@Claude - yes! Figure I start him with soldering and he can step into typing and forum discussions later 
@ffarges - putting the caps in was ummm a trying experience, didn’t go quite as smoothly as I would have liked though my son had a blast bending the leads all over the place to try and get them to fit, so all worth it in the end.
We’re working on the house so I don’t have my full setup to listen to the preamp on so I have to run it to a couple powered mo it it’s right now. Looking to install a quick dpdt switch on then so I can invert phase quickly. I think that’s the easiest method of correcting the phase given my situation? If I’m reading Claude correctly I could also shoot for the null point of 12v for bias adjustment. Though I don’t know if that solves for phase or just nulls the second order harmonics (believe the latter as Claude mentioned this was at the cost of absolute polarity),
@ffarges - putting the caps in was ummm a trying experience, didn’t go quite as smoothly as I would have liked though my son had a blast bending the leads all over the place to try and get them to fit, so all worth it in the end.
We’re working on the house so I don’t have my full setup to listen to the preamp on so I have to run it to a couple powered mo it it’s right now. Looking to install a quick dpdt switch on then so I can invert phase quickly. I think that’s the easiest method of correcting the phase given my situation? If I’m reading Claude correctly I could also shoot for the null point of 12v for bias adjustment. Though I don’t know if that solves for phase or just nulls the second order harmonics (believe the latter as Claude mentioned this was at the cost of absolute polarity),
Hello again,
I don't know if you can install a dpdt switch to invert phase easily, depends a lot on your source etc., all I know is it can also lead to electrical probs...
What I know is that you can indeed shoot past the null point, say aim for over 13V and get the negative H2 IF you don't invert the LS cables (or anything similar from power amp to LS). Sadly, you lose then indeed absolute polarity. Might be an issue or not, depends on your sensitivity for absolute polarity (a hot debate otherwise).
You could though regain absolute polarity by not changing anything (eg over 12V and no LS connection change) but having a source that enables to switch polarity (sometimes called phase inversion, you can find that on modern DACs and some computer players, MC cartridges...)
Last but not least, your null point might not be strictly 12v so I found it best to adjust by ear. AFAIC, if your are at a symmetrical setting around your null point, I found exactly the same sonic signature except for the absolute phase bit. So the B1K can be used past the null point with its negative H2 and that's a plus if you are using HP as these don't allow for an easy ... LS connection swap
So to wrap it up, if your source enables phase inversion, then you get absolute polarity and negative H2 just by:
- inverting phase at the source
- adjusting the B1K past the null point (and not below)
- not inverting phase afterwards (eg not swapping LS connections)
If your source doesn't do phase/polarity inversion, then you simply lose absolute phase but retain negative H2. My case currently... old DACs and MM don't do phase inversion without additional transformers or op amps :-(
I hope this helps
Claude
I don't know if you can install a dpdt switch to invert phase easily, depends a lot on your source etc., all I know is it can also lead to electrical probs...
What I know is that you can indeed shoot past the null point, say aim for over 13V and get the negative H2 IF you don't invert the LS cables (or anything similar from power amp to LS). Sadly, you lose then indeed absolute polarity. Might be an issue or not, depends on your sensitivity for absolute polarity (a hot debate otherwise).
You could though regain absolute polarity by not changing anything (eg over 12V and no LS connection change) but having a source that enables to switch polarity (sometimes called phase inversion, you can find that on modern DACs and some computer players, MC cartridges...)
Last but not least, your null point might not be strictly 12v so I found it best to adjust by ear. AFAIC, if your are at a symmetrical setting around your null point, I found exactly the same sonic signature except for the absolute phase bit. So the B1K can be used past the null point with its negative H2 and that's a plus if you are using HP as these don't allow for an easy ... LS connection swap
So to wrap it up, if your source enables phase inversion, then you get absolute polarity and negative H2 just by:
- inverting phase at the source
- adjusting the B1K past the null point (and not below)
- not inverting phase afterwards (eg not swapping LS connections)
If your source doesn't do phase/polarity inversion, then you simply lose absolute phase but retain negative H2. My case currently... old DACs and MM don't do phase inversion without additional transformers or op amps :-(
I hope this helps
Claude
Ah ok great - looks like I’ll have to play around a bit with the bias and see what I like
My last preamp was also phase inverting so I’d just switch the LS cables but cannot do that with the powered monitors. Interesting that a dpdt switch installed in the monitor itself between the amp and speakers would cause electrical issues. Wouldn’t have guessed it would have had any effect - but I’ll take your advice here.
