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Post by ticktockman on Feb 6, 2008 23:08:23 GMT
Just picked up a HFN009 Headcase on ebay anyone know much about them. Had a quick look inside looks to be some obvious places for improvement but what is its potential. I think I remember seeing a thread on this one some time ago suggesting it is designed by Tim DP . It seems pretty well controlled on first listen but have only tried it from the squeezebox line level outputs not on the proper rig so far. Your thoughts gentlemen please. Tried so far with senn px100's and Ergo2's
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bullpup
Been here a while!
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Post by bullpup on Feb 7, 2008 10:15:37 GMT
Congratulations mate you beat me to it I thought the winner might show up here sooner or later.
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Post by PinkFloyd on Feb 7, 2008 11:27:05 GMT
Yes, have one myself and have fully modded it. I'm in a library at the moment but will find all the info on this amp when i get home. Basically it was designed by Tim De Paravacini and sold in kit from by Hi-Fi News and record review. A very nice amp indeed, especially if you replace the opamp with an OPA2134. Try this for starters and this
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Post by PinkFloyd on Feb 7, 2008 11:40:44 GMT
A discussion between Tim and myself:
The HeadCase is a 1987 Tim De Paravicini design and was sold (at the time) through Hi Fi News and record review in kit form for £88. It's called the HFN-009. Possibly one of Tim's more zany designs (the PCB tracks can be considered "art") but a lovely sounding amp nonetheless. I asked Tim about it and the following may be of interest:
Me: I recently bought a Hi-Fi news "headcase" HFN-009 headphone amplifier which I believe you designed?
Tim: Correct.
Me: I totally stripped the board and have replaced the carbon film resistors with metal film types and replaced the original capacitors with low ESR types, it sounds pretty damned good but I'm sure there's a bit more performance to be squeezed out of it and wonder if you, 20 years after designing it, have any little tips or tweaks up your sleeve which I could apply to the headcase? The volco positioned adjacent to the phono sockets is a very good idea and I wish more designers would implement this idea, it keeps the PSU separate from the amp proper and the connecting rod just adds a touch of peculiarity to the amp.
Tim: Not peculiar, Just very logical!
Me: Checked the DC offset at the output and it was pretty large (267mV & -78mV respectively) so I decided to fit 1000uF output caps in series with the output to null any offset present on the output. I also fitted an extra 4400uF capacitance to the PSU section which made a slight improvement especially to the dynamics and general "drive" of the amp.
Tim: As to offset, this is due to the opamp. Do not put output caps in, as this does effect the sound. 20 mV is more than good enough. See next comment.
Me: I'm not too sure if it's a good idea to remove the 120 ohm output resistors and replace them with zero ohm links, what do you think? I know 120 ohm was industry standard 20 years ago but many amp designers seems to think zero impedance is the best way to go, your comments appreciated.
Tim: The 120 Ohm is there for a good reason. This is so that virtually all dynamic headphones with impedances from 8 to 600 Ohm have similar volume levels and to prevent serious overdriving of low impedance types with serious hearing loss and damage to the drivers. Also the amplifier operating on about plus minus 10 volt (if memory serves me) does not have the current ability to drive full voltage into 8 Ohms of about 12 watts. The 120 Ohm limits the power to a few tens of milliwatts. Do you see my point?
Me: Could you possibly tell me what function the TL082 opamp undertakes and if there are any better modern chips I could use in its place? I have literally hundreds of assorted dual chips but won't roll them in just for the sake of it unless I'm doing the amp any justice.
Tim: The TL082 was cost effective, likewise the carbon film resistors. If the unit had been another £100, would you have purchased it? I doubt it. The OPA2134 would be best in current times. did not exist 20 years ago. This is history you know. Hindsight is wonderful. Once I have completed a design I move on to the next thing, In all my 40 plus years there are lots of product out there. Everybody thinks they know more than me but reinventing the wheel is tough. I don't have a copy of the circuit, sorry about that.
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Post by PinkFloyd on Feb 7, 2008 11:41:40 GMT
There's another long thread about it here (in this forum) I'll try and dig it out later on.
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Post by PinkFloyd on Feb 7, 2008 14:15:59 GMT
And here it is Just goes to show this place has a wealth of information in the archives.... always worth searching
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Post by ticktockman on Feb 7, 2008 22:44:29 GMT
I thought the little beast had more than a little potential. I didn't realise it was so far back into the past. Did you come to any final conclusions about what level of modifications are most effective(cost effective). A mod pack might appeal as I have very limited skills on the DIY front. Final question can it drive the Ergo2's properly. I do hope so!!!!!
