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Old 28th November 2012, 11:18 PM   #1
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Default Marshall 1959SLP build - Your opinion?

Hey everybody,
I built a couple of HiFi SE amps and I am now thinking about building a guitar amp for a buddy of mine. His dream would be to have something as close to a Marshall 1959SLP as possible.
I do have the schematics for the amp created 08/92, but nothing else, i.e. no parts list, component types, etc.

Am I on a path to failure even trying to replicate that schematic?
Has anyone successfully done something similar?

I have done a fair amount of research already, but haven't come up with a lot of details, or a good DIY success story on this specific amp schematic.

I'd appreciate your comments and opinions and I have no problems with candid language...

Thanks in advance for your time!
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Old 29th November 2012, 01:27 AM   #2
Enzo is offline Enzo  United States
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That is not all that simple an amp, up to you how involved a project you want to make. MANY people have built their own guitar amps, everything from the most basic Fender Champ, up to and including more complex amps than the one you propose. As with any project, many succeed and some do not.

Building from a schematic is about as minimal as it gets. You are on your own for everything. I will list some resources below. For example, you intend to make a chassis from sheet metal? There are various suppliers who sell ready made amp chassis for various models, and some generic chassis. These usually come with holes already drilled for tube sockets and controls and jacks and switches. SOme have silk screened panel legends, nice to have labels over the controls.

Parts list? Weell you start at one e3nd of the schematic and work towards the other, using a pen and pad of paper. Pretty soon you have a parts list.

Resistors and capacitors are generic. You may care to agonize over carbon film, metal film, carbon comp, whatever. But the amp will work with any. The internet will provide a zillion opinions on which are "better."

Good general suppliers like Mouser have many of the parts, but you may have better luck sourcing higher voltage caps and transformers at places selling specifically to guitar amp people.

Transformers will be a very important part. You can order actual Marshall transformers from any Marshall dealer or parts seller, but you can also buy aftermarket transformers sold as replacements or upgrades. You will not find them at Mouser, you will need to go to amp part places.

Many of the places that sell tubes also sell the other stuff, like caps and transformers. We tend to use certain pots as controls, but a 1 meg pot is a 1 meg pot, you could certainly build with any brand you prefer.

But you might also consider buying an amplifier kit. These come anywhere from complete kits including wooden head cab all the way down to nothing more than a kit of all the electronic components. The advantage of kits is that all the parts will be there. You will not get 2/3 through the project, slap your forehead and realize you forgot to order a fuse holder or power cord. SOme have good instructions, some do not.

Good general suppliers are places like Mouser and Digikey.

A good general guitar amp supplier is Antique Electronic Supply - AES. They sell tubes, sockets, transformers, caps, controls, most stuff.
Antique Electronic Supply LLC

Mojo sells parts and kits, and even cabs, check them out.
Amp Parts, Cabinets, Guitar, Bass, Pickups, Pedals - Mojotone.com

And the late Ted Weber's web site is still going strong, selling parts and kits, and well respected speakers too.
Weber Speakers - Making the world a bit louder each day.

I have no experience with them, but Angela also sells kits, chassis, parts
Angela Instruments Online Catalog - Home

Ceriatone makes kits and chassis, including some Marshall style ("British style") that might work for your project.
CeriaTone.Com - DIY Guitar Tube Amp


I would point out that building an amp is not a way to save money. Many people go into it thinking so, but...no. One does it for the satisfaction of making something themselves. Or you can value your labor at zero and make it sound less expensive.
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Old 29th November 2012, 04:21 AM   #3
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Default Thank you!

Thanks a lot for sharing your thoughts!
I haven't even started to think about chassis options yet, but I would probably try to find one of the pre-made ones for guitar amps available on the inter webs.
I am very familiar with Mouser, DigiKey, AES and a couple of other tube/iron suppliers, so the question of where to source wasn't weighing on me much. What I don't have much experience with is picking proper types of components, mostly related to non-electrolytic caps (i.e. ceramic/film/oil, required voltage ratings etc.). I am very comfortable with the remaining passive components. That's what I meant when I said 'parts list'; sorry for being unclear.

