed any values but i just adden a 1m pot in front of the first tube.

2
i live in belgium and i have a tranny with 230 on primary, do i have to get another fuse value?

thanks

gr guitarfreak
1.You don't need to change anything, it already has preamp volume,500K after first tube.What you did is just another volume pot of your guitar on amp.
2.1A slo-blow fuse will do the job.

Toner

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Re: 18w minimalist
« Reply #2 on: February 08, 2012, 02:23:14 PM »
Yeah, what is your objective to adding the volume on the input? That is the same as your guitars volume control.

  I would put a dual 470k volume on the 8k2/470k junctions for each EL84. That would let you turn up the pre-amp and still have a lower volume out while driving the two 12ax7's into distortion, if that's what your after, often called a Master Volume.

guitarfreak666

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Re: 18w minimalist
« Reply #3 on: February 18, 2012, 01:18:12 PM »
but my guitar doesnt has a volume, and i am kinda looking for a clean tone that can overdrive good but also can stay really clean

btw thanks for the help

phatt

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Re: 18w minimalist
« Reply #4 on: February 21, 2012, 09:09:51 AM »
Wow an Electric guitar without a volume control :o

I'd be looking at getting a Volume control.  I'm assuming it is an electric guitar?
Phil.

guitarfreak666

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Re: 18w minimalist
« Reply #5 on: March 03, 2012, 07:41:51 AM »
yes it is but it was a selfbuilt sg and there wasnt enough space to put a pot in

joecool85

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Re: 18w minimalist
« Reply #6 on: March 06, 2012, 11:15:27 AM »
yes it is but it was a selfbuilt sg and there wasnt enough space to put a pot in

Can we see some pictures of this guitar?  Sounds neat.
Life is what you make it.
Still rockin' the Dean Markley K-20X
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guitarfreak666

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Re: 18w minimalist
« Reply #7 on: March 07, 2012, 07:49:52 AM »
sorry, i cant right now but maybe later. i have another question. the tube sound is it based on the preamp or poweramp? because if i find out that my minimalist doesnt have enough gain, could i be able to build a ss preamp with massive gain?

J M Fahey

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Re: 18w minimalist
« Reply #8 on: March 07, 2012, 05:11:35 PM »
You are "wasting" a triode by using them in parallel.
Build a conventional, 2 triode preamp and you will have *a lot* of gain.
Check the Marshall 18W, or similar amps.

guitarfreak666

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Re: 18w minimalist
« Reply #9 on: March 10, 2012, 05:22:49 PM »
is it posible to add a switch to install a switch for parallel/series for the first 12ax7? i heard some things about coupling capacitors, can anyone explain that to me? my understanding of it is that if u dont have it u will burn ur tube out , is this correct?

guitarfreak666

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Re: 18w minimalist
« Reply #10 on: March 10, 2012, 05:38:46 PM »
also would it be able to do an evh sort of mod to the first tube? can i just change the capacitor to 0.68 µf?
thanks for all the info btw, just by posting on this forum i learnt more from tub amps than i did from reading books about it

J M Fahey

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Re: 18w minimalist
« Reply #11 on: March 10, 2012, 10:30:03 PM »
Start by building a classic amp, you'll have a lot of fun doing it, *later* you start experimenting.
Otherwise you do not have a reference sound in your head.
You will never know what any mod is doing.

phatt

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Re: 18w minimalist
« Reply #12 on: March 11, 2012, 08:33:01 AM »
I quote Mr Fahey;
"Start by building a classic amp, you'll have a lot of fun doing it, *later* you start experimenting.
Otherwise you do not have a reference sound in your head.
You will never know what any mod is doing
."
-------

What is written above is the BEST Advice you will ever get.
Sadly few will take note of such wisdom. :-X

FWIW, I built my first Valve Amp and quickly built far more complex valve circuits *Assuming* I was improving things,,,,, well 20 Years later all the fancy stuff went and I found that one of the very first simple Valve Amps I built was the best. I still use it today.

A lot of Valve circuits/mods are over rated and often don't reap the rewards that are often claimed by forum blabs.

As to bypassing coupling caps,,, DON"T.

You have DC and AC inside these circuits as the cap *Decouples the AC signal from the DC operating points on the Valve. **a Capacitor in that configuration Blocks DCV but allows the ACV signal to pass onto the next stage.**
Most Valve circuits are AC coupled, you can have DC coupled circuits with Valves but not often used.
Go look at the guts of a simple 741 opamp or similar and you will see that all the transistors Are in fact Directly coupled.

Remember that Amplification is AC voltage (the signal you hear) floating on a DC voltage.

So there are two things happening at the same time when you look at the schematic.
You have to set the DC parameters so that you get the best transfer of the AC signal.

**Think of a schematic as 2 separate circuits drawn as one**

Tiss not very hard to see the AC signal path through a Valve amp but some learning is required to see the more complex DC parameters.

Some reading and experimenting with simple BJT transistor circuits will soon reveal biasing procedures and help you get a handle on DC biasing. (setting the Q or quiescent point)

This will also reveal that transistor and valve circuitry is not so different.
The beauty of transistor circuits is that you can mess with them LIVE and not kill yourself.
(at low voltage they are a very safe learning tool)

It takes forever to rewire valve circuits and AB test stuff. :grr

Learning on transistors is good as It will speed up the Valve understanding.
Blowing up small transistors is way way cheaper than blowing valves or worse melting transformer winding which is an extremely expensive way to learn. :(
Phil.
« Last Edit: March 11, 2012, 08:39:36 AM by phatt »

guitarfreak666

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Re: 18w minimalist
« Reply #13 on: March 11, 2012, 05:12:41 PM »
wow, nice advice. i now decided to built it according to the schematic. if it works and i dont like it i can still make some mods, maybe a tone stack or something.
thanks for all the good advice. when my amp is ready i will post some pics and samples.

phatt

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Re: 18w minimalist
« Reply #14 on: March 12, 2012, 09:28:07 AM »
If you are hell bent on finding how Valve stuff works this will help. :tu:

http://www.freewebs.com/valvewizard/index.html

If you are new to electronics and struggle with it then a book might be of more use but with a reasonable grasp of how amplification works then web pages like V wizard can fill in a lot of gaps. :tu:

And don't forget google,,, 
Let's say you see an odd word in text.

Example; *Cathodyne Phase Splitter*
OK it's obviously some kind of PI but if you search for *phase splitter* (a common term) you will get a million meaning less hits.

Type *Cathodyne* (Not so common)  leave off  *phase splitter* may give even better results.

I've found some really good stuff by typing in words that are only used by scientific geeks.
Heck some words the scientific chaps use I can't even pronounce.  :lmao:

Have fun and don't forget to turn off and pull plugs Before you work on Amplifiers.

And Fur Gads sakes don't work on live Amps when you are alone :trouble 8|