Headphone amps to build or buy

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ed
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#16 Re: Headphone amps to build or buy

Unread post by ed »

you are neither ignorant or forgiven.....thanksfully you are my safety net.

please ignore that sentence relating to the bias....

most pleasing wave is attained by biasing the fet with vr1 so that there is 6v ontop of the 317 at the source pin...this is half the rail voltage(if using 12v power supply)
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#17 Re: Headphone amps to build or buy

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That would make sense.
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#18 Re: Headphone amps to build or buy

Unread post by Tony Moore »

Also, i do have a wad hd83 sitting here unused that you could try out.

Not free probably but certainly you can borrow it indefinitely. I have no use for it now. Better someone uses it than sat gathering dust.
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#19 Re: Headphone amps to build or buy

Unread post by Ant »

Eds hpa boards arrived today, many thanks ed! Be prepared for dumb questions....
First thing is a case, and first thing to acquire is a pair if heatsinks
Onwards!
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#20 Re: Headphone amps to build or buy

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Image
 
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#21 Re: Headphone amps to build or buy

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:headbang:
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#22 Re: Headphone amps to build or buy

Unread post by Ant »

Tonys wad hd83 came through the post yesterday, and after perusing the docs for it which greg kindly supplied, ive (with tonys permission) rewired the output tx's for 16-50r impedance. I tried it with some of the kids nasty gaming headphones first so if id done something wrong i wasnt blowing my good headphones up........


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The wires were a little short to get them to the termination pins, tony hadnt used them originally either and had configured the windings separately, so ive added the small tag strip just to the right of the black cap to terminate the windings onto to configure all 4 in parallel.

Tony found he had built this unit back in 2002!

Much much better sound through the p7s than using either the jack on the phone or the astell and kern bluetooth dac.
The phone us plugged into the m1 dac via usb and is just streaming tidal.

Thankyou to tony for the loan, and Greg for the docs, i now know what these cans can do

Ive also bought a couple of pairs of sennheiser momentums, a(nother) pair of on ear m1s because they were absolutely dirt cheap and a pair of m2 over ear ones because i want to try out different ones to try and find a preference. Im also eyeing up a pair of beyerdynamic dt770s or 880s as i have never tried beyers apart from quickly trying rays at owston but i cant remember what model they were.

Found some heatsinks for eds boards so that's the next step

Onwards!
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#23 Re: Headphone amps to build or buy

Unread post by Tony Moore »

I am glad that it survived the journey and that you're enjoying it!

I cannot remember how I wired the secondaries but I had high impedance Senheiser phones so it was set to all series. I probably stuffed it up and cut the wires too short for subsequent alteration. The tag-strip mod looks fine to me! Whatever works. 8)

Those Blackgates may take some time to come back on-song, the amp hasn't been used (for any length of time) in years.

I did test it out and check for safety, as you know, before sending it to you and it did sound pretty sweet I have to say.

Happy Listening!
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#24 Re: Headphone amps to build or buy

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Yep the secondaries were series wired, joined up then sleeved and tucked away. It came up and on song pretty quickly, about an hour or so and then settled
Its very smooth and the detail comes through very well. Nothing swamps anything, and dynamics also come across very well. Much more controlled bass too. The p7s seem to come alive with some oomph behind them, a phone or the little portable amp/dac wotsit i have dont seem to have the required grunt to get the best out of them which is not really surprising

I dont take headphones out when im out and about. Apart from when the formula 1 practice sessions are on and i listen to them on radio 5 live, but i have some 5 quid jvc earbuds for that, so using a dedicated headphone setup is very enjoyable
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#25 Re: Headphone amps to build or buy

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Done a bit of a/b listening to the b&w p7s and the sennheiser m2s. Both over ear, the senny m2s are the equivalent to the p7s in the respective ranges at the time they were new.
Not much between them, the p7s are better to me on rock though (deep purple - child in time)
Sennys get abit muddled in the midbass area and the top end is abit hit and miss on rock. Although the m2s are a bit punchier the mid seems to swamp the top end abit so they sound abit cluttered

