Thank you Juma! Another simple gem of a circuit.
It so happens a package of 40 BF862's just arrived the other day.
Sort of unrelated but related to all your schematics is how clean and easy to read they are - some of the best drawing on this site IMO. What software do you use to create these nice diagrams? They look like ASCII character based.
PCB's completed (iron on transfer), now off to soldering those little SOT23 packages onto this 22mm x 35mm board (ea channel).
My DT880 250ohm headphones just arrived today and I am listening to this DAO amp and it sounds wonderful. Even without a preamp, it gets quite loud driven by an XMOS U8/BB PCM5102A DAC. Probably about 80% of all the volume I would ever need. So this preamp will really drive it over the edge.
I am taking a chance here with no protection circuit but DC offset has been stable at sub 2mV and I burned it in for 24 hrs with no issues.
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You're going to maybe get a 'chuckle' at this but before I rewired my 880's (250R, same as yours) I played around with adding series and shunt resistors just out of curiosity more than anything as these ideas of artificially changing the drivers 'Q' have been around for a long time, and using a 'current drive amp' adds another variable on top - the change in the actually balance of the sound of these relatively 'smooth' headphones was remarkable especially as I'm usually a k701 listener (AKGs)
PCB's completed (iron on transfer), now off to soldering those little SOT23 packages onto this 22mm x 35mm board (ea channel).
My DT880 250ohm headphones just arrived today and I am listening to this DAO amp and it sounds wonderful. Even without a preamp, it gets quite loud driven by an XMOS U8/BB PCM5102A DAC. Probably about 80% of all the volume I would ever need. So this preamp will really drive it over the edge.
I am taking a chance here with no protection circuit but DC offset has been stable at sub 2mV and I burned it in for 24 hrs with no issues.
How do you like it cmpared to the F5-based headamp?
What values of R did you use on the DT880's and was the higher Q giving deeper bass?
I don't have a working F5 HA at the moment as it was dismantled to test out the new Juma BJT HA. So I can't do a comparison with the new headphones I just got yet. But from my old MDRV6's I think the DAO sounds better from standpoint of neutral, very immediate impact of percussion and bass, clear and precise, very quiet. I have to get my F5 back up and will let you know.
Everything seemed backwards to the 'normal' resistive loading suggestions - for example, the common 120R series loading skewed the freq response on the DAO about 3 - 5 dB in the wrong direction for me as I was looking to increase the dynamics and 'drive' (or maybe 'bass punch' if you get my idea) as the 880's to me were far too 'polite' and laidback - however, adding about 450R in shunt kicked up the bass a bit without loosing the clarity plus added a bit of extra treble - this changed depending on the volume but I didn't get around to continuing with this 'stuff' - a couple of years ago now and forgotten much of details - I did find the Senn 650's were rather different but didn't like them very much
You have to play with this yourself to get an idea of just how to set your 'phones up - the beauty of the DAO is that it is so much more dynamic without a hint of fatigue - similar to those current drive amps from Korea with the Japanese circuits - I would imagine the F5 based sound would be rather different indeed but again, that circuit itself is easy to manipulate 'sound-wise' just by working on the power supplies and the active components
And there's always those dastardly, pesky 'tone controls' if analogue manipulation is required- if used with some disgression, can be very good indeed
You have to play with this yourself to get an idea of just how to set your 'phones up - the beauty of the DAO is that it is so much more dynamic without a hint of fatigue - similar to those current drive amps from Korea with the Japanese circuits - I would imagine the F5 based sound would be rather different indeed but again, that circuit itself is easy to manipulate 'sound-wise' just by working on the power supplies and the active components
And there's always those dastardly, pesky 'tone controls' if analogue manipulation is required- if used with some disgression, can be very good indeed
I got my F5 HA (with 2SK2013 and 2SJ313 outputs and Cap Mx) and connected the new DT880's - wow, that is some amazing sound. The extra voltage gain makes all the difference. These headphones are seriously better than my Sony MDRV6's. Sounds very nice, very clear, great deep bass, still very quiet. I think the DAO may have an edge once you get a preamp running on it, but the convenience (and simplicity) of the F5HA not needing a preamp is really good as I am keeping the chain very simple. Just a complementary pair of 2SK170/2SJ74 and one pair of 2SK2013/2SJ313 for everything.
