Tweaking Sextets.

[Black Stuart]

Alex,
are the caps voltage @250V necessary. How lowin voltages can I go.

[Alex Kitic]

The caps need not be 250V, actually 63V (lowest voltage of polypropylene types I know of) is more than enough.

If you check the voltage rating of the (one) electrolyte in the midrange network, the one I disconnected, it is 63V. This should suffice up to 150W RMS...

[Black Stuart]

Hi Alex,
even though I want to go active in the future I could'nt resist buying some of my favourite caps - Russian K73-16. 4 x 4.7uF/2.2uf and 20 x 1.5uf yes I know i don't need that many but there was no choice. If you want to try the 1.5uF i can send you some.

My x/over is very different from those posted here. I will post the values tomorrow.

[Alex Kitic]

Looking forward to seeing your crossover schematics: does it differ in value, or in composition altogether?

While ther have been several versions of the Sextet, the only difference in hardware is the change of the bass unit between version 1 and 2. As the rest has not been changed, it is difficult to understand the changes in crossover components and design... probably motivated by the wish to cut production costs.

Makes you wonder, once one has a good review and distributors with "good" samples for demo-ing, they can start shipping lower quality versions of the same product? Mind you, some crossover components are not cheap, like coils, while others are rather bulky as well and could be difficult to implement in production standards...

[Black Stuart]

Alex,
here's my x/over:

Bass - graphite cored inductor and 30uF/100V (Alcap) with a 5W/8.2Ohm resistor in series.

Mid - 4.7uF/250V (ICW) paralleled with 2 x 60uF/100V (Alcap) and a choke (indeterminate value).

Tweeter - 2.2uF/250V paralleled with a 1.5uF/250V.

Wiring - beefy 1.5mm bass / mid and tweeter Heybrook's own, very similar to the DNM i/c , signal and return approx. 10mm apart.

I would like to use s/plated OFHC 1.5mm for bass / 1mm s/plated OFHC for mid both of these used with oversized PET tubing making effectively an air dialectric, as I use for all i/cs and chassis wiring.

For the tweeter I would like to use UP-OCC copper wire/24/25AWG. I would also like to use an air dialectric for this as well but as it's copper it has to be sheathed in an airtight dialectric.

I would'nt say that my Sextets have a mid forward sound. The sound is a bit dark and this I put down to the caps used. changing these where possible for Russian K73-16s should cure this - they are fast, clean and very dynamic.

I can source K73-16s for the 4.7/2.2 and 1.5uF but I need to find an alternative for the 30/60uF Alcaps.

The 5W/8.2Ohm ceramic I would replace with a 10W Mills wirewound - that's it!

[Black Stuart]

Hi Alex,
I would appreciate your thoughts on my x/over.

[Alex Kitic]

Originally Posted by Black Stuart

Hi Alex,
I would appreciate your thoughts on my x/over.

I would have answered earlier but I have received no notification that there was a reply to the thread...

I think that there is some mistake in your "depiction" of the crossover. Some elements are described as series or parallel, where I do not expect them to be, since they do not make much sense (to me).

It is obvious nevertheless that your crossover does include the choke that is missing from mine (and some other crossovers in this thread).

Assuming that we do have the same components (i.e. loudspeakers installed in the box), I can only advise you to try to replicate the crossover modification I have explained above. Try to do it in such a manner to be able to put everything back in place in case you do not like the result - but I guess you would probably like it. Some parts of the crossover anyway resemble very much what I have done with mine.

Try to get rid of the bipolar caps anyway (they might also be aged), and if you have no other better ideas, try to replace with a number of paralleled WIMA caps, like 10uF/63V - they are relatively small and square which facilitates grouping.

If that is the case, in the end just extract the "unnecessary parts"...

Frankly, those speakers are good, but after all the years and after finding out about so much inconsistency in crossover and manufacturing versions, I cannot advise beyond the replication of what I have already proposed. I guess that whether it would work for you, or not, depends also on your taste...

[Black Stuart]

Hi Alex,
I did'nt make a mistake with series or paralleled caps, that's how they are.

As I have already said in another post - I am happy with the overall presentation and in the future I will almost certainly go active but as you say all these components are old and having a bit more knowledge now than when I bought them, I can choose better components which I already have or have bought/can buy cheaply.
Most of the caps will be replaced mainly with K73-16s - never would I use Wimas, every time I replace them with something else the result is always a much better sound.It's well known that I prefer to use Russian K73-16 caps where ever possible, I suggest you buy some of the 63V if you can find some that are the value you want. Apparently all the K73 series caps have no obvious glaring differences, I have just bought some K73-11, 2.2uF/250V - so cheap!

I will remove the x/over from the cabinet and probably use the existing x/over panel without putting it in a box - much better and less work this way.

[Alex Kitic]

Stuart,
As usual no info on reply to thread posted, I guess this is the only forum board that I am not able to set properly?

Nevertheless, I still think you got wrong the crossover, not the parts values. It can happen easily because it is not particularly tidy nor accessible. The connection between some of the parts mentioned just falls out of the pattern consisting of simple first order cuts and a Zobel correction.

Externalizing the crossover might be a good idea but it is actually mounted on the binding posts carrier piece and it means removing the parts and placing the new crossover in a box separate from the loudspeaker. In that case you may use even large parts that would not fit otherwise.

Multi-amplification might be another interesting option if you can provide all the amps relatively easily (like I could) but it is a different topic.

I do not think that these speakers deserve or would repay particular investment in parts. While you may choose to use Russian stuff or Wima at your own taste (and your findings here only reflect your taste or bias), I suggest to keep it clean, small, tidy and inside the box, and that was my initial idea when posting about a simple tweak with more or less existing parts and minimum expense.

Had the driver been of higher lineage, like Dynaudio Esotar and the ilk, it would have had better cabinet and crossover solutions, like for instance the Sonus Faber Electa Amator, or Extrema... and it would also have a different price tag, even as second hand. So this is just about a simple and cheap tweak to improve on factory routine. As such, it is worth trying and the results might be very pleasing to most.

Regards,
Alex

[Black Stuart]

Alex,
externalising the x/over is a good idea in any speaker and I don't intend to make a new box for the x/over, just create a new back board feeding the wiring through rubber grommets and re-soldering onto the original positions.

Re. the K73-16s - do you have personal experience of them? There are so many truly primitive myths in the audio world which just don't match reality. I have seen these awful Wimas recommended all over the place. Manufacturers use them because they are cheap, small and fit snug to a PCB, this last is a good point but that's all. Yes the specs look very good but to choose any component on specs is ludicrous - how does it sound is the only criteria for a rational mind.

I have only one taste and that is for neutrality. Bias is like political and religious indoctrination I have total contempt for both.

There is a thread on diyaudio about just these caps - hilariously, the few negative comments come from those that have never tried them and only one who has - all the rest mention the wonderful neutrality, clarity without a hint of brightness at the top end and superb bass response - this is what all neutral components do they let the signal pass through without adding or subtracting anything.

Ali has the Temple Audio class D amps fitted with the Wimas - lets' wait and see what he thinks when he has replaced them with the K73-16s.

It is your personal opinion that the Heybrooks are only so-so speakers, also to compare them to speakers that cost $4,500/£3000 in 1992 when the Heybrooks cost £1200 is'nt a fair comparison is it?