One stop shy of fishtanking?

[Findm-Keepm]

Saw the ad for this in the google ads above:

http://3ryan.com/3ryan/About.html

Had to laugh at the "tubes undigitize the sound"

Anybody got the story behind this site?

Cheers,

[ctc17]

Does it still work as a radio too? Why would someone want to listen to an ipod in mono through a 1950s radio?
The ipod has been around for a few years but its hardly a standard that will last like the am broadcast band. The ipod will have maybe a 10 year run then no one will know what it is.

[VintagePC]

I believe the two mantras of choice here are, "There's one born every minute", in conjunction with "if you build it, they will come (well, buy)."

However, their prices (over 300 quid!!) are ridiculous, so the business model is somewhat prohibitive, fortunately.

[Findm-Keepm]

Scary part is the non-technical gibberish, even scarier is the implication that they've sold several already.

Cheers,

[wa2ise]

Originally Posted by ctc17

Does it still work as a radio too?

Good question. was wondering where they find room to install a power transformer.

During the restoration process of our tube radios, a safety transformer is installed, making each radio compatible with US 120v and UK 240v.

Just remove the tuning cap, IF transformers, and associated tubes, and use that space for the transformer...

[Findm-Keepm]

Originally Posted by wa2ise

Good question. was wondering where they find room to install a power transformer.



Just remove the tuning cap, IF transformers, and associated tubes, and use that space for the transformer...

Signal used to make a line of "flat" transformers with dual primaries. Their dual-56V secondary transformer with 120/240 primary rated at 180VA (great for isolation duty) was about the size of a a deck of playing cards. Mounting would be the issue - they were designed for circuit boards used in telecom systems that fit in a card rack. Pricey, about 55 bucks a pop.

Seems to me they could easily attach a smallish interstage transformer, 25K:75K ohm or the like just after the detector (before the volume control) and get both isolation and input. Dunno how they'd switch it...

Cheers,

[maxhifi]

yes but would the interstage transformer really be rated for line voltage?

I wonder what he did to that cathedral. Have to say this is at least several steps better than the fish tank idea though, mind you to me the cabinet has always been secondary to the 'guts' of any piece of electronics. hopefully this doesn't involve discarding half the innards of the radio.

[Findm-Keepm]

Originally Posted by maxhifi

yes but would the interstage transformer really be rated for line voltage?

I wasn't referring to isolating line voltage, but a means of interfacing the ipod to the radio without the need for power isolation. Ipod=> 25K||75K => Radio ( grid level voltage, before the volume control) Panasonic had a 7-tube AM/FM RC/RS-??? radio that had a phono input via a similar transformer lash-up. Hot chassis radio, but the transformer provided isolation for the phono (mono) inout.

Sort like the old isolation transformer used in "hot" XLR mic systems. They allowed any audio source to be fed to an amp that was wired to power the microphone. We had one in our church until recently.

Cheers,

[wa2ise]

Originally Posted by Findm-Keepm

I wasn't referring to isolating line voltage, but a means of interfacing the ipod to the radio without the need for power isolation. Ipod=> 25K||75K => Radio

Such isolation transformers still need to be safety rated. I think it calls for the ability to take 1.4kilovolt DC "HiPot". Seems that that's above the biggest expected transient spikes one usually sees on the powerline.

[maxhifi]

If the chassis is at 120 or 240 with respect to ground, it better be isolated from the ipod with better than a little radio shack quality audio transformer, that's all i was saying. Imagine one hand on metal case of ipod, the other on kitchen faucet. I'd want more than a cheap transformer designed for something else in between!

[Findm-Keepm]

Originally Posted by wa2ise

Such isolation transformers still need to be safety rated. I think it calls for the ability to take 1.4kilovolt DC "HiPot". Seems that that's above the biggest expected transient spikes one usually sees on the powerline.

Most transformers (at least with the "CE" mark) already meet or exceed this. Urethane varnish 4 mils thick has a dielectric strength around 1.8KV, making it quite easy to meet the spec. I'm no engineer, but anybody who's ever seen the transformer in an Asian wall wart can see that HiPot ratings aren't too difficult to achieve even with the lowest grade materials.

I'm not advocating cutting corners, just comparing methods used to achieve the same results. Me, I'd stick to a thermally fused isolation transformer (faraday shielded - we're talking AM reception!) at the AC end of things, and an interstage transformer wired in to provide audio isolation/ground loop avoidance. Just my fantasy build. I'd never "fishtank" an antique/old/tube radio by lashing it up for some fad-driven ipod.

Cheers,

[Rodzilla]

i dunno i'm thinking they just install a cheap isolation trans...i've bought a few such transformers to play with lately...a 50watt rated one from Triad,meets required electrical specs,is wireable for both 120 and 240v input,and is about 2" square max[and that's pushing it really,even smaller are available]...these transformers are brand new,name brand,and cost all of about 10-12 bucks.

i think they're quite popular retrofits in vintage guitar amp circles,they're often used for old and cheaper tube amps using a hot chassis which of course present the same type of safety issues as old radios..only worse!the ISO trans mod is really not unwise in those cases

however these small Xformers have awful regulation and tend to step up the voltage significantly unless loaded to near the max.unless they sized the xformer pretty close to the wattage of the radio,the tube filiments are gonna get pretty roasted in a AC/DC set,and if they did size it right the Xformer is gonna get warm and be close to it's rated limits at all times...it ain't an elegant solution,but i bet that's what they're doing

[Electronic M]

Why would anyone who has one or more sets with a phono input ever want one? I remember a couple years ago I used two table sets with phono imputs to play Swing music and vintage radio programs from my mp3 player. I've been known to connect a variety of old and new recording equipment to my radios on a whim to see how it sounds. One of the more memorable occaisions was one of the last two times that I trick-or -treated, that hollwoeen I left the house later than usual so I could finish reccording a cassette tape of the spookyest Swing music in my collection which I then poped into an auto reverse walkman that was connected to a Cool warn looking Silvertone console set out on my front porch with the volume all the way up!

It got a bunch of nice comments!

Tom C.