|
Post by PinkFloyd on Nov 1, 2010 0:11:15 GMT
That's a great build Mick. Thing about a build going a bit wrong at the start, you appreciate it all the more when it starts to deliver quality sound, which Panda surely does. One thing I wonder, I see the legs on your Varistor etc are not insulated. Are they not a risk? I don't mean this negatively, I haven't fitted any to mine yet and it would be easier if they could be left like that. Syd Re: varistor... ONLY a problem if you TOUCH those exposed parts.... if it's all cased up then no problem. If you "must" comply with regulations then best you heatshrink all exposed conductors..... there will not be a problem as long as you keep your tongue / fingers away from the "live" parts
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 1, 2010 0:34:17 GMT
That's a great build Mick. Thing about a build going a bit wrong at the start, you appreciate it all the more when it starts to deliver quality sound, which Panda surely does. One thing I wonder, I see the legs on your Varistor etc are not insulated. Are they not a risk? I don't mean this negatively, I haven't fitted any to mine yet and it would be easier if they could be left like that. Syd Re: varistor... ONLY a problem if you TOUCH those exposed parts.... if it's all cased up then no problem. If you "must" comply with regulations then best you heatshrink all exposed conductors..... there will not be a problem as long as you keep your tongue / fingers away from the "live" parts Mike I wasn't trying to be smart and of course it will be safe if boxed up. I wondered if, given my poor knowledge of electronics, that going across + and - might 'negate' a shock hazard. It seems weird enough to me that you can do that in the first place without the Varistor or cap going bang. Syd
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 1, 2010 11:36:31 GMT
That's a great build Mick. Thing about a build going a bit wrong at the start, you appreciate it all the more when it starts to deliver quality sound, which Panda surely does. One thing I wonder, I see the legs on your Varistor etc are not insulated. Are they not a risk? I don't mean this negatively, I haven't fitted any to mine yet and it would be easier if they could be left like that. Syd Hi Syd, Oh yes, i see where you mean and have made them safe, already had three "belts" from the push on terminals there before deciding to insulate them, so yes a good idea, as the third "belt" made me feel a little queezy!! ;D Mick.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 1, 2010 12:41:29 GMT
That's a great build Mick. Thing about a build going a bit wrong at the start, you appreciate it all the more when it starts to deliver quality sound, which Panda surely does. One thing I wonder, I see the legs on your Varistor etc are not insulated. Are they not a risk? I don't mean this negatively, I haven't fitted any to mine yet and it would be easier if they could be left like that. Syd Hi Syd, Excuse my ignorance, do you mean the resistors on the back of my HP socket. Mick. Mick, Syd was talking about the 10p-sized blue disc (varistor) that straddles the +ve and -ve terminals on the mains socket. It was only mentioned as both Mike and Alex have repeatedly told us knobbies to insulate everything, to avoid any remote chance of electricution when doing any further testing or measurements. As Mike pointed out, once the unit is closed there is zero risk. Chris edit, too late ;D
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 1, 2010 13:52:27 GMT
�
Yes realized that after my initial posting Chris, thicko me.
Thanks anyway, its safe now.
Mick.
|
|
|
Post by PinkFloyd on Nov 1, 2010 20:22:27 GMT
That's Panda Three populated I'll fire her up tomorrow and have a listen. Panda Four will be next and it will be a bit of a different beast entirely Just awaiting the Galaxy enclosure (from audiokit.it) and I'll get P3 housed up. Just to recap.... Gain resistors are 220R, 246 transistors have been closely matched, 22pF ceramics have been replaced with 22pF silvered mica. All electrolytic caps have been bypassed with 2.2uF (2u2) WIMA film caps (metalized polyester) apart from the 3300uF which have been bypassed with 3.3uF Wima metalized, 100nF EVOX polypropylene, 220pF WIMA polypropylene and 470pF polythene caps (you can see the polythene caps nestled up against the body of the EVOX polyprops)..... Nothing "radical" but I do want to hear if there is a difference between the naked electrolytics and bypassed 'lytics.... it should go one way or the other, better or worse.... sometimes I have had major improvements from bypassing, other times it has sounded awful Oh well, I'll soon know I've set panda three to 1.5V (across 1K5) too but for comparison tests between Panda one and three I will re-calibrate it to 1.3V. Not the best of pics, light was bad.......
