Quote from: phatt on May 07, 2022, 06:37:30 PMYes open back delivers a more spatial sound hence fuller effect especially in small spaces but can present weird sonic issues in larger venues.
You may notice that a lot of big pro gigs tend to use closed back cabinets.

A player friend noticed this weird effect at an old wooden school gig where his open back rig was giving him a crossover of out of phase in the position he was limited to in the building. It can mess with your brain and the sonic result can be off putting.

That does not happen as much with a closed back cabinet.
Although it can still effect a closed back cab it is not as bad.
Venues with big Glass windows can have really bad reflections.
Phil.

I never really thought about it as I don't typically play out, but just at home.  That makes a lot of sense though.

Quote from: phatt on May 04, 2022, 08:26:15 PMFor me personally I tend to like Sealed Cabinets for single speaker combos.

Phil.

I was just talking about this with a co-worker.  I believe combos should be open-back, the way God intended.  Just kidding, though I am an open-back believer.

Quote from: FenderDeluxe112Plus on May 03, 2022, 03:57:37 PMThanks, will do. I do have an Mc1436 in my parts box from a supplier that I have bought good components from in the past. Can I test it in any way to check if it would be suitable?

Throw in a socket on the board and then try it.  If it works, you can leave it in the socket, if not, take it out :-)

Quote from: phatt on April 29, 2022, 02:23:11 AMJust turn the amp on and with a length of wire with alligator clips on the ends and just probe the Known ground points of the pcb and related ground points back to chassis.
**Just make darn sure you don't short power nodes back to ground.**
Use the schematic to verify test points and ground nodes.

If hum increases then you have created a ground loop.
If it reduces hum then you know there is a ground missing somewhere.

BTW the speaker Neg terminal is NOT Ground. This is a current feedback system and spk NEG is lifted from circuit common via that big 10 Watt resistor, R76.

You can visually work out the ground path but often not obvious.
Hence the wire probe can help define the problem.
Maybe post some circuit pictures and we might be able to help more?
Phil.

I'm with Phil on this one.  I actually have an old test lead from a dead multimeter than I connected an alligator clip to for this purpose - works great.

Quote from: FenderDeluxe112Plus on April 28, 2022, 11:45:12 AMI am reading around 24ohms resistance from cp4 to chassis ground.

What about from CP2 to chassis ground?

Quote from: phatt on April 24, 2022, 09:39:20 PMA scope may not help much if it's ground hum.
I'm assuming the amp is working and passing signal except for the hum?

Well as there is no ripple on the supply and voltages are within spec then the most likely issue is one of 2 possibilities.
1/ open ground connection somewhere.
If the star ground node of main supply is not connected back to chassis correctly then it can cause hum issues. (Which is the node between C47 & C48 or Conn CP4)
You can test simply by shorting the main Common back to chassis with a wire. If the hum stops then you found the issue,, if hum increases then you just created a ground loop,, which brings us to,, 2/ Something is grounded that should Not be grounded, which would cause a ground loop hum.
Ground plane issues can be a nightmare to track down.
sometimes in design phase one has to use an alligator clip to find the best ground path before committing to a layout.

Often components like input jacks, FX loops and speaker outputs,  even the PCB need to be *Isolated from chassis*
This will depend on how the circuit common was designed which is hardly ever noted on schematics.

Tiss easy to loose these little isolation washers or forget to reinstall them.

If you acquired this amp with issues then someone may have already worked on it and if small parts have been lost then you have no idea why it hums.

*I would be researching ground path issues long before replacing parts in hope.*

I got caught once, I did not notice an isolation washer dropped off a PCB post and the hum drove me nuts for a few days.
finally found it hiding in the chassis corner.
Phil.

Been there.  I did this on my Dean Markley amp years ago.  Took forever to figure it out!

