Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Amplifier Discussion => Topic started by: Tassieviking on July 22, 2022, 01:39:40 PM

Title: 12w Marshall
Post by: Tassieviking on July 22, 2022, 01:39:40 PM
I started to looking into building a 12 watt Marshall by mixing all the 12watt Preamp circuits I found, and also mixing the 12 watt and a 30 watt amp circuit in Marshall amps so I could make any one of the 12 watt amps with 12 to 30 watts output on the same PCB. You just had to pick the right components to make the version you wanted.
Some 12 watt amps had a Bias pot and some did not. Mk1 preamp has diode clipping and the later ones dont, etc.

I got derailed when my dad got sick, traveled from Tassie to northern NSW (Australia) and spent 4 weeks with him. Had to go back to Tassie for medical reasons and be with my family for a week, then back as dad passed away as soon as I left, stayed 5 weeks then back home for Doctor visit and now I am going back up to pack what I want to keep and sell the rest, sell houses, cars,  etc.
I am going to sort all my stuff nice and neat when I get a chance because its hell trying to go through your parents stuff when they are both gone and everything is all over the place.

Anyway, this is as far as I got on a 12 watt amp before the wheels fell off.
I was going to post the KiCad files  of the PCB when I finished and still might when or if I get back to it. I put a jumper on the board if reverb is not wanted, and a place for effects to be inserted which can be bridged if not wanted.
I made the PCB so TO3 transistors had to be wired in or TO247 can be used on PCB.


Title: Re: Re: Adafruit PAM8302 Amplifer
Post by: Jazz P Bass on July 30, 2022, 12:41:30 PM
Nice work!
Title: Re: 12w Marshall
Post by: joecool85 on August 08, 2022, 08:51:11 AM
Great work!  I split the topic though and made this it's own so it can be an easy resource for others later.
Title: Re: 12w Marshall
Post by: Tassieviking on September 05, 2022, 10:49:37 AM
I have finally gotten back home a week ago and had some time to  work on this PCB, I can't guarantee it's correct but I will order some PCB's for myself later this year to test.

I decided to squeeze in a 9V regulator for pedals as its a smaller amp and is good for practice and learning on, and it cant hurt to be able to run a pedal or two from the amp.

I have made the Gerber files for JLCPCB to make the boards, but feel free to use the project any way you want.
I am going to use the KiCad schematic to make a pedal eventually as well, without the reverb circuit (unless I can get the correct mini spring pan).
Title: Re: 12w Marshall
Post by: Tassieviking on September 05, 2022, 10:51:44 AM
If you want to see the pictures larger, right click on the small picture and select open in new window, this makes the picture really large.
Title: Re: 12w Marshall
Post by: joecool85 on September 06, 2022, 03:55:30 PM
If I could like this more than once, I would!  Please share results when you get a chance to build it.  I'd love to hear it play too!
Title: Re: 12w Marshall
Post by: Tassieviking on November 10, 2022, 04:38:11 AM
Slowly making progress, I got some PCB's made so I can test make some.
I ordered the PCB's from JLCPCB and picked the cheapest shipping, I have too many other things going on so I was in no hurry to start.
They got to me faster then I thought so now I have to get some components I don't have on hand.

I also found a circuit for the 12 watt Bass amp so I modded the PCB so that can be build as well as all the other 12 watt Marshall circuits I found.Marhall 12 watt PCB's .jpg

I made a PCB for a front panel as well, I always wanted to try that out.

I also got some Sound Lab L4 Bass pre-amp PCB's made for an experiment, I don't know if they will work or not but I added one  LM13700 chip instead of a CA3080 and a CA3094 as original. I am to lazy to breadboard the whole pre-amp to try it out because it is so bloody big.
 
Title: Re: 12w Marshall
Post by: joecool85 on November 10, 2022, 07:23:40 PM
Quote from: Tassieviking on November 10, 2022, 04:38:11 AMSlowly making progress, I got some PCB's made so I can test make some.
I ordered the PCB's from JLCPCB and picked the cheapest shipping, I have too many other things going on so I was in no hurry to start.
They got to me faster then I thought so now I have to get some components I don't have on hand.

I also found a circuit for the 12 watt Bass amp so I modded the PCB so that can be build as well as all the other 12 watt Marshall circuits I found.Marhall 12 watt PCB's .jpg

I made a PCB for a front panel as well, I always wanted to try that out.

