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Post by PinkFloyd on Feb 3, 2010 21:09:07 GMT
They are a lovely phono socket, Mike. I've used them in my AK Class A and Buffalo DAC, and they really look and feel like a quality component. One thing that struck me about them is that they weigh quite a lot for what they are  Doesn't mean 'owt, but there you go! Yes Will..... they don't fit  |
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Will
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Post by Will on Feb 3, 2010 21:30:21 GMT
Ah, Bugger.  |
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Post by leo on Feb 3, 2010 21:32:10 GMT
The layout looks quite different but probably the circuit is the same as Sijosae's so its hard to say exactly where to measure
The trimmer adjusts the anode voltage, the different valves loads will vary so you adjust the trimmer until the anode voltage is set the same as the stock fitted valve if that makes sense?
Sijosae's are set 17-18v on the valves anodes, I presume these ebay amps are the same?
On the Sijosae amp theres a 220R resistor on each channel (I can't see the colour bands very clear in those pics , their too bleached out), one end goes to the Mosfet (Gate) the other end goes to the Valves anode pin so the voltage should be able to be measured from that resistor to gnd (the end which goes to Anode)
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Post by PinkFloyd on Feb 3, 2010 21:56:18 GMT
The layout looks quite different but probably the circuit is the same as Sijosae's so its hard to say exactly where to measure The trimmer adjusts the anode voltage, the different valves loads will vary so you adjust the trimmer until the anode voltage is set the same as the stock fitted valve if that makes sense? Sijosae's are set 17-18v on the valves anodes, I presume these ebay amps are the same? On the Sijosae amp theres a 220R resistor on each channel (I can't see the colour bands very clear in those pics , their too bleached out), one end goes to the Mosfet (Gate) the other end goes to the Valves anode pin so the voltage should be able to be measured from that resistor to gnd (the end which goes to Anode) The 2K2 trimpots adjust the bias. I have spoken to the designer (Peter Cheung) and Peter has sent me this guide to biasing using a multimeter: The simple adjustment is as below.
Insert the tube and power on,
Let it pre heat for 5 min,
Measure the volts to tube plate (pins 1 & 6)
Turn the pots one by one reach to 16-17V, pin 1 & pin 6 should be same Volts after trimming.
Recheck after one hour and turn the pots again to fix the plate volts (16-17V)
This is not a real precision adjustment, but it will be 90% near to the correct point.
BTW please watch the circuit diagram:  I have e-mailed "Bravo" several times and they haven't even responded with so much as a "hello". Peter Cheung of Indeed has been EXCELLENT and extremely helpful and, as such, I would recommend the Indeed amp over the bravo when it comes to customer support. 6800uF capacitor aside I feel the Indeed amp is the better quality of the two amps, it just has that "edge" that suggests it's the real deal  |
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Post by leo on Feb 3, 2010 22:14:22 GMT
Anode , plate same thing Looking at the diagram you posted there is a few differences between these ebay ones and the Sijosae, I seem to remember using a jfet wired as a current source instead of the transistor, the trimmer was also on the anodes (plate) and it was battery biased instead of the trimmer on the cathodes |
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Post by Will on Feb 3, 2010 22:27:48 GMT
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Post by PinkFloyd on Feb 3, 2010 22:31:47 GMT
INDEED..... Better quality parts across the board  Right, that's the preamble / component count out of the way now it's time to get down to the nitty gritty...... the "sound quality"..... I've got both amps burning in and will report back after 240 hours (ten days time). One thing I've noticed, pretty early on into the burn in is that BOTH amps will alert you to an incoming mobile phone call before the phone does  This could be considered a "feature" to some but, to me, it's a pain in the "ass"  Fortunately, I am not "popular" and only receive one "mobile" phone call at 8pm every evening so I can pretty much discount this as "quirky" but if you are a power "texter" or a rabid sex line addict this may become quite annoying ;D Pretty much RFI city and if you live next door to a taxi cab outfit you may find you are listening to "got a pick up for 23 wellington road, what's your status?" over your favourite "tune" Just kidding, not that bad but I'd like to hear how the amp performs (with regard to RFI) from members who live in built up areas (cities)...... as I've previously stated, I live near the Orkney Isles and airborn noise pollution is as close to zero as you're likely to get these days so it will be interesting to hear from City dwellers. |
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Post by leo on Feb 3, 2010 22:44:29 GMT
BTW in post 123 going by the pics, it seems a Panny NHG is fitted for one channels coupling cap and the other channels coupling is panny FC  |
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Post by PinkFloyd on Feb 3, 2010 22:45:09 GMT
