toad
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I am the Super Toad, the Original Toad, the Whole Toad and nothing BUT the toad.... don't forget it!
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Post by toad on Nov 17, 2010 17:53:09 GMT
I actually listen to my Aune at work most days often for a few hours so TBH the Aune sound is the one I know the best. Maybe I'm just weird prefering the Solo  |
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Deleted
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Post by Deleted on Nov 17, 2010 18:03:06 GMT
I have 68 ohm output resistors in mine soon to be replaced with 75 ohm ones, would lowering the resistors value in Ians(100 ohm) give him the SQ he is looking for do you think Mike,Frans or anybody else in the know. I could detect a difference when i A-B them, but not sure now where the differences were Mick. Mine's at 120 ohms. so is very close to Ian's. Gain is high so it really pushes hard into the K701. You do tend to 'learn' sounds and sometimes a new sound needs to have time for your head to settle!! I found that the Panda strengths are much further reaching than I first thought, depending on what I was listening to. Now, I just relax and listen and enjoy the surprises. However, if you're in 'test' mode you can almost feel forced into hearing some massive improvement which can be a let down!! My wife expects amp A to sound absolutely totally different from amp B and then is underwhelmed when they are both close to each other and differences are slight. However, with the Panda, you play something and suddenly, this massive bass comes out of nowhere on one recording while on another, it isn't as pronounced. Long term is very different. Poor imaging may be a result of not burned in yet. |
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XTRProf
Fully Modded
Pssst ! Got any spare capacitors ?
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Post by XTRProf on Nov 18, 2010 5:43:46 GMT
Wow, 74 pages. To cut a long story short, how does this thing even up with the SCHA, the SC Class A amp or even the MF HAs? Just doesn't want to got thru the 74 pages ...........  Thanks.  |
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Post by Deleted on Nov 18, 2010 5:55:53 GMT
Wow, 74 pages. To cut a long story short, how does this thing even up with the SCHA, the SC Class A amp or even the MF HAs? Just doesn't want to got thru the 74 pages ........... Thanks. Chong It's not really possible to directly compare them, as they have very different sound attributes. It's a little like trying to get a consensus about whether valve amplifiers sound best, or SS amplifiers sound best. It all comes down to personal taste. Alex |
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Post by PinkFloyd on Nov 18, 2010 10:25:55 GMT
Ian (Toad) you're looking at a few hundred hours before she'll settle (just look at the solo for example, doesn't sound good until it's been left on for 3 weeks!  ).... Panda is the same as all amps, requires time before it really "blossoms". Maybe the Solo suits your ears better but NO WAY does it do bass like the Panda? Main reason I got rid of all my Solo amps was I found them relatively thin sounding (especially the "green" one).... The LM4562 is a nice chip though so will have changed the signature a little bit. |
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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
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Post by toad on Nov 18, 2010 12:20:52 GMT
I'm happy with the Panda as is but is it does indeed "blossom" then I'll be even happier.
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leo
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Post by leo on Nov 18, 2010 19:15:31 GMT
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Post by Deleted on Nov 18, 2010 19:50:24 GMT
RG led the way ....... again.  Take that dirty link off immediately Miguel!!!  |
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Post by PinkFloyd on Nov 18, 2010 20:29:33 GMT
Blimey, I've never known that guy to EVER say "that's a nice amp".... he's always commenting from his arm chair but never seems to actually "listen" to any of the amps he comments on... it must be a Belgian thing |
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Post by Deleted on Nov 18, 2010 22:09:24 GMT
There is absolutely nothing in this design that has anything to do with the Panda, nor could the PCB be used to build this design on. It's a completely different design with completely different parts and completely different topology Technically I would prefer the Panda myself (the 'improved' design does not have the needed internal power supply). If I were to do some mods 'RG style' I would mod the power supply transistors Q3 and Q12 and pull an 'Alex' on it (insert JLH's as everyone seems to like that) The comment on the TIP42/41 being outdated and then replace with the even older BD139/140 in a totally different configuration is a bit funny. ;D Simulations (which he did) are just that and do NOT take board layouts into consideration which can f#@k up this kind of 'fast' amps. A bandwith of 11.5MHz is nice for video amps. Myself I would limit the input of every amp to 100kHz to avoid TIM and amplification of unwanted signals. There simply is NO audio source/nor studio in the world that can even produce (audio realated) signals below 10Hz and beyond 50 kHz so there is no need for a bandwith bigger then DC (0Hz) to above 100kHz. In fact I have never seen any recordings with relevant info above 35kHz. Even 35kHz harmonics are below 90dB in these cases anyway. That's MY opinion at least |
