Ok, here is a pdf version though the resolution is not quite as good.
http://homepage.ntlworld.com/lez/YAQIN MC10/A LOOK AT THE YAQIN MC10L.pdf
Les
http://homepage.ntlworld.com/lez/YAQIN MC10/A LOOK AT THE YAQIN MC10L.pdf
Les
Where did you buy your amp from Data? What was the cost in the end of shipping and import duty?
Thanks mate! Hope your enjoying it.Hi mate
A ebay seller that goes by "hi_audio"
Yes, I am enjoying it, although I might be nit-picking, but with mine the cut-outs in the top plate for the valves and test points are a bit out of line with the positions on the PCBs , and I think they should have done more to ventelate the can over the PS transformer.
Nothing I can't get over though
Nothing I can't get over though
I picked up some NOS 6P3S tubes and they do not fit through the cover hole. Did anyone else find this out, too? Is there a size difference between the 6p3S and the 6p3S-E's. or has the hole size on the Yaqin changed? I recieved mine in August 2010. I'll confirm the Chinese tubes do sweeten up a little with time, but the bass could use some tightening up as it is a little slow sounding. Just like others are saying. I've been runing this amp with 2 sets of home brew speaker systems. A studio monitor made of Vifa tweeters and Peerless woofers, and another set made of full range Audio Nirvanna drivers. I preferr the studio monitors for their extended range, but the Nirvannas are no slouches either. I will be moving my Watt Puppies
onto this amp soon to see what happens.
Did anyone else find this out, too? Is there a size difference between the 6p3S and the 6p3S-E's. or has the hole size on the Yaqin changed? I recieved mine in August 2010. I'll confirm the Chinese tubes do sweeten up a little with time, but the bass could use some tightening up as it is a little slow sounding. Just like others are saying. I've been runing this amp with 2 sets of home brew speaker systems. A studio monitor made of Vifa tweeters and Peerless woofers, and another set made of full range Audio Nirvanna drivers. I preferr the studio monitors for their extended range, but the Nirvannas are no slouches either. I will be moving my Watt Puppies onto this amp soon to see what happens.I put the 6P3S-E's back in, and they sound great now, the amp Itself needed to run in a bit more in my case.
With these coin base 6P3S-E valves the envelope (glass) was in contact with the stainless cover so I have removed the cover and am running it naked now *shrugs*
Next week I'll try strapping these in Triode mode.
With these coin base 6P3S-E valves the envelope (glass) was in contact with the stainless cover so I have removed the cover and am running it naked now *shrugs*
Next week I'll try strapping these in Triode mode.
Damn it!
Just noticed that two of the 6P3S-E's are a little gassy
I had some GU50s that were the same, they cleared up after about an hour of running. You can bake then in an oven at 200C for a couple of hours too - it's just residual gas that gets in during storage - unless the pins are super smooth they leak at the pin/glass interface over time.
Data - Could you confirm that to convert to triode mode simply requires the removal of the UL Tap on pin 4 of each EL34, the removed wires being well insulated or placed on a safe insulated anchorage. Then a 5W resistor is added between pin 3 and 4 on each EL34 base.
I note that most designs use a 100 Ohm resistor but I fitted 820 screen limiting resistors. Can I use these? Or perhaps I should reduce them to 100 Ohms? I guess the EL34 tubes will have to be re-biased? Did you encounter any problem using the original bias circuits?
If I can get a well proven method reported to me I will add it to my MC10-L data pack with the relevant acknowledgement of course.
Les
Oh Yes, one last thing, did you have to alter the feedback components or even disconnect them? Cheers
I note that most designs use a 100 Ohm resistor but I fitted 820 screen limiting resistors. Can I use these? Or perhaps I should reduce them to 100 Ohms? I guess the EL34 tubes will have to be re-biased? Did you encounter any problem using the original bias circuits?
If I can get a well proven method reported to me I will add it to my MC10-L data pack with the relevant acknowledgement of course.
Les
Oh Yes, one last thing, did you have to alter the feedback components or even disconnect them? Cheers
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If it is this simple, I'd take it a step further and use some 2 pole switches so the amp can run in either mode with the throw of a couple switches for each output tube.
Sorry for the late reply, no net access.
A safe range for the strapping resistor is between 270R and 1K according to an amp designer friend of mine, we used a 2.5w or 3.5w 570ohm carbon. UL taps were well insulated and then zip tied back to the wires coming from out-put transformers.
With the feedback I snipped out the resistor and cap in the global feedback line on each channel.
I found the difference bettween tubes to be much less once the amp was triode strapped, so I am running the original EL34's again till a quad of Winged C's arive next week.
last week I replaced the Coupling caps with Mundorf Silver/Oils (0.1uf) and the cathode bypass resistors? (the ones we measure across for bias) with Kawame 5w 10ohm carbons.
Huge improvement in the sound stage and transparancy/clarity and detail retreval, though it has taken near 80hrs for the Mundorf caps to burn in.
Of course choise of caps & resistors is a personal preference.
I can never go back to UL again
Cheers
Ian.