leo
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Post by leo on Mar 27, 2010 8:22:24 GMT
Are we sure that the crosstalk is not on purpose in the Indeeds ?? After all it is very much,but it is not noticed when both channels are ín use, so it does not bother me, I just did the test like Frans described and was amazed how much the wrong cup sings.. Certainly not the distortion, saying that though I listen to headphones at lower volumes than most so it wasn't a huge problem for me, only noticeable on louder more busy than normal music Cranking the Anode voltages up helped a little too
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Post by leo on Mar 27, 2010 8:12:52 GMT
Couldn't have put it better myself
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Post by leo on Mar 27, 2010 8:08:35 GMT
This was mean't for driving very low impedance speakers , you also need a suitable front end
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Post by leo on Mar 26, 2010 23:07:25 GMT
BTW tried another valve but it was noisy
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Post by leo on Mar 26, 2010 23:05:33 GMT
Frans..... try the IRF510.... it adds bags of "top end" sparkle whilst not detracting from the overall warmth of the amp.... Leo has also tried it and seems to like it better than the stock Mosfet. I have been going through quite a few of my amps checking for crosstalk and none of them "audibly" suffer from it like the G1 / G2 does... the only amp I was ever aware of crosstalk on was the Solo but all my Solos have long gone to another home... All of the other amps I own (over 50) have no perceptible "audible" crosstalk so the G1 / G2 are real "party Pieces" and great demonstrators to prove that crap specifications don't, necessarily, equate to crap sound IMO, the IRF630 is the weakest link in this simple "out of spec" design.... fire in an IRF510 and you'll "hear" what I mean.... it really does add some sparkle and energy to the mids / HF. You have been busy "measuring" but you haven't yet commented on the SQ.... I trust you will let us know what you think when you've had a good listen? IRF510 "with" added crosstalk is an even MORE pleasant listen than IRF630 with crosstalk.... please do fit an IRF5** (of your choice) for Ian.... I'm sure he will love the sonics as much as I do. Mike. Certainly gives the impression of more High frequency after the IRF510 is fitted, so far sounds better balanced to me, still a little lighter in bass but thats no problem for me I've resisted the urge so far to stick it on the scope
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Post by leo on Mar 25, 2010 1:30:51 GMT
It should be up and running now, come on, get your finger out
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Post by leo on Mar 24, 2010 0:27:32 GMT
Nope, to my eyes (and ears) the parts are the real deal (what do you think Leo?) it's just that pot that looks a bit iffy to my eyes. Mike. I'd say they are genuine too, Its possible all these parts are not ROHS compliant, as you know most places like Farnell , RS etc sold off none ROHS compliant parts very cheap because of the stupid green regulations. The parts are good, just not lead free This is just a guess, I do know those Dale resistors are leaded parts
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Post by leo on Mar 23, 2010 22:21:05 GMT
Its really starting to look a serious bit of kit Alex, keep those updates coming.
Nice work on the JLH's Greg, the look of these have come on a lot compared to the early ones we was home etching, layout looks top notch
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Post by leo on Mar 23, 2010 22:02:36 GMT
Many Happy Returns Friedrich
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Post by leo on Mar 23, 2010 20:50:54 GMT
Mick..... leave me with it a couple more days...... you haven't seen anything yet Bring it on Pinkster I fitted the IRF510's today, those screws was very tight, I removed the LM317's first to allow easier access to the IRF610 screws. Certainly has altered the sound, bit more in the high's now and a bit less bloom, there does seem to be less low end but it maybe just tighter. A cap change or alternative valve may help the bass. Its only early days but so far I prefer it with the IRF510's
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Post by leo on Mar 23, 2010 20:26:18 GMT
If it's as good as he says it is, it's a shame the subsequent DAC isn't up to scratch ;D Nice one Phil BTW my emails jacking about again, I'll get back to you soon as its sorted, bloody Virgin
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Post by leo on Mar 22, 2010 21:35:22 GMT
I can see how much work has gone into this, well done! you have far more patience than me
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Post by leo on Mar 22, 2010 17:52:42 GMT
Ok, quickly adjusted bias L&R to 15v, the heater voltage obviously goes up too (now at 6.34v) At my listening setting the distortion is greatly reduced, the distortion starts getting more noticeable when the vol is increased but this is too loud for me personally anyway so its not a problem at my setting. So if your amp crackles distorts when playing music at your favoured vol setting its worth increasing that bias, if you get no problems at the standard 12v then its the simple case of don't worry The cross talk is still there, not quite as bad but still there, you may not even notice it in normal use ;D Will measure the temps later
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Post by leo on Mar 22, 2010 15:36:35 GMT
BTW I didn't have to crank it up loud to hear the distortion using just the right input, about 10 o'clock on the pot and you can hear it through the left ear piece, it sounds like the music is overblown
Also as already mentioned this varies depending on the music/track used
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Post by leo on Mar 22, 2010 15:20:59 GMT