I do appreciate all the other guitar-amp specific resources you provided; thank you!!

I have found a large number of DIY stories for guitar amps. I am evaluating this specific one, because my buddy says that it is a match made in heaven (his words) for the pickup he has on his guitar. He knows nothing about building anything with wires, I know nothing about guitars, pickups or (unfortunately) how to use your own hands to make music (other than pushing buttons on CD players).

I will try to get an idea on what I could use for the iron and what it would all add up to. This is NOT an attempt to save money and I don't count my own time in the final bill, because - as you said - this is purely driven by the satisfaction of building something that might even work in the end. And by a strong desire to learn all the things I will undoubtedly learn if I decide to do it.

First of all, I need to fully decipher the CCT diagram. Most of it is clear, but there is some detail missing around the preamp tubes.

Again, thanks for your thoughtful response and for sharing what you know!!
Stefan
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Old 29th November 2012, 06:23 AM   #4
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Mouser actually does sell quite a few of the Hammond audio transformers, although I'm not sure how good a cross any of those will be in this case.

These guys sell Heyboer transformers in many standard and custom flavors and stock lots of other relevant parts too: Amp Parts, Cabinets, Guitar, Bass, Pickups, Pedals - Mojotone.com

Enzo already listed the vast majority of the other vendors I buy tube amp parts from, including Mojotone. If I were doing this I would procure (borrow, or even buy and resell) the amp I wanted to clone and take lots of pics and notes on specific components. Failing that, I'd try to make friends with a working tech with access to one.

Best of luck, sounds like a fun project.
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Old 29th November 2012, 10:22 AM   #5
Enzo is offline Enzo  United States
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Yes, you can get generic transformers from Mouser et al, I just meant they won't have "Marshall 100 watt OT" specifically.

FIlter caps voltage - consider about 500v for the B+ and make caps appropriate. As to film caps, always make them up to the highest power supply voltage, even if they don;t usually see it. With a 400v B+, the plate of some tube might be sitting at 200-250v, but if the tube is removed and the amp powered, then the ful 400v will sit on that plate pin, and any cap connected to that plate will see 400v. SO I generally use 630v caps for all interstage stuff.

I am not a cap snob. SOme guys came out of their mother's womb chanting "orange drops, orange drops, orange drops." I am happy with little Mallorys, but they will all work. I'd avoid ceramics for the most part. You can probably find a silver-mica for anywhere you might use a ceramic. The only ceramics I generally use might be little caps like brightness caps on a Fender, maybe the treble cap in the tone stack. Or little stability caps.

I'd say build it first, you can worry about ssubtle nuance later. I am much more concerned you have your wire dress right than the type of cap.
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Old 29th November 2012, 02:34 PM   #6
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Quote:
Originally Posted by Enzo View Post
Yes, you can get generic transformers from Mouser et al, I just meant they won't have "Marshall 100 watt OT" specifically.
Not with Marshall branding per se, but:

1750U Hammond Manufacturing | Mouser
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Old 29th November 2012, 06:12 PM   #7
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So does anyone make a good kit clone of your target?

I've been in and out of guitar amp building for a long time, but just re-discovering a whole new world of tube amp kits. So in many ways I'm a newbie myself. It really helps if you play guitar. This is science but also art. I'm still working on getting the science background and accumulating the retro tools like multiple VTVMs.

You can also investigate Edcor transformers. Quality and prices are good but I don't know whether they make what you want.

There's always Mercury Magnetics. They are way overpriced, and that really turns off many techs who appreciate value. Guitarists seem to be split on their opinions about MM. On the other hand, they make power & output transformers for many classic amps, and their transformers are specifically meant for guitar amps. A reputation as a premium product may lend more psychological credibility to your resultant product.

