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Topics - mckayprod

Honey Amp / Thoughts on my new Honey Amp
July 28, 2021, 11:21:32 AM
I just built mine over the weekend, and I want to start by saying "thanks" for adding a project to all the conversations and information on the forum.  This is a good way to bring it all together and stimulate more discussion.

Next, stuff I like: Excellent board, quality components...real pro stuff and I appreciate that. The distortion sound is smoother than I expected, especially on the higher-gain end of the tone range. The tone control mellows out any fizziness which could be a problem depending on your guitar/headphones/speaker.

And, my criticisms: Too much distortion, and not enough volume with the gain turned down to the edge of breakup.  I'll modify it to the clean buffer preamp option one of these days. No power switch, but I can understand the omission, since this is supposed to be highly customizable. I have to pop the battery connectors to power down, but my enclosure choice makes that easy enough. Finally, what can you say about the lack of volume from a LM386 that hasn't been said before?  I'm running two 9v in series for +18-ish volts, and this is sufficient for headphones, but just.  I haven't tried a speaker yet.

That's my experience, and I look forward to more SSGuitar projects and discussions!
My Fender Champion 110 pops when I shut off the power switch.  I find the same problem, but louder, in the Frontman 15R we use as a bench amp in the guitar shop I work at.  I think the amps are pretty similar, so I think the same fix should work on both.  SO...what's the fix?  We used to cut switching noise by adding a cap across the contacts but I don't remember the value of the cap and I'm not sure the problem is the same (this was a remote switch for a broadcast turntable which was generating a spike that the preamp picked up).

Seems like this symptom is common with solid state amps.

Thanks for the ideas.
Amplifier Discussion / Discrete Op-amp module
May 29, 2017, 11:42:39 PM
OK, who wants to start the discussion on this baby?

I guess there are other similar modules out there.  This one sure is expensive, compared to the chips it replaces.  Besides bragging rights, what do we get for our money?
Tubes and Hybrids / Noisy pots
May 24, 2017, 12:54:41 AM
I've been working on an old Stromberg-Carlson PA amp hoping to get some tube mojo to drive with my (also in-progress) Elliot preamp.  When I get the PCB done, I think it'll be fine, but I've noticed that my guitar's volume controls are awfully noisy when I plug directly into the mic inputs. According to the schematic, the input preamp is a 12AX7, running grounded grid (nothin' fancy here) with a 4.7megohm grid resistor.  Somewhere in the back of my mind I remember seeing where too HIGH of an input impedance can give you that "scratchy pot" problem.  The problem is worse with my humbucker pickup guitar, better with my Tele-clone.  Am I mis-remembering something, or is there a problem with the amp I'm missing?  And, why would the input z make a difference?  I thought input impedance had more to do with frequency response by loading of the pickup.
Amplifier Discussion / Award Sessions "Blues Baby"
October 04, 2016, 02:02:06 AM
Just stumbled onto this british SS amp today.  Not sure what chip he uses for the final (TDAxxx, I think, can't confirm) but somewhere on the site he references TL072 opamps.  Quite a thoughtful design, IMO.  Anyone on the forum ever see or play through one?

Good reading on this site for design philosophy, etc.
Amplifier Discussion / Howe Audio 701 MA...Help?
July 09, 2016, 08:52:24 PM
I hope my pic attaches correctly, or I'm gonna look dumber than usual!  This is a monitor amplifier module from an old Howe Audio broadcast console we scrapped back in the '90s.  Couldn't be simpler, operationally, with balanced input (line level, probably), gain adjust, speaker out (not much power judging by the connector) and 40vac power input.  I think I'll play around with it, but documentation is nonexistent and I'd like to roughly figure out a schematic.  I can trace the wires, but can anyone identify the opamp or power transistors from the case markings?  Thanks in advance.
The Newcomer's Forum / ESD precautions
May 29, 2016, 12:56:43 PM
Not sure where this topic fits in the forum, but I haven't seen it addressed.  I wonder what static discharge precautions the experienced builders and techs are using in this field.  I notice all the semiconductors I buy come in ESD packaging, and my previous job in an ISO 9001 factory setting had all workers in conductive smocks with shoe straps, wrist straps, controlled humidity, the whole deal.  They told us even passive components could be fried or weakened by ESD.  So, to prevent that kind of damage in my own shop, I use a grounded soldering iron and a wrist strap attached to the ground screw on the mains outlet.  Pretty minimal, but better than nothing.  I'd hate to toast a fancy opamp.  Thoughts?
The Newcomer's Forum / Simple low power amp
May 27, 2016, 11:35:14 PM
This guy is a hoot.  Add a decent preamp to this (and maybe a zobel network) and I bet it'll work well for a low-power application.  Discrete components, easily adjustable sensitivity.  For some reason I can't copy & paste a link to this exact page, but go to, then to the "Projects" tab then the "AF/Amps circuits". then "4-w AF amp".  Sadly, he doesn't have a board to sell us but the artwork is there.  Thanks, Harry!
I am nobody's amp designer, so I'm drawn to existing amps that I can tweak into my own devious plans.  First question:  I've been looking at Rod Elliot's P27 amp, and the power amp seems pretty well-respected on this forum.  I'd like to build a lower-power version, so what's the simplest/best way to accomplish that?  If I reduce the supply voltage from +/- 35v to something like +/- 20v, would the amp still operate, but at lower power (and less stress on the transistors, less heat...)?  I don't mean to be too specific about the design; I understand this is a pretty straightforward (representative?) topology.  Does this approach work with SS power amps generally, or am I missing something important?  Second question:  how do I calculate some of the changes that would follow from this?  How much power change could I expect from a given voltage change?  How much less heatsink can I get away with?  Would different transistors be needed and how do I spec them?  Thanks for any help anyone can offer, and I'll be searching the forum to see if anyone else has looked into this.
Amplifier Discussion / speaker substitution
August 17, 2015, 03:01:40 PM
I'm working on a friend's Marshall AVT50 combo.  2 main problems: The speaker is bad (a Celestion G12-412 AVT, 4 ohm), and the cooling fan bearings are shot and it makes a lot of noise. My 2-pronged solution was to swap in a random 8-ohm 12-inch driver from an old organ, and disconnect the fan.  The speaker sounds surprisingly good.  My question is, with the new 8-ohm load, the power output from the chip drops from 50 watts to 25-ish, right?  That also reduces the heat it dissipates, and maybe makes the fan unnecessary, right?  Did I miss anything?