I also got some Sound Lab L4 Bass pre-amp PCB's made for an experiment, I don't know if they will work or not but I added one  LM13700 chip instead of a CA3080 and a CA3094 as original. I am to lazy to breadboard the whole pre-amp to try it out because it is so bloody big.
 

Awesome! Stoked to see this come together!
Title: Re: 12w Marshall
Post by: phatt on November 11, 2022, 09:47:39 PM
Brilliant work TassieV,
Can I ask how much this has cost you so far?
Of course one would still have to add the cost of a Chassis and a Cab for a complete build.
Phil.
Title: Re: 12w Marshall
Post by: Tassieviking on November 12, 2022, 09:30:27 AM
I'm not sure how much this one cost.
10 off 12 watt PCB's  US$ 11.40
10 off 12 W front facia PCB's US$ 18.60
5 off Lab Series L4 PCB's US$ 8.00
Shipping cost US$ 23.10

I have most of the components, but I had to order some pots and transistors for them.
I also bought a toroidal transformer for the Marshall 12 watt, 30V CT 50VA.


Title: Re: 12w Marshall
Post by: joecool85 on November 12, 2022, 09:20:47 PM
Quote from: Tassieviking on November 12, 2022, 09:30:27 AMI'm not sure how much this one cost.
10 off 12 watt PCB's  US$ 11.40
10 off 12 W front facia PCB's US$ 18.60
5 off Lab Series L4 PCB's US$ 8.00
Shipping cost US$ 23.10

I have most of the components, but I had to order some pots and transistors for them.
I also bought a toroidal transformer for the Marshall 12 watt, 30V CT 50VA.




+1 for the toroidal!
Title: Re: 12w Marshall
Post by: Tassieviking on December 24, 2022, 04:10:41 AM
The 50VA Toroidal I had ordered lasted 1 minute before the primary went O/C, I went to a local shop and grabbed a 20VA 30V CT transformer yesterday and tried again, all seems good so far.
I tried it with the 12 watt reverb circuit and mostly ok, when I tap the box I get reverb noise even with reverb pot on zero, possibly feedback through the final OP amp ?
Anyway, it sounded good through a Celestion V-type 70watt speaker I had on hand.
I built this one using 2N3904, 2N3906, TIP142 and TIP147 transistors in the power amp.
I borrowed the reverb from a Marshall G15RCD someone gave me earlier in the year, not the correct reverb tank but close enough for trying out.
At least it worked first time so I'm happy.
Now I just have to get some ply and make a cab for it, and a speaker and reverb tank.
I am also making a 12watt Bass version at the moment so I will have to see how that goes, I might have to modify it as I think the Bass version has some HP filters that are a bit too high for my liking.
I might make the cabs slightly larger then original because the original Bass cab was open back the same size as the lead cabs.
I might make the bass cab a lot deeper but the same front size as the lead and reverb cabs I am going to make for these.
Here is the Gerber file I sent to JLCPCB to make the PCB's, and the latest revision of the BOM.
I have noticed one fault with the BOM already, C24 on the 30W Bass 5503 list should be 220nF and not 22nF.
The schematic is a combination of all the 12watt schematics I found, and the power amp section is a mix of all the 12 and 30 watt schematics I found.
Just use the right combination of components and it should be ok.
Title: Re: 12w Marshall
Post by: guzzis3 on January 18, 2023, 09:05:19 PM
Hi,

If you had to order extra PCBs that you want to sell I'd be very happy to buy them from you. I am in Brisbane,

This is my first post to this forum. I was pointed to this thread by a person on the marshall forum. I've been building electronic stuff since I was a kid but while I have built quite a few valve guitar amps I've not built a SS one.

I have the complication that I had 2 strokes in 2020 and am now part blind. The part of my brain that processes the written word was also damaged so I can barely read. I don't mention this looking for sympathy. I just need to explain sometimes I can't read things and sometimes it takes me a long time to get to things, so your patience is much appreciated.

I have a 8008 marshall power amp, 80w a side into 4 ohms. I could build a stereo preamp and run it into that or build a stereo amp including output stage. Have you determined if the 5005 etc develop their distortion in the preamp, power section or both ?

I realise you haven't finished your design, and there may be problems, but starting even with a flawed PCB is probably easier than laying it out on tag strips or breadboard.

