The extra MUR120 diodes also give a voltage drop. You don't need those. I'm currious if you hear a difference in sound between level 1 and level 2. Please let us know
Thanks, I will remove them.
After having to put up with such ungainly heat sink, I sure hope to hear improvements
May be I should try level 3 as well as I have heat sinks for F5 Turbo version 2. In the interest of advancing audio knowledge, you know
Hi Salas,
I am using F5 power amp, with no input cap, and I have a pre-amp based on DCB1 with optical resistor volume, and an input switcher that I haven't used with the F5 yet.
Is there a danger that if I join them, any small DC offset from the DCB1 would be amplified in the F5 and cause a huge DC offset at the speaker terminals? Should I be just cautious and test at the speaker terminals, or simply not risk any long term pairing of them together without a cap, in your opinion?
I am using F5 power amp, with no input cap, and I have a pre-amp based on DCB1 with optical resistor volume, and an input switcher that I haven't used with the F5 yet.
Is there a danger that if I join them, any small DC offset from the DCB1 would be amplified in the F5 and cause a huge DC offset at the speaker terminals? Should I be just cautious and test at the speaker terminals, or simply not risk any long term pairing of them together without a cap, in your opinion?
the F5 will multiply the output offset of the DCB1. But an output offset of say 1mV for the DCB1 plus the output offset of the F5 at say 10mV still only gives a worst case output offset of 16mV.
No Problem !
The far bigger problem is destroying your speakers if an input offset arrives at the DCB1 with a DC coupled amplifier system.
I have said in the past and it appears very few pay any attention:
A DC coupled amplifier needs a DC detection and speaker protection "system".
No Problem !
The far bigger problem is destroying your speakers if an input offset arrives at the DCB1 with a DC coupled amplifier system.
I have said in the past and it appears very few pay any attention:
A DC coupled amplifier needs a DC detection and speaker protection "system".
Hi.
For a while back I replaced my preamp (a Electrocompaniet EC4R) with a Dcb1 hot rod, build from a complete kit from Tea-bag. I am wondering about gain, my DCB1 are build for balanced operation. How much are gain for this amplifier?
I have to turn the volume much higher to achieve the same level as before. I assume this is because the power amplifier (a Electrocompaniet AW120DMB) and DCB1 doesn't fit?
Is it possible to change my DCB1 gain?
I hope you understand my bad English :-/ and understand what I mean...
Best wishes
Simon
For a while back I replaced my preamp (a Electrocompaniet EC4R) with a Dcb1 hot rod, build from a complete kit from Tea-bag. I am wondering about gain, my DCB1 are build for balanced operation. How much are gain for this amplifier?
I have to turn the volume much higher to achieve the same level as before. I assume this is because the power amplifier (a Electrocompaniet AW120DMB) and DCB1 doesn't fit?
Is it possible to change my DCB1 gain?
I hope you understand my bad English :-/ and understand what I mean...
Best wishes
Simon
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The gain is about 1. See it as a passive pre amplifier with impedance correction.
I do realise that there is little point to putting a DCB1 at the front of an F5, as it doesn't provide any amplification (which would be nice) and the F5 doesn't need an impedance correction, but the volume control and input selector on my preamp are useful.
I will probably build a new dedicated preamp for the F5, with a relay input selector, relay volume control and a 2x gain stage based on J74 and K170 fets.
Disme, your older preamp is a real pre-amplifier, increasing the voltage, whereas the DCB1 isn't really a preamp but a buffer (hence the name B1). It corrects impedance, does not amplify voltage, so perhaps it's not the right preamp for your amp.
I will probably build a new dedicated preamp for the F5, with a relay input selector, relay volume control and a 2x gain stage based on J74 and K170 fets.
Disme, your older preamp is a real pre-amplifier, increasing the voltage, whereas the DCB1 isn't really a preamp but a buffer (hence the name B1). It corrects impedance, does not amplify voltage, so perhaps it's not the right preamp for your amp.
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Is there info on the voltage gain of AW120DMB amplifier? To need turn the volume up when using a X1 buffer preamp vs a gain preamp is a normal thing, gives more level range and less noise. Bad thing is if toward max can not drive the amp loud enough given the speakers sensitivity and room size. From a 2V max CD or DAC source and a buffer like DCB1 why not able to drive a European commercial power amp, they are usually around 1V sensitive for nominal power.
Lucas tells it all. One other thing. Make your voltage gain happen as early as possible in the gain-chain in as low noice environment as possible. That is because early noice gets amplified as well as your wanted signal. High gain in last stages, where big transformers etc are involved are more difficult to take out. Ideally full voltage gain to the power stage and then just an impedance concerter, sa Lucas says,
But what else is in the chain Stajo? Surely the entire chain is source gain, pre-amp gain, power-amp gain. All I can think of is the selectors and volume control and they don't introduce any noise really, do they? Are you saying that the volume control (and buffer if required) should go between pre and power amp gain stages? I think that the volume should go before the pre-amp stage, between source and gain. I think if anything, that the preamp should be designed specifically for the power amp and incorporated into it, ideally, and a pre-amp should just be volume control, perhaps a buffer, and input selectors.
Input sensivity for rated output 1v
So there are nothing to do? Except changing back?
I can play loud, I just need to turn the volume very high.
If its cleaner than the previous preamp with gain I see no reason to ditch a buffer because it gives more volume setting resolution until loud in a system. Maybe the volume pot has a slow contour too? What type and value is the volume pot? You could add a good gain module before the pot also, and combine.
Disme, as Salas says, if your amp is loud enough for you on full volume, then you didn't need the gain stage of the old preamp, and the DCB1 has theoretically have given you a cleaner signal by removing an unnecessary gain stage, and providing a higher resolution through the pot by using more of the signal (throwing less away).
The further upfront you got the gain the better the SNR. The headamp concept. You see that concept in phono and microphone preamplifiers mainly. When the pot is after that, it brings down the noise too along the signal volume when you adjust it lower. Optimally it needs a buffer after it not to be changing the drive impedance to the power stage.