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Old 9th Nov 2019, 9:46 am   #1
Alan's MagicEye
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Default Homebuilt Copy of Ampeg B15 Bass Amplifier

After seeing the excellent post recently about the homebuilt Fender Combo on the forum, I thought that I should put a link here to my home brew Ampeg B15 bass amplifier and speaker which I made some time ago.

YouTube link here:

https://youtu.be/Elnz8E32EY0

I wanted to recreate as near as possible, the original B15 and put in the various options, for example, solid state or valve rectification, fixed or cathode bias etc. as the B15 was made with these different options over the life of its production.

After a bit of research I found some details on the net of a build which met my spec. on an Australian website (CtG electronics)

Link here:

http://ctgelectronics.weebly.com/cus...-fcbn-51b.html

I used this with some modifications to the biassing arrangement which I felt did not work correctly on the schematic provided by CtG. I also added a hum balance pot to the design.

The transformers were ordered, custom wound from Majestic Transformers in Poole, UK.

I managed to get a 15 inch driver from a Hammond PR40 tone cabinet which I understand was the same driver as fitted to the early B15's from eBay for 30 which I thought was a good outcome.

I'm very pleased with the result and have used the Ampeg at a small local gig which I do regularly. It sounds equally good with electric bass and double bass and I have had positive comments about the amp so I'm quite pleased that the gamble of making a homemade copy has paid off.
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Old 9th Nov 2019, 9:56 am   #2
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

Beautiful work !

The screen printing is a very nice touch. Did you find that it worked first time or that there was a bit of trial and error before it turned out so well ? I sometimes get Leak valve hi-fi amps in for repair and most of them were screen printed. This makes restoring the paintwork all but impossible without sacrificing the original labelling. It would be nice to know whether or not reproducing the screen work would be practical.

Cheers,

GJ
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Old 9th Nov 2019, 10:06 am   #3
Alan's MagicEye
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

Thanks GJ

I had some trouble making the screen, the original screen which I purchased was pre-coated and was supposed to be suitable for exposure in sunlight but was a dismal failure. I then stripped the screen and brought a kit from Amazon

Link here: (Hope that this is okay with forum rules as it is hopefully relevant to your question)

https://www.amazon.co.uk/Speedball-D.../dp/B0007ZHGWI

I exposed the screen as per the instructions which came with the kit using a photo flood lamp with "pie tin" reflector. The result was very good.

As for the printing, I had several goes, but when the print was not good I simply wiped the paint off with a rag and had another go.

It would be a good thing to use on those old wonderful Leak amplifier chassis for restoration in my opinion.
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Old 9th Nov 2019, 10:07 am   #4
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

Outstanding work and attention to detail.

Andy.
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Old 9th Nov 2019, 10:23 am   #5
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

Thanks Andy

I'm glad that you liked it. It was quite a satisfying exercise, lots of different challenges to get the job done.....

Alan
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Old 9th Nov 2019, 10:36 am   #6
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

Quote:
Originally Posted by Alan's MagicEye View Post
... As for the printing, I had several goes, but when the print was not good I simply wiped the paint off with a rag and had another go ...
That's how I imagined it would be. Direct onto stainless I'm sure that works perfectly. I haven't checked the Leak paintwork closely, but I think it may be a three-layer process: base coat (bronze, or grey, or champagne) then screen print then (maybe) lacquer. I'm a bit concerned that wiping the screen print paint off the base coat without affecting the base coat at all could be tricky, especially if it has to be done several times. Doubtless it will depend on the finish on the base coat (gloss or matt) and how long it's been left to dry completely, maybe with a bake, before the screen printing is tried. Whether the screen paint (ink ?) is solvent-based or water-based might also matter.

Cheers,

GJ
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Old 9th Nov 2019, 10:58 am   #7
Alan's MagicEye
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

Hello GJ

Yes, the consideration of the wiping is probably an important one.

Perhaps if the base coats on the chassis were in cellulose and you used something like "Humbrol" for the lettering, which I think can be wiped off with white spirit, then I think the base coat should not be affected?

I restored an old Lorry some time back and I used polyurethane paint on the majority of the vehicle but black cellulose paint on the petrol tank so that it would not be damaged by petrol spills. I would guess that Leak probably also used cellulose as the original paint?

You could do a simple test on a sample before deciding which combination would work I suppose....