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leo
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Post by leo on Nov 18, 2010 22:38:00 GMT
There is absolutely nothing in this design that has anything to do with the Panda, nor could the PCB be used to build this design on. It's a completely different design with completely different parts and completely different topology Technically I would prefer the Panda myself (the 'improved' design does not have the needed internal power supply). If I were to do some mods 'RG style' I would mod the power supply transistors Q3 and Q12 and pull an 'Alex' on it (insert JLH's as everyone seems to like that) The comment on the TIP42/41 being outdated and then replace with the even older BD139/140 in a totally different configuration is a bit funny. ;D Simulations (which he did) are just that and do NOT take board layouts into consideration which can f#@k up this kind of 'fast' amps. A bandwith of 11.5MHz is nice for video amps. Myself I would limit the input of every amp to 100kHz to avoid TIM and amplification of unwanted signals. There simply is NO audio source/nor studio in the world that can even produce (audio realated) signals below 10Hz and beyond 50 kHz so there is no need for a bandwith bigger then DC (0Hz) to above 100kHz. In fact I have never seen any recordings with relevant info above 35kHz. Even 35kHz harmonics are below 90dB in these cases anyway. That's MY opinion at least I thought you'd like it Frans (joke) its why I added the smiley BTW Simulations (which he did) are just that and do NOT take board layouts into consideration which can f#@k up this kind of 'fast' amps.
A bandwith of 11.5MHz is nice for video amps.Spot on with that! |
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leo
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Post by leo on Nov 18, 2010 22:41:51 GMT
There is talk of HIFIDIYNET supplying a fully built and tested Panda... would anybody be interested? Each amp would have to meet STRICT quality control procedures. They have promised me that they will match the transistors and test each unit (soak test) for 48 hours and then trim the DC to as close to zero as poss.... Let me know the interest levels..... I will ensure the build quality is first class. Mike. Makes sense, theres obviously those out there not interested in diy but would like to try out one of these amps |
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Post by Deleted on Nov 19, 2010 16:54:39 GMT
If there are those that want to increase the output voltage of the Panda (will not make the output transistors get hotter) and thus the output power ?
You can squeeze out a higher voltage to drive the HD800 nearer it's maximum power rating but need to be aware that you can over-drive other headphones if the output resistance is not increased at the same time.
As is the output voltage is around 11 Vrms (if no headphone is connected or no output resistors are fitted.
This can be increased to 15V Vrms.
With a 120 Ohm output resistor you can drive an HD800 to 0.4 Watt (standard with 120 Ohm = 0.2W)
a K701 can be driven to 0.4 Watt also but this headphone is rated at 0.2 W so only recommended for HD800.
Will post the how to if people are interested.
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Post by Koolind on Nov 19, 2010 17:18:46 GMT
If there are those that want to increase the output voltage of the Panda (will not make the output transistors get hotter) and thus the output power ? You can squeeze out a higher voltage to drive the HD800 nearer it's maximum power rating but need to be aware that you can over-drive other headphones if the output resistance is not increased at the same time. As is the output voltage is around 11 Vrms (if no headphone is connected or no output resistors are fitted. This can be increased to 15V Vrms. With a 120 Ohm output resistor you can drive an HD800 to 0.4 Watt (standard with 120 Ohm = 0.2W) a K701 can be driven to 0.4 Watt also but this headphone is rated at 0.2 W so only recommended for HD800. Will post the how to if people are interested. I dont have the HD800's.. However i have noticed that the Panda doesnt really like my AKG K340¨s. It doesnt really seem to have the same energy as my Darkvoice 336i and also i need to turn it up at full power to get a sufficient output volume. I am using 68ohm output resistors. I suppose that it might be beneficial to lower, or maybe completely remove the output resistors (i actually have bought a stepped turning swich for swiching between output resistor values to try it out) I suppose that i would gain a bit of power by lowering the output resistance ? Does this increase the voltage swing (i have read that the K340 requires a large voltage swing) The AKG K340's are by the way 400ohms, so quite high-ohmic! |
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Post by Deleted on Nov 19, 2010 17:23:30 GMT
deleting the output resistors in this case (400 Ohm) will only increase the output voltage slightly ( 1.17x) which is about 1.4 dB in SPL gained.
the higher output voltage will give 3dB gain.