Yeah, in parallel with the load - weird 'ain't it'
One thing you have to be rather pedantic about with this type of circuit is the ground returns for the 2 channels - as I ended up using C-Multipliers instead of the Shunt Regs that I started with, the Common or central Ground point was at the C-Mx O/P cap for each channel then this was sent to separate 10R Thermistors and then joined at the main chassis earth IEC plug - sounds rather cumbersome but made quite a difference in my setup and seemed more sensitive to wiring than voltage gain amps that I've built altho I do this pretty much to all the gear these days to minimize the ......
One thing you have to be rather pedantic about with this type of circuit is the ground returns for the 2 channels - as I ended up using C-Multipliers instead of the Shunt Regs that I started with, the Common or central Ground point was at the C-Mx O/P cap for each channel then this was sent to separate 10R Thermistors and then joined at the main chassis earth IEC plug - sounds rather cumbersome but made quite a difference in my setup and seemed more sensitive to wiring than voltage gain amps that I've built altho I do this pretty much to all the gear these days to minimize the ......
On all "big iron" class A amps like this the proper earth ground return is important so that a failed component doesn't turn into a fire. This circuit needs head amp protection though otherwise one risks smoking the cans very easily. I only tested my new DT880's after seeing DC offset was stable under 2mV for days. But one failed component and bam! It hits the rails.
Jameshill, what circuit are you using for protection, if any?
I am currently debugging the Juma BF862 SE preamp with Juma's help.
Jameshill, what circuit are you using for protection, if any?
I am currently debugging the Juma BF862 SE preamp with Juma's help.
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xrk971:
Since you seem to love to build headamps have you seen this?
http://www.diyaudio.com/forums/analog-line-level/296406-salas-dcg3-preamp-line-headphone.html
I haven't built it, but I have a PCB ordered during the group buy.
Since you seem to love to build headamps have you seen this?
http://www.diyaudio.com/forums/analog-line-level/296406-salas-dcg3-preamp-line-headphone.html
I haven't built it, but I have a PCB ordered during the group buy.
Jameshill, what circuit are you using for protection, if any?
This maybe silly of me but I've not used any 'phone protection at all - just lazy, I think - the dc drift on this thing is pretty low over the years so just crossed fingers that I don't suffer a component failure - all the valve h/amp have either transformer or blocking caps on the o/p and maybe this encourages me to be so complacent
I did notice that Patrick did develop a working circuit for headamp protection awhile back and always meant to build a set but ...
On power amps, I've found that the little IC based protection worked pretty well for me and surprisingly, it's been quite a long time since I've seen a dc condition on an amp output - on the 'pro-gear' I generally use some sort of series cap or minimum passive Xover on all speakers apart from the bass drivers (Pascal dsp switchmode amps used here)- maybe I'm overdue or living on borrowed time - yes, that must be it - I'll see if I can find the EUVL one and maybe see if can get 'prasi' do a board for it ...
Nice bit of work on your handmade pcb and still big enough to easily play with those small smds - I presume that there's still a difference in the sound of smd resistors like thru hole ones, yes?
What are those little 'boots' on the end of the wires that makes everything SO neat? - that's a new one - I like those, so much easier than heatshrink - I wonder if they come in different colours?
This maybe silly of me but I've not used any 'phone protection at all - just lazy, I think - the dc drift on this thing is pretty low over the years so just crossed fingers that I don't suffer a component failure - all the valve h/amp have either transformer or blocking caps on the o/p and maybe this encourages me to be so complacent
I did notice that Patrick did develop a working circuit for headamp protection awhile back and always meant to build a set but ...
