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 Post subject: 5998A SET
PostPosted: 02 Sep 2009, 16:11 
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Joined: 02 Mar 2009, 12:41
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Location: Vänersborg, Sweden
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This is my 5998A SET prototype. All attached to a piece of plywood with scotch (tape). All is working OK and the amp is playing load and powerful, but with high efficient horn speakers anything will do. :mrgreen:
The power element, if I am to put it that way is a 5998A dual triode, not very unlike 6080 or 6AS7G.
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The idea was a schematic lurking on my HDD from an Italian site. The amp was called Triodino 2.
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As can be seen it is a very simple design - two tubes, no fancy components (I am using a pair of 1N4007) instead of the tube rectifier. I now notice that I have a beefier PSU (2 470uF caps, but no choke).

The end result will look like this. The box was drilled for another project and I had to layout the components in this fashion in order to cover som holes and keep the iPod away from the power triode. The amp has a line input and a dock for my iPod.
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I am right now getting the stuff into the Hammond box, which by now, is green. Power inlets and LSP connectors in the back, where the mains switch is situated. Line inputs on the left side next to the iPod to avoid 50Hz leaking over to the signal cables.

More later.

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“If you don't know where you are going, any road will get you there.”
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 Post subject: Re: 5998A SET
PostPosted: 02 Sep 2009, 18:18 
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Joined: 28 May 2008, 21:53
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Location: Winnipeg, CANADA
Hi Magnus, Looks interesting and I am looking forward to your results. Where do you find these tubes?

With those decorative tube socket covers, do you drill holes to help with cooling? Now that I see them again, I am going to order some for myself.
Cheers

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[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


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 Post subject: Re: 5998A SET
PostPosted: 02 Sep 2009, 20:40 
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Joined: 14 Oct 2008, 17:35
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Location: Dartmouth, Nova Scotia
I've got to see this project! :P

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 Post subject: Re: 5998A SET
PostPosted: 03 Sep 2009, 06:11 
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Location: Vänersborg, Sweden
Hokey, the pagina italiano are to be found here: TRIODINO. Here you have kiloohms and microfarads for the components.
I bought the tubes ... errr .. the tube from Radio-Daze in Florida (together with their last 6T9s. If you need any of those, I got 11 tubes), but I guess you can get them at AES.
Tube sockets and the covers are from http://www.vt4c.com. I haven't made any efforts to enhance cooling of the tubes; I think and hope that as they sit close to the edge they will have enough of fresh air.The covers are great stuff as you can drill, or cut or saw or file the must ugly hole you can think of and just cover it with the aluminium plate. However the covers goes with just certain sockets :idea: . There are covers you can adopt to any kind of sockets too. VT4C also sells transformers, knobs, tubes, and all kinds of useful hardware. I've been buying stuff from them for some years and I consider them having fairprices, high quality and VERY quick delivery.
Some more facts (the RCA and SPKR connectors are also from VT4C. I've seen the same speaker conns here in Sweden för 5 times higher price :eek: ) of used components.
Mains transformer comes from a German company Welter Electronics, that have a good supply of various transformers at good prices. Output trannies are Danbury (UK) and bought from a guy who likes Enya and Kate Bush; the Danbury audio transformers are sold by him exclusively. I've used their transformers before and they are OK (and cheap). Box is Hammond and all caps and resistors and stuff are bought from local electronic web-shops in Sweden.

It's difficult to calculate the overall cost but I guess I've spent some $40-45 in total.

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“If you don't know where you are going, any road will get you there.”
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 Post subject: Re: 5998A SET
PostPosted: 03 Sep 2009, 23:45 
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Joined: 26 May 2009, 18:51
Posts: 130
Location: Lilburn, Georgia USA
Hi Magnus! That is a good looking amp. I like the way the 5998 Tube filament shows its entire length. Not many do that. I wouldn`t mind having a couple pairs of 6T9s to play around with. Maybe I`ll find some over here someday. Right now they are kind of dried up it seems. I am sure there are venders of electronic parts I haven`t discovered yet. I finally with the help of Gio got pictures of my Oddwatt KT77-88 tube amps on the Forum. Talk to you later, Robert P.


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 Post subject: Re: 5998A SET
PostPosted: 12 Sep 2009, 08:45 
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Location: Vänersborg, Sweden
I must update this thread with some new pics.
The Hammond chassis is green (rolled-on Hammerite)
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Things getting mounted in the chassis (crammed in there).
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Fuddling with the volume knob as I want a LED in it.
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More to come...

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“If you don't know where you are going, any road will get you there.”
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 Post subject: Re: 5998A SET
PostPosted: 13 Sep 2009, 18:56 
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Location: Winnipeg, CANADA
Good start Magnus. I'm interested to see how the volume knob and LED turn out.

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[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


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 Post subject: Re: 5998A SET
PostPosted: 14 Sep 2009, 01:33 
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They turned out good. Very good. I wound the cable around the potentiometer axle 1-2 turns, had it hooked up to a diode/reistor/cap and it glowed nice and fine. But there was something that didn't work OK. The sound came out very distorted, at least one channel.
Made a trial with the optical potentiometer, but that didn't work at all :confused: . So I am back to square one, or zero. I cannot find a nice potentiometer with a correct value really. :evil:

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“If you don't know where you are going, any road will get you there.”
―Lewis Carroll


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 Post subject: Re: 5998A SET
PostPosted: 14 Sep 2009, 02:08 
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As it is supposed to look like:

Image

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Image

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But still got to fix the volume control. :nuke:

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“If you don't know where you are going, any road will get you there.”
―Lewis Carroll


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 Post subject: Re: 5998A SET
PostPosted: 14 Sep 2009, 11:01 
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Location: Vänersborg, Sweden
I had managed ( :down: ) to swap two wires to the input tubes, but now everything's working OK ( :up: ). I am not 100% pleased :confused: with the 50K potentiometer so Ihave added a pair of 33K resistors to give me some more "dynamic range".

Well when everything is working this is waht it lokks like.
Image

Close-up of the green LED.
Image

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