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Messages - phatt

Hi and welcome,
Q does the amp have an effects loop?
If so plug your guitar directly into the RETURN socket and if you can hear sound then

bridge the Send and Return with a short lead and if that resolves the issue then the switch in the return socket is faulty.
It's a very common problem.
Do that first then tell the outcome, if no go then we look deeper.
Well this site is not really setup to give a start up course on audio electronics,,
but try this site;
Scroll down to *Beginners' Luck*

Main page is here;

There is a so much info on this site I doubt I'll ever be able to read it all in one lifetime. ;)

Sorry but it's all in English. Phil.

I agree with Loudthud, Vero is not ideal, only use for very simple circuits with small part count.

Regarding home made PCB;
If you have a laser printer then this will open up some simple ways to make PCB's at home.
But Breadboard test the circuit before you make a pcb otherwise you will end up making landfill.
You will of course need to use a CAD program to print the Circuit.

There are likely many utube vids of guys showing how they do it.
Hi Koreth, Note; I'm not a qualified teck,
I just got sick of music shops exploiting my lack of knowledge so I started learning how audio gear works by reading lotsa books (long before computers and the net)
Now it sounds like you have a more in depth learning than myself.
Well I went deep trying to learn a lot of tecky stuff which sent me quite mad for a while.
But over time I started to come to understand a lot better by simplification and basic observation.

We all Ask why do Valve Amps have the magic mojo?
I came to understand a Valve power stage for *What it DOES*
rather than *How it Works*.

**It's a COMPRESSOR that distorts badly with big signals**
Most of the favored Valve amps of a bygone era were of very basic design.
My no 1 rule of thumb (Valve or SS);
If you want a great rock guitar amp, just build a crappy basic circuit.

Old OTx,s were cheap and suffered from all the quirks you likely already know about. Leo built to a budget so interleaved OT were out of the question.
(at least in the early days)
As the signal goes big the bandwidth gets truncated as they can't pass low freq well at high volume hence the classic flabby bass when cranked up.
The highs also get rolled off as well. This of course is exactly what you need for
Overdriven guitar Sound/Tone. Leaving plenty of bandwidth to cover the rather limited range of guitar. Some Tx spec sheets actually show this as a chart.
So by design cheap Tx's can't pass all the high freq hash which magically filter off all the nasty top end fizz. A simulation would likely show a lot of hifreq crud on the top edge of the signal at the plates of the power valve but vanishes on the secondary. Bingo a filter altering as signal goes big.

While in a SS power stage this does not happen hence they often got a bad wrap as being harsh. (a lot of those issues can be filtered out with smart design)

You have to spend a lot of money to get an OT to do a clean 20/20 hifi bandwidth.
Don't fool yourself into thinking Valve amps can't do hifi clean, they can be on par with even the best SS hifi rig. But OT will cost big money.

The compression in those classic guitar amps happens simply because of the often
**Overlooked soggy power supplies that were used**. It has a profound effect on the
outcome. plus Add in all of the other limitations and quirks you already know about.

A SS PSU is rigid while the old valve amps used high voltage supplies which were very soggy. So the moment you belted a big cranked power chord the HT drops like a brick and hence the compression effect.

Also don't forget the voltage drop from Screen grid to PI section. Just altering those voltage nodes along the supply paths can result in a very different performance.
I've tweaked a couple of later model Marshall's which use a 4k7 drop from screen to PI. Simply changing back to 18~22k makes them respond/sound much more like the older models.  This thickens up and tends to smooth out the crunch effect.
the PI stage then distorts before the power valves.

Unlike most compressor circuits whether they be builtin or in guitar pedal format may well compress but seldom do they distort an if they do it's often crappy.

One way I found to get a simple SS discrete power stage to do this magic trick;

Years back I scored a little 20 watt combo with a 10 inch speaker.
While trying to tweak it and draw out the circuit I had the mains running through a light bulb limiter. It finally sounded really good but the moment I removed the limiter bulb the magic was lost.
So I permanently installed a 40Watt light bulb into the chassis with a switch to bypass it. A 20watt bulb was too low and the sound just cracked up badly.