Thank you for reading.
Title: Re: 12w Marshall
Post by: Dino Boreanaz on January 19, 2023, 01:14:07 PM
Hey guzzis3, I'm glad you made it over here!  Lots of amazing, knowledgeable, and helpful people here.  Enjoy!
Title: Re: 12w Marshall
Post by: Tassieviking on January 19, 2023, 08:34:25 PM
G'day guzzis3, welcome to the forum.
I often drop in on the Marshall forum as well.
I don't own a Marshall, but one day....
I can't afford one on a disability pension.
I sent you a PM for your mailing information.
Well se what happens next time I go into town.
Title: Re: 12w Marshall
Post by: joecool85 on January 20, 2023, 11:37:36 AM
I'm super excited to hear this playing!
Title: Re: 12w Marshall
Post by: phatt on January 20, 2023, 08:05:38 PM
Quote from: guzzis3 on January 18, 2023, 09:05:19 PMHi,

If you had to order extra PCBs that you want to sell I'd be very happy to buy them from you. I am in Brisbane,

This is my first post to this forum. I was pointed to this thread by a person on the marshall forum. I've been building electronic stuff since I was a kid but while I have built quite a few valve guitar amps I've not built a SS one.

 Have you determined if the 5005 etc develop their distortion in the preamp, power section or both ?

I realise you haven't finished your design, and there may be problems, but starting even with a flawed PCB is probably easier than laying it out on tag strips or breadboard.

Thank you for reading.
Hello Guzz, just note on SS rigs,
Most do not respond to power stage distortion, some rare ones try to do that but likely not as convincing as a full Valve powerstage.

With SS Amps all the dirt, grit, compression and like attributes of Valve amps needs to be done in the preamp stages.

My main rig is just a basic SS amp and all the magic is done with my pedal board. Most of the pedals are my own design, some of my schematics are posted on this site.

40 plus years back I wanted to build an amp that did it all in one rig.
Took me many years to realize that I was just building land fill.
I now  have draws full of failed ideas (other wise called spare parts 8) )
I have built both Glass and Sand designs and although I like Valves there many benefits to SS designs.

If you are lucky enough to find an amplifier (Glass or Sand) that works for you then lucky you, sadly more often than not you'll spend a fortune trying to find it.

BTW I'm up the road in Morayfield if you want to make contact I'm happy to help with my years of researching. Just pm me for my phone number.
Phil.
Title: Re: 12w Marshall
Post by: guzzis3 on January 20, 2023, 10:01:58 PM
Thank you for the replies.

Morayfield! Goodness it's a small world. I'm at Mt Crosby.

Yes I now unfortunately am on the pension. Humiliating but I'd run out of options. The blindness is one of several problems.

I found your thread on the 100W models also. I assume all these generate clipping in the preamp and you can dial it in at different volumes ? Maybe I'll build one of those instead. I have developed an interest in stereo setups though. Some of the effects sound a lot better on 2 channels. I could hang on to the 8008 and build a preamp to feed it. Another option.

A PCB would be helpful though. I've built on..tag strips ? before. I forget what they are called. When you get a lot of components that can get messy. Building a pair of preamps though should be manageable.

Limited component availability is disappointing.

I'm not looking for distortion, just an amp with terrible frequency response :D I've got a Boss GT8 and of course if I want a singing sound I've any number of valve amps to play with.

I have grabbed an 8020 and VS15 at very good prices but it's surprising how disappointing both are. The VS15 oddly seems to be the nicer clean amp. The 8020 need a bit of help. Reverb seems not to work and I suspect other problems. Perhaps there is a mouse living in there.

I have a plexi marshall major. Bought it when I was young and dumb. There was a super lead, lead and major second hand. The lead and major were the same money, the super lead was out of my price range. It would have been better had I bought the lead but I figured if I couldn't be good I'd be loud :D Oh to be young again.
Title: Re: 12w Marshall
Post by: phatt on January 21, 2023, 07:29:07 AM
Hey Guzz,
I assume when you say *Terrible Freq response and then Boss GT8 in the next sentence* then you are maybe chasing the old sweet magic of limited bandwidth valve gear.
This can be done with SS gear but you have to in a different manner than you do with Valves.
Phil.
Title: Re: 12w Marshall
Post by: guzzis3 on January 22, 2023, 12:33:51 AM
I have several valve amps. I've built quite a few over the years but people keep talking me into selling them, then I have to build more. Blessed bother.

These last some years I have had many occasions when I have maybe 1/2 hour or something for a quick practise. I am reluctant to use valves for this. I have a limited stock of old valves and when they are gone I will be condemned to the modern market of overpriced NOS or awful new valves.

