Author Topic: DIY tube amplifier workshop in Gauteng - October 2019  (Read 2080 times)

Offline Mars

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DIY tube amplifier workshop in Gauteng - October 2019
« on: August 13, 2019, 12:29:27 PM »
Hi All

We have decided to move the DIY workshop on to 18, 19 and 20 October. Anyone who is interested are welcome.

If you need a kit to build, let us know your needs. Kits are available at www.marsamps.co.za and we also do custom orders for your dream project.

If the kit you want is either not listed, or you would rather have a different kit/price range let us know, and we work out a solution.

Otherwise you can bring own project and work on it in the company of very able gentlemen who will help you every step of the way.

The workshop costs R1200 per day (or R2400 for the two day venture when you build a 18watt guitar amplifier or 70 watt hifi amplifier)

You'll need to bring your own soldering iron and basic tools.

We will supply a table, chair and power point + expert technical assistance.

PM for more information, or reply to this post.

Soldar en!
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Offline Mars

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Re: DIY tube amplifier workshop in Gauteng - October 2019
« Reply #1 on: August 30, 2019, 09:07:13 AM »
There has been requests for cheaper kits for the workshop.

Here I am looking at kit options that would be more affordable, and still deliver good sound. So feel free to share your impressions and/or needs.

Since the biggest cost is the transformers, push-pull kits give more bang for the buck. Single Ended kits like big iron and a big choke to boot.

Of the push-pull amps, you basically have the the following options:

1) EL84 push-pull (the cheapest is the ST35 style single preamp tube per channel)
2) 6V6GT push-pull with 6SL7 driver/phase inverter
3) EL34 push-pull
4) 6L6GC push-pull
5) any other tubes? FU32 push-pull?

Looking at cheapest output transformer options we have:

RS audio transformers:

6.6kΩ, 10W Push-Pull Output Transformer for Valve Amplifier
RS stock no. 123-7240 Mfr. Part No. D29A09F Manufacturer OEP

This could be used in an EL84 or 6V6GT amplifier: price + shipping = R1000



and

5.6kΩ: 4 Ω/8 Ω/16 Ω, 25W Output Transformer for EL34
RS stock no. 123-7237 Mfr. Part No. V78A01F Manufacturer OEP

This could be used in an EL34 or 6L6GC amplifier: price + shipping = R1500



Power transformers:

Most economical option is SWIFT toroidals A.F.A.I.K.  - I am getting quotes and will post.

I can also get quotes from SJ Andrews and other suppliers.

Point to point, or PCB assembly?

I see quite a few pcb's on offer for the amplifiers on our list. Would anyone prefer a PCB type kit? It seems to raise the kit price marginally, but assembly is relatively fool proof (really?) There we even have options of unpopulated and populated pcb's.

Comments will be appreciated.


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Offline Mars

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Re: DIY tube amplifier workshop in Gauteng - October 2019
« Reply #2 on: August 30, 2019, 04:48:13 PM »
Next in line is the popular Mars Kit 1 Mk 2

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Offline Mars

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Re: DIY tube amplifier workshop in Gauteng - October 2019
« Reply #3 on: August 30, 2019, 04:49:27 PM »
EL84PP

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Offline Mars

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Re: DIY tube amplifier workshop in Gauteng - October 2019
« Reply #4 on: August 30, 2019, 04:52:19 PM »
Mars 5-10 stereo

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Offline Mars

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Re: DIY tube amplifier workshop in Gauteng - October 2019
« Reply #5 on: August 30, 2019, 04:54:14 PM »
If you prefer KT88 - try the Companion

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Offline Mars

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Re: DIY tube amplifier workshop in Gauteng - October 2019
« Reply #6 on: August 30, 2019, 04:56:06 PM »
If you want fixed bias and premium parts, then build the Performer:

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Offline Mars

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Re: DIY tube amplifier workshop in Gauteng - October 2019
« Reply #7 on: August 30, 2019, 05:05:14 PM »
Guitar amplifiers

5 watt Tweed Champ clone



18 watt British style with plexi channel (or tremolo option)



or USA Tweed Deluxe

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Offline Family_Dog

Re: DIY tube amplifier workshop in Gauteng - October 2019
« Reply #8 on: August 30, 2019, 07:27:32 PM »
As a suggestion, an affordable, but nonetheless excellent, beginner's amp will be the Mars 5-10, which will present superb audio reproduction at a reasonable price and will drive many speakers without any problems.


-F_D



-Eric

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Offline Mars

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Re: DIY tube amplifier workshop in Gauteng - October 2019
« Reply #9 on: September 04, 2019, 12:26:42 PM »
I realised that there may some people wanting to do a Single Ended amplifier? Since the wiring is less complicated than the other kits, this might be an attractive option for the workshop.

SET, DHT, 2A3, 300B or KT88/KT90 take your pick. PM me for pricing.

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Offline Mars

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Re: DIY tube amplifier workshop in Gauteng - October 2019
« Reply #10 on: September 05, 2019, 11:13:15 AM »
Update: We have two participants for the workshop. Two more seats left. If you want to secure your participation PM me.
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Offline fredeb

Re: DIY tube amplifier workshop in Gauteng - October 2019
« Reply #11 on: September 05, 2019, 07:11:10 PM »
I realised that there may some people wanting to do a Single Ended amplifier? Since the wiring is less complicated than the other kits, this might be an attractive option for the workshop.

Other than being less complicated than the other kits , Single Ended amplifiers also offer a more refined sound compared to Push-Pull amplifiers which offer higher power . Single Ended amps are more likely to be paired with high efficiency loudspeakers .
...evolution is the gradual development and stratification of progressive series of wholes, stretching from the inorganic beginnings to the highest level of spiritual creation.
Jan Smuts

Offline Qualityten

Re: DIY tube amplifier workshop in Gauteng - October 2019
« Reply #12 on: September 09, 2019, 12:46:15 AM »
I can recommend the 6k6 transformer from RS Components for EL84 builds. The SA price is cheaper than in the UK.

For participants wanting to learn how Amos is irk, i would also recommend point to point construction. It helps beginners to see exactly what is connected to what. This aids circuit understanding and makes repairs easier.

Offline Mars

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Re: DIY tube amplifier workshop in Gauteng - October 2019
« Reply #13 on: September 09, 2019, 11:56:38 AM »
Following on the different kits available:

Here you can see the inside of a Kit 2 Mk 2



And this is a SE88:



And this is the Mullard 5-10 stereo:

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Offline Mars

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Re: DIY tube amplifier workshop in Gauteng - October 2019
« Reply #14 on: September 19, 2019, 12:51:18 PM »
UPDATE:

It is just under a month till the workshop. Anyone still wanting to be included should PM me a.s.a.p.


If all goes well there will be a Tube T-shirt for all attending.

Venue tentatively in Randburg at Wheelwell. I took a few photos of the venue.






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