18 watt kit or DIY?

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rattatattat
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18 watt kit or DIY?

Post by rattatattat »

Hi all, very long time since I have posted. Read more books visited other forums and built some amps in that time.

I became interested in 18watt again after seeing a Doug and Pat show episode on the original and the reissue, and most recently watch Colin’s video of his 18watt.

Great player and great sound too read the notes great story. And read the post on this forum “who is Colin”. I’m keen to build an 18watt!

One thing is that I live Australian and most kits are US as far as I understand. Not sure that an eBay special will be any better than me finding parts from electronic shops or other amps rebuilds locally either.

I have collected enough donor parts including Bell & Howell projectors, 60s 6GW8 push-pull radiograms etc to make a junkbox amp that sounds good but might not look pretty amp.

With all the collective experience here, what do you suggest?

Thanks
Rattatattat
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JMPGuitars
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Re: 18 watt kit or DIY?

Post by JMPGuitars »

Kits are useful for beginners that have access to them.*

Your best bet is to look in the downloads section, and decide which build version you want to make. Then source the parts yourself. (feel free to ask about build types/versions)

A word of warning: carbon comp resistors are noisy, and only beneficial on the PI plates. That means 2 of them out of the whole amp. Many kits use carbon comps because that was popular a million years ago. Carbon Film are better than carbon comps. Good metal film are better than that (but people will argue about this).

Personally I've been using CMF Industrial Metal Film resistors, along with those 2 carbon comps on the PI plates. I have not noticed any tone loss compared to the other types. I'll be posting a demo of a few amps with those resistors soon.

No matter what you use, the 1M resistor on the input jacks should be metal film.

Get good quality capacitors. Brand hype isn't important.

Thanks,
Josh
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Re: 18 watt kit or DIY?

Post by zaphod_phil »

rattatattat wrote:
Fri 05/01/20 8:05 am
I have collected enough donor parts including Bell & Howell projectors, 60s 6GW8 push-pull radiograms etc to make a junkbox amp that sounds good but might not look pretty amp. With all the collective experience here, what do you suggest?

Thanks
Rattatattat
6GW8s are also called ECL86s. You can use those to build 13W versions of just about any Marshall 18W variant. You can use the two triodes from a pair of 6GW8/ECL86s for the phase invertor and the two power pentodes from the 6GW8/ECL86s for the power amp stage. You probably have appropriate transformers in your 6GW8 push-pull radiograms. Given decent speakers, 13W can be very loud! See this thread on the topic, for more details - viewtopic.php?p=216496#p216496

BTW my current Avatar picture is a 13W Lite IIb, built into the carcass of an old Marshall 2060 combo, with a vintage Greenback speaker.
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Re: 18 watt kit or DIY?

Post by crgfrench »

+1 for the Dale CMF resistors. The CMF60 series is your normal go-to in amps. CMF55 for pedals, and I just got a single CMF65 because Mouser was out of 60s in the value I needed. I think I'm going to make the CMF65s my normal amplifier resistors everywhere 1/2 Watt is specified. Big Bad & Beefy.
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Re: 18 watt kit or DIY?

Post by crgfrench »

Jelle Welagen lives near me; he has a bunch of NOS Draloric carbon films for sale if anyone's looking for some of those. He has them listed on his website and also on the Amp Garage forums IIRC.
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Re: 18 watt kit or DIY?

Post by JMPGuitars »

crgfrench wrote:
Sat 05/02/20 6:39 pm
+1 for the Dale CMF resistors. The CMF60 series is your normal go-to in amps. CMF55 for pedals, and I just got a single CMF65 because Mouser was out of 60s in the value I needed. I think I'm going to make the CMF65s my normal amplifier resistors everywhere 1/2 Watt is specified. Big Bad & Beefy.
Oddly enough the voltage rating doesn't go up at all between the 60 and 65 series. They're all good though. I use CMF60 wherever the correct values are available, but for lower voltage spots with unavailable voltages, I usually can find them in the half watt variant. It's odd that some of those values aren't available higher.
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Re: 18 watt kit or DIY?

Post by colossal »

crgfrench wrote:
Sat 05/02/20 6:44 pm
Jelle Welagen lives near me; he has a bunch of NOS Draloric carbon films for sale if anyone's looking for some of those. He has them listed on his website and also on the Amp Garage forums IIRC.
I used a set in a recent Dumble 102 build.
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