Building Marshall clone from scratch

Tube or solid-state, this section goes to eleven!
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slashfan
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Post by slashfan »

Hello Guys, I am new to this forum. Before proceeding to the subject let me tell you somethings about me that you should keep in mind before replying (as much as possible). I am an 18 years old boy living in the South Asian country of India, fancy DIY amp kits are not available in our country and shipping them from other countries make them 70% more expensive.

Now coming to the topic, I am super new to the topic of building amps. The sound I wish to achieve is most probably of a Marshall 1959 SLP with the AFD mod as I really love the tone of Slash's guitar in Welcome To The Jungle. But besides building the real amp which is a 100 watt head, I need same tone or close to it in a 5-10 watt range. If anyone wants to help this poor boy get his tones please post the schematic diagram of the amp along with a whole list of important parts like number/type of tube, output transformer name and wattage and all the other important things. One last thing... lol... just tell me everything as simply as you can.. I am not an expert in electronics...

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lolbou
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Post by lolbou »

Hi and welcome!
slashfan wrote:I am super new to the topic of building amps
Wow, building a 100W marshall as a first build is a big step! Maybe too big I'm afraid... Sorta like William Tell, but with an AK-47.

Building it from brand new kit is dangerous if you don't know what's going on inside. There are lethal voltages in a tube amp so I would not recommend doing it for starters...

Obviously trying to make it from scratch requires much more knowledge...

Aren't there any oldies amplifiers you could start from in India?
- Are you a mod or a rocker?
- Uh, no, I'm a mocker.

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Post by fuzzfiend »

This might get you close without risking electrocution... http://revolutiondeux.blogspot.com/2012 ... d.html?m=1

Then all you'll need is any decent 5 to 10 watt amp. Hope this helps.
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Post by deltafred »

fuzzfiend wrote:This might get you close without risking electrocution... http://revolutiondeux.blogspot.com/2012 ... d.html?m=1

Then all you'll need is any decent 5 to 10 watt amp. Hope this helps.
As a first project this would be a far more sensible approach.

A 5 or 10w tube amp usually has less HT voltage than a 100w, but still enough to be lethal if you get careless (and unlucky).
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Post by slashfan »

Thanks for those replies!!! #lolbou i m not building a 100 watt marshall clone... im just saying i want to build the same type of amp giving me the same sort of sounds but in a small 5-10 watt version...

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Post by phatt »

If you want to go the easy road? These are very popular
Yamaha THR10



There are 2 models aimed at Rock and Metal, both are editable via usb and free software.
It's not my thing but will give a whole lot of options, far more than you could get from DIY analog amp build.
Phil.

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Post by slashfan »

yeah... i know these are great sounding... but i wanna get into the amp making business and this wud be a starting point... anyways.. the yamaha is a digital amp... it sounds good but it doesn't has the tone i want... neways thnks..

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Post by Zozobra »

For low cost and power you could look at building something with a dual triode push-pull power amp such the JTM-1, which uses a 12AU7 for about 1W output. If you want a bit more power you could look at using the JJ ECC99 which can squeeze around 4W of output (see Doug Hammonds dragonfly).

You are going to need to get a few difficult to source parts to build this, namely a suitable output transformer. If you can source Hammond transformers locally you're in business, otherwise you're looking a importing. For low powered amps there are ways to use coupled small mains transformers to get a heater and B+ supply but I'm reluctant to disclose them if you don't know what you're doing with high voltage stuff as they'll still give you a very nasty zap.

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Post by Scruffie »

Zozobra wrote:For low cost and power you could look at building something with a dual triode push-pull power amp such the JTM-1, which uses a 12AU7 for about 1W output. If you want a bit more power you could look at using the JJ ECC99 which can squeeze around 4W of output (see Doug Hammonds dragonfly).