|
|
|
Post by PinkFloyd on Nov 1, 2010 20:34:29 GMT
BTW.... I don't propose to have tons of Panda's kicking about the place so as soon as I have compared Panda one to Panda three there will be one fully populated (and tested) board available for sale. It will be parts cost (£50) plus my time (the time it takes me to populate a board and test it / set it up).... I may even do that with the rest of the kits I have here as there doesn't seem to be many people interested, maybe if the boards came "populated" and tested there would be more interest? One word of warning though, they won't be "cheap".... if I'm going down that route I will have to offer a warranty and after sales service..... I'll leave it at the "one" board being available in the next few weeks and see how it goes from there... it's very time consuming putting these together and if you make a mistake even more time consuming rectifying it Nope, I am already convincing myself that selling populated boards is not a good idea
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 1, 2010 20:44:19 GMT
Nice work Mike, Looks the business, i see you have increased the gain by 3dec on this one, do you feel that`s enough, as opposed to 6dec. Be interested to hear what sort of difference these mods make to the SQ. Mick.
|
|
|
Post by PinkFloyd on Nov 1, 2010 21:14:58 GMT
Nice work Mike, Looks the business, i see you have increased the gain by 3dec on this one, do you feel that`s enough, as opposed to 6dec. Be interested to hear what sort of difference these mods make to the SQ. Mick. As far as my listening needs go I was quite happy with the stock gain of the amp.... the headphones I use are pretty easy to drive and I found it quite "different" being able to use the pot all the way around instead of just the first quarter of it. The 150R will give you a pretty much "conventional" type behaviour.... the type of thing you are used to from commercial designs..... the 220R will extend the useable range of the pot a bit further and the stock 300R will give you, pretty much, full use of the pot. What does this mean in layman's terms? Well, if you have a relatively hard to drive 'phone like the K-701 and are listening to low level classical passages it may be that you have to crank the volume up to the 3 0' clock position..... fit the 220R and you are down to the 12 0' clock position (to hear the same volume).... fit the 150R and you will get the same volume @ the 10 0'clock position. In Ian's case, the amp simply wasn't "amplifying" the quiet passages enough.... if he wanted to crank them up and analyse them then "full" volume wouldn't be enough..... the stock 300R is perfectly good on normal passages but if you really want to listen (at a decent volume) to the quiet parts then you'll have to adjust the gain....
|
|
|
Post by PinkFloyd on Nov 1, 2010 21:47:15 GMT
It's actually not that nice Mick.... I have flooded too much solder into the joints (in places).... I put this one together with Cardas solder I had laying about and it required flux... it was "so" free flowing that it was sometimes hard to judge just how much had flooded through to the other side of the board.... with the flux it's like "water" flowing through. What we are looking for (ideally) when soldering "through hole" boards is for the pad on the bottom of the board to be coated and the pad on the top of the board to be coated..... both should resemble a nice shiny dome. The idea is that the solder floods through the joint and should look the same on the bottom of the board as it does on the top (and vice versa)....... Look closely at this photo.... this is the "top" of the board and all joints should be uniformly coated in solder (same as the bottom).... if you look closely enough you will see that some joints have had too "much" solder flowing through and others (check the silvered mica capacitor) have not had enough..... This is all perfectly "good" as the through hole pads are connected but for a REALLY first class "milspec" job we are looking at both bottom and top pads being flooded with a shiny dome of solder, not too much not too little. I will "rework" each joint tomorrow and they will be perfect... as they were in Panda one and two... I'm not used to working with flux (haven't had to use it for years thanks to rosin cored solder) but will spend a few days "honing" the art again
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 1, 2010 21:50:30 GMT
Nice work Mike, Looks the business, i see you have increased the gain by 3dec on this one, do you feel that`s enough, as opposed to 6dec. Be interested to hear what sort of difference these mods make to the SQ. Mick. As far as my listening needs go I was quite happy with the stock gain of the amp.... the headphones I use are pretty easy to drive and I found it quite "different" being able to use the pot all the way around instead of just the first quarter of it. The 150R will give you a pretty much "conventional" type behaviour.... the type of thing you are used to from commercial designs..... the 220R will extend the useable range of the pot a bit further and the stock 300R will give you, pretty much, full use of the pot. What does this mean in layman's terms? Well, if you have a relatively hard to drive 'phone like the K-701 and are listening to low level classical passages it may be that you have to crank the volume up to the 3 0' clock position..... fit the 220R and you are down to the 12 0' clock position (to hear the same volume).... fit the 150R and you will get the same volume @ the 10 0'clock position. In Ian's case, the amp simply wasn't "amplifying" the quiet passages enough.... if he wanted to crank them up and analyse them then "full" volume wouldn't be enough..... the stock 300R is perfectly good on normal passages but if you really want to listen (at a decent volume) to the quiet parts then you'll have to adjust the gain.... Good explanation Mike, I was thinking along those lines myself, that clarifies it nicely. Mick.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 1, 2010 21:56:01 GMT
That's exactly what the problem was. The whole range of the pot is used and on some classical stuff, I was approaching full whack. The amp doesn't struggle in any way but for less 'compressed' stuff I just need a bit more on the K701.