So I went looking for an alternative. SS is the obvious answer. It needn't distort but I would like something "nice.

I bought a Vox Pathfinder 10, too bright. Marshall VS15 (UK) nicer but still a bit glassy. 8020 despite the 10" speaker is ok but not great. It also needs repairs. Reverb does not work and I suspect there may be more amiss.

I got a Hotone Boogie Siva which arrived the other day. I've ordered a second. VERY nice clean amp. No distortion but it sounds like a clean valve amp. Into a 2x2x12. I'm quite shocked.

Also as a result of my gumtree ad a chap in SA has contacted me about swapping my 8008 for his 8200. The bi chorus has some issues (seems common among the valvestates). We shall see what comes of this.

Not sure what I am going to do with the valvestate combos. The hotones will do me just fine. I am quite surprised at how nice it is. Perhapse if the price of the purple wind or the vox copy (can't remember the name) come down I'll get some of them. At $140 though they are a bit rich for me atm.
Title: Re: 12w Marshall
Post by: phatt on January 22, 2023, 01:32:36 AM
Go here for real in depth insight into guitar amp tones.
The end will likely make you wonder why no one ever researched this before.
I've been quietly babbling on about this for years but this chap pretty much puts it all together well.

I'm not a marshall fan mainly because they only have one trick and the tone controls are pathetic. (though I'm sure many will argue) lol

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


I use an old Laney Keyboard amp which is super clean.
Everything else is done with my pedal circuits, half of those are my own designs

I can produce Hank clean all the way to ZZ top at the press of a button or 2.
If you have built amp/pedal circuits then it will not be hard to work out how it's done when you see the end of the video  8)

The game of guitar tone is in understanding the frequency range the guitar needs. most gear today has insanely wide bandwidth and it totally destroys your tone (Especially for hard driven OD tones).
You have to dramatically limit the bandwidth for rock guitar sounds otherwise it's just one clangorous mush of eFd up noise.
which is why I steer clear of all in one pedal like Boss GT's as they have way too much hi freq crud and tonal adjustment is limited.
Go build some pedals and save a fortune and your back ,,,winky Phil
Title: Re: 12w Marshall
Post by: guzzis3 on January 22, 2023, 07:32:20 PM
I have invaded this thread and it's drifted way off topic. If you really want to continue this line of discussion please start a new thread.

I will just make one more comment though. I can build a valve amp in a few hours. I've never built a copy valve marshall. I avoid complicated preamps, I've never really used the tone knob on the guitar let alone preamps on an amp. Volume is all I need. I just wanted a nice clean amp for quick practice not a deluxe rig. I've been quite surprised at how hard this has been. 3 practice amps, all very ordinary. I have ordered a second hotone boogie siva. I don't know what they did with that but it sounds very nice and at $72 delivered it's cheap enough. It will do.

It still might be interesting though to build a stereo Lead 12/30 or whatever and see what can be had from that into 2x2x12 speakers.

It is afterall just a bit of fun :)
Title: Re: 12w Marshall
Post by: phatt on January 23, 2023, 06:21:47 AM
All good, Just throwing in some observations from my experience sorry if you think it's off topic.
Phil.
Title: Re: 12w Marshall
Post by: Tassieviking on January 23, 2023, 10:13:33 AM
Guzzis3, where are you getting the Hotone Boogie Siva for $72 from ?
I might be interested at that price.

I am not worried if this topic has drifted a tiny bit of topic, and I started it.
As long as I find out new things I'm happy.

I am especially happy now since I have found out about the Hotone Nano series.

Michael.  :)
Title: Re: 12w Marshall
Post by: guzzis3 on January 23, 2023, 07:50:19 PM
Ebay. The seller is in Australia and the power supply is correct. It's very clean, no distortion at all but I think it must have some shape to the response curve, probably drop off at low and high like a valve amp. $71 and some cents.

