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About zeta4

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Personal Info

  • Location
    Oxford, , United Kin

Wigwam Info

  • Turn Table
    Rock 7
  • Tone Arm & Cartridge
    excalibur benz micro
  • SUT / Phono Stage
    own design with SUT
  • Digital Source 1
    Tom Browne Starlight
  • Digital Source 2
    Mirand usb Dac
  • DAC
    Discrete r2r
  • Pre-Amp
  • Power Amp/s
    300B SE/Ucd400
  • My Speakers
    own design
  • Headphones

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  1. Im interested in how you get on (glad its not my cartridge !). Initially I thought that this wont work because the increased horizontal effective mass would bring the cartridge/arm resonant freq down into the record warp freq with would cause massive pumping in your reflex speakers as well as giving your cartridge a hard time. But then if you increase the mass very much you might get the res freq down so low it would avoid trouble. Best of luck !
  2. Most of these mains transformer noise problems are caused by transformer makers running their products too near the flux density limit for cost reasons. So its easy for any dc component or overvoltage to cause saturation. Some makers like Canterbury Windings use oversize cores ie a 500VA one on a 300VA transformer but they cost. This is not the same as just using a bigger transformer. Sorry that doesnt help much but at least its an explanation . Sometimes a step down autotransformer can help.
  3. zeta4


    Yes absolutely. I think its a common misconception that it will all be over after Oct 31. Far from it. If its a no deal the negotiations will begin again over the same subjects as the Irish Prime Minister reminded a sheepish looking Boris.
  4. Just seen this on a card in tesco,s. Thats lovely miss jones but Im sure I said "Hold my calls"
  5. zeta4


    Two good posts. I still fail to understand why the far right is so intent on a no deal brexit. How are they going to benefit?
  6. zeta4

    Naim molestation...

    Ah fine. Just thought I would mention it in case.
  7. zeta4

    Naim molestation...

    I used to do a lot of that in the past. If you havent tried it already already I found that one of the biggest improvements i could make was with the power supply. These Naim circuits are singled ended and so have relatively poor PSRR. The Naim supplies use (or used) LM317 type regulators and if these were changed for a discrete design with lower noise you could easily hear improvements in clarity etc particularly with the phono stage circuits . I used a version of the Walt Jung regulator at the time but there are probably other better ones now even some of the new LDO regulators from Analogue Devices or Linear Technology could be considered. Changing decoupling caps for oscons like your doing is certainly helping here as well. While changing components in the signal path did bring improvements they were not much as gained from the power supply ones in my experience. Hope this is of help
  8. zeta4

    Time for another preamp

    Yes I just thought I would mention it as they worked well for me. In theory they might be better at filtering hf noise on the power rail if that was a problem. In my case I was using triode strapped russian rf pentodes which can oscillate if given half a chance and it was something that Ale recommended. I dont know about 5687,s. Anyway hope your build goes well.
  9. zeta4

    Time for another preamp

    I recently built a very similar power supply for a headphone amp and needed similar values of caps for the power supply. Ale Moglia of Bartola Valves fame told me about some Polypropylenes which are used for the DC-Link application and are available in sizes like 100uf/500V at reasonable prices. I found some Kemet ones in Farnell which worked very well. I think modern electrolytics are getting quite good but if you are a bit ocd like me I thought you might like to know about them if you dont already know of course. Your build quality looks much better than mine !
  10. Thanks. No offence taken. Certainly looks good.
  11. Fine no problem. It might help others though.
  12. I spoke to Max about it and he said the early Merlins were 110V to reduce motor noise. The Rocks are 240V so need altering to accept 110V. Apparently some Rocks have a a swotch for changing over otherwise a dropper resistor has to be bypassed. Hope that helps.
  13. Julian There are a lot of other companies producing similar products like Chomerics for example so what is it thats different about your product. Also to get an idea of its effectiveness for a given application do you have graphs etc of say attenuation versus frequency?
  14. Does seem suspiciously like a roll off within AudioTools or the phone as youve tried different mics and got the same result. What happens if you place the mic very close to a tweeter ?
  15. Your different speakers will present different reactive (ie inductive/capacitive ) loads to the amplifier depending on the number of drivers and the crossover design.. Class a/b solid state amplifiers have to use high levels of negative feedback and if the loudspeakers reactive load is excessive it can play havoc with the amps feedback network causing negative feedback to turn positive and cause the amp to oscillate. To guard against this sensible amp designers usually provide two networks, one is a zobel or boucherout network of a cap and resistor from the amps o/p to ground which protects the amp against excessive inductive loads and the other is a small series inductor which protects against excessive capacitive loads. Naim and the very similar Exposure amps dispensed with the series inductor and instead relied on their proprietry cable to provide this protective inductance. I can only guess why they chose to do this but they did (dont know if they still do). Your chord cable being twisted pair will be less inductive and more capacitive than spaced twin naim/exposure cable and when used with speakers with a more capacitive load is probably causing the amp to marginally oscillate. In my opinion its not the cable thats at fault but the amp design but if you want to keep the amp you have to change the cable (or add the inductor). To check it out try some flat mains cable . Hope this is of help.