EASY class d amp / amp / cabsim modelling fiasco

[petey twofinger]

long rambling post from a not very bright person .

i realize there are very bright hard working folks out there who have done amazing things with technology in diy . this is not me . what i can say is that i have done alot of things and learned very little but i have imporoved the over all quality and come to some realiztions of what does not work so well , while taking the path of least resistance , or plug and play type applications rather then genuine diy or circuit design. i must stress how much of a hack i am now , to avoid further character assasination .

i have been blindly tinkering with class d amp boards and i thought perhaps this info may be useful to someone . this is not a modeling debate , or me claiming i am a tone god , to state or argue that class d is good , or better than tube amp . its a solution for me . i am not boasting . this is a report of my findings after years of tinkering with these cheap chinese amp boards.

first and foremost , of COURSE this is NOT a traditional guitar amp - its more of a powered speaker .
but the closest i got for a guitar amp idea i would recomend the following

tpa3116 mono 100 watt board, rog tonemender as preamp, 3 amp fuse , 9-24v dc supply , larger ga power input wire (short) same with the speaker wires .

https://tinyurl.com/vf32xkf

the tpa3116 boards will often sport a input attenuater , trimmer . i will desolder this,i like to snip them into three pieces with a side cutter first and remove individual pins . at that point i will cut in three wires and sub in a 100k a input vol pot.

tonemender in front , you end up with a "clean pedal platform" type amp , i have one of these built into an old computer vga (tan) switch box , with a chrome handle. this thing does well with pedals and with a modeler front end , it will run on what ever dc i throw at it between 9-24 .

my application is outdoor , which translates to "there is no ac power availible" .
this means i need a battery powered front end , no ac , so that means no pc , no anything that needs ac . i need a battery or dc powered preamp .

i choose a zoom g3(older one not the newer g3n) firmware TWO. of course this isnt going to be better than a tube amp . this is not a tone machine . it is loud it does the job , there is much variety in the sounds . programming your own patches via the software is a must . any decent amp modelling device will work , even an old rp50 is better than nothing but this is where we want to look for a better than average solution , ie the hotone ampero is new , mooers new suff looks interesting , and inddors with ac , get a helix/kemper/axe fx if you can affoard it . the other idea is using software bias/ amplitube / guitar rig , th3 etc .

points of interest

the mono 100 watt tpa3116 will run on a 9 v battery with no compromise in sound .

this didnt make sense to me when i read it , but thru testing i have found it to be oath truth inescapable . i i dont have a link so forgive my ineptitude ... when you "amp model" or cab sim , which is  what i chose as the more versatile and even better sounding choice than trying to turn a class d amp into a traditional guitar amp ... when you model a traditional amp/cab , you MUST have a full range speaker with proper tweeter to supply the high frequencys required to make amp cab modeling sound real .

Now to me this doesnt make sense , all the great guitar amps dont have tweeters so why need one to copy it? but ... after playing around , filming live performances and editing them , listening ,  then playing with adding tweeters then playing thru proper studio monitors / full range pa speakers i saw the light . its a fact . perhaps this is one of the reasons some guitar players HATE on digital . they bought the thing and plugged it into their amp/stack . ultimately what we play thru does not define us as musicians . yes these modelers have settings like "front combo , or stack input" but when you line in them and run them thru a porper full range set up this is where these deivces perform as they were designed to .

the typical face in the croud / joe or jane music consumer , well no one  ever thought to themselves " that turkey is MODELLING , dun dun DUN !!! or WOWEE  that guitar player is hot , i bet he rolls tubes" no one ever thought this , well besides another guitar player and unfortunately i feel this about what sums up what is going thru a lot of the less creative type players heads.

This "full range"  realization lead to me experimenting trying to add tweeters with a crossover to a proper 12 inch 8 ohm guitar speaker. I have to say yes this hackish solution works better WAY then no tweeter , depending on the choice of tweeter - perhaps you want to impliment a real compression horn , not piezo stuff. I feel ideally a full range speaker solution is the superiour choice for better tone performance - yes , for me this is the way to go , if you choose amp modeling for your front end .  it lacks the "amp in the room" sound, feel ? forget it , but you can add a pedal for some sag , and at the end of the day its more of a mastered album sound which mixes well in a trio format of bass drum guitar , using mastered mp3s of drum loops of course . i find it to be very workabble and not a compromise in the final product - hear for yourself below a short montage of several outdoor performaces thru this rig .

16 ohm speaker loads are not recomended for class d , this amp boards are lookin for 4-6 ohms or 8 , less power

https://tinyurl.com/rkwdlzj - untested but cheap

i have used recycled from lap top power pack li ion 18650 cells.ebay sells 3x carriages . 2 of those 3 x carriages wired to another pair gets me anough dc to play all day and into the night. so 3 18650 = 12 volts , two of these packs in series  gets me 24 , i make two sets of those 24 volt packs and wire them both in parallel to double my availible currant . forgive me i am not exactly fluent / a goof .

i got lucky on an ebike battery pack (usd500) used for 5 at a resale . this large li ion solution powers our new diy "powered mixer"

i have switched over to a 2.1 pa type speaker system , 2 8 inch mains with compression horns , and a bass bin , gk neop 2 10.

the powered mixer is a monoprice 12 volt 8 channel mini mixer on a chassis housing a 2.1 class d tpa3116(x4)  - a bridged pair @100 for the sub , and 50x2 for the mains . this board has mains tone/vol , sub freq/vol , maser vol. also a built in mp3 with pause play footswitch for triggering live drum loop mp3's . this sytem can be set up and torn down very quickly , we use 2x18650 packs for pedals , all in all this class d powered mixer solution - its over powered for our needs - and it will run thru a full day and JUST into the night with out loosing its edge.

