Marek
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« on: September 24, 2022, 08:47:35 AM » |
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Hi. So as I mentioned earlier I finished my EAR / Douk with Thorsten etc modifications.
First of all left channel started to sound strange like 50% of right without power etc. Looking for problem - 100R resistor replacing 0,1uF caps is broken - to be changed asap. Is it so important to keep there carbon as recommended. Are metalized so bad from your experience ? I have a local source for carbon but 0,5 W instead of 0,25W - big problem to use bigger one ?
Second question I missed change of resistor at V3 68 k to 120 k/3W for ECC83 - 1mA for tube V3. Will change of course but has it impact for sound or only for tube working point.
Now what are your experience with sound ? After some hours spent in front of it I found it very offensive, bright, aggressive. Maybe something is wrong with my execution but tried to follow all modifications as recommended here. All my tubes are SPAX7A as V1, V2,3 E83CC from JJ
Comments please. Thx. Marek
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analogadikt
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« Reply #1 on: September 24, 2022, 10:23:02 AM » |
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Where is this 100R register? Is it a grid stopper?
Regards,
Anwesh
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niclaspa
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« Reply #2 on: September 24, 2022, 11:45:54 AM » |
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Is the resistor carbon film or carbon composite? If it is carbon film you can use a metal film resistor instead. I doubt that you will hear the difference. Carbon composite have the advantage that they can take a larger surge current. If that is the reason why it is there, you could possibly replace it with a metal film resistor that can sustain more power.
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Niclas
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dtroise
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« Reply #3 on: September 24, 2022, 02:56:51 PM » |
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Hi
I have found that using all 12AX 7 will give an aggressive bright bite, it has too much gain. I use one 12AX7 in V1 one 12AY7 in V2 and one 12AU7 in V3, the sound is as smooth as a hot knife through butter, in answer to your question about the .25w vs .50-watt R, it can be bigger but not smaller however it would be better to use the specified R
Donald
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dtroise
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analogadikt
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« Reply #4 on: September 24, 2022, 03:16:51 PM » |
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Hi
I have found that using all 12AX 7 will give an aggressive bright bite, it has too much gain. I use one 12AX7 in V1 one 12AY7 in V2 and one 12AU7 in V3,
Donald
Agree with this. The three builds that have been done by my friends all have 12AU7 in V3 position. Regards, Anwesh |
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Marek
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« Reply #5 on: September 24, 2022, 05:09:04 PM » |
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This is source. Just from first thread here at Phono Stages and step ups  Carbon composition resistor |
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niclaspa
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« Reply #6 on: September 24, 2022, 06:35:02 PM » |
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The carbon composition resistors are used to stop oscillation. Such resistors are the best for this job since they have tiny inductance. However, the tubes involved here are not prone to oscillation. You will have no problem replacing them with metal film resistors.
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Niclas
Ernst ist das Leben, heiter ist die Kunst
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Marek
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« Reply #7 on: September 24, 2022, 06:48:37 PM » |
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Thx. Already ordered two composite carbon 100R/0,5W just next corner from my house so will be replaced as one installed is broken/cracked probably during previous installation. How/Why no idea? More important question was - does exchange of resistor on V3 to 120K instead of 68K will change aggressive sound with ECC83 installed there. Value change is double up so massive change. OK. Will do that change soon and will let you know what was an effect. I missed this advice doing all changes acc. to Thorsten method. OK. Lets wait a moment  |
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Tomcat1969
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« Reply #8 on: September 24, 2022, 07:13:26 PM » |
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Hi Marek.
One of my carbon comp resistors went way out of spec and I didn't replace them I just put wire bridges in and I can't say I noticed the difference.
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Peculiar Permali Platform PTP5, 12"SUPATRAC Blackbird/881S or FR24 mk2/SPU #1e. Parks Puffin, B1 with Korg triode, DIY Pass Aleph J power amp and Tannoy Eaton speakers. Oh, and Nigels Speed Controller.
Billy
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dtroise
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« Reply #9 on: September 24, 2022, 07:29:32 PM » |
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The recommended carbon resistor is to assure that there is no oscillation, it is very unlikely that this tube would oscillate. You can use a direct link in place of it, the R is only for peace of mind. If you wish to run a 12AX7 in V3 then the recommendation is to change the R from 68 k to 120 K. From Thorsten " If you wish to retain an ECC83 for V3 change R9 from 68K to 120K. If you plan to change the V3 to a 12AU7/ECC82 or at least 12AT7/ECC81 leave it as is in Value."
Donald
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dtroise
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Marek
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« Reply #10 on: September 24, 2022, 08:13:21 PM » |
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Hi Marek.
One of my carbon comp resistors went way out of spec and I didn't replace them I just put wire bridges in and I can't say I noticed the difference.
Thx Will keep it for future |
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Marek
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« Reply #11 on: September 24, 2022, 08:14:30 PM » |
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The recommended carbon resistor is to assure that there is no oscillation, it is very unlikely that this tube would oscillate. You can use a direct link in place of it, the R is only for peace of mind. If you wish to run a 12AX7 in V3 then the recommendation is to change the R from 68 k to 120 K. From Thorsten " If you wish to retain an ECC83 for V3 change R9 from 68K to 120K. If you plan to change the V3 to a 12AU7/ECC82 or at least 12AT7/ECC81 leave it as is in Value."
Donald
OK This is what I am going to do as last step. Than - To be or not to be ......  |
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Marek
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« Reply #12 on: September 24, 2022, 08:20:35 PM » |
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Just as direct comparison. I've connected my Rega Phono Mini a2r just to compare to EAR.
- first and most noticeable difference - two different worlds - Ear has much higher gain than Rega - I had to turn amp volume knob up with Rega. And sound was much more flat.
Now will try Graham Slee Communicator to compare to Rega.
But first subject is to close EAR/Douk project. Thx.
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