A new pair of Silbury speakers: newbie questions

[zintolo]

Hi, I would like to give a similar color to the Silbury I finished (the light brown part, without the scratches). Can anyone suggesting me how to proceed?

Thanks
Roberto

 

[zintolo]

I have another question: I've placed both speakers close to a wall, far from corners, with a low Zout Class D amp, and Silbury still sound full and without any need of subs, while in comparison FHXL would benefit from a sub on certain genres. Is it normal and would it be balanced with an higher Zout amp? I've not tested them both with a feedback-less tube amp.

 

[planet10]

What you gain from the larger mouth of Silbury.

dave

 

[zintolo]

Thanks Dave, will the FHXL in a corner come closer to the Silbury close to the wall?

 

[zintolo]

Can anyone suggesting me how to proceed?

I started with light walnut stain with a small amount of black, sanding, light walnut stain with a small amount of rusted red, sanding, light walnut stain. It is very similar.

 

[zintolo]

After a few trials on spare blocks, I’ve never reached the colour I wanted, so I would like to go to something different.

I would like to give a warmer colour to the wood. Would an oil finish be suggested? How would you do it?

Thank you in advance,
Roberto

 

[zintolo]

I’m designing a tube SE amp for the Silbury and the FHXL. Do I have to consider 6 Ohm for the former and 8 Ohm for the latter?

 

[taotao]

Thanks! I used vinavil, so not the best choice. Anything I can do now to check if it is leaking somewhere, or to fix it?

Hi Zintolo,
you can run an impedance measurement once finished. Compare left and right. If one speaker leaks, there will be less impedance peaks.
If there a leaks you could try, lay the speaker on its side and pour water mixed with white glue, just enough to cover the sidewall from inside. Hopefully it will flow into the seams. Ah and move the speakers a little bit to spread the glue inside

 

[mdpaudio]

Try both 4 and 8 ohm outputs to see which sounds better to you. One will give slightly more power, the 8 ohm with 6 ohm speaker, with slightly more distortion and the other the opposite. It might not even be audible. It won’t hurt the amp trying either.

 

[zintolo]

@taotao thank you, how to perform impedance tests? I’ve never done it.

@mdpaudio I’m still in the designing stage, so I can define a better working point based on the real impedance of both speakers.

I will wait for @planet10 answer before finalizing the working point.

 

[taotao]

The most convenient way is a little Box from Dayton Audio (DATS V3).

 

[zintolo]

@taotao thanks, I will wait for the official answer.
Not reasonable to spend almost 200 € to measure the impedance of a speaker.

 

[taotao]

Yes, but it's also possible with some cheap resistors and the free Version of arta measurement software. Just search in this forum.
Btw. My Nagaoka D57 Horns had one speaker that leaked inside. The Bass from one side was somehow muddy. I compared it with the other side (impedance measurement) and i could clealy see, that the bad side had lesser and not so sharp peaks in the diagram. I applied White thinned wood glue and it worked perfectly.

 

[zintolo]

Thank you @taotao , if I only had a voltage controllable signal generator, a simple Arduino could sweep, measure the voltage at the voltage divider at every frequency, and plot all data. I will check if I can find something cheap. I will check Arta as well.

Thanks for the thinned wood glue tip!

 

[shadowplay62]

Arta Jig

Post in thread 'Test equipment for loudspeaker measurements?'

2022-07-09 3:33 pm

Thanks for the suggestions. As written above, Mic is omnitronic mm-1c. I do not have an audio interface yet (other than laptop headset-jack), any suggestions that would work for both sensitivity and impedance measurements?

Any half decent 2 channel USB audio interface will do the trick, I use Steinberg UR22mkii and it's great! For a mic, a calibrated mic would be a better option but at least you have something to start with to learn the tools and design process.

The key to using this equipment for speaker impedance and time accurate acoustic measurements is a simple jig that is...

• DcibeL

 

[planet10]

I will wait for @planet10 answer before finalizing the working point.

I’m goinna guess what the question is: Which impoedance tap?

Answer: the one that sounds best. MDP gives the basics, but no (well almost none) have a flat impedance. The OPTs are typically tapped for a nominal 4 + 8 Ω (or a compromise 6Ω), Note that more than not, tube amp makers don’t even know what i am talking about when i ask them wht the output impedance of their amp is.
so use the 8 and 16Ω taps for comparison purposes.

In a horn there will be some added ripple/impedance peaks in he LF, The 8Ω line is completely under the loudspeaker impedance, The 16Ω is closer (on average) to the real impedance). Add to this: how did the maker choose to specify where the taps really are, and we assume it is flat,likely iusn’t.

So what it sounds like …

dave

 

[GM]

Note that more than not, tube amp makers don’t even know what i am talking about when i ask them wht the output impedance of their amp is.

IME none I, or had folks query, though a few did go back and measure them and surprised how different it was from typical 4, 8, etc..

 

[zintolo]

Thank you all, I am defining the working point (voltage and current) of the SE amp, and I have a pair of 3k primary to 4 and 8 Ohm secondary output transformers. On the Silbury page ( https://www.wodendesign.com/Silbury.html ) it is claimed for a nominal impedance of 6 Ohm, while FHXL is declared a 8 Ohm. On a 8 Ohm load. That amp, with that specific output transformer, has an output impedance around 3 Ohm.