WHY ?

For anything about cans, and the amplifiers that drive them
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JackOfAll
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#16

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Greg
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#17

Post by Greg »

Hi Clive,

Thank you so much for your informative response. That's very helpful.

I looked at Little Dot and as you say, in many ways it's a no brainer to buy something from them although they do have several models on offer. Cost in this area is no objective so which of their headphone amps would you suggest as a best buy?

Thereafter, apart from basic component swapping, what do you recommend as upgrades or even, can you point me towards where such things are discussed?

Are schematics available for these amps?

As a point of interest, I have listened to both the original WAD amp and the later WD head phone amp. The sound was good but there was in both cases intrusive hiss. I don't know if that is something easy to remove, but it did put me off as they were factory samples I was listening to.

Regards,

Greg
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#18

Post by davebms »

As a point of interest, I have listened to both the original WAD amp and the later WD head phone amp. The sound was good but there was in both cases intrusive hiss. I don't know if that is something easy to remove, but it did put me off as they were factory samples I was listening to.

Regards,

Greg[/quote]

i have a WAD amp, when i rebuilt it i used a piece of ally to shield the mains transformer ,put a choke in the power supply used a earth lift resistor and a bit of wire re-routing and it has no hiss (it did have when i got it )
dave
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JackOfAll
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#19

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simon
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#20

Post by simon »

Fascinating discussion again Clive. HD800s are perhaps 4x the price of the HD650s I have. But in the mad world of audio why not?

In the past I built Broskie's OTL headphone amp which sounded okay but was so blighted by hum that I couldn't cure I broke it up. http://www.glass-ware.com/tubecircuits/ ... ifier.html
I now have the Aikido All in One headphone amp I need to finish sometime. But (as I haven't got enough projects on the go!) it would be interesting to hear your perspective on what might be worth trying in the future if I'd like to get to the "high end", if you have the time.

We're all different but it would be a good starting point to hear what you think is worth trying amp-wise, whether the 650s would show the difference in amps, and indeed where you think the 650s and All in One figure in the overall scheme of things.

At a guess you'd use the Sowter txs and HD800s? But valve choice and topology might be interesting.
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JackOfAll
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#21

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JackOfAll
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#22

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Nick
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#23

Post by Nick »

Gas tube, shunt regulation. PSRR is not good from the cathode follower output. So the shunt reg serves two purposes, but the most important is this. We want to take the PSU cap out of the AC current loop. I don't care what cap you use as the last cap in the power supply, it will never sound as good as removing it from the AC (output) current loop by using the gas reg.
Only problem in my experence with that is that gas regs are very poor at passing signals, they conduct with slow moving heavy ions, so have very frequency dependent inpedance.
Little known fact, coherent thought can destructively interfere with itself leaving no thought at all, that’s why I prefer incoherent thought.
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JackOfAll
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#24

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simon
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#25

Post by simon »

JackOfAll wrote:
simon wrote: In the past I built Broskie's OTL headphone amp which sounded okay but was so blighted by hum that I couldn't cure I broke it up. http://www.glass-ware.com/tubecircuits/ ... ifier.html
No reason why you wouldn't be able to get that quiet enough to use with Senns, even with AC heaters. Did you bias the heater secondary winding up to say 40V, (so it was referenced to ground as well as reducing the strain H->K on the CF), either at the heater winding centre tap, or creating a virtual centre-tap with a couple of 100R resistors?
Yeah, I got rid of a lot of it but it was built in to a small case that was more pain than it was worth to work within. Call me lazy, call it a salutary lesson learned.
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#26

Post by simon »

JackOfAll wrote:Please read this twice......

Do not even think about this unless you have a scope with bandwidth, ie. 200MHz, not 20MHz and the smarts to know how to use it. I do not want to hear anyone telling me that this circuit sounds sh*te, metallic, hissy, noisy..... That means you're listening to the tube while it's oscillating, way outside your hearing range, but it is affecting what you can hear back down in the audible range.
I now have a 200MHz scope :). I don't really know how to use it properly yet :(.

I take your point entirely and respectfully, I remember the "fun" I had when I first played with a C3g wondering why the VR tubes kept pulsing. That was a memorable way to learn about grid stoppers. I need to have another read of your post when I have more time to take it in.
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pre65
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#27

Post by pre65 »

Just seen this on the BBC web site. :)

http://news.bbc.co.uk/1/hi/programmes/c ... 565041.stm
Life is what happens to you while you're busy making other plans. John Lennon

G-Popz THE easy listening connoisseur. (Philip)
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