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Post by PinkFloyd on Feb 7, 2008 23:30:24 GMT
I thought the little beast had more than a little potential. I didn't realise it was so far back into the past. Did you come to any final conclusions about what level of modifications are most effective(cost effective). A mod pack might appeal as I have very limited skills on the DIY front. Final question can it drive the Ergo2's properly. I do hope so!!!!! Best amp for the ERGO2 is the ERGO amp 1. Please read this thread.I don't think the HFN009 has enough grunt to drive the ERGO 2 to their full potential, I tried it but have found the ERGO 1 amp to be the best amp for the purpose as it has a mighty 3 watt output.... the ERGO 2 sound positively weedy when driven by some other amps. First thing you want to do with the HFN 009 is recap it, the existing caps will be well past their sell by date by now. You can also remove the opamp and replace with an OPA2134, this brings about quite a nice improvement especially in the mids / bass, I'll have a look inside mine just to refresh my memory and see what all the values under the bonnet are. Nice amp though (albeit an ugly bastard!) and probably worth taking the time to restore it to its former glory
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Post by ticktockman on Feb 8, 2008 1:12:24 GMT
The QED chip amp may be better suited once suitably modified to the Ergo's then . That may have to take priority. Have been considering a pair of Goldring 150's I take it that that would be a good match to TdP's little monster
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Post by gaztop on Mar 22, 2008 2:23:08 GMT
I need a little help, I dropped my HFN009 at work yesterday and the POT separated from the board... I now have no way of measuring the specification. Which model number of ALPS should I order as a replacement ?
I converted it to 110V and have been using it daily with my micro mega micro DAC and Sony Headphones. It been a very relaxing change from the daily pressures.
Sounds like I need to get modding, does anyone buy Hifi component upgrades in the USA and if so where from ? do I need the black gates and resistors.
Thanks Graeme
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Post by gagaryn on Aug 17, 2015 18:27:48 GMT
Hello all, I'm new here, so be gentle! Resurrecting this old three to say I purchased an old Hi-Fi News Headcase HFN009 from eBay today, the seller mentioned this website. :-)
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pingu
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Post by pingu on Sept 21, 2015 11:47:44 GMT
Hi All,
Just to see if anyone has any more info because a friend just asked if I could sort out his "black brick" for him. I have read the stuff earlier on, but the RG link is dead other stuff very informative. So it looks like new caps, resists and pot.(he can swap OPAs as I will put in a socket for him.) Luckily I have a spare 50K blue alps spare
1 will fitting Rubycon 1800uF caps in place of the 1000uF caps (same vpltage) cause any probs? 2 has any got a circuit diagram or a resistor placement diagram. Most of them are badly discoloured and probably will not read well on on the MM
Help appreciated Just another thing to do while I try to find time to put the HA/PSU/JLH RE together or at least get the BOMs sorted, Oh thens there's the modded Chiara. :0
Regards Martin
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jc
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Post by jc on Sept 21, 2015 12:37:33 GMT
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pingu
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Post by pingu on Sept 21, 2015 23:03:45 GMT
Thaks Chris, that's it Now I only need a circuit or a resister list Martin
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Deleted
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Post by Deleted on Sept 21, 2015 23:36:23 GMT
Thaks Chris, that's it Now I only need a circuit or a resister list Martin
Lotsa luck I couldn't find one.
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pingu
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Reallising what has been taken on with the GB
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Post by pingu on Sept 21, 2015 23:58:29 GMT
Gee thanks Alex, looks like it is gooing to measure then take a guess. Maybe I will not sort it for him after all Martin
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Post by Deleted on Sept 22, 2015 0:22:54 GMT
Gee thanks Alex, looks like it is gooing to measure then take a guess. Maybe I will not sort it for him after all Martin Hi Martin Its a shame that the original photos by Mike were so poor by today's standards, that we can't just read off the resistor values by their colour coding.
Regards Alex
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Post by PinkFloyd on Sept 22, 2015 8:58:33 GMT
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pingu
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Post by pingu on Sept 22, 2015 12:02:24 GMT
Thanks Mike I had a quick scan and will have a proper look later.
See the caps have been up rated to larger uF was thinking of going to 1800uF for him. also the switch is a good idea too.
Martin
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Post by PinkFloyd on Sept 22, 2015 12:13:26 GMT
Thanks Mike I had a quick scan and will have a proper look later. See the caps have been up rated to larger uF was thinking of going to 1800uF for him. also the switch is a good idea too. Martin The resistors should be easy enough to check with a multimeter Martin as long as you remove each one from the circuit to test the values. I've got a TRUCKLOAD of Panasonic FR / 35V / 1500uF which would fit in the HFN009 quite nicely and would be happy to send you some. Mike.
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pingu
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Post by pingu on Sept 24, 2015 9:51:55 GMT
Hi Mike, Yes pls I'll have a set for the "brick" . I'll PM you Think it will be guess work and a clues from the pix to get the resists about right, but some are ok so a quick read of the value and then the MM measure should be spot on.
Yes Alex your idea would have been great but every little bit helps anyway
I'll post pix when it is all done (eventually)
Martin
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Post by PinkFloyd on Sept 24, 2015 12:08:42 GMT
Hi Mike, Yes pls I'll have a set for the "brick" . I'll PM you Think it will be guess work and a clues from the pix to get the resists about right, but some are ok so a quick read of the value and then the MM measure should be spot on. Yes Alex your idea would have been great but every little bit helps anyway I'll post pix when it is all done (eventually) Martin Hi Martin,, I sent you a PM Mike.
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pingu
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Reallising what has been taken on with the GB
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Post by pingu on Sept 24, 2015 12:49:01 GMT
Thanks Mike
Martin
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