Deleted
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Post by Deleted on Aug 14, 2011 21:13:02 GMT
I suppose it has very similar features and design (mimicing an opamp with discrete parts).
I expect the output voltage and current capabilities to be much the same.
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Post by pandapops on Aug 19, 2011 2:40:17 GMT
Just added a bypass cap to the four big caps and the four 100UF caps in the voltage regulators, and the difference is massive - the sound has really come together with this, amp now a keeper. Either I had a problem with my setup, else not bypassing these caps is a design mistake.
Caps were 100pf and 120pf polystyrene ones I had in spares box, cheaper ones would probably just as good.
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Post by pandapops on Aug 27, 2011 3:37:59 GMT
Replaced all eight ceramic 22pf with polystyrene 22pf, with two effects:
Like lifting of veils, Panda is now beating modified Neco for detail.
Better channel match, seems odd this, perhaps the ceramics in my kit were from a bad batch.
Bought off ebay from a guy doing two for £1, easily worth the money to do the amp in one go.
I'd recommend getting these before the build and avoid trying to get parts off the PCB with its little holes.
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elysion
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Post by elysion on Sept 13, 2011 18:44:25 GMT
With which Neco amp did you compare? Portable or MOSFET/BOSSFET?
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Post by pandapops on Sept 14, 2011 17:39:15 GMT
Mosfet, probably the one before BOSSFET, I bought it used over a year ago and the original owner hadn't had it that long.
My mods were: SPOWER regulator for the 3pin reg.
Shinkoh? tanatlum resistor on each input. The impact of these 2 resistors was very substantial, they're a bit chunky( had to go under the PCB) and pricey @£3 ea plus P&P.
Takman metal films all over.
Used some single core wire in place of some multi strand cable.
Also one cap upgrade, there was a 1uf which seemed an oddly small value.
And even with that my slightly modded Panda extracts more from my CD player for my HD600s. I don't have a good explanation as to why: the NECO has a great plugin PSU, quality low ESR multiple PSU caps, premium opamps and class A output. Rail splitter PSU the problem?
I suspect a more heavily modded Panda could live with any sub £1000 amp and cost £300ish to put together.
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Post by pandapops on Sept 21, 2011 1:40:52 GMT
My Panda had been running from a 30VA transofrmer that I already had, shifting to a 60VA model made a big improvement in weightiness, although a little detail may have been lost. However not one but two 60VA were purchased and the Panda is now running with a dual-mono PSU, and the result is bloody brilliant, a combination of detail and control beyond anything I've ever had.
Is no one else tinkering with their Panda anymore?
Transformers used standard toroidal from Rapid 18V 60VA Vigortronix and are a bit hummy. In total I've had three Vigortronix from Rapid the first was simply fauly and these not totally quiet, in the future I'll probably look elsewhere for open toroidals.
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xerxes
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Post by xerxes on Sept 21, 2011 13:40:35 GMT
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Post by pandapops on Sept 21, 2011 14:05:35 GMT
I had a couple of the encapsulated from Rapid many years ago and found that after a while they hummed a little and had mixed results with the open Clairtronic they sold, looks like Antrim are gone from the consumer market, thought I'd try Nuvotem next time.
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Post by PinkFloyd on Sept 21, 2011 20:26:26 GMT
I find the Vigortronix toroidals to be the best available at the moment... I buy "direct" and they custom wind them in the UK for me so maybe that's why  I will make Vigortronics aware of this thread... really surprises me as they are the best UK based company I have ever dealt with (Quality wise)..... Clairtronic have gone bust, their transformers had a tendency to "GO ON FIRE" and many manufacturers are STILL chasing them for recompense.... Don't go anywhere CLOSE to Clairtronics, a bunch of hoods  they are no longer www.clairtronic.com/Nuvotem / Talema are a good brand, Irish "front" Chinese manufactured.... thing is, all of these companies have "in-house" custom services and you can get your transformer "wound" in the UK (to your specs) if you batch buy and specify "audio grade;) Steer WAY clear of anything "Clairtronic". |
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xerxes
Been here a while!
