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Old 14th February 2011, 07:54 PM   #1
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Default replacing tubes with circuitry

Hi guys is it possible to replace tubes with modern circuitry cause tubes are expensive?
Thanks.
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Old 14th February 2011, 08:02 PM   #2
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Yes in general its possible, but may not be excatily the same. What kinds of stuff are you in to?
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Old 14th February 2011, 08:21 PM   #3
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Note that there were several manufacturers of solid state plug in substitutes for common small signal audio triodes like the 12A*7 series tubes. They don't sound at all tube like IMLE.. IIRC They went by such trade names as "Tubester" etc. Rectifier tubes in most cases have current plug in solid state replacements available - need to buy ones that don't overvoltage supply capacitors and the like during warm up.

AFAIK there were no replacements available for power tubes or any specialized RF types. I expect good ones would have cost more than the tube they were meant to replace.

In some cases suitable arrangements may be put together with high voltage mosfets and jfets - getting the exact right characteristics in a given circuit may be more trouble than it's worth.

Guitar amps are very poor candidates for these sorts of mods, as are IMHO most hifi gear. So knowing what you are talking about would be helpful.

Many common types of tubes are reasonably cheaply available on eBay.

Depending on where you are it might make more sense to sell the item in question and replace it with a solid state unit.
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Old 14th February 2011, 10:58 PM   #4
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Tubes aren't all that expensive as a rule. Transformers are though. Some rare tubes are a bit spendy but you can often modify for less expensive options. Can you be more specific about what you are trying to do? Are you trying to replace a tube in an existing piece of gear or are you wanting to replace the whole thing?
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Old 15th February 2011, 08:42 AM   #5
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Default Tubes to Circuitry

Quote:
Originally Posted by mashaffer View Post
Tubes aren't all that expensive as a rule. Transformers are though. Some rare tubes are a bit spendy but you can often modify for less expensive options. Can you be more specific about what you are trying to do? Are you trying to replace a tube in an existing piece of gear or are you wanting to replace the whole thing?

Hi Mashaffer I have a meazzi concertorama amplifier about 30w output. It is sounding alot of noises crackling sounds. I changed one preamp tube and it became a little better but I don't have another cause there are two preamps as read and other small four. So I would like to change to circuitry if possible just leave it to plugin too. Hope you understood what exactly I want.
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Old 15th February 2011, 09:15 AM   #6
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Oh man, please don't junk the innards of that nice ol' sound machine...you said it basically works, but sound quality is lacking. That means that most likely the transformers are still good. I bet the tubes themselves are not the problem either. With equipment of this age, especially (all) capacitors will need to be replaced, which need not be that expensive at all. I bet this amp can be brought back to like-new sound quality with just a little tender love & care. I checked on the net and found a pic of the preamp stage; looks like it'll be pretty easy to trace a schematic of the amp and use it to restore it to good condition.

Alternatively, you could rip out the innards and stuff in a simple chip amp. Won't cost an arm and a leg and it's a very easy project. But it'd be the heartless thing to do, and instead of owning a vintage piece of equipment in working condition, you'll be left will a queer old box with some cheap and uninteresting electronics in it (i.e. a worthless pile of junk).

Oh and btw, tubes are not expensive. They are if you want to buy NOS-bugle-boy-gold-pin-whatchamacallit-fancy-audiophool-black-plate-side-getter-etc. types, but most types used in 1950s consoles like yours can be found for a couple of euros.
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Old 15th February 2011, 06:13 PM   #7
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Quote:
Originally Posted by mastodon View Post
Oh man, please don't junk the innards of that nice ol' sound machine...you said it basically works, but sound quality is lacking. That means that most likely the transformers are still good. I bet the tubes themselves are not the problem either. With equipment of this age, especially (all) capacitors will need to be replaced, which need not be that expensive at all. I bet this amp can be brought back to like-new sound quality with just a little tender love & care. I checked on the net and found a pic of the preamp stage; looks like it'll be pretty easy to trace a schematic of the amp and use it to restore it to good condition.

Alternatively, you could rip out the innards and stuff in a simple chip amp. Won't cost an arm and a leg and it's a very easy project. But it'd be the heartless thing to do, and instead of owning a vintage piece of equipment in working condition, you'll be left will a queer old box with some cheap and uninteresting electronics in it (i.e. a worthless pile of junk).

Oh and btw, tubes are not expensive. They are if you want to buy NOS-bugle-boy-gold-pin-whatchamacallit-fancy-audiophool-black-plate-side-getter-etc. types, but most types used in 1950s consoles like yours can be found for a couple of euros.
Hi Mastodon thanks for response I was not going to touch from circuitry but just do an add-on to the pins. This amplifier works cause sometimes I plug my synth to it but just for home not to play in audience cause as said when it heats up crackling sounds will be heard. If you're sure that these are because of caps it would be no problem cause I have others but have to be sure.
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Old 15th February 2011, 08:19 PM   #8
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Start by replacing all electrolytics. Also check if there are bad contacts anywhere or fried resistors. Odds are that some resistors have drifted quite a bit from their original values. Drawing up a schematic and doing some measurements would definitely help figure out what's wrong.

As for replacing the tubes with silicon-based subcircuits: sounds like a very cumbersome and time consuming solution. It's much easier to troubleshoot the amp as it is!
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Old 15th February 2011, 08:39 PM   #9
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Tube sockets may need a good cleaning too. As others have said a little bit of maintenance should bring this up to snuff. Worst case I would say sell it and by a sand amp to replace it and pocket the difference. But me I would spruce it up.
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Old 15th February 2011, 09:30 PM   #10
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So you're saying it's not tube problem it's contact problem?. I try to clean up pins as mashaffer said and then try searching for bad contacts as mastodon said then if nothing happens I have a window and try to measure the height with it just kidding.
Ok so I have a job to do.
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