On jazz they are quite similar, the sennys maybe resolve a little better, the bass end is tighter. Jazz shows up a little bloom on the p7s that the sennys dont have. Sennys are a little more open on jazz, xylophones and pianos are more lifelike (crystal silence - gary burton and chick corea) but more forward, the top of the xylophones are abit hot. Stabs at the piano keys are more immediate, the p7s are a little softer but smoother

On pop, (simple minds - alive and kicking) its more obvious that the p7s are voiced 'flatter'. the sennys have some bass emphasis and some treble emphasis, the bass is not overblown, its tighter than the p7s but its as is its one click louder. Its more fun, like i remember this song sounding on the radio in the decade of excess. as is the top end which is not so fun, again a little hotter a smidge too much emphasis.
Going back to the p7s and playing sanctify yourself it had me start singing tunelessly because i cant hear myself. Thats the excuse and i will stick to it.
Big 80s drums are bigger on the sennys, top is smoother on the p7s. I cant decide which i prefer on pop.

On balance so far its the p7s that get the nod because they dont get middled in the mid when the music gets complicated

This is fun.

Need some open back cans to try too
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#26 Re: Headphone amps to build or buy

Unread post by ed »

Ant....

I've just been reading Paul Tiernan's comments about i/c shielding and it's relevence to class2. It prompted me to mention:

With the budget hpa I noticed a very subtle buzz when using the class d amp with the topping. Both of which are run on wall warts and have no connection to mains earth. Obviously the class d wasn't operating when the hpa was switched on because of the relay in my circuit. When I used a normally aspirated amp instead of the class d, even though it wasn't operating, there was no buzz at all, as all my amps have the chassis earthed.

I discovered that if I earthed the case of the hpa when the class d amp was in the system there was no buzz at all.

I mention this because you may use the hpa with a class 2 amp, in which case there may be no connection to earth via the i/c, and a possible noise.
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#27 Re: Headphone amps to build or buy

Unread post by Ant »

Thanks ed, i was considering a psu for it that uses a vellemann reg board and a transformer, the reg boards with heatsinks on the 317 are good for up to 1.5a although i have got a 12v brick from an old tv box somewhere.

Quick question re the heatsinks, the nice curved ones i had bought have been refunded because they are damaged apparently, although i never saw them and im not convinced they ever got posted in the first place.....
The ones you used on the original one appear to be give or take 150mm x 60 ish, presumably thats plenty big enough? I can get that sort if size easily
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#28 Re: Headphone amps to build or buy

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Edit: the hpa will be used as a stand alone thing with a dac plugged into it as a source rather than as part if the main system because if where it is and where the seating has to be
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#29 Re: Headphone amps to build or buy

Unread post by ed »

The heatsinks in the photos are far and away too big for this amp....These still seem to be available on ebay but I would say more expensive than is necessary. The sinks in the photo don't register any temp rise.

I don't have much experience with on board sinks but I had imagined that something 2" square would be adequate to deal with 3watts. There are loads of these on-board sinks on ebay and I had imagined that something like that would be adequate. At a guess I think the regulator will dissipate about 1.25 watts so I think it should be ok without a heatsink.

somebody else with some experience of small sinks may like to comment about this.

something like this is what I originally had in mind....I think this kind of thing will let the fet get to about 15 degress above ambient:

https://cpc.farnell.com/multicomp/mc332 ... dp/SC15491

just found this which looks useful:

https://www.anglia.com/product_guide/he ... a_423e.pdf
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#30 Re: Headphone amps to build or buy

Unread post by Ant »

I am currently trying a pair of fostex t50rp mk3 headphones out on the end of tonys hpa
These are rather nice
Reportedly they need a bit of running in but straight out of the box they are pretty enjoyable
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