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Messages - phatt

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Schematics and Layouts / Re: guitar amp diagram revision help
« on: January 26, 2020, 07:44:48 AM »
Thanks Joe, yes I was fairly certain that was the case. :tu:

Yeah I get your point about the fun of building your own rig,,,,but you have to buy and build everything. xP
Yes a kit is a good way to go, assuming you are talking just a power amp kit?
BUT you still have to pucha$e; a speaker, transformer, face plate, knobs, maybe some paint and vinyl covering,, add speaker cloth, a cab handle, rubber feet, corner caps.
Then you have to design a circuit from scratch that may end up no better than a $40 bargain from a second hand store. The circuit posted is a small 10/15Watt basic circuit and these can be found on landfill sites if you hunt around and you may even get lucky and pickup a whole amp for nicks. (well that depends on where you live I guess)
Having built a lot of amps from kits and from scratch,, I can tell you that the chance of success at first attempt is very low. Even worse if it's a first attempt. :-X

On the other hand ""IF"" *Watermelon33* has played an amplifier that uses this EXACT Design and it delivers the sound he wants,, then yes it then makes logical sense to build one because you have already heard the result.

My advice would be buy something cheap and back engineer it, you will learn a lot faster and avoid the eternal frustration of building a circuit only only to find it sounds nothing like what you hoped for.
cheers, Phil.

Schematics and Layouts / Re: guitar amp diagram revision help
« on: January 24, 2020, 07:39:05 PM »
BTW, X1 is NOT a buffer. As for distortion, just adding diodes won't work well, you would need to add an extra stage to get a reasonable outcome.
You could add an input buffer stage and alter X1 to work like the link *Joecool* noted above.

Also, I believe the TDA2050 is no longer made, though you could use LM1875, others here will know more.

The reality of this is that you it would work out a lot cheaper and many times easier to just purchase a small amp. xP

That would be a waste of a good malt whisky.
Your tone would sound a lot better if you drank the whole bottle. ;)

Tubes and Hybrids / Re: 12 v tube preamp
« on: January 17, 2020, 08:59:30 PM »
hi Flester,
AFAIK, Tiny Terror is all valve running on high voltage.
I have no doubt that running Valves on low voltages will work but I doubt you will do much better than SS pedals.
The big thing with Valve rigs is the High voltage and the way in which the supply is delivered to each stage.
I think the term is  High Impedance supply, these sag as power is increased giving the classic compression feel. There are of course many other things that make all valve amps do the magic but just altering the values of the drop resistors in the supply chain changes the way the whole amp responds to how you play.
I doubt that will happen if running an AX7 at 12Volts.

Amplifier Discussion / Re: Crate CR112 tone stack
« on: January 10, 2020, 07:33:11 AM »
Hi Jopy, Your amp circuit is an oddball and I doubt it will ever be ideal.
The Treb & Bass are Passive while Mid is Active, (mid similar to TS9 tone control).
I've just done a quick simulation of the preamp and it looks like it might be a design hickup. :loco
Sims are not perfect but handy for giving clues as to what might be wrong. 8|

The first thing I noticed is p2 (Level) is not grounded in clean mode causing a wacky tone curve and your bass starts with a 5dB hump at 5hZ,,, WTF? no guitar amp will work well with a response curve that low. :duh
That might explain why you have to back off the bass so much.
In clean mode p1&p2 are not in circuit but if I ground p2 while in clean mode then IC1 works in a normal manner, bass rolls off at ~100hz. Though you would then need to lower the value of C3. try 50pF.

The best I can make out is p2 needs to be grounded all the time otherwise IC1 works more like a notch boost at 5hZ.  :crazy2:

I've noted the area of schematic in question, see pic. maybe check that on the pcb as schematics are not always correct.
Of course when the OD is engaged the response curve is closer to what I would consider a normal curve. but then the diodes conduct and you might have more diode fizz to deal with.
It's complicated to explain as there would be a lot to do to make it work the way you want.
Hope that helps, Phil.

Tubes and Hybrids / Re: JTM60 Combo rectified diodes fried
« on: January 03, 2020, 07:38:20 AM »
Do you have the schematic? That will help you decipher which is which.
The pcb will likely have the reference numbers printed on the pcb.
Maybe post a pic as that will help us. 8|
I'm guessing you have about 8 secondary wires, 2 for HT, 3 for Filaments and another 3 for the opamps.
HT will be ~ 300 ish VAC,  Filaments will be around 3v5-0-3v5 AC and the opamps will be ~ around 12-0-12 VAC.

not sure about the bias,, might be tapped off the HT?
Others here will know more.

