Seduction build question

[bainjs]

When I did the resistance check, all the values are correct except for A3,B3 and A8,B8.  The manual says the values should be 1M ohm +.  I'm getting .0L for all of them.   These are the LED connections on page 32.  The silver side of the LEDs are oriented correctly.

Any help is appreciated.

Joel

[Paul Joppa]

1M+ means "more than 1000000 ohms" - in other words, a very high resistance. OL stands for "overload", in other words, higher than the meter can indicate. The purpose of this measurement is just to make sure you have not shorted the LEDs accidentally, or damaged them with excess heat, either of which will cause a much lower resistance reading.

Background: the LEDs need more than 1.5v applied before they will conduct any current, and most meters use less than 1.5v to test resistance , so you almost always get a high reading. But it varies from meter to meter, so it's hard to predict - the actual value can be all over the place.

Incidentally, the LEDs conduct in only one direction, so you might get different readings if you reverse the meter leads.

[bainjs]

I suspected that was the case, but wanted to make sure before I went to the next step. 

Thanks Mr Joppa!

[bainjs]

I finished the Seduction and played it a few days before I installed the C4S board.  I'm really pleased with the outcome.  I do have a question:  I'm getting a faint buzz when the volume is fully up.  Is this typical?  I can't hear it at normal listening levels. When I turn the unit off, the buzz goes away so it's not the Foreplay or SEX.

thanks

[Grainger49]

Joel,

Try a pair of shorting plugs in the input rather than the TT leads.  See if that cures it.  It could be the TT/wiring that is the source of noise.

[fullheadofnothing]

Is the noise equal in both channels? The right channel is theoretically more likely to be noisy because it is closer to the power supply components. The design does allow for an internal shielding chassis to be installed if needed, but I don't think it has proven necessary very often. This is primarily a strategy to block out RFI and other nasties, it might help whatever the source of your issue is.

More likely, however, is that your noise is the noise of the tubes. You could try another pair, but it also sounds like it is at such a low level that it is basically a non-problem. I also found that the springs in the tube shields exacerbated my microphonic tubes and removing them made a big improvement. YMMV of course, and use a tool NOT your finger to poke out the springs...

[Laudanum]

When you turn the unit off, you also kill the signal from the turntable.  I'd bet that the turntable and/or phono cart has got the be the source that is the biggest PITA in terms of hunting down noise (hum and buzz) .  Well, aside from maybe the computer as a source (dont know about that yet).   I had a hum and buzz from my table and/or cart when I set seduction up.  This was for the headphone system where it could really be a much bigger annoyance than with speakers.  It was only at fairly high volume levels.  Drove myself nuts troubleshooting.  It was as simple as flipping over the turntables non polarized 2 prong plug.   The hum is essentially gone now, the buzz is not completely gone but inaudible unless the volume knob gets pretty close to wide open, far louder than I could possible listen and it would only be heard when the needle was in dead wax.   On a related note,  I have a slight amount on the main system (loudspeakers, not phones) as well, different stage, different table.  Again, not obtrusive at listening levels and volume needs to be up pretty high to hear it.   I remember that there was some on my first real system years ago as well.   Point is, while Im sure some folks have dead quiet vinyl systems at full clockwise rotation of that "volume knob", I highly doubt that it's uncommon to have a little bit which shouldnt be a problem if it is unobtrusive when listening. 

[mchurch]

I too have a very slight hum when wide open, but when I used the shorting plugs instead of the Cartridge the hum is gone. Most noise I have experienced comes from the TT or Cart. Some carts are worse than others as well as some tonearm wiring is not as good as others. At the levels I have to turn it up to for the hum to be noticed it would like destroy my speakers, eardrums and get me evicted in that order. At normal levels even when played through extremely quiet passages of music it is impossible to notice. Also, no matter how much care we take with tube purchase there will always be a chance of tube noise at those levels.

One thing you can also confirm is that the metal shields on the tubes are, in fact grounded, this is easy to confirm with a meter. I had a case once where the painted top plate actually insulated the tube shield, entirely my fault for not properly cleaning before installation. Even then the hum was hardly an issue.

Cheers

[Grainger49]

Mike, good point!

Joel has heard my system with both the Seduction and Eros in it.  My Seduction has a little hum, no buzz.  I don't think he ever heard it .  And maybe I turned it all the way up so he could hear it.  But at my listening chair, where I listen, there was nothing to be heard.

BTW, Joel, you have boxes winging (joke) their way to you as of yesterday afternoon after my pacemaker battery check.

[Laudanum]

I got it backwards ... buzz is gone, tiny bit of hum.

[bainjs]

Grainger,

I received the caps and LPs today.  Thank you. Paula's package should be there soon. 

I believe I understand the KKs - the .47uf along with the .102 used as a coupler to replace the stock .47uf, correct?

What about the 2uf Obligato - which stock cap does it replace?

Joel

[bainjs]

One more thing about the hum. I disconnected the phono and the hum did not change. I'll try shorting plugs tomorrow. The hum can only be heard when the volume is turned up all the way so I don't think it's anything to worry about.

When I install the new caps, I'll go over all the joints to make sure the solder looks good. 

Thanks for everyone's comments!  I really enjoy seeing all the different perspectives.


Joel

[Grainger49]

Grainger,

I received the caps and LPs today.  Thank you. Paula's package should be there soon. 

I believe I understand the KKs - the .47uf along with the .102 used as a coupler to replace the stock .47uf, correct?

What about the 2uf Obligato - which stock cap does it replace?

Joel

Yes, the silver bodied KK caps in parallel with the black Obbligato caps.  The others are just for fun.  You can use them as a power supply bypass cap.  They are PETP, another plastic, caps.

Don't worry about hum that is only heard with either your ear to the speakers or with the volume all the way up.  Nobody listens that way.  If I had turned my system all the way up when you were listening to the Seduction you would have heard a slight hum.  As I said elsewhere, I blame audio reviewers for this insanity. 

[bainjs]

Now I'm confused.   Do I use the .1uf coupling cap with the .47uf or the 2uf obligato?

And if it's to be coupled with 2uf obligato, which stock cap do I replace with them?


Thanks

[Grainger49]

The black Obbligato goes at the output.  You can use the 0.1uf to either bypass that Obbligato or between stages replacing a 0.1uf brown (mine were brown) cap.  They are wired to the grid of the second stage.  

Edit: the interstage (0.1uF) caps go from T29-T26 and T39-T36.

The other ones are just to try clipping to other things to see how they sound.