Alan
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Old 9th Nov 2019, 11:35 am   #8
Craig Sawyers
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

I had no idea that there were silk screen lettering kits - must find out more.

Craig

PS Stunning job on the Ampeg!
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Old 9th Nov 2019, 11:41 am   #9
GrimJosef
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

Print-making is quite a popular craft hobby, it seems, and expert groups can sometimes be found. I did wonder if contacting my local group would be a quicker way to get up the learning curve. They are primarily creative artists whereas my problem is strictly technical. But they do seem pretty well equipped https://www.oxfordprintmakers.co.uk/equipment.html. I wouldn't be surprised to find they had a good deal of expertise too.

Cheers,

GJ
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Old 9th Nov 2019, 12:00 pm   #10
Alan's MagicEye
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

Seems that GJ posted whilst I was typing my response, here it is anyway:

Hello Craig

Just to clarify in case you are unclear (apologies if you are clear ;-) the link to the silk screen kit in my earlier post is just for the photo emulsion and screen stripper for removing old emulsion.

The process is as follows:

Buy a screen which is suitable for the paint you wish to use, they come in different mesh sizes, from memory you need a smaller mesh for solvent paints than for the ink used for T shirts etc.

Obtain the emulsion kit and an emulsion applicator together with a squeegee (not sure if I spelt that correctly) which is a suitable size for the screen.

Mix and apply the emulsion to the screen in a low light environment using the applicator and allow to dry in the dark.

Make your artwork on a PC or Mac

Print (I use a laser printer) onto clear film, transparency media.

Lay the film on the screen and hold down with a sheet of clear glass and expose using a photo flood lamp, the instructions for this are in the emulsion kit.

Wash the screen to remove the unexposed areas where the artwork was and dry the screen.

Position on the job to be printed and squeegee the paint onto the surface of the job.


Hope this helps.....

Alan

Last edited by Alan's MagicEye; 9th Nov 2019 at 12:06 pm. Reason: Another post arrived whist I was typing
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Old 16th Jan 2020, 12:25 am   #11
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

Just found this post and I must say you've done a excellent job and gone to a huge amount of effort to give it a truly professional appearance.
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Old 16th Jan 2020, 9:03 am   #12
Alan's MagicEye
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

Hello Retailer

Thanks very much for your kind comments, it's nice to know that you liked the result. Yes it was an effort but I wanted it to be a close a replica as possible.

Alan
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Old 18th Jan 2020, 7:58 pm   #13
ColinTheAmpMan1
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

Beautiful piece of work, I have to say. I do have one reservation, though, and that is your rather naughty use of a genuine "Ampeg" logo. This might well be a better build than any real Ampeg, but it isn't actually one, is it?
Colin.
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Old 18th Jan 2020, 8:11 pm   #14
Alan's MagicEye
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

Hello Colin

Thanks for your compliment.

To allay your fears please follow this link:
https://www.dropbox.com/s/qsmxxu11ry..._1399.JPG?dl=0

The amp is solely for my use anyway not for sale at any point.

All the best

Alan
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Old 23rd Jan 2020, 5:01 pm   #15
ColinTheAmpMan1
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

Quote:
Originally Posted by Alan's MagicEye View Post
Hello Colin

Thanks for your compliment.

To allay your fears please follow this link:
https://www.dropbox.com/s/qsmxxu11ry..._1399.JPG?dl=0

The amp is solely for my use anyway not for sale at any point.

All the best

Alan
Ok Alan,

Fears allayed - not that they were actual fears. I have made a few "homebrew" guitar amps, too, but I tend to make my own nameplates using a piercing-saw and Formica. Instances are my 15-watter which I called an "Earp", using the Marshall icecream script because it is a sort-of Marshall (marshal?), a bigger head which I called a "Mega-Bluesy" because it looks a bit like a Mesa Boogie. I am currently slowly making a clone of a Fender Deluxe Reverb which I was going to make a logo for with "Fooldya" in as close to the Fender script as I could fashion. Then I found that Deluxe Reverbs didn't have a logo on the speaker-grille....

More power to your elbow.

Colin.
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Old 25th Jan 2020, 10:13 am   #16
Alan's MagicEye
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

Hello Colin

They sound great, (no pun intended). It would be good to see some photo's.....