I did prefer my last preamp with the phase “corrected.” Reversed definitely gave a more holographic presentation but seemed at the expense of some midrange thickness. To each their own though, could just be my OCD getting the best of me. Thanks again!!
My last preamp was also phase inverting so I’d just switch the LS cables but cannot do that with the powered monitors. Interesting that a dpdt switch installed in the monitor itself between the amp and speakers would cause electrical issues. Wouldn’t have guessed it would have had any effect - but I’ll take your advice here.
I did prefer my last preamp with the phase “corrected.” Reversed definitely gave a more holographic presentation but seemed at the expense of some midrange thickness. To each their own though, could just be my OCD getting the best of me. Thanks again!!
Interesting that a dpdt switch installed in the monitor itself between the amp and speakers would cause electrical issues. Wouldn’t have guessed it would have had any effect - but I’ll take your advice here.
> If you are dead sure the switch is located after any active stage and between amp and LS section the it shouldn't indeed be a prob.
I didn't see in the initial post where the switch would be, hence the warning...
Sorry for the confusion
Claude
> If you are dead sure the switch is located after any active stage and between amp and LS section the it shouldn't indeed be a prob.
I didn't see in the initial post where the switch would be, hence the warning...
Sorry for the confusion
Claude
Perfect thanks Claude!!
Yes - it would be installed directly on the LS wires as they come out of the internal amp in the powered monitor. So B1 Preamp -> Powered Monitors -> Internal amp in monitor -> LS outputs from internal amp -> would install switch here between LS wires and input to speakers.
Looks like my three year old will need to fire up the soldering iron again - he'll be very happy
Yes - it would be installed directly on the LS wires as they come out of the internal amp in the powered monitor. So B1 Preamp -> Powered Monitors -> Internal amp in monitor -> LS outputs from internal amp -> would install switch here between LS wires and input to speakers.
Looks like my three year old will need to fire up the soldering iron again - he'll be very happy
Hi, I now have instaled V-Cap ODAM in the signal way. Using 0,47uF - 1,0uF - 2,2uF.
Have played for 50 hours now. Its sound good with elctrolyts but with ODAMs I must say it sound more open, bigger soundstage,tight bass, sound not coming from speakers themself but more like mixed togther. Im not good at explane sound but I like what I hear ( ;
Frank
Have played for 50 hours now. Its sound good with elctrolyts but with ODAMs I must say it sound more open, bigger soundstage,tight bass, sound not coming from speakers themself but more like mixed togther. Im not good at explane sound but I like what I hear ( ;
Frank
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I've started building a pair of these. Thanks to the build guide (thanks 6L6!!), it's going well so far. But I have a couple questions now.
First, I have some sorbothane I am planning to use for damping purposes. Can that be put under the tube? Or does that need to remain clear?
Second, I usually build these into wood cases, with slots and holes as necessary for heat release. With the B1K, of course, I guess I don't want the holes, due to microphonics. But then: How much is heat an issue here? Wood isn't a good heat conductor. If need be, I think I could put some metal on the top or bottom.
Thoughts? Thanks in advance!
First, I have some sorbothane I am planning to use for damping purposes. Can that be put under the tube? Or does that need to remain clear?
Second, I usually build these into wood cases, with slots and holes as necessary for heat release. With the B1K, of course, I guess I don't want the holes, due to microphonics. But then: How much is heat an issue here? Wood isn't a good heat conductor. If need be, I think I could put some metal on the top or bottom.
Thoughts? Thanks in advance!
rikiheck, according to Nelson's diy document, "the
preamp will draw about 60mA in operation" so 1.5W to dissipate?
Congratulations