Getting into ambiguous terms. I don't have a spectrum analyzer so I can't be precise, but it sounds a bit warm or creamy or something, not cold and precise like say a hifi amp with the impedance fixed to accept a guitar in. By comparison the 2 valvestates and the vox pathfinder sounded "glassy" clean with a lot of top end. I usually like bright amps but they are just too much. It doesn't help that I don't understand the knobs..

https://www.ebay.com.au/itm/354057429136?epid=11018833546&hash=item526f77a090:g:egsAAOSwBetduoCR&amdata=enc%3AAQAHAAAA4HKJlVQx7uUaNQIt8AGhA7TBtNdUv29YBnUT9FCBwOVqBppfGQy5AjCNyFU3tVj5WSZIjNTOvKjRG16ctokT6mXr2G6JJYqrPMrm%2BjxLhitv0gmNxP9c9s40xNj9v8M7R14Q%2BFIL3zgdtiZ57NQJOHf%2BNzP3%2FkbFtzOdQ5RGinp69nIe4DA4uxUc%2F2ObpdIW3W7KCGtpwrtdOaHSXWN9w5e4XNt3KPCneqVlmbxPb2%2BpfH6OibzvQ9wMxMTQt%2Fbri7su7LyhJfiY48p0wPAGRpTMaOifYe9K18VqcRU3duHA%7Ctkp%3ABFBM8I3Lk7xh

There are lots of clips on ewtube but they seem to exaggerate the distortion. For want of a better reference it sounds like a really nice fender clean.

Well if we are drifting off topic I have a question if I may. The amp says "class D". I don't know what that means. Normally a SS amp is less loud into 16 ohms than 8 then 4. This seems not to be the case. I am running it into a 4x12 (8 ohms) wired as 2x2x12 at 16 ohms. Plug in one and flat out it's about right for practice. Plug in both pairs in parallel it should be seeing 8 ohms but there is no discernible increase in volume. I don't understand this. The speakers are chinese celestions.

As I say I've a second coming. With the GT8 and the 2x2x12 it should give some pleasant stereo chorus etc sounds if I want to play with that.

Title: Re: 12w Marshall
Post by: Tassieviking on January 24, 2023, 12:17:06 PM
Guzzies3, have you considered trying to build some of BajaMans Pre-Amp pedals from https://www.freestompboxes.org ?
Some of those can work well in front of an amp I believe.
He has made Amp sims for several different amps as well as speaker sims etc.
They all have vero board layouts for them.
I made up some of them as PCB's but I havent had time to make any yet.

As far as hijacking a thread goes, I don't think Joecool85 minds it happening, at least I hope he doesn't.
As long as it is in a friendly manner and it keeps this site as a friendly forum where like-minded people can have a chat and share ideas and stuff.

Michael


Title: Re: 12w Marshall
Post by: phatt on 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;
https://www.howtogeek.com/792135/what-is-a-class-d-amplifier-and-what-are-they-useful-for/

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.
Title: Re: 12w Marshall
Post by: joecool85 on January 26, 2023, 10:14:17 AM
I don't mind as long as the topic goes back to the original - I'm very excited about this 12w Marshall!

The Hotone Nano's sound neat, but I also have only heard them on the Tube.  Any time more good-sounding SS gear is out there, it's a good thing.  It gets people to play, and with modern gear.
Title: Re: 12w Marshall
Post by: guzzis3 on January 26, 2023, 07:02:30 PM
Thank you phatt. Does this trickery explain why it's as loud into 16 ohms as 8 ? I just assumed that as you loaded the outpput of the transistors it's decrease power ?

I wasn't interested in distortion, I just wanted something for practise. If I wanted singing distortion in a SS amp I'd build a Lead 12. (see what I did there?)

Hotone have built a floor mount amp with 2 of the models built in. The one I would buy is the Britwind which combines a plexi and AC30 in a 70W package, but they are far too expensive for what they are..

https://www.ebay.com.au/itm/234080413858?epid=3049063806&hash=item368047a8a2:g:nTkAAOSw1T1cAAcz&amdata=enc%3AAQAHAAAAoDwDsL5qWEAqWy%2BJFDrTazBfqLcnXCktk7k87uz%2F9%2BJbxkVpC0AAWRsGFyqkVRuk217VbCghjYJx3D6PJnC%2FNGj%2FK0rzT6OaziCXKqVpurB7aMFa4r4K9vL%2BTe5nXWDvpv4rL2v%2FwEn1uDpgaD8KEiRj%2B1Lpvyb%2FAXgcGmAJcIadN1ETjwXdkk3xshg1%2Ba4kdV2iKERXGTQJ2CX96CN494c%3D%7Ctkp%3ABk9SR9Crroi-YQ

As I say I can knock together a valve amp in some hours mostly from stuff I have laying around, but that was never the problem I was trying to solve.

Anyway have fun!
Title: Re: 12w Marshall
Post by: phatt on January 27, 2023, 07:23:46 AM
Quote from here;
https://www.soundonsound.com/techniques/what-class-d-amplification

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.
Phil.