I have fond memories of playing along with some Clapton songs and impressed that my tone sounded very much like Clapton's tones.
Darn stupid of me to swap it for bigger amp, thinking I could do the same trick and get a bit of extra volume but alas it had a Chip power stage and the idea did not work.
Those power chips are too perfect for that to work, obviously it only seems to work with a discrete power stage.
Now I'm sure far greater minds than mine have come up with even better ways but That's  what I have come to understand after years of sending perfectly working transistors to smoke heaven.
I hope that helps, Phil.
If another house resolves the problem then time to call an electrician and get your house wiring checked for faults.
Hello Koreth,
I admire your conviction but are you aware this would Definitely takes years of R&D to perfect and in the end may not be any better than what is already available.

It would take years of bench testing to perfect,, I should know as I've worn out 6  breadboards (and counting) and sent many perfectly healthy transistors to smoke heaven in the last 30 plus years.

Regards the Tx output using discrete components is likely no better that using current Feedback which is very commonly used in a lot of Guitar amps now.

If you are chasing Tx output design ideas then find some of those Factory pa systems as a lot of those use Tx drive for line drive.
I have and old Inkel Pa with Tx output giving 4 or 8 Ohm as well as 70V and 100V out puts.
I used it a lot years back as it was 120W output driving a Quad box, gave me a massive sound.
Amplifier Discussion / Re: Orange 35RT humming/buzzing
February 27, 2023, 04:46:59 PM
Well obviously this is the price you pay for budget bedroom amps. :-X
These things are designed to a price not quality R&D. They just bump up the gain and tweak the EQ for the kids to get that crunch tone as that is the fashion now.

Q, Are you using high quality guitar cords?
When using these hi gain amps you definitely need the best cables.
Canare is one of the best but not cheap.
Another thing that may not be obvious, at home the buzz is nearly always annoying but in a band situation the music level is a lot louder and the Buzz is not so obvious, at least while you are playing.

As I mentioned last post, When you design a circuit and just use one stage to crank all the gain the result is noise. Which is most likely the issue in this Amplifier.

I Actually use a very basic keyboard amp with no fancy crunch circuits.
All my sound is derived by intelligent pedal circuits.
Even at bedroom level with all 3 distortion circuits engaged the noise is hardly noticed when not playing. May I say this took me years to workout exactly what was going on but glad I perceived.
Amplifier Discussion / Re: Orange 35RT humming/buzzing
February 24, 2023, 04:50:33 PM
Hey Joe,
Yes, possible but as these things are fairly recent, i.e. not 30 years old then likely they are Sw-mode.
I did find a couple of demos on the tube and I noted they do buzz on the high gain setting, as do a lot of budget amps.

I spent a long time trying to find ways around noise issues with hi gain circuitry. Sadly the market is flooded with Amps/Pedals that are badly designed and the novice is ever burdened with the dreaded noise issue.

Then they are told they need a noise gate,,so everything becomes a patchup job to overcome a design problem.
I can do drop D on my strat and crank the gain and play some suspect heavy metal riffs and although there is more hiss it's way way less than what these amps sound like.

I spread my Drive/Dist over 3 dirt circuits,, if you try to do that much gain with just one circuit then say hello to the dreaded noise issue.
Oh Tassie, yes it does conjure up a picture I guess. ;D
Mate I have trouble going from a fender to a Gibson as the different scale length just messes my brain something shocking.
And PRS scale length I'm get lost past the 7th fret.
So a Bass scale length is just way out of my ability.
As for drums you have to use hands and feet. ARRH!
My feet are too far away from my brain. ::)

