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Old 14th Feb 2004, 1:36 am   #1
avro
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Default Optical Output

I am looking at a DAB radio that has optical output. Is there any way of playing this through my Vintage German sets? ie an optical to DIN cable? It may sound like heresy in this forum but there are some good stations on digital and analogue Radio reception in the wilds of Wiltshire leaves much to be desired.
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Old 14th Feb 2004, 2:05 am   #2
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Default Re: Optical Output

Does it only have optical output? The Pure models at least (Evoke 1 and 2, DRX601-EX) all have standard audio out sockets, 3.5mm. in the Evokes, phono for the DRX...

Paul
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Old 14th Feb 2004, 9:22 am   #3
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Default Re: Optical Output

As regards DAB radio, there is no point in going for optical output - quality of the broadcast sound isn't particularly high - it's OK, little background noise, but some channels are very compressed though to what extent depends on the channel. R3 is good (though dropping), BBC7 is average yet Kerrang is aweful compared to a CD.

Before splashing out on a DAB radio you might consider buying a TV set-top box instead as
1) They are significantly cheaper
2) The channels are nowhere as near as compressed, AND
3) some of the stations that are mono on DAB broadcast in stereo via set-top boxes. I'm specifically thinking of BBC7 here.

Also note that certainly in the case of the Evoke the line-out signal isn't high enough as it stands to drive a PC's line-in should you intend to record something to play through the old radios later.

TTFN,
Jon
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Old 14th Feb 2004, 11:12 am   #4
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Default Re: Optical Output

The set that I am looking at is a Roberts Gemini 5 that operates from the mains and D Cell Batteries. I want something that can move around the house and take with me when I am on holiday or travelling with work.

We have a Freeview set-top box but it has been crap ever since I had my VHF aerial installed (I think said dweeb doing the installing must have hit the TV aerial and moved it, and he has become strangely unavailable ever since ).

The Gemini 5 only has an optical output.

I am aware of the shortcomings of DAB due to transmission bit-rates but it provides many extra stations in the radio desert known as North Wiltshire
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Old 14th Feb 2004, 11:54 am   #5
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Default Re: Optical Output

An optical output is irrelevant to driving analogue equipment. It's meant to connect to an optical input on someting like a minidisc recorder or computer soundcard, though you could also use it to drive an external (better) D-A converter.

It costs the manufacturers very little to add an optical digital output, which is why you find them on all sorts of low-end junk, but the bitrate used for DAB is so low (128K and down for everything except R3) that you'll get no benefit whatsoever from using optical even to link another digital device.

Presumably the radio you buy will have a headphone socket? That's likely to be as good as anything for driving old valve radios, though lots of DAB receivers have line level phono outputs which are likely to be a bit cleaner.

The bitrates used to transmit radio on DTT are much better than DAB (for most of the BBC radio stations at least). If you want to listen to the new stations you should have your aerial fixed!

HTH, Paul
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Old 14th Feb 2004, 3:55 pm   #6
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Default Re: Optical Output

Could be worth your while considering the Evoke-2 if you haven't already: about £10 more, but it's stereo (for what that's worth with 7" between the 'speakers), conventional audio output is provided, pleasant veneered cabinet, makes an agreeable enough noise, and when mains isn't available it runs on 6 SP11s or whatever they're called these days...

Paul.

Last edited by Jeremy M0RVB; 2nd Jan 2005 at 12:45 am.
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Old 14th Feb 2004, 7:06 pm   #7
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Default Re: Optical Output

Thanks for the advice guys. I have contacted the National Office of the aerial installation company and I hope to get a result this week (chappies' name was Kev but Roger would have been a better name for him!

I still want a battery/mains portable and the Roberts looks like about the best bet. It is going for about £80 on eBay while the Evoke 2 seems to go for about £120 and the Evoke 2 goes through C cells very quickly.

Interesting review of the Roberts Gemini 3 DAB in SWM. They reckon the batteries would need replacing about every 2 weeks and noted that the Roberts R200 used a PP9 every 2 years . That is progress for you!

I think the best solution for me to play it through my Saba would be to use a miniplug (for the headphone jack) to 5pin Din cable. I use this setup for my CD player and I am very pleased with the results.

I am still none too pleased with the DAB selection at the moment as Roberts seems to have an odd appreciation of what the market wants-desirable features are spread across the range and all are not included in any one model. Sony is due to come out with a full-featured portable set at the end of the month and I may well wait for its introduction.

Last edited by Jeremy M0RVB; 2nd Jan 2005 at 12:46 am.
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Old 15th Feb 2004, 10:01 pm   #8
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Default Re: Optical Output

I agree with Paul RK about the Evoke 2 it is by far the best of the bunch of stereo DABs. It is very sensitive (on DAB) and has the best tone as well. Interestingly the best mono DAB portable for sesitivity and tone is again the Pure with it's Evoke 1.
If you are going to play anything through old radios surely it's best to use a modulator so you are not just using the amplifier/output stage of your valved sets. If you do take this approach the quality of DAB should be ok for the average AM stages of most radios.
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Old 16th Feb 2004, 8:37 am   #9
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Default Re: Optical Output

Simon,

Why would I need a modulator? Surely the stereo input of my Saba should be adequate.

