Most of these things use a regulated SMPS so they can come pretty close to doubling power with half the load impedance.

Those power specs are, should we say .... too optimistic?

No way they can put out 30 Watts into 16 ohm and 60W into 8 ohms.
Not at just clipping that is.

This is what Texas Instruments say about TPA3118 ... they should know:

With a 24V supply, 60W into 4 ohm, around 33W into 8 ohm
That, at 1% distortion which is *just* clipping and the proper way to rate RMS.

The 10% distortion spec actually means a quite clipped signal.

No spec for 16 ohm but it should be about half the 8 ohm rating, some 18 W at clipping.

The video tests it with a puny 12V supply

Best case some 14-15W into 8 ohm, not even near the 30W claimed.

Oh well.

Captured the TI datasheet Power vs. Supply Voltage but found I can´t actually paste it gere.

Tomorrow will find some image site and link it here.

Quote from: DavesNotHere on February 03, 2025, 01:49:34 PMHi, newcomer here. I've got a Fender Frontman that I'm upgrading. I replaced the reverb tank and am replacing a bad pot next. While looking up other mods, I saw that replacing the op amps is popular for upgrading the sound and reducing the noise floor, so I'm planning to do this using the NE5532 op amp. I'm pretty experienced with microelectronics, and have done a lot of wiring on guitars and other micro projects, but this is my first time working on an amp. I've seen the process for desoldering and replacing the stock op amps, it looks pretty straightforward, but I've also heard there can be problems with messing up the board, etc. I'm pretty confident in my skills but don't want to brick my amp. What tips or other advice do you have for me? Is this as straightforward as it looks, or should I just leave it alone?

thanks,
-Dave

Might I suggest rather than swapping opamps, you figure out sticking a "master volume" pot somewhere around u3b or u4a. I know at least one guy successfully put an fx loop right after u3b.

That little amp is ridiculously loud, and the reality is you're probably playing it at like 1, in a quiet environment, and the idle noise is bothersome in that setting.

You could easily knock off a few db with a master volume, that would lower the noise floor to where it's barely noticeable. It would still have plenty of power set like that, and if you wanted full power, just turn the master up all the way. In that kind of setting (jamming with others), the stock noise floor would be barely noticeable.

My 2 cents... Anyway... maybe someone can chime in with the best place to put it. Here's the schematic.

Mooer has released their new rechargeable amplifier, the Mooer Hornet 15w Li.  This amplifier features a 6.5" guitar speaker, 15w RMS of power, and a 4,000mah li-ion rechargeable battery.  This amp features 9 preamp models, 5 effects, 3 band EQ, bluetooth input connectivity, and headphone jack as well as an onboard tuner.

Currently these are selling for $109 USD at various online retailers.

https://www.gearnews.com/mooer-hornet-15w-li/

Lichtlaerm has released it's new pedalboard amp - PandorA.  Providing 30 watts at 16 ohms, and a claimed impressive 60 watts at 8 ohms, the PandorA features simple level, depth, and presence controls.  This is meant to be fed by an equalizer, preamp, or "amp in a box" pedal, or from a lineout on another amplifier.  Pretty great tones to be had here, mostly because rather than just a simple "flat" amplifier, they have adjusted the input impedance and EQ curve to match quality analog guitar gear.  Great job guys!

MSRP is 199 british GDP, or $219 USD.

https://www.gearnews.com/lichtlaerm-audio-pandora/

At the very least, if you are going to pull the stock IC, I highly recommend putting in a socket so you can swap ICs and play with different ones to see in real time if it changes anything and by what degree.

ICs you could try:

TL072
OPA2604
LM4562

Quote from: kellanphil on February 10, 2025, 08:50:20 PMI have OneOdio A70 fusion headphones and I plugged it into my amp and sounds coming out of both the headphones and amp? Both the amp and headphones were gifted so maybe I just need to get better, not so cheap headphones/amp but I'm hoping maybe it's just the settings or something.

The headphones wouldn't be at fault here, but rather what you were plugging it into.  What is the make and model of amplifier you are plugging into?  If you don't know, pictures can help us sort this out.

I fixed it.


The main issue was the MT3608 DC-DC boost converter I was using. I think it was inducing high frequency oscillation into the circuit. Subbing it for an XL6009 solved it.
I also isolated the input jack from the panel because I think it was causing a ground loop with the output jack.

That appears to be derived from an old (now) RCA circuit. Note the transistor types 40xxx all RCA type numbers.

Quote from: Bandito on February 14, 2025, 04:41:04 PMExcellent! I am East Devon, UK. Done the cleaning. The Amp works but sounds weak and different on channels 1/2 compared to 3/4.

It should.
Channels 3-4 are Instrument (Guitar/Bass) level so  more sensitive, 1-2 are high impedance Line level, think a Grammophone with a crystal/ceramic pickup, a radio tuner or tape recorder output, etc.
Any modern pedalboard would work fine there.

If you want to convert 1-2 to 3-4 specs, replace current 1M pots and 1M mixing resistors with 50k pots and 47k rtesistors, look at inputs in the schematic kindly provided by G1

QuoteHas 3 sockets for speakers.  1 and 2 (straight parallel connection) work, but the slave (3) does not.

1 and 2 are regular speaker outs, 8 ohm impedance *total* so 16 ohm each if using both.



The 3rd one, clearly marked Slave, is NOT a speaker out but a Line out, meant to drive an extra power amp with its own speakers.

Old school design, not surprising in an early 70s amp.

QuoteIs this a "good" amp, worthy of investment?

You should ask your Financial Manager for that.

In my book, for a Musician, Amps (and Instruments and any Musical stuff) are either useful, good sounding, etc. or not.

I reserve the word "investment" for Tesla stock, gold, Bitcoin and similar stuff.

FWIW that amp is quite old style but very well made, working fine (except for some "cleaning" issues, of course) for 50 years now.