It was fine with the HD600 and 250. The K701 needs quite a bit more for it to bloom. I'm not trying to deafen myself but the AKG's need a lot of power for 68 ohms (is it?). (Or a lot of current)
|
|
|
Post by PinkFloyd on Nov 1, 2010 21:56:35 GMT
By the way, Ian..... Your Panda is on it's way home tomorrow, it should be with you on Wednesday.
Mike.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 1, 2010 22:01:04 GMT
By the way, Ian..... Your Panda is on it's way home tomorrow, it should be with you on Wednesday. Mike. OK Mike, Thanks ever so much. I hope the damage wasn't too drastic. I had visions of the PO guys dropping it straight down on to a corner or something. PM me the parts and post and I'll send it off to you. Mike, you'll have quite a few soon. One in the bathroom, one in the bedroom, lounge, kitchen. There's four!! I leave amps everywhere with matching headphones!!
|
|
|
Post by PinkFloyd on Nov 1, 2010 22:08:56 GMT
By the way, Ian..... Your Panda is on it's way home tomorrow, it should be with you on Wednesday. Mike. OK Mike, Thanks ever so much. I hope the damage wasn't too drastic. I had visions of the PO guys dropping it straight down on to a corner or something. PM me the parts and post and I'll send it off to you. Mike, you'll have quite a few soon. One in the bathroom, one in the bedroom, lounge, kitchen. There's four!! I leave amps everywhere with matching headphones!! Ian. It wasn't at all drastic..... the knob had taken a knock and sheared off the potentiometer..... fortunately, all the pads were intact.... it's a lot better now and will be bullet proof in the post.... don't worry
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 1, 2010 22:27:12 GMT
It was fine with the HD600 and 250. The K701 needs quite a bit more for it to bloom. I'm not trying to deafen myself but the AKG's need a lot of power for 68 ohms (is it?). (Or a lot of current) Indeed the K701 needs more 'power'. This is because of the efficiency, which is poor but might be so for a reason (namely better linearity at higher volumes). Effieciency means how much power (voltage) is needed to reach a certain SPL (sound pressure level) It simply needs more voltage then most other cans so therefore you have to crank up the volume control to reach the same SPL. because it needs more voltage AND it has a rather low impedance (usually the low impedant cans have a high efficiency) more current is drawn from the amp. An amplifier gives an output voltage and must be able to deliver the current that is a result of the applied voltage through a certain resistance (impedance actually, there is a difference). So amps that must drive a K701 must have a large output swing (voltage) AND must be able to deliver enough current. Both are very easy feats for the Panda.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 1, 2010 22:27:28 GMT
You've got me sussed haven't you, Mike? You know I worry..... It's because I love the sound of that amp so much. (and how it looks)
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 1, 2010 22:49:11 GMT
It is extremely effortless with the K701. I really think it's a good match. The first time I've ever felt that it's 'just right' and a comfortable listen that keeps scaling up as you push the volume. Normally with the K701's I get to a point where it needs backing off due to a 'harsh' top end. I don't get this at all with the Panda.