I found one of the more problematic issues was getting the corect Tolex and Grille cloth. For the "Ampeg" (maybe following your lead I should have called it "Alpeg"?) I ended up using a Fender type Tolex as the Ampeg blue chequer Tolex was only available in large quantities. Did you find a good source for your supplies, or does it vary from project to project.

Making the logos is also a problem, your method of piercing saw and Formica sounds good. I was lucky making the Perspex, light up "Ampeg" badge which sits in front of the valve cage as I have the luxury of being given a pantograph copying mill, this makes it easy to make such things by copying off from a scaled up paper print. If you need more logo plates, PM me and I may be able to save you a considerable amount of time if the logo is complex but suitable for making by my method, I'm happy to do it gratis.

All the best

Alan
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Old 25th Jan 2020, 9:27 pm   #17
ColinTheAmpMan1
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

Quote:
Originally Posted by Alan's MagicEye View Post
Hello Colin

They sound great, (no pun intended). It would be good to see some photo's.....

I found one of the more problematic issues was getting the corect Tolex and Grille cloth. For the "Ampeg" (maybe following your lead I should have called it "Alpeg"?) I ended up using a Fender type Tolex as the Ampeg blue chequer Tolex was only available in large quantities. Did you find a good source for your supplies, or does it vary from project to project.

Making the logos is also a problem, your method of piercing saw and Formica sounds good. I was lucky making the Perspex, light up "Ampeg" badge which sits in front of the valve cage as I have the luxury of being given a pantograph copying mill, this makes it easy to make such things by copying off from a scaled up paper print. If you need more logo plates, PM me and I may be able to save you a considerable amount of time if the logo is complex but suitable for making by my method, I'm happy to do it gratis.

All the best

Alan
Alan,
Did you have a look at this source?

https://www.cedist.com/products/gril...=Brand%3DAmpeg

They don't just have Ampeg, but others, too. I also think that Weber amps (in the States, unfortunately) have some useful stuff, too:

https://www.tedweber.com/cabinet-covering

My "Earp" and "Mega-Bluesy" were fashioned from other chassis and I made the cabinets myself - they weren't really made to be so much copies as "inspired-bys". I intended to fashion the Fender Deluxe Reverb clone as cheaply as possible, but I decided it might be easier to buy some kit-type parts from Weber after I had a bit more cash to play with. That solved the problem of the cabinet, chassis and circuit-boards. I decided to make a few changes to the original Fender circuits, such as adding some extra controls to the reverb (Tone and Dwell), putting in a Middle control on the Vibrato channel and an overall Presence control. I also decided it might be a good idea to use separate cathode resistors and capacitors on the odd occasions where they had been commoned between the twin triodes.

I will try to take some photos when I can; the "Mega-Bluesy" head is easy to get at, but the "Earp" is rather jammed-in behind my keyboard stand. (I don't play keyboards at all well and to be quite honest, I haven't played guitar in months).

I am currently in the process of resurrecting my Vox AC30. Some years ago, I thought stupidly that it would benefit from having new components (1% metal film resistors - aargh!). Fortunately, I kept all of the old components, so if I take my time, I should be able to work out where the within-tolerance originals came from and those that are out-of-tolerance I will replace with good carbon-composition resistors and NOS or better modern capacitors. I am also planning eventually to install a top-boost circuit which will be reversible and have some refinements such as a Top-Boost/Non-Top-Boost switch and a switch to change the circuit with regard to the controversial Bass control earth connection. This will all involve making a new back-panel with the appropriate aperture for the Top-Boost controls without hacking the original about (you see, I've learned the error of my past ways).

Like you, I have no intention of selling any of my amps, but when I go to the big workshop in the sky, I don't want those who stand to benefit in my will to not get the maximum benefit from a good-as-new AC30.

Colin.
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Old 26th Jan 2020, 4:58 pm   #18
Alan's MagicEye
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Default Re: Homebuilt Copy of Ampeg B15 Bass Amplifier

Hello again Colin

Thanks very much for the links, I looked at the Weber one when I was considering the Ampeg build. You might want to take a look at the Solsound shop on EBay (hope that this is okay with the moderator, it should hopefully be as it is connected to the discussion...) https://www.ebay.co.uk/str/solsoundlimited
They do lots of nice bits and I have brought from there several times, I have no connection other than being a happy customer.

Repurposing chassis is a good idea, it would certainly save all the work of bending and drilling.

The Vox sounds like a gem, worth getting back to as near original as possible.


All the best

Alan
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