You are going to need to get a few difficult to source parts to build this, namely a suitable output transformer. If you can source Hammond transformers locally you're in business, otherwise you're looking a importing. For low powered amps there are ways to use coupled small mains transformers to get a heater and B+ supply but I'm reluctant to disclose them if you don't know what you're doing with high voltage stuff as they'll still give you a very nasty zap.
An SMPS can power an amp that small, no mains power involved that way, just a 12V DC supply. Still dangerous at 220V+ but much lower current.

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Post by okgb »

Do allot of research without posting and you'll start to see common themes and direction
and then have a better informed decision, good luck

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Post by Zozobra »

Scruffie wrote:
Zozobra wrote:For low cost and power you could look at building something with a dual triode push-pull power amp such the JTM-1, which uses a 12AU7 for about 1W output. If you want a bit more power you could look at using the JJ ECC99 which can squeeze around 4W of output (see Doug Hammonds dragonfly).

You are going to need to get a few difficult to source parts to build this, namely a suitable output transformer. If you can source Hammond transformers locally you're in business, otherwise you're looking a importing. For low powered amps there are ways to use coupled small mains transformers to get a heater and B+ supply but I'm reluctant to disclose them if you don't know what you're doing with high voltage stuff as they'll still give you a very nasty zap.
An SMPS can power an amp that small, no mains power involved that way, just a 12V DC supply. Still dangerous at 220V+ but much lower current.
Interesting. Boost converter/inverter?

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Post by Dr Tony Balls »

FWIW.....it sounds like you want to build a small amp anyway, so this may be moot, but in general dont let anyone tell you that you cant build a full sized amp as your first build. A 50W Marshall was my first amp build. They arent complex amps at all and the voltages on a Champ are just as nasty.

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Post by Ice-9 »

slashfan wrote:yeah... i know these are great sounding... but i wanna get into the amp making business and this wud be a starting point... anyways.. the yamaha is a digital amp... it sounds good but it doesn't has the tone i want... neways thnks..
Are you saying you want to get into the amp building business in a sense you want to sell the amps you make ? If so, you need to know more about how to make high voltage equipment that isn't going to kill anyone. This is not a criticism of what you are doing but a general thing you should know about first.
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?

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Post by ivan H »

Hi, I would like to say, first learn about the safety measures you need to work on valve amps. Then, as long as you put those into practice, of course you can achieve your goal. I have built a fifty watt version of the amp you are talking about (SIR #36 mod) & can tell you where to find the information you need. This modification to a Marshall superlead came about as a result of trying to recreate the "Tim Caswell SIR #39 mod from memory of seeing inside it, & IMHO the #39 mod sound better (my amp now has it, & the #39+ relay switchable) & will still get you there tonally. You need to go to the Metroamp forum & in the Marshall amps section there is a 690+ page long thread entitled "SIR 100 watt superlead." Somewhere around page 140 you will find a basic "ballpark" scematic, layout etc, BUT, much later in the thread there is a couple of accurate scematics for Tim Caswell' #39. Use that as your pre amp starting point. Read the whole thread, you will find a lot of good tweaking info buried in amongst it (& a lot of shite, bickering etc etc). Now for your power amp I suggest building it around the ECC99 twin triode rather than a 12AU7, more power & much better low end response (I've built a practise amp using one). And the guys that said that even a little amp like this will contain lethal voltages are VERY RIGHT, so your first step is learning those safety precautions needed to work on valve amps. While you're doing that, research your upcoming project. Hope this helps. Cheers

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Post by slashfan »

Thank You guys.... i m doin my bit of research daily and have learnt a lot the fast few weeks about tube amps, how it works and how to work safely around tubes and especially the filter cap... dont know that much so as to start my first build but still learning... regarding the topic i have some very basic doubts tht i cant find in any forums or videos.. so if u feel comfy.. can i PM u regarding those doubts???

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Post by Ice-9 »

slashfan wrote:Thank You guys.... i m doin my bit of research daily and have learnt a lot the fast few weeks about tube amps, how it works and how to work safely around tubes and especially the filter cap... dont know that much so as to start my first build but still learning... regarding the topic i have some very basic doubts tht i cant find in any forums or videos.. so if u feel comfy.. can i PM u regarding those doubts???
I think you would be best posting your doubts and questions rather than PM.
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?