The concept of 'touch response' is critical and too much to discuss here in any depth. Some players want dynamic range as part of emotive expression. Other players require extreme compression, distorion, power supply sag, choke limits, tube compression, trnsformer saturation, to impart a type of 'technique correction' which causes each note, whether picked or rolled or swept or hammered or pull-off to sound approximately the same because the envelope and tone is from the amp rather than touch. But most players expect both; a clean dynamic sound up to a limit, then emotive compression and distortion beyond that limit, so that playing harder gives the same kind of emotional distortion as a voice, saxophone, stuck pig, trombone etc. Then there's the issue of controlling the tone of the distortion independenty from the tone of the clean signal. Pre-emphasis and post-de-empahsis allow you to control the tone of the distortion independently from the tone of the clean signal. For instance, it is common to provide an option to boost the treble very early in the signal path, then reduce the treble later, so that the clean guitar sound is relatively unaffected but the distortion that is generted between the pre-emphasis and de-emphasis has the most irritating treble smoothed out. Listen for the sound of additional harmonic complexity for chords or multiple notes versus single-note picking. Observe your customer playing and the adjsutments he/she makes, so you get some idea of what the guitarist is 'going for'. Lead players want a long decay "sustain'. Chord players may want the complex additional harmonics yet need more clear individual articualtion of eacn note. You're not designing an amp in making a clone, but there are things to consider and listen for, and many are extremely personal. A clone your friend can try, or a kit that gives predictable results, might be less risky.

Many people believe that limitations of the output transformer are critical to the exact nature of overdrive distortion; personally I don't really like that sound much and prefer the tubes or power supply be the limiting factor. It also depends on the bandwidth you require (not much for a Marshall). Power transformer limitations and power supply choke do affect compression and sustain envelope.

Building your own clone of a classic can be far cheaper than the inflated prices for collectibles. Getting your exact target is priceless. On the other hand, nowadays there are many companies making cheap clones of the real classics, but with prices competitive against each other. You have your choice of whether you tolerate printed circuits that sound great but are more difficult to modify, versus the cost reduction of large scale and cheap labor of an insertion machine. Sometimes the best buy is to shop for kits someone already built, as you can get good hardware and few competing bidders.

Clones are never perfect, and there's always different psychological reaction too. You may improve your chances of success if you buiild it to be more adjustable so you can 'tune' it to your customer's tastes afterward.

Good luck. Enzo has experience and good advice.

Last edited by cyclecamper; 29th November 2012 at 06:18 PM.
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Old 30th November 2012, 05:22 PM   #8
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Quote:
Originally Posted by cyclecamper View Post
Enzo has experience and good advice.
Absolutely. I don't do clones, just mods or my own designs.
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Old 30th November 2012, 10:24 PM   #9
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You might want to check out the Metroamp site:

MetroAmp, Amplifier Kits and Parts Online Store

Also check the forums there, as people have started threads looking for parts after George stopped selling kits.


And here:

ValveStorm



And please, take note of cyclecamper's comments. A tube guitar amp is a musical instrument. You're not trying to achieve measurable goals such as flat response and minimal distortion. If it was that simple, your friend wouldn't want a replica of a 40 year old amp, he'd want something new, and better. But there's no 'better' - it's like ice cream, and if someone wants gooey caramel, you can't sell them chocolate chips no matter how good the chocolate is. Plexi's are very gooey.

Last edited by Keriwena; 30th November 2012 at 10:36 PM.
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Old 1st December 2012, 01:46 PM   #10
Trout is offline Trout  United States
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Quote:
Originally Posted by Keriwena View Post
You might want to check out the Metroamp site:

MetroAmp, Amplifier Kits and Parts Online Store

Also check the forums there, as people have started threads looking for parts after George stopped selling kits.


And here:

ValveStorm



And please, take note of cyclecamper's comments. A tube guitar amp is a musical instrument. You're not trying to achieve measurable goals such as flat response and minimal distortion. If it was that simple, your friend wouldn't want a replica of a 40 year old amp, he'd want something new, and better. But there's no 'better' - it's like ice cream, and if someone wants gooey caramel, you can't sell them chocolate chips no matter how good the chocolate is. Plexi's are very gooey.

I have a couple original SLP's, I also have a later SL that I rebuilt to vintage spec with all metro parts. Honestly even though his kits are no longer available, the information & resources on that site are top notch. they will get you as close as it gets.
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