On power amps, I've found that the little IC based protection worked pretty well for me and surprisingly, it's been quite a long time since I've seen a dc condition on an amp output - on the 'pro-gear' I generally use some sort of series cap or minimum passive Xover on all speakers apart from the bass drivers (Pascal dsp switchmode amps used here)- maybe I'm overdue or living on borrowed time - yes, that must be it - I'll see if I can find the EUVL one and maybe see if can get 'prasi' do a board for it ...
Nice bit of work on your handmade pcb and still big enough to easily play with those small smds - I presume that there's still a difference in the sound of smd resistors like thru hole ones, yes?
What are those little 'boots' on the end of the wires that makes everything SO neat? - that's a new one - I like those, so much easier than heatshrink - I wonder if they come in different colours?
Hi Jameshill,
Thanks for the kind words on my handmade PCB. It was a real eye opener how well the laser printer iron on transfer process worked. The traces and features are quite small and accurate. You have been like me not using protection and even on my main poweramps, none have protection. Loss of left channel on my 20yr old Sony MDRV6 was a wake up call and the first time I had an event with an amp that destroyed my driver. But had hat not been damaged, I probably would never have gotten the DT880's which are quite an amazing piece of engineering. I got the new black chrome special edition ones which look especially cool.
Those boots on the wires are molded rubber strain reliefs on solderless breadboard hookup wire. The tips are hard tin plated steel so can poke through those solderless breadboards well. I got them as part of a kit and yes they are multicolor and different lengths. They gave me so many I use them for audio leads on my amps cuz I ran out of small gauge wiring.
Here is the whole kit with breadboard, switchable regulated power supply daughter board (3.5v and 5v 78xx regs). Amazing value (free shipping).
3.3V/5V MB102 Breadboard power module+MB 102 830 points Prototype Bread board for arduino kit +65 jumper wires wholesale-in Demo Board from Computer & Office on Aliexpress.com | Alibaba Group
Thanks for the kind words on my handmade PCB. It was a real eye opener how well the laser printer iron on transfer process worked. The traces and features are quite small and accurate. You have been like me not using protection and even on my main poweramps, none have protection. Loss of left channel on my 20yr old Sony MDRV6 was a wake up call and the first time I had an event with an amp that destroyed my driver. But had hat not been damaged, I probably would never have gotten the DT880's which are quite an amazing piece of engineering. I got the new black chrome special edition ones which look especially cool.
Those boots on the wires are molded rubber strain reliefs on solderless breadboard hookup wire. The tips are hard tin plated steel so can poke through those solderless breadboards well. I got them as part of a kit and yes they are multicolor and different lengths. They gave me so many I use them for audio leads on my amps cuz I ran out of small gauge wiring.
Here is the whole kit with breadboard, switchable regulated power supply daughter board (3.5v and 5v 78xx regs). Amazing value (free shipping).
3.3V/5V MB102 Breadboard power module+MB 102 830 points Prototype Bread board for arduino kit +65 jumper wires wholesale-in Demo Board from Computer & Office on Aliexpress.com | Alibaba Group
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Jeez, a whole U$3.50 - had to get one - couldn't resist that!
The 880's sound a whole lot better after about 50 - 100 hrs use at normal listening volumes - I generally just plug them into any old tuner/amp and leave them play for a week. From memory, I think I ended up rewiring mine with 4 x silver wire in poly, not Teflon - sounded a bit brighter - a friend has them on that 'never-never' loan idea and I think he uses a standard Xfeed and says that makes a difference - he's a 'jazzer' (jazz nut) and loves the big brass sound up load w/out 'tearing the ears off' - he recently bought one of those Korean current drive amps Bakoon HPA-21) and it's rather good indeed - not the cheapest unit, about U$3k, I think, but in comparison to say the Cavalli Gold (about U$6k), a real bargain!! Love the sound of the Cavalli on anything - who wouldn't!
You've got me going again on this DAO unit - maybe, just maybe, an Aikido gain stage in front with Uriah's Clone Note vol control plus the Xfeed .....