I like the Evoke models but the battery life of the Evoke 2 is woefully inadequate, the Evoke 1 has no FM and neither have RDS. I travel a lot with my work (both here and abroad) and the lack of these features means that neither is really suitable for my needs.
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Old 16th Feb 2004, 12:21 pm   #10
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Default Re: Optical Output

Avro, lots of people like to drive their old radios using an AM or FM modulator or microtransmitter. It's just a pleasant experience to use the radio as a radio rather than just an amplifier.

That said, the sound quality will be better if you drive the gram input directly.

Best regards, paul
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Old 16th Feb 2004, 12:32 pm   #11
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Default Re: Optical Output

Going back to the original question: does anyone know of a simple and cheap converter for the serial digital format?

I looked up the chip set that processes this stuff in the hope of a simple solution, but it is the usual thing of over complexity - you can get an SM chip with millions of pins that just needs a CPU to tell it what to do - but all I want is digital-in and analogue-out and never mind about the other features. That's 5 pins by my reckoning! After all, the serial digital output isn't particularly complicated!
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Old 16th Feb 2004, 2:11 pm   #12
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Default Re: Optical Output

GMB, why would you want to do that? You're talking about building a digital-analogue converter. However, everything except very high end CD transports will have a D-A converter built in to produce analogue output. Why should you want to build an external one (other than for audiphile reasons)?

Best regards, Paul
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Old 16th Feb 2004, 2:18 pm   #13
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Default Re: Optical Output

Recently I was at the Vintage Wireless Museum and somebody had brought along a DAB portable which I think was a Bush if memory serves me correctly. We were running the line output into a valve amp and the sound quality was awful. Massive bass boost. Tried with the speaker output and things were much better. I can't imagine that the valve amp could upset the line output to that extent. We didn't have the time or inclination to solve the mystery.
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Old 16th Feb 2004, 4:25 pm   #14
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Default Re: Optical Output

Paul, you asked why I wanted to do this....
Well, the problem with DAB is the time delay - you cannot have any other radios on in the house at the same time. The solution: distribute the digital output round the house on spare pairs of CAT5 doing other networking - then all you need is a DtoA in each room. Doing actual audio on the same cabling will probably be too noisy. (And there are some other things I could do with this technology if it was more tractable.)
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Old 16th Feb 2004, 11:56 pm   #15
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Default Re: Optical Output

Simon and Paul,

Simon wrote 'surely it's best to use a modulator so you are not just using the amplifier/output stage of your valved sets'.

I understand that some purists find that using a vintage set for anything other than radio is 'not kosher' but I have a keen interest in German sets of the 50s and 60's and all my sets were designed to have other equipment (eg a tape recorder or record player) played through them and using a CD player is merely a continuum of this-even my Bush AC 34 and VHF 94 accept an auxiliary input as do my Hacker trannies.

But I like to have things look right and this summer, when I have an albeit temporary break from school fees, I think I will opt for the wooden Tivoli CD player.

When it comes down to it the more listening pleasure and use I get out of my valve sets the better it is not only for me but others are impressed by what enjoyment can be had from such sets and they look a heck of a lot better than some black boxes-and in my opinion sound just as good.
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Old 17th Feb 2004, 1:52 am   #16
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Default Re: Optical Output

Hi Avro
I suppose I can understand what you are saying. If off air radio reception is so bad where you live then I suppose there is no alternative. I can understand medium wave and FM reception being poor but you should have no problems with Long wave reception on 198Khz. But then I suppose it depends on what you want to listen to. Many years ago I use to struggle to listen to radios 1&2 on medium wave as I drove around Wiltshire in my Radio Rentals Fiesta. The M4 through Wiltshire was particularly bad as well.
A few years ago when my music centre broke down I ran my new cd player through my old HMV1124 via the gram socket and a home built matching unit + stereo to mono convertor. The quality was ok and it impressed some of my mates, but not all. The Hi Fi Purists amongst them were not happy . It was one of the reasons I stuck with this arrangement just to wind them up
But I must admitt I was always glad to switch back to the radio to make sure all was still well with the world.
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Old 17th Feb 2004, 9:40 am   #17
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Default Re: Optical Output

Simon,

Don't get me wrong, I love listening to the Radio-Classic FM, Radio 4, Radio 2 and 5 Live are a daily part of my diet-all done on Vintage Radio unless I am in the Fiat Multipla.

Wiltshire reception (both TV and Radio) is absolutely terrible but I have installed a 6 element VHF aerial from Maplins and most days it gives me a decent stereo signal for my six speaker Saba Fredenstadt 16. Unfortunately, although being directed towards the Classic FM transmitter, this is the weakest signal but most days it is okay

But there are times when I like to listen to some of Vivaldi or Wagner or other types of Classical music that I have on CD (Naxos CDs are great at under a fiver). The Saba is my favourite set for this (it has a stereo decoder and six speakers) but strangely enough Wagner sounds better on Grundig 5088. Sorry no black or silver audio boxes in the Millson sitting room!

I have a period cottage up in North Yorkshire and I love it to bits but I sure am glad that it has (solid fuel) central heating and a few other mod cons. I like using my Vintage Receivers as much as I can and I enjoy it very much.
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