I used to have a Lespaul copy for years but once I started playing Fenders I was able to expand my ability further up the fret board.
Because I tend to finger pick a fair bit
It's darn hard trying to play a 3 note triad past the 12th fret on a Gibson whereas on a fender it's so much easier and I'm able to do much more on the higher frets.
I know many players seem to have no trouble swapping scale lengths but my brain just grabs the wrong fret even if I'm looking at the fret board.
But I know my ability improved rapidly once I started using Fender Scale length.
Well This is about as easy as it gets you need 2 sockets one with a switch.
The return switch opens when you insert a lead. See pic.
You may be able to just lift the input end of that 10k resistor or you may have to cut a trace on the pcb and insert the loop there. Don't forget the ground back to the circuit board
You cannot view this attachment.
Amplifier Discussion / Re: Orange 35RT humming/buzzing
February 21, 2023, 01:54:40 AM
Yes if you turn down the volume on the guitar you are grounding the audio input and hence no noise.

These Smode supplies radiate hash out into the air and the high Z input of the Guitar audio circuit picks this up.
And yes ANYTHING that uses Smode supplies in the room/house such as computers and like can wreak havoc on your sound because they travel back through the wiring of the house as well as into the air.

With the old Copper and Iron transformers any noise was low freq hum. but unlike Smode they did not radiate very far into the surrounding space.

With a Transformer you just had to keep the power Tx away from the sensitive input when you designed the layout of the chassis and usually there was no big problem.
Welcome bardaro, :)
Best place is most likely between output of Volume and R131 (10k)
Amplifier Discussion / Re: Orange 35RT humming/buzzing
February 20, 2023, 06:06:50 PM
The buzz on the video is most likely switchmode power supply high frequency switching.
IF these Smode supplies are not well grounded then the hi Freq switching will bleed through into you audio circuitry.
Some are horrendously noisy if badly designed.

Just one thing you may not have tested is the power cord back to wall.
If the earth wire is faulty (Open circuit) then even the best designed Smode system will bleed through.
  Swap the cord for another and report back.

One other possible issue, your house wiring may not be up to standard.
Try another house, see if the issue resolves.
Amplifier Discussion / Re: 12w Marshall
January 27, 2023, 07:23:46 AM
Quote from here;

Under, The limitations of Class D
(near the bottom of page)

"Thirdly — not finally, but enough for now — a Class-D amplifier has a **relatively poor damping factor.** The damping factor is the ratio of the impedance of the loudspeaker to the output impedance of the amplifier (it's a little more complex than that, but let's not get bogged down with details). In simple terms, it's a measure of how well the amplifier can control the movement of the diaphragm of the loudspeaker. A good amplifier doesn't just give it a push and hope for the best; it senses where the diaphragm is from moment to moment and controls its position. To do that, a high damping factor is desirable, and, as mentioned above, a simple Class-D amplifier has a low damping factor."

I think of this much like a Valve Amp where the same power output is delivered to  4,8 or 16 ohm speakers partly because most Valve amps have *Low damping factor*.

So even if you drive an 8 ohm speaker from the 4 ohm tap the power is much the same but freq suffers a little.

Better minds may explain this better but there is obviously a connection.
Amplifier Discussion / Re: 12w Marshall
January 26, 2023, 06:29:02 AM
In answer to Guzzis3 previous Q, Class D  are a switching amplifiers which use a Pulse Width Modulation system.
 They switch so fast that very little heat is generated thanks to mosfet teck, so no need for big heat sinks. 

C0mplikated to ezplain but some info here might help;

The Hotone circuit tricks, after a little bit of analog at input the rest is most likely all done in the digital realm using IR's  (Google *Impulse Response* for clues on that)
Hence each one is programed with a different flavor. ALL the shape and grit is done in the digital chip while the D class output would run clean.

The one I liked most was the "Mojo Diamond" gives a good balance between clean and drive but I've only heard them on the tube.
I'd be waiting till they realise they can make a unit with 4 or more different modes in the one unit but the Diamond would work well with my existing pedal setup.
hope that helps, Phil.