Been a little busy lately (which is why I've been quiet) so not had time to stick the G2 on the scope or do any proper tests yet, I'm actually glad Mike suggested I keep the G2 for a little while so it gives more time with it Anyway as I've mentioned before my hearing is pretty sensitive, I can't listen to music through any headphones loud so tend to always have the vol set which would probably too low for a lot of folks. Going through a wider range of music with the G2 I did notice some light distortion (mainly left channel) with some busy music, most noticeable with piano, I thought it maybe just a crappy valve, I was going to wait until I'd tried the E88CC gold pin Mullard before commenting. I've just read Frans post regarding the crosstalk, out of interest I unplugged the left input and played the same busy piano tracks but now just feeding the right input. I had a listen to the left headphone and could hear low level music which is distorted (that'll be the distortion I've noticed playing in stereo) , it actually sounds like rustling tracing paper , crackling I'll try highering the anode voltages tonight, at the moment its still 12v L&R I'll also do some temp measurements I still find theres a bloom added to the mids and upper bass, the valve replacement should alter things so I'll try that as soon as its here. Its best to go over everything first before giving a proper opinion
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Post by leo on Mar 21, 2010 18:11:51 GMT
By the way..... the sound quality since I have matched both channels @ 13V and fitted 2200uF coupling caps has taken a decided LEAP up in performance.... I am hearing details in Yello's "Junior B" that I have never heard before.... a definite improvement for the better.... not as "sweet" sounding, a bit more grain and grit to the proceedings. Leo, I would like to send you a few of these Samwha VA caps, and a couple of the 3.3uF WIMA caps so you can replicate this.... I don't doubt my own ears but it is good to have a second opinion..... I don't know "why" but these Samwha caps have injected some real magic dust into the G2. Don't worry about sending the sample G2 to Attilio, I'd like you to spend time with it, without worrying about sending it on to the next on the list..... I will send Attilio mine..... I really want you to to replicate the above and tell me what you HONESTLY think Mike. Hi Mike, Ok no probs I'll try the caps before the IRF540's At least with the Samwha's higher 130C temp rating you'll get a longer lifespan compared to the stock jobs, if they prove to be sonically better too that'll be a bonus. I was surprised that pillar does transfer some heat to the rear heatsinks, it does get pretty warm, I'll have to measure it just to see the difference
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Post by leo on Mar 19, 2010 20:50:30 GMT
Anyone going to try it with a linear regulated supply-if only to tell the rest of us not to bother? Ok, sure I have something I can try
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Post by leo on Mar 19, 2010 20:29:49 GMT
I may also try alternative mosfets just out of interest, if I get around to it that is if so I'll put the originals back in before passing it on Not a huge amount I'd change on these amps, Possibly the Mosfets depending how the lower capacitance IRF5** types compare, I'd prefer to see a higher voltage rated DC input cap but thats mainly because I don't like running caps near their max voltage, to me 24v is a bit too close to that 25v max rated cap. Also the coupling caps, I'd personally swap those stock 85C Elna's to a higher temp grade. (just being picky tbh) BTW Mike, this amp tramples all over that Mr Doo Doo amp in the SQ department in my opinion
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Post by leo on Mar 19, 2010 20:07:02 GMT
Let's confirm first that the feet "are" grommets. Mike. I thought they was grommets too when I first seen the pic tbh
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Post by leo on Mar 19, 2010 19:00:09 GMT
Its fiddly to get the higher bias voltages to match both channels , its much easier to stick with the 12v bias on both channels so I put it back as was. Also have a gold pin Mullard E88CC on the way to try
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Post by leo on Mar 19, 2010 0:47:50 GMT
At least thats one question cleared up
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Post by leo on Mar 19, 2010 0:10:20 GMT
I am not meaning that 6.3V is bad sound for any tubes with any circuit, I just say for my G2 only! Will the very low voltage increase the risk of cathode poisoning ? Brimar recommended in their handbbook that heater voltages should be kept within +-5% Cathode poisoning was actually my concern too Alex in all honesty, you know more about valves than I do but I have seen cathode poisoning in valves before in some of the old guitar amps
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Post by leo on Mar 18, 2010 23:38:59 GMT
Yes, I just listen to it as it came to start with, mainly because majority of others buying one will just unwrap it and plug it in. I doubt a lot of folks buying one even have a multimeter so I'm interested in seeing what its like straight from the box, setting bias and heater voltage yourself may be beyond what some owners are capable of so we need to know is it a simple plug and play amp or does it require some tuning .
5v for the heater is below spec , it should be able to be brought up by altering the resistors around the LM317's.
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Post by leo on Mar 18, 2010 20:40:32 GMT
The ground plane on the newer one should be better than the grounding for the old one
Just measured the voltages on the G2, just under 12v on left and right Anodes (pin1 and 6 ) Heater voltage is 5.09v This is with the stock tube
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Post by leo on Mar 18, 2010 19:44:46 GMT
BTW, without the rubber feet it would be sliding about all over so thanks for adding those before sending it
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