The 880's sound a whole lot better after about 50 - 100 hrs use at normal listening volumes - I generally just plug them into any old tuner/amp and leave them play for a week. From memory, I think I ended up rewiring mine with 4 x silver wire in poly, not Teflon - sounded a bit brighter - a friend has them on that 'never-never' loan idea and I think he uses a standard Xfeed and says that makes a difference - he's a 'jazzer' (jazz nut) and loves the big brass sound up load w/out 'tearing the ears off' - he recently bought one of those Korean current drive amps Bakoon HPA-21) and it's rather good indeed - not the cheapest unit, about U$3k, I think, but in comparison to say the Cavalli Gold (about U$6k), a real bargain!! Love the sound of the Cavalli on anything - who wouldn't!
You've got me going again on this DAO unit - maybe, just maybe, an Aikido gain stage in front with Uriah's Clone Note vol control plus the Xfeed .....
Jameshill,
The new Juma preamp I just built and now adjusted for proper currents works very very well. It is so clear and transparent and has just the right amount of gain to let me hit max volume when volume is turned to max. I typically listen at around 80%. You should try this BF862 single ended class A pre. It has a wonderful quality.
Here it is running with the DAO as a system:
Is the Cavalli Gold amp better sounding than this DAO?
I will try the break-in by letting play all week long (on a safe CD player headphone output).
The new Juma preamp I just built and now adjusted for proper currents works very very well. It is so clear and transparent and has just the right amount of gain to let me hit max volume when volume is turned to max. I typically listen at around 80%. You should try this BF862 single ended class A pre. It has a wonderful quality.
Here it is running with the DAO as a system:
Is the Cavalli Gold amp better sounding than this DAO?
I will try the break-in by letting play all week long (on a safe CD player headphone output).
In some ways the Cavalli is better and in others it's not - about what you'd expect between a current drive fet stage and a u-beaut valve stage - mind you it's very different on different 'phones - on the JPL, for example, the Cavalli's sound exceeded the detail you expect from those Stax ribbons without sounding 'thin' and this gives a sound that has enormous depth, etc, etc but still retains that warmth with really good valve designs -really really nice music - the DAO doesn't get this far in the detail department but has a better controlled bass, and 'grunt' - I fitted some Rhopoints on the input to get a bit more 'air' in the top end without any 'edge' for the k701s fitted with Chimera Labs cryoed UPOCC wire - went a bit over the top as I sometimes do and here it worked quite well - pretty nice sound also - just my opinion mind you - my DAO was completed a few years ago and I never felt the need to change it after playing around with components, and so on - from memory, it's running at a bit over 300mA and just over +/- 20 volts for a total around 15W/ch - runs quite hot, above 45*C
I'd say the Bakoon has more in common with the DAO than any of the others I've listened too but it's all a pretty personal view particularly with digital data stream vs an analogue source
As you can tell, I'm no technical guru.
I'd say the Bakoon has more in common with the DAO than any of the others I've listened too but it's all a pretty personal view particularly with digital data stream vs an analogue source
As you can tell, I'm no technical guru.
xrk971:
Since you seem to love to build headamps have you seen this?
http://www.diyaudio.com/forums/analog-line-level/296406-salas-dcg3-preamp-line-headphone.html
I haven't built it, but I have a PCB ordered during the group buy.
Thanks for the tip Hikari. I have not seen this one yet but does look very promising. It's a bit more complicated and uses an LTP input stage so sound signature will be different. Lately I find myself oreferig then harmonic profile of a singleton input. I will keep in mind though.
My next venture will be to try and make a pocket class Ansibgle endednheadamp using lots of BF862's in parallel.
Here's another one that I might try. From this thread:
http://www.diyaudio.com/forums/solid-state/298026-tin-fets-headphone-amplifier-2.html
Design by EUVL. I did layout with PowerPoint.
http://www.diyaudio.com/forums/solid-state/298026-tin-fets-headphone-amplifier-2.html
Design by EUVL. I did layout with PowerPoint.
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