To some extent, I think I've been happier with lesser amps as long as their top end is less. It calms the AKG treble, but it ain't exactly hi fi when you compare it to what you get from the Panda. Much more in control to say the least.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 1, 2010 23:06:42 GMT
It's actually not that nice Mick.... I have flooded too much solder into the joints (in places).... I put this one together with Cardas solder I had laying about and it required flux... it was "so" free flowing that it was sometimes hard to judge just how much had flooded through to the other side of the board.... with the flux it's like "water" flowing through. What we are looking for (ideally) when soldering "through hole" boards is for the pad on the bottom of the board to be coated and the pad on the top of the board to be coated..... both should resemble a nice shiny dome. The idea is that the solder floods through the joint and should look the same on the bottom of the board as it does on the top (and vice versa)....... Look closely at this photo.... this is the "top" of the board and all joints should be uniformly coated in solder (same as the bottom).... if you look closely enough you will see that some joints have had too "much" solder flowing through and others (check the silvered mica capacitor) have not had enough..... This is all perfectly "good" as the through hole pads are connected but for a REALLY first class "milspec" job we are looking at both bottom and top pads being flooded with a shiny dome of solder, not too much not too little. I will "rework" each joint tomorrow and they will be perfect... as they were in Panda one and two... I'm not used to working with flux (haven't had to use it for years thanks to rosin cored solder) but will spend a few days "honing" the art again Mike, I can understand what your saying, and i accept the fact that you like the job to be perfect( i am the same with what i do), however it still looks pretty damn good to me, i am sure it will have reached your standards by this time tomorrow, so you should then be 100% happy with the build, and hopefully the SQ also. Mick.
|
|
xerxes
Been here a while!
Posts: 1,115
|
Post by xerxes on Nov 2, 2010 2:25:58 GMT
Hi Mike, I've been reading this thread with interest. I'm still using a WNA MkII which you helped me modify some time ago: www.tdsf.co.uk/Audio/WNA.shtml and wondered how the PANDA compares to your WNA, I assume you still have one knocking about somewhere. When I use the WNA with my current Monica DAC via a USB -> SPDIF converter it sounds a little soft and polite when compared to my little Pimeta amp. However when connected to my CD player, a Cyrus CD8x, which is said to have a very detailed if rather forward sound, I still think it sounds pretty good. By the way, what happened to WNA? I notice the web site has dissappeared.
|
|
toad
Been here a while!
I am the Super Toad, the Original Toad, the Whole Toad and nothing BUT the toad.... don't forget it!
Posts: 1,223
|
Post by toad on Nov 2, 2010 10:07:47 GMT
Hi people with far more electronics experience than myself I am planning on using my Arcam DV135 as the main source for my Panda so what's the best way to phrase a question to Arcam about whether the DV135 gives out DC as Mick's CDP does? Thanks in advance for any advice. Ian
|
|
|
Post by PinkFloyd on Nov 2, 2010 10:35:38 GMT
Hi people with far more electronics experience than myself I am planning on using my Arcam DV135 as the main source for my Panda so what's the best way to phrase a question to Arcam about whether the DV135 gives out DC as Mick's CDP does? Thanks in advance for any advice. Ian Is there any DC present on the output?
|
|
toad
Been here a while!
I am the Super Toad, the Original Toad, the Whole Toad and nothing BUT the toad.... don't forget it!
Posts: 1,223
|
Post by toad on Nov 2, 2010 10:37:35 GMT
Without a multimeter is it possible to check?
Or is this the way to phrase the question to Arcam and if so wouldn't I need to know the amount of DC if it was present?
Sorry to sound like an idiot but Electronics is like an Alien language to me.
|
|
|
Post by PinkFloyd on Nov 2, 2010 11:03:20 GMT
Yes, ask them if there is any DC on the output.... ask them if they employ a DC servo or do they use output coupling capacitors.
You can get a multimeter quite cheaply Ian and it's easy to measure... can you even borrow one from somebody?
Mike.
|
|
|
Post by PinkFloyd on Nov 2, 2010 11:04:56 GMT
I can tell you that the T585 has zero DC at the output
|
|