You will need to build your self a limiter before you turn it on other wise you might just blow up more parts.
See here for details on how to make one;
3rd post down.


Tubes and Hybrids / Re: Laney VC30 Output Transformer
« on: December 13, 2019, 12:03:26 AM »
1760J looks like it would be close.

Generally a pair of 6V6 use ~6k pp
while a pair of EL84 would be ~8k pp

The reality is,
there are many OT parameters that effect the final outcome.

Tubes and Hybrids / Re: Laney VC30 Output Transformer
« on: December 12, 2019, 09:01:56 AM »
The links are mostly for 6V6, you need a Tx for EL84.
IIRC a quad of EL84 needs a primary winding plate to plate of 4k.  Pri Z is usually just written as (4k pp) on data sheets.
Others here might know places in your location to find a Tx that will work well for that amp.

The Newcomer's Forum / Re: Fender Mustang II v.2
« on: December 08, 2019, 06:08:35 AM »
Rule out the simple things first;
If the Amp has an Effects Loop then bridge those in/out sockets with a guitar cord.
This bypasses the internal switch inside the socket.
This is a very common fail point in many amplifiers as they all seem to use flimsy contacts for the internal switch now days.

Amplifier Discussion / Re: The Dangers of Speaker Impedance Mismatching
« on: December 05, 2019, 03:28:27 AM »
"Amp going bad" is a very vague term.
Maybe explain the symptoms and folks here might be able to help you out.
I doubt the damping is an issue.

Amplifier Discussion / Re: Ibanez TSA30 - buzzing
« on: November 12, 2019, 08:52:26 AM »
This might help;
Read second post by Bajaman.
Cheers, Phil.

If the Amp works (makes music as intended) then unlikely replacing transistors will fix it.
hint, Use Enzo's logic,, bang your fist on the amp and see if you can get it to pop.
If so it would point to a mechanical problem, i.e. a cracked solder or similar issue.
If something has been ripped out then look for hairline cracks in that area.

Tubes and Hybrids / Texas tone made simple
« on: October 24, 2019, 12:23:19 AM »
Hi all,
I've been messing with this for a few years so thought I'd show folks this simple trick.
If you are lucky enough to own an old BF Fender or similar Valve amp from that era this may help. This is unlikely to work with a lot of amplifiers made now days (both SS and Glass) but I have had some success with my all SS setup,,so some experimentation may be required to work with your particular SS setup.

The Video should be fairly clear for those who understand the basics of how tone is created.

Note the audio circuitry in my little camera compresses quite hard so you won't hear just how much the bass splatters when the trick is bypassed at high volume,
When engaged you will loose perceived power but the whole point of doing this is to get the amp running at full volume without the bass splattering, read clean headroom. 8|
With those old amps the bass is big and sounds full at low volume but the bass collapses with many of those old valve circuits if you try to get to full volume,
Even worse if you have overwound PU's. xP

So here is what just one small cap can do when used in the right place.
Keep in mind this is all done on the cheap,,So no Tx special pu's and the small amp is old valve radio junk.
the pu's in this guitar are 4k ceramic (read,, about as cheap a copy strat as you can buy)

Enjoy, Phil

The Newcomer's Forum / Re: I want to ask a question
« on: October 11, 2019, 07:23:27 PM »
There are likely quite a few small amps like yours that don't have short circuit protection on the output, so likely you have blown the output transistors.
Pull the chassis and take some pictures of the internals and some here might know how to fix the issue.

Amplifier Discussion / Re: Fender 85 tone help
« on: October 01, 2019, 07:54:06 AM »
A lot of those mid price range amps are often a hit and miss affair.
Often clean is ok and drive channel can be anything from a duck fart to a screeching cat but as for that smooth sweet OD you mention,,,well I've never found one that works for that sound.

You could just use the clean channel and go try some OD pedals,, and maybe an optical Compressor.
If I'm looking at the right schematic the second ch has an optical limiter which would likely help the compression effect you need to get the clean channel onto a sweeter OD. But that is major rewiring with no guarantee it will work.
I can post a simple Hi pass filter you could wireup as a test to see if it helps but the Amp must have a lot of bass for it to work well.
It's just 2 resistors and a cap in front of the input.

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