i have to say it sounds better than anything else i have built going back to 2010 with a full band rig of class d stuff built into a bunch of individual cabinets of nothing smaller than 12's , dual 12 bass cabs , dual 15's 3 way pa speakers for the drum machine , 12/horns pair for keys , gaus 2148 pair for lead guitar, similar mono 12 for rythm guitar . so i was kind of thrilled this stripped down rig sounds better , than all that other mess , but the guitars and bass are using modelers so it makes sense to me . full range is the answer to making amp modeling sing . despite the manufacturers pretend its all good thru your amp , it isnt trust me .

yes i tried a lot of the smaller amp boards but at this point have chosen the 3116 stuff over-all value ,  the 7498 , the fancy sure brand stuff is great but i can not discern a huge difference.  paying 5 over 35-55 yass please .

often i would build booster circuits for the front end , they warn about over driving these but often if i was using headphone out type levels i found it was lacking and needed the boost , so you CAN push these amps but you have to watch it and dont get silly ... often a pair of npn smalley circuits for guitar , or even using "bass guitar eq harness" circuits from ebay worked very well for bass when outputting thru quieter devices of course . 

ebay sells full range stereo boost preamp boards very cheaply . finding stuff that will all run @ 24 volts is advantageous but voltage regs can be subbed in to pad out your voltages if needed be.

if you look for lm1036eq you can find some two and three band hi fi type eq circuits ready made to slap as a front end depending but for guitar the tonemender works very well imo . it just depends on the design requirements what one would wish to choose. i have found it very muych so worth it to go with a tonemender if its for giutar.

regaurdless of what i may have heard about the fragility of these boards we have lost one board and i was nto present , it happend at power up , i am cluelesss, but they seem very robust , and i have made quite a few of these untis over the years - i would have expected to loose more, as we also put them to great use , almost every weekend noon till dark all spring summer and fall.

i find these boards dependable and so affoardble i have been building an amp or two every year now , which i find very much more rewarding than pedals no offense and i still build pedals but ... i am thinking with this mini mixer rig  i am about set now .

hear the class d powered mixer full range outdoor rig -

https://www.youtube.com/watch?v=XL_JGwbHQrY

https://www.youtube.com/watch?v=o7-ygM1UhNM&t=17s - early 2019 tour of the outdoor rig - this is an older amp unit with a lesser stereo mixer out of a super 8 converter box lol ... hey it works !

https://www.youtube.com/watch?v=SHCVVU5ealw - fireside chat class d

https://www.youtube.com/watch?v=9PZinxE6RO0 - volvo amp

https://www.youtube.com/watch?v=JGDNr_t9Fv4 - class d slideshow

perhaps this could be helpful to someone considering to build an amp . i had nothing but bad luck with every other type of amp i attempted , but i never tried the tiny giant that looks great , but the lm386 stuff well  i was not a fan. the punch amp on the other hand is great aslo the stella amp for a kit isnt bad but i felt these are pea shooter amps , and i can often find this sort of thing "first act dual 9 volt type amps , in the sale papers for 10 usd or at a resale for 3-5 .

if the class d bug gets you let me know. it got me very hard .

the point of this is , the class d experience does not seem like a universal fit , but with a little coersion it can find its niche for non traditional applications and if you are into modelling , well i would twist your arm to dive in but dont forget the importance of that full range speaker idea. there are rockville 8 inch speakers with compression horns for 30 i am using one right now along with a DAS , and i cant hear the difference  .



100 watt mono w/ rog tonemender



gut shot




rg q/d tone gen and a 2x mixer but the rest = class d in those switch boxs



final photo is of a pair of monobloc 7.5 watt tube amps , relax ... everything is gonna be ok ... calm down

[PRR]

> you MUST have a full range speaker with proper tweeter to supply the high frequencys required to make amp cab modeling sound real .  Now to me this doesnt make sense

Speaker on amp F-5F6 has peaks at 2.5kHz and 4kHz, on F-5E1 3kHz and 4.5kHz, M-1899 2.7k and 5k, on MOD8 4k and 6k (just examples) with deep notches between the peaks. You can't get "the" sound of one amp's speaker on another speaker (without massive measurement and digital EQ). It is *much* simpler to use a "flat" speaker, much flatter than any single guitar speaker, which will reproduce the modeled peak/dip of the original speaker.

[petey twofinger]

not sure what you post means ?

again

my experience has shown me that using a full range speaker with my modeling devices gives me better tone  , clearer more realistic , than when NOT using a full range speaker , or even using a hacked 8 ohm guitar speaker with a crossover and a tweeter .

i noticed a handfull of thread where people where asking if folks had experience playing around with these boards .

i am saying in my experience what i found something to be better than something else  ... not my set up IS better than . if that makes sense .

perhaps my perception being that a percentage of guitar players have missed out on the higher performance availible to them on their disgaurded modelling devices is directly proportional to improper speaker implimentation is incorrect .

ultimately i will continue on my path as my life is a journey .

happy holidays , all the best to you and yours ,sincerely Pt2

[DIY Bass]

I think that Paul is basically getting all technical to agree with you.  He is saying that a particular guitar speaker will have it's own frequency response.  If you play a model of that speaker on a guitar amp with a different speaker and different response then it won't sound right.  You will do better with a full range system to use modelling.  That's what I get out of it anyway :-)

[Kipper4]

Good to have you back Petey.