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Post by ivan H »

Yes, you'd be best off posting. I would like ask, do you know roughly what the #39 or #36 modification consists of?? I would also like to point out that the power amp, speaker cabinets, speakers & studio production are all part of the tone you hear on appetite for destruction (not just the pre amp & NFB loop that are encompassed in the mod.) Even the actual #36 amp used by slash sounded different in the room to what is heard on the album. Add to that you will be using a much different power amp/speaker combination (no one knows what speakers he used, except that he used a "1960B" cab). So you will need to do a LOT of tweaking if you're chasing his exact tone. I wasn't after his tone, just the Marshall on steroids tone, (which the #39 circuit nails). I'm not trying to discourage you, but many people have shown you can get really close to his album tone by pushing an amp with overdriver & eq pedals. For bedroom playing I'd go with that & then, if you really want, build a 50 or 100 watt version that will do it properly. Cheers

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Post by slashfan »

Okay so i was reading about the amp slash used on AFD... and came across a video in which slash said himself that he used a #36 modded (frank levi) jcm 800...in the original #39 mod which was done by caswell the amp was a super tremolo 1959 plexi... in which caswell took the rarely used 12ax7 intended for tremolo and modded it to add an additional gain stage... since the amp was already lent to another guy at that time... frank levi came in and replicated a new amp to the #39 spec... which was given to slash... now it gets wierd as an employee of S.I.R told tht the amp used for replication was a non tremolo plexi... as opposed to slash saying it was a jcm 800....so for now i decided to do a clone of a jcm 800 combo.. nd later if required i ll do the mod...

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Post by ivan H »

Slash used #39 (an in demand amp by big name players) in rehearsalls for AFD & specified it for the recording sessions, however George Lynch had rented it for part of the under lock & key tour, so Glenn Buckley & Levi, who was the replacement tech when Casswell left, decided to "recreate" #39 into another amp from Levi's memory of looking inside #39 to see what made it so special. This is how the difference between the two (circuit wise) came about. Levi added a cathode bypass cap that wasn't in this original version of #39, though it is switchable in later variants. 39 also had better transformers than 36. Caswell has posted on several internet forums & there is a schematic, Levi hasn't (its not his mod). Many have speculated that Levi modded the SIR#34 amp that slash later used though Caswell confirmed that John Rymas of SIR had loaned slash his stage one modded amp (34). This is modded for extra gain & revoiced without using an extra gain stage. Oh, they had to drill the chassis on 36 to add another 12AX7. Only one triode is used as a second cold biased stage. This is fed HT from the node at the cathode follower (must be decoupled), with this stage in parallel with the rest of the pre amp. The rest of the pre amp is converted to a MV (2203) type pre. The voltage divider preceeding the added stage is 470k/470pf/270k (270k to ground). NFB resistor is changed to 27k, as in the super trem. A hot shield is used on the input. Later 39's mod's done by Caswell have an 0.0022uf plate load bypass on the added stage. People building 36's experiment with smaller values (220 - 470pf) on the 1st, 2nd & sometimes 3rd stage's. There ya go. Cheers

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Post by slashfan »

Ok!! I still don't get 70% of the stuff written above, I'm still learning. Okay, now my doubts. Try to answer simply. Still a newbie here.
1) Are there different sockets for different types of tubes? If yes then which ones have common sockets?
2) I have a schematic diagram of a JCM 800 combo which is a 50 watter. How can I re-design the circuit to make it around 20 watts?
3) What are gain stages.
4) What function does a choke do?
5) What does the amount of gain depend upon?
6) How can I choose a proper output/matching transformer?
7) Does the number of output tube have anything to do with the amount of gain, because the SL 5C has only 1 output tube and still delivers lots of gain.
8) What dies biasing an amp do? What is cold bias?

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