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| [#4244] ESL dear CP and King, Did I make any mistake? should bias be measured in mv or ma? |
dkyyu 正式會員210.xxx.xxx.23 |
2007-08-22 15:32 | |
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| [#4245] ESL Here goes the GM20 schematic. -------------------------------- cp, can you blow it up a bit? i can't read see the details. |
drwkng 正式會員 203.xxx.xxx.134 |
2007-08-22 19:33 |
| [#4246] ESL can you blow it up a bit? ________________________________ That's the best I can do. My copy is as blur and I can only faintly identify the component number. But at least you can tell that the VR adjusts the grid voltage. I have to check against the actual circuit across which resistor the voltage is measured. |
cpsjj 正式會員 218.xxx.xxx.4 |
2007-08-23 01:07 |
| [#4247] Graaf GM 20 Try this one: http://www.audiodesignguide.com/otl/graaf20.gif |
feikeung 正式會員 219.xxx.xxx.63 |
2007-08-23 02:11 |
| [#4248] Graaf GM 20 cp, please check the actual circuit. and see which resistors are being measured. is this a simplified circuit? where are famous/infamous protection circuits? |
drwkng 正式會員 203.xxx.xxx.133 |
2007-08-23 08:19 |
| [#4249] ESL dkyyu, Thanks to Patrick’s help, I now got my MF X10v3 and tested. I endorse your observation that the TVC works better with the Graaf without the buffer, if the MF is anything similar to the BBA. I have the GM20 retubed and biased to exactly 30mV and tested the X10v3 both at the front end and the back end of the TVC. At the front end, i.e. between the cdp and the tvc, the source signal seemed to be contaminated and everything was blurred and tasteless. At the back end, it was not as bad and the buffer acted more like blowing up a balloon. Not only the soundstage was inflated, everything was stretched proportionally larger and images were like patterns on a balloon which when inflated were not as clearly delineated. They might seem a bit more full bodied but blur and distorted at worst. Perhaps the X10v3 needs more time to run in. I then gave the X10v3 to Wah Gor to try with his Axiom passive preamp. As expected it worked much better with the resistor based preamp. The effect was like at the back end of the tvc but more on positive side. Soundstage and images were also inflated and edges smoothened, but the full bodied images also brought out the liveliness of the music which is somewhat lacking before. The result could be quite easily attributed to the basic function of the buffer which is for impedance matching and which is what required by the resistor based passive preamp to work properly. For the tvc, which itself is already a rather effective impedance matching instrument, the buffer becomes redundant and superfluous. |
cpsjj 正式會員 218.xxx.xxx.96 |
2007-08-25 00:38 |
| [#4250] ESL spare parts Dennis......Please check yr pm for my son's address. Regds Patrick |
Pcs100 正式會員 221.xxx.xxx.46 |
2007-08-26 17:59 |
| [#4251] ESL spare parts Dear Patrick, Gotta. Have contact the seller for shipping rate to CA. |
dkyyu 正式會員 210.xxx.xxx.23 |
2007-08-26 23:16 |
| [#4252] ESL spare parts Denis, Are you still using the TVC with the BBA now? The BBA should be very different from the MF X10 as it has much higher and varibale gain. Any chance to have compared the two with the TVC yet? |
timtube 正式會員 203.xxx.xxx.140 |
2007-08-27 11:31 |
| [#4253] ESL spare parts Dear Limage, I have left something for you in the pastry shop. Please check tomorrow. |
dkyyu 正式會員 210.xxx.xxx.23 |
2007-08-27 18:48 |
| [#4254] ESL spare parts Dear Tim, Why don't we have a trial between BBA and MF X10? |
dkyyu 正式會員 210.xxx.xxx.23 |
2007-08-27 19:14 |
| [#4255] ESL spare parts Dear CP, You can borrow my BBA to your place any time or lend me your MF for one-day comparison to my BBA. I also suggest we make available a standard active pre-amp for reference. |
dkyyu 正式會員 210.xxx.xxx.23 |
2007-08-27 19:38 |
| [#4256] ESL feikeung, I have just retune both of your Modena monoblocks ready to try the Maggie. The tubes of one of the Modena must be close to end of their life as the bias drifted from 22mV 2 weeks ago to 10mV only. I have now biased it to 30mV but they are a little unstable. Offset remains at about 2V. Unfortunately I do not have enough tubes to replace them all. The other monoblock is perfect. The bias is stable and the offset can be accurately set to 0V. If you are ready to enjoy them at home, let me know and I'll send them back right away.  |
cpsjj 正式會員 219.xxx.xxx.124 |
2007-08-28 11:25 |
| [#4257] ESL cp, have you found out what voltage are you measuring for bias? |
drwkng 正式會員 210.xxx.xxx.111 |
2007-08-28 11:37 |
| [#4258] ESL drwkng, The voltage across the resistor is R32. As I couldn't flip over the pcb I can't relate it to the schematic. The schematic diagram is very unclear and I figure that R32 should be what I pointed here.  |
cpsjj 正式會員 219.xxx.xxx.124 |
2007-08-28 11:56 |
| [#4259] ESL he voltage across the resistor is R32. ------------------------------------------ you get 30mv across that resistor? what value is that resistor? it does not make sense though. |
drwkng 正式會員 210.xxx.xxx.111 |
2007-08-28 12:22 |
| [#4260] Maggie feikeung, Here's your monolith singing beautifully. One word - huge. There seems a bit too much nasal but other than that I didn't notice any distortion. Wanna just pop over and just it out?  |
cpsjj 正式會員 219.xxx.xxx.124 |
2007-08-28 13:07 |
| [#4261] Maggie Bad news!!! After a harder passage from the Phantom, the treble started to distort and suddenly the RHS sounded much lower than the LHS. On closer examination,I think the ribbon on the RHS is broken. Mission aborted!  |
cpsjj 正式會員 219.xxx.xxx.124 |
2007-08-28 13:28 |
| [#4262] Maggie CP, Will consult Master Limage's advice this Thursday. I do like the 3.5R very much. Coupled with the Modena, the Maggie is capable of delivering the kind of speed and clarity (not slam though, due to it's rather limited power) that I have not heard with other tube gear. I suspected that there must be something grossly wrong with either the Modena or 3.5R because there was a rather strange glare when playing Southerland's or de Los Angeles', which I am too familiar with. |
feikeung 正式會員 203.xxx.xxx.141 |
2007-08-28 14:33 |
| [#4263] Maggie CP, Check the fuse first. There are 2 fuses located next to the speaker connections at the back of the speaker. One is for the mid-range and the other for the ribbon. If the ribbon has been blown, there is nothing left to be done but to have the whole tweeter replaced. You’ll have to call Master Yu of Excell to check the replacement ribbon. It was something like 2,000 bucks ages ago. I have had no problem with the ribbons for the last 20 years so I don’t really know how much it is going to cost now. It is likely that I still have a spare ribbon but have to check it out though. Normally it is impossible to snap the ribbon unless a colossal amount of distorted power is fed to it. Feikeung has made a good guess: either the Modena is grossly wrong when called upon to pump out excessive power; or the speaker’s impedance has become alarmingly low to near short circuit that the amp just cannot do anything but to dump whatever amperage it can muster. Worst of all, it might well be both. No worries buddies. For the ESL you have Patrick, for Maggies, you have me here. |
limage 正式會員 220.xxx.xxx.29 |
2007-08-28 16:21 |