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Post by Koolind on Nov 19, 2010 17:32:55 GMT
deleting the output resistors in this case (400 Ohm) will only increase the output voltage slightly ( 1.17x) which is about 1.4 dB in SPL gained. the higher output voltage will give 3dB gain. So presumeably raising the output voltage will have some sideeffects ? Or what ? If not, it sounds like a quite nice mod? Does it require much tweeking? I suppose that i could also "just" raise the gain.. That just doesnt solve that fact that the panda doesnt seem to have enough muscle to throw the K340 around. I would have thought that the panda would seem more powerfull, it just doesnt sound like that to me though. The Darkvoice 336i isnt a bad amp either though (or so i think, at least) |
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Post by Koolind on Nov 19, 2010 17:34:50 GMT
It could also just be that the K340 have a nice synergi (or that i have gotten very used to the sound ) that i think this is the case.. |
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Post by Deleted on Nov 19, 2010 21:19:19 GMT
Raising the gain doesn't give it a higher output voltage. Just a lower vol pot setting to give the same SPL. This is what needs to be changed: I believe the voltage on the big caps is around 27V - 28V which it be at least for it to work. If it's not, the 18-0-18V transformer should be replaced by a 20-0-20 or 22-0-22V type. Then DZ1,DZ3,DZ5 and DZ6 need to be changed to 24V/0.4W types (were 18V 1.3W). The capacitors C3, C4, C10, C12, C20, C22, C29 and C30 need to be replaced with the same value but 35V types (they are now 25V I believe) R7, R18, R35 and R51 need to be changed to different values (depending on the used transformer) or, even better replaced by CCS like Leo suggested (FET's with the Gate connected to the Source) or real CRD. That's it....  It is also the absolute maximum you can squeeze out of it. Any higher and the used 2SA1015 and 2SC1815 transistors will have reached their maximum voltage limit. For the K340 doing this mod and deleting the output resistors (or putting in something like 10 or 22 Ohm) will provide about 4 dB more headroom. Increasing the gain is helpfull as it needs to deliver a higher output voltage. Won't start to sound like a tube amp. The sound will remain the same it will only be able to play a bit louder without reaching clipping levels.  |
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Post by PinkFloyd on Nov 19, 2010 21:44:00 GMT
The K-340 are VERY amp dependant I'm afraid, especially if they are starting to lose charge.... Karl peschel (AKG Technical) told me the electrects would hold charge for about 30 years and after that they would slowly degenerate.
Rick reckoned they could be recharged with a cell battery / resistor (or some such contraption) I can't find the original thread but it's here somewhere (headphone section)....
Here's a bit I said on the K-340 a few years ago:
"I tried them with the Solo, the X-CAN v2 and the Chiarra at the time and from what I remember they all sounded pretty weedy with them..... no bass to speak of but a really nice midrange.
Rick had a theory about recharging the electrets with a battery cell.... maybe he'll chip in when he returns to the forum. Possibly the one biggest area to concentrate on is recharging the electrets as, according to Karl Peschel, their lifespan is only 20 to 30 years.... of course this plays no part in the bass department and to get any decent bass out of these guys you'll need to find an amp than can really drive them.
Nigel reported a "lot" of bass and others have also reported the HEED as being able to drive the AKG K-1000 so maybe the HEED is the way to go with the K-340.
If we can find a way to recharge the electrets then possible these guys will really sing a different tune.......... "
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Post by Koolind on Nov 19, 2010 23:35:00 GMT
The electrets is fine i think and there is plenty of bass, thats not the problem. It would be great though, if they could actually be improved by re-energizing the drivers. They have sounded like this from when i got them a couple of years ago. The other pair i have heard sounded very similar also.
My problem is however that the SPL is slightly in the low end using my source (which is a bit "weak" also) at this point. The Darkvoice does go a bit more loud. Maybe the Darkvoice is just a nice match for the very odd K340. I doubt that the HEED will do any better, atleast i wasnt that impressed when i heard it with some other headphones last year.