Anode , plate same thing Looking at the diagram you posted there is a few differences between these ebay ones and the Sijosae, I seem to remember using a jfet wired as a current source instead of the transistor, the trimmer was also on the anodes (plate) and it was battery biased instead of the trimmer on the cathodes It's a lovely sounding amp Leo, I'll be happy to send it over to you or you may prefer to breadboard it? I'll be trying a 24V regulated / linear PSU with it as soon as the 240 hours has passed |
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Post by PinkFloyd on Feb 3, 2010 22:50:47 GMT
BTW in post 123 going by the pics, it seems a Panny NHG is fitted for one channels coupling cap and the other channels coupling is panny FC You are on the ball!........ my usual stash of 1200uF panny FM were too big so I fitted an NHG and a FC (1000uF) which were to hand ;D I'll fit a matching NHG tomorrow (I'm out of 1000uF FC)...... 700 panny 1200FM in stock but they are 2mm too tall Hehe |
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Post by leo on Feb 3, 2010 22:58:46 GMT
I thought maybe one ear liked FC and the other NHG , either that or you was just testing us I may be tempted to knock one up, these ones will sound a bit different to the Sijosae I built anyway |
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csdam
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Post by csdam on Feb 3, 2010 23:00:01 GMT
Hello! everybody, my name Peter, I would like to answer any question about my product..........Indeed !! |
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Post by leo on Feb 3, 2010 23:05:02 GMT
Nice link, Leo. I have most of the bits, just need the fet's and one of those glass tube thingies. Never done valvey stuff, so this could be a bit interesting. Sorry I missed this Will, you have to give me a prod Maplin used to sell the Mosfets for about a quid each, don't think I have any here, valves or fets isn't something I usually have in my stash I think you'll find this sounds quite different to the SC classA  |
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Post by gomez on Feb 3, 2010 23:29:01 GMT
Hello! everybody, my name Peter, I would like to answer any question about my product..........Indeed !! Hi Peter Welcome aboard  I'm sure you're going to be busy around here. |
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Post by PinkFloyd on Feb 3, 2010 23:30:02 GMT
Hello! everybody, my name Peter, I would like to answer any question about my product..........Indeed !! Hi Peter! Welcome to the forum Feel free to join in the discussion, I hope we can learn from you and you can learn from us.... it's all good  Mike. |
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Post by Deleted on Feb 3, 2010 23:34:17 GMT
Leo Which, BTW, you still aren't getting the most out of ? Alex |
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Post by csdam on Feb 3, 2010 23:36:58 GMT
 Nice to see you! I will try my best to everybody!!  |
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Post by leo on Feb 3, 2010 23:38:21 GMT
Leo Which, BTW, you still aren't getting the most out of ? Alex told you I'm going senile you better also give me a prod |
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Post by PinkFloyd on Feb 3, 2010 23:46:36 GMT
Nice to see you! I will try my best to everybody!! Just go with the flow Peter and allow the thread to "evolve" It's an honour to have you on board. China speaks to the rest of the world...... I never thought I'd see the day...... superb! |
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Post by Deleted on Feb 3, 2010 23:54:50 GMT
Leo Which, BTW, you still aren't getting the most out of ? Alex told you I'm going senile you better also give me a prod Leo Just get yourself an 18-0-18 30VA toroidal transformer and a couple of 2,200uF 35V electros for the PSU. You will always find another use for the recovered 15-0-15VAC 30VA toroidal. Alex |
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Post by PinkFloyd on Feb 3, 2010 23:59:40 GMT
Leo Which, BTW, you still aren't getting the most out of ? Alex Alex, Please take the SCHA discussion to the SCHA "zone"..... thanks |
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Post by csdam on Feb 3, 2010 23:59:53 GMT
Yes! China is being change now! Especially let the products to unbelievable price! |
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Post by PinkFloyd on Feb 4, 2010 0:05:28 GMT
Yes! China is being change now! Especially let the products to unbelievable price! Yes, the price is good Peter but we would like to discuss the "performance" and future upgrades ;D Mike. |
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Post by csdam on Feb 4, 2010 0:17:44 GMT
I gona to explain the filter capacitor later now is HK time AM 8:19 I logout now,,Bye |
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Post by PinkFloyd on Feb 4, 2010 0:24:31 GMT
I gona to explain the filter capacitor later now is HK time AM 8:19 I logout now,,Bye Cool Have a nice sleep, sweet dreams Look forward to the filter cap explanation Mike. |
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Doesn't mean 'owt, but there you go!
This could be considered a "feature" to some but, to me, it's a pain in the "ass" 
Fortunately, I am not "popular" and only receive one "mobile" phone call at 8pm every evening so I can pretty much discount this as "quirky" but if you are a power "texter" or a rabid sex line addict this may become quite annoying ;D
I'm sure you're going to be busy around here. 
