who says a passive preamp has no"oomph"?
this is a 18hz signal at 30V on the output of an UCD400 on 8 ohms on both channels. Timebase 5ms/div.
PSU ripple is 3V at this signal. Very clean ripple, no RF. timebase 10ms/div.
Measured with preamp and 2mtr cable between pre and power amp.
I tried to see the pumping effect but could not get it. I tried to go to 8hz square but my protection did not allow it to put it on full output. At 20hz square I reached full output till distortion but no pumping.
this is a 18hz signal at 30V on the output of an UCD400 on 8 ohms on both channels. Timebase 5ms/div.
An externally hosted image should be here but it was not working when we last tested it.
PSU ripple is 3V at this signal. Very clean ripple, no RF. timebase 10ms/div.
An externally hosted image should be here but it was not working when we last tested it.
Measured with preamp and 2mtr cable between pre and power amp.
I tried to see the pumping effect but could not get it. I tried to go to 8hz square but my protection did not allow it to put it on full output. At 20hz square I reached full output till distortion but no pumping.
BTW, preamp has switched grounds and switched "tape out"(also the ground). This way you have no polution of the signals by other sources, the worst are radio(antenna to ground) and pc output(rf).
Bgt said:
What is the power supply you used? What was the load at the amps (8Ohm?).
Best regards
Gertjan
psu is toroid 300VA, 2 normal bridge rectifiers, 1 /channel, 10.000uf/63Vx2/channel both channels on 8 ohms.
This is the amp. measured.
Any other tests you want?
This is the amp. measured.
An externally hosted image should be here but it was not working when we last tested it.
Any other tests you want?
about the step att. from http://www.diyfidelity.com.au/product_info.php?cPath=0_33&products_id=32 , he said the pot is made in such a way that max. = 0.72 x the input voltage, it is ment for active preamps. You can take the last divider out and make a shortcut here so your last step is full throttle.
JP, maybe you could talk the guys at www.speakerworld.nl into including the much cheaper hifi 2000 galaxy in their range... Everybody seems to use these as they are pretty good value for money!
matjans said:
Yes, value for money is good, just shipping can be expensive, shipping 4 cases to japan costed me as much as the cases themselves :-(
Gertjan
Bgt said:
OK, I see, those funny triangle like steps in the scope signal probably correspond with the point where the square wave switches from + to - or vice versa?
I guess with a sine wave load, things would look cleaner?
Best regards
Gertjan
Bgt:
I like your thick aluminium plate supporting the UCD's a lot. Very clever idea 😀
Is it OK to run the wires that close to the big Tx?
Regards.
M
I like your thick aluminium plate supporting the UCD's a lot. Very clever idea 😀
Is it OK to run the wires that close to the big Tx?
Regards.
M
maxlorenz said:Bgt:
I like your thick aluminium plate supporting the UCD's a lot. Very clever idea 😀
Is it OK to run the wires that close to the big Tx?
Regards.
M
Max, its ok to run the wires next to the transfo. There is no crosstalk from it. The plates make it easy to mount the UCD's.
Bgt said:
will do a test tonight to see crosstalk at 20hz full output on 1 channel and see if the other channel has crosstalk.
20hz full on 1 power output is visible in the noise on the other output at -65db. I measured with a square wave which is always more difficult for a system. No triangle wave like crosstalk here at all.
Question for Pasi P
Wondering how this worked out for you, as I am considering this route myself.
Thank you!
Rich
Pasi P said:
Wondering how this worked out for you, as I am considering this route myself.
Thank you!
Rich
Thanks Bgt:
Isn't this bad?
I value your effort to teach us, stone heads 😉
Best regards
Mauricio
Isn't this bad?
I value your effort to teach us, stone heads 😉
Best regards
Mauricio
Re: Question for Pasi P
Hi,
Unfortunately i havent been time yet to build it. I have all parts in hand and i hope that next week it is ready. I will tell results.
Richidoo said:
Wondering how this worked out for you, as I am considering this route myself.
Thank you!
Rich
Hi,
Unfortunately i havent been time yet to build it. I have all parts in hand and i hope that next week it is ready. I will tell results.
Not really, such a low frequency has not a lot of direction(phase) info. But monoblocs will be better. This also was a square wave. A sine will be a bit better.maxlorenz said:
My Dact pre is ready
My 6-ch Dact + Orion filter combination is ready for first test. Bent audios remote is installed also. Wiring needs cleaning and front plate some leds.
Sound is soo good
Clarity is in new level.
I had before Alps blue based passive.
I dont know is improvement coming more Dact or using volume control (6-ch) after active filter.
My 6-ch Dact + Orion filter combination is ready for first test. Bent audios remote is installed also. Wiring needs cleaning and front plate some leds.
Sound is soo good
Clarity is in new level.
I had before Alps blue based passive.
I dont know is improvement coming more Dact or using volume control (6-ch) after active filter.
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