Frans; Thanks for the technological view. It sounds like quite a few components to change though if the improvement isnt that significant?
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Post by PinkFloyd on Nov 19, 2010 23:50:33 GMT
The electrets is fine i think and there is plenty of bass, thats not the problem. It would be great though, if they could actually be improved by re-energizing the drivers. They have sounded like this from when i got them a couple of years ago. The other pair i have heard sounded very similar also. My problem is however that the SPL is slightly in the low end using my source (which is a bit "weak" also) at this point. The Darkvoice does go a bit more loud. Maybe the Darkvoice is just a nice match for the very odd K340. I doubt that the HEED will do any better, atleast i wasnt that impressed when i heard it with some other headphones last year. Frans; Thanks for the technological view. It sounds like quite a few components to change though if the improvement isnt that significant? The Panda is also CRAP driving my Sennheiser HD-414 (600 ohm), fortunately I only listen to the 414's once every couple of years..... to be totally upfront Koolind, I'd stick with the DarkVoice for K-340 duty and use the Panda for more efficient "modern" headphone duty. I don't think the Panda is suited to driving the 330 ohm K-340... they need a bit more voltage (as opposed to current) to drive them..... the Panda is maybe not the best amp for them  |
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Post by Koolind on Nov 20, 2010 0:26:50 GMT
The electrets is fine i think and there is plenty of bass, thats not the problem. It would be great though, if they could actually be improved by re-energizing the drivers. They have sounded like this from when i got them a couple of years ago. The other pair i have heard sounded very similar also. My problem is however that the SPL is slightly in the low end using my source (which is a bit "weak" also) at this point. The Darkvoice does go a bit more loud. Maybe the Darkvoice is just a nice match for the very odd K340. I doubt that the HEED will do any better, atleast i wasnt that impressed when i heard it with some other headphones last year. Frans; Thanks for the technological view. It sounds like quite a few components to change though if the improvement isnt that significant? The Panda is also CRAP driving my Sennheiser HD-414 (600 ohm), fortunately I only listen to the 414's once every couple of years..... to be totally upfront Koolind, I'd stick with the DarkVoice for K-340 duty and use the Panda for more efficient "modern" headphone duty. I don't think the Panda is suited to driving the 330 ohm K-340... they need a bit more voltage (as opposed to current) to drive them..... the Panda is maybe not the best amp for them I suppose that very few are suited. I actually also bought the 336i specially because that people at that time was claiming that there was a really good synergy. I wonder what they were thinking 25 years ago making them before all of these headphone amplifiers have been introduced. If you connect them to a regular output, that be cd-player or soundcard they sound like absolute crap. Throw a bunch more power in and they perform really nice. I must say though that the Panda isnt doing very bad at all; Better than most amps i have tried it with. Its just that its running on full steam at some of the mildly low-level tracks where it could have used a tiny bit more power. Using my other headphones, the panda really shines also! My Sony SA-5000 has become a completely different beast that actually produces a decent amount of bass. |
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Post by mrslim on Nov 22, 2010 19:50:52 GMT
Ok, I just pushed the button on a Panda. Would there be any issues using a 20 - 0 - 20 transformer with it? Antek doesn't have a 50VA 18 Volt model.. www.antekinc.com/gview.php?d[]=0 |
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Post by Deleted on Nov 23, 2010 14:28:05 GMT
No issues,
the total power consumption of the amp = about 11W (11VA).
I wouldn't go beyond 24-0-24V AC transformers.
The power caps will be reaching 35Vdc (spec'd at 42Volt) and total power consumption will go up a bit to 13.5W (and thus the cooled transistors will get somewhat hotter when a 24-0-24V AC transformer is used)
With the modifications mentioned in reply Reply #1117 the output power of the Panda could easily be doubled when a 20-0-20 or 22-0-22V transformer is used + mods.
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Post by yellowjeep on Nov 26, 2010 8:24:19 GMT
Read the entire thread over the course of a few days and decided that this is my next project come to find out that they are no longer on eBay. Here's hoping that he posts some more in the next few weeks or so...
Oh yeah first post! Hello. I like your style over here.
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).... Panda is the same as all amps, requires time before it really "blossoms".