Quote from: phatt on April 20, 2022, 11:16:12 PMThese are small practice amps and In My Experience a waste of time changing every cap that will likely not make any difference to the sound these cheap amps produce.
Re scratchy pots
I just spray the pot guts with RP7 or WD40 and unless the pots are totally stuffed they usually come back to life.
As example, I scored a home Hifi years ago that had a scratchy volume pot, a squirt of WD40 and still going fine, that was 10 years back.

Note; some tecks will frown on using RP7 or WD40 but Cricky it's a cheap guitar amp.

If you want the best pots then track down the conductive plastic units as they last much much longer.
Phil.

100% agree.  I use contact cleaner rather than WD-40 though lol.  And I like conductive plastic pots as well.

I'm sure someone will correct me if I'm wrong, but I've always only replaced electrolytics - and even then, only if they were causing an issue.

Quote from: Loudthud on April 12, 2022, 07:05:24 AM

Quote from: Enzo on April 11, 2022, 12:54:41 PMIt is like an electrical appliance in your home.  If double insulated, no need for earth.   Just my opinion.

All you need is a double insulated guitar and you're set. Without the safety ground, you can get hum and mild shocks when you touch microphones or other guitar players

I always fully ground my amps.  No reason not to, and plenty of reasons for it.

While they may be a little late to the game, Hughes and Kettner has released a new pedalboard amp - the StompMan.  Offering 50 watts of solid state power, it features two channels (normal and solo boost) as well as an effects loop with bypass footswitch.  Master, Sagging, Gain, Presence, Resonance, and Tone round out the 6 control settings on the front, with a solo volume control at the top.

Street price is $239 USD right now, with RRP being $199.

https://www.gearnews.com/hughes-kettner-stompman-for-those-who-want-a-light-50-watt-amplifier/

Boss has announced the release of the Katana 110 and 210 bass amplifiers.  The Katana 110 uses a single 10" speaker and 60 watts of power, while the 210 is two 10" speakers pushing a combined 160 watts of power.  Vintage, flat, and modern preamp settings along with four band EQ and tone switch allow for multiple tonal options.

MSRP is $399 USD for the Katana 110 (KTN110-B), and $649 USD for the Katana 210 (KTN-210B).

https://www.gearnews.com/boss-introduces-new-amps-for-bass-players-katana-110-and-katana-210-bass/

Apparently Josh Homme wasn't joking when he said that the Peavey Decade (inexpensive solid state practice amp from the 1980's) was "his secret weapon" for the Queen's of the Stone Age sound.  Ever since he announced this a year ago, people have been buying the old amps as well as trying to emulate the sound.  Now it's Acorn Amplifier's chance.  Their take on it is a pedal that doubles as a 10 watt pedal board amp.  They call it the Solid State.  Super original name, and super generic.  Solid state amps can (and do) sound like anything.  It'd be like a baker calling their new muffin the "Wheat".  It takes like it has wheat in it...

Acorn Amplifiers wants $299 USD for this, and who am I to judge?

https://www.guitarworld.com/news/acorn-amps-solid-state

Quote from: yeto on March 27, 2022, 09:29:16 AMThank you for taking time to reply. I understand this won't be a true reverb but I am hoping this will help to keep the audio from sounding so "dry". I am only looking for a "touch" of reverb-like effect.

Thank you for replying,
yeto

I think it may do what you are looking for. I found a few clips on YouTube of this board and it's actually pretty decent.  I put in an order for one myself so I can play with it too!

Honestly, it should be as simple as run the Uno circuit into the PT2399 board.  That said, most reverb units using PT2399 chips have three or more of them.  I've thought about building a basic reverb using a single PT2399 but haven't gotten there.  I'd be curious to hear how this one works out for you if you do it!

Quote from: pinkjimiphoton on March 24, 2022, 04:20:55 PMapparently admin has crippled my ability to upload files. sorry man. i'll try and upload them on diystomps or something.

i guess i did something wrong? wtf?

Nothing done wrong, we updated to SMF 2.1.1 and lost certain functionality.  I'm looking at this now.  Sorry for the trouble!