So, serious question: I've read some rave reviews of this preamp here. Has anyone ever compared it to Pass's conventional offerings? E.g., the XP-10 or XP-12?
I have an XP-12, it’s absolutely fantastic. The BA2018 holds its own quite nicely in comparison.
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Thanks. I have an XP-20, so I guess it will be comparable. I'll be trying out a balanced B1 shortly. It's taken me ten years to finish it for some reason....
I am considering a balanced version of the BA2018. I know that will require two of the stereo boards currently available in the store. My question is I read through this discussion and did not see a BOM so that I can calculate the costs. I'm sure it is here! Could someone point me in the right direction? Thanks!
Just buy two of the pcb and parts kits from the DiyAudiostore if they are in stock..I would be surprised if you could buy the parts cheaper on your own.....
I hadn't checked that most-obvious of locations...that's me, trying to make everything difficult!
Thanks!
Thanks!
One quick question...
In these kind of dc coupled circuits, I've never seen some kind of output dc protection, what if source has XmV dc offset, that is amplified and on the output of the line stage, we have for example, +100mV DC offset. Of course it will work, but we are applying 100mV of offset to the input of amplifier, that could be also DC coupled, further amplifying DC offset...
Is it better to leave the servo and DC protection functions to the power amplifier, and why not even quality cap in the feedback loop for unity gain at DC?
Cheers.
In these kind of dc coupled circuits, I've never seen some kind of output dc protection, what if source has XmV dc offset, that is amplified and on the output of the line stage, we have for example, +100mV DC offset. Of course it will work, but we are applying 100mV of offset to the input of amplifier, that could be also DC coupled, further amplifying DC offset...
Is it better to leave the servo and DC protection functions to the power amplifier, and why not even quality cap in the feedback loop for unity gain at DC?
Cheers.
Nothing prevents you from designing and building your DIY projects with input coupling capacitors and with output coupling capacitors. Nothing prevents you from adding a DIPswitch or a header-block-jumper across each of the coupling capacitors, so you can either (a) leave them in the circuit; or else (b) short the capacitors out; according to your whims. You could perform measurement tests and listening tests in both configurations, then decide which test results please you the most.
Additionally, nothing prevents you from using high quality, high precision, telecommunications relays to perform the capacitor-in versus capacitor-shorted-out experiments. Now you can operate the relays without open the equipment chassis; you could arrange the relay control to be on the front panel and/or on the remote control, for maximum ease of use. This gives A-versus-B testing with immediate, no-delay switching between the possible options.
Additionally, nothing prevents you from using high quality, high precision, telecommunications relays to perform the capacitor-in versus capacitor-shorted-out experiments. Now you can operate the relays without open the equipment chassis; you could arrange the relay control to be on the front panel and/or on the remote control, for maximum ease of use. This gives A-versus-B testing with immediate, no-delay switching between the possible options.
Nothing prevents me... 😀 I`m not critical, just asking what is the benefit of such configuration? Real life, example in previous post , not to repeat my self..
Can someone help me understand how to orient the KSC 2690 and the KSA 1220 with respect to the PCB screen print symbol on the blue boards please? I want to make sure I do it correctly the first time.
argh! bungled!
I did it: I hooked up 1 channel the wrong way (+ to - and - to plus)
I realized that the led was off (on one channel) after 15 seconds or so came the pfft of death, and both 220 uF seem to be gone (bloated)
Is there more that's probably/definitely gone?
I was too confident
🙁
I did it: I hooked up 1 channel the wrong way (+ to - and - to plus)
I realized that the led was off (on one channel) after 15 seconds or so came the pfft of death, and both 220 uF seem to be gone (bloated)
Is there more that's probably/definitely gone?
I was too confident
🙁
Thanks, i know that part, my question was about safety and possible problems with sources with small offsets etc.
It's not a question about this circuit, but any dc coupled circuit in general.If for what ever reason circuit fails and output goes to + or - rail, is it safe then to relay on the dc protection of the power amplifier alone?
I guess Pass Labs, or any other company is using some kind of output protection circuit in their dc coupled preamplifiers?
Sorry for hijacking the thread, i thought that opening new thread just for this question is not necessary..
Cheers.
Shorting outputs
I wanted to add relay at the output and short the output to mute it. I think it should be safe but wanted a confirmation from the more experienced people. The preamp makes a bit of noise when I power it.
Thanks
I wanted to add relay at the output and short the output to mute it. I think it should be safe but wanted a confirmation from the more experienced people. The preamp makes a bit of noise when I power it.
Thanks
Not all amps or preamps have DC protection. What is the risk for no protection? I don’t know, but I don’t think it is that common. There are a few system configurations i could assemble at home that would leave no DC protection. I am not too worried about it. Some OEMs might have protection some might not. I guess you take that risk when you buy or build equipment right? BTW there are DC protection boards for sale in the DIYaudiostore.com.
@dine1967
In the Pearl 2 threads there was also discussion of diode clamps at the outputs to protect the next stages.
In the Pearl 2 threads there was also discussion of diode clamps at the outputs to protect the next stages.
I'm building a dc coupled line stage, so exploring safety issues, that's why I'm asking... And I know also that in diy that is not a big deal if you are careful and don't try stupid things... 😁
Btw, most known protection circuits have about +/-700mV threshold for detecting DC. Now, for example, you could have 600mV of DC offset with the signal on the output of the line stage, without DC protection triggered...
Am I thinking right or I'm missing something..? 😊
I would put a DC protection circuit on the DC coupled amplifier before speakers, not linestage.