Posts: 1,115
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Post by xerxes on Sept 21, 2011 21:32:33 GMT
I've got four 200VA EI Clairtronic transformers in my mains filter and they do tend to join in a bit, (hum along); they haven't burst into flames yet though. I think it's Vigortronix that pandapops is having trouble with.  In another thread someone, can't remember who now, mentioned Airlink and that they were very pleased with both the transformers and the service: www.airlinktransformers.com/ |
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Post by pandapops on Sept 22, 2011 1:01:31 GMT
My dealing with Vigotronix went like this: I got a faulty one so emailed them in case a faulty batch had gone out, they replied and asked for the dodgy one to be posted saying that they'd send a replacement; I asked if with the replacement they'd include the postage cost it I'd incurred, they weren't sure that this was possible and ummed and urred then said okay; I sent the transformer it was tested as bad and then they sent nothing back and wouldn't reply to email. Got a refund from Rapid. Best part of a year later and I needed a couple of transformers and some bits to finish the Panda, I ordered from Rapid, and the Vigos hum. I'll live with the Vigos for now, turning it off when not in use, and look to get something better for Panda 2. This guy does 50VA 18V audio grade as a standard model: www.canterburywindings.co.uk/standard_range.html |
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Post by PinkFloyd on Sept 22, 2011 7:49:53 GMT
Talk to Adam Betts at Vigortronix, he will sort you out  |
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Post by PinkFloyd on Sept 22, 2011 8:46:22 GMT
I'll be building one next week sometime... will post pics etc. Mike. |
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Post by pcourtney1 on Sept 22, 2011 11:52:37 GMT
This guy does 50VA 18V audio grade as a standard model:http://www.canterburywindings.co.uk/standard_range.html can confirm that Terry Monaghan at Canterbury Windings is a perfect supplier for one offs, he also does an audio grade version with a screen and GOSS band, very nice chap and quick to reply via email etc In tests we have found that the GOSS (grain orientated silicon steel) band is just as good as expensive mu-metal in reducing stray fields ! |
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Post by rob100 on Sept 23, 2011 21:16:11 GMT
I'll be building one next week sometime... will post pics etc. Mike. Mike - I'm hoping that could be the one coming my way!  How many have you built now? Rob |
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Post by PinkFloyd on Sept 23, 2011 21:45:53 GMT
I'll be building one next week sometime... will post pics etc. Mike. Mike - I'm hoping that could be the one coming my way! How many have you built now? Rob Hi Rob, Yours will be the fourth..... I don't do the personal build thing that often Mike. |
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Post by PinkFloyd on Sept 25, 2011 20:46:50 GMT
Had a little tinker today and made a noise nulling screen (between the transformer and board) for "nothing".... I have plenty of sticky back aluminium, copper foil tape and hardboard kicking about so put it to good use. Apply sticky backed alu tape onto a piece of hardboard (you have pre measured / cut) and then apply some copper tape.... ground it as shown and, voila!.... you have a very effective shield. I am actually AMAZED with the results and cannot believe that a simple shield (such as this) could improve the SQ so much.... I will do a "step by step" guide soon along with a list of materials required..... I have only one roll of the alu tape and one "large" roll of the expensive copper tape but would be happy to to "share" a length or two with fellow Panda owners.... More on this when I have time.      |
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Post by PinkFloyd on Sept 25, 2011 20:56:57 GMT
Once the lid is bolted down it's pretty much shielded (transformer from amp).... a 45 minute job but "easy" and WELL WORTH doing Mike. |
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Post by pandapops on Sept 25, 2011 21:27:27 GMT
Thats really cool; I get around transformer interference by sticking 'em in another box, it works but its not a neat solution.
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Post by PinkFloyd on Sept 25, 2011 21:59:04 GMT
It's logical and cheap to impliment so, yes...... it's "cool"  |
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Post by PinkFloyd on Sept 25, 2011 22:22:38 GMT
I've also got some pretty effective tweaks to the caps / diodes AND an easier way to match the transistors,,,,, stay tuned |
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Post by PinkFloyd on Oct 5, 2011 20:01:12 GMT
I'll be building one next week sometime... will post pics etc. Mike. Mike - I'm hoping that could be the one coming my way! How many have you built now? Rob Hi Rob, The enclosure from HiFiDiy.net arrived yesterday and it's an absolute cracker! VERY solid and beautifully machined, possibly the best quality enclosure I have yet worked with. I worked on the amp yesterday and today and, at last, it is ready to ship to you... I will double check the DC offset tomorrow and have it in the post to you on Friday. Not too keen on the "Chinese" extension rod as it is a bit scratchy in operation but that will bed in and smoothen up after a good few rotations.... I have packed some grease into the mount so it will smooth out with use... It's the rod making contact with the mount, not a biggie and will soon bed in. The PCB is pretty standard apart from silvered mica caps, UF diodes and extensive polyprop bypassing of the electrolytics.... sounds fantastic! The input cable is Evolution OFC pro OFC and the output wiring is silver PTFE.... the output resistors are carbon composite 100 ohm.... I may add 4.7uF polyprop input caps tomorrow depending on what your source is? Took some "indoor" pics and they have come out pretty crap so will take a few outdoor shots of the guts tomorrow before I pack her up, ready to go.....          |
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Post by pandapops on Oct 5, 2011 20:50:02 GMT
Polystyrene vs Sivler Mica for those 22pfs?
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Post by rob100 on Oct 5, 2011 21:15:25 GMT
Wow - Mike it looks amazing! Can't wait to hear it I'll be using it with a Cyrus CD8x CD player and Q701 headphones. I've no idea what input caps are let alone what they do (a DIY headphone forum is probably not the best place for me  ) but have total faith in your judgement of whether you should add them or not  Can't believe I'm going away this weekend so not going to be able to have a proper listen until the weekend after  |
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Post by PinkFloyd on Oct 5, 2011 22:06:09 GMT
Polystyrene vs Sivler Mica for those 22pfs? I don't understand the question. BOTH are overkill, I just happened to have a box of silvered Mica to hand.... The "stock" ceramics are probably just as good...... playing it safe tho', Silvered MICA have fanboy appreciation |
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I will make Vigortronics aware of this thread... really surprises me as they are the best UK based company I have ever dealt with (Quality wise)..... Clairtronic have gone bust, their transformers had a tendency to "GO ON FIRE" and many manufacturers are STILL chasing them for recompense....
they are no longer 
) but have total faith in your judgement of whether you should add them or not 
