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A Crossover Design on Single Exposed Board


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Full Range,

 Just curious, what transformer did you use that has 1dB steps?

At first I used the original Klipsch type Autoformers

However as I was in tweaking mode I was kindly offered by another member to buy a set of them he had in storage

He said he purchased them from a guy in Germany that makes some very nice double c-core autoformers

http://www.ebay.de/itm/Autotransformer-passend-fur-Altec-and-other-Horn-Projekte-/221435457601?pt=Lautsprecher_Selbstbau&hash=item338e94f041&clk_rvr_id=791323793053&rmvSB=true

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Thanks Full Range,

 Its all German to me. :)

Here is a copy and paste of the English version for your good self and other members

( please note my autoformers are @ 1 dB increments )

A pair of autotransformers to allow the perfect adjustment of volume improvement of phase for mid-range and high-range hornspeakers.

The sound volume can be adjusted in 14 steps, each at 1,5 dB per step. Other extraction stages are available on request.

Very high quality versions wound on Double Core.

This is for all horn enthusiasts who want to get the absolute optimum out of their speakers without using resistors and volume controls.

The old horn specialists such all use autotransformers.

Klipsch corner-horn without autotransformers is unthinkable.

Unfortunately, autotransformers have been largely forgotten.

However, they have great advantages compared to conventional crossovers not only when looked at from a technical point of view (see electrical diagram) but even more so when comparing the sound quality, which improves immensely.

Horn and woofer build a homogeneous entity, becoming more coaxial, they perform together and not separately.

The aficionado/ adept will know exactly what I mean.

The old master Shindo employs autotransformers and paper in oil capacitors. He knows why!

+++++++++++++++A few explanatory notes about the autotransformer (AT)+++++++++++++++++++++++++++

The AT is used for level adaption on multiple-combination loudspeakers.

The operating mode is similar to that of a power transformer, for example from 230 to 115 volt, it thus forms a voltage divider for AC voltage. The advantage of an AT however compared to alternating current voltage dividers lies in its much lower internal resistance, below 0.1 Ohm.

Thus the electrical damping of the connected loudspeaker is considerably higher. The power factor (BxL) also takes on considerably higher data. This is a very important factor when operating horn-drivers, as the BL-faktors have a great influence on the characteristic curve.

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Those autoformers are sole by a gentleman called Werner Jagusch. They can be either purchased off ebay, or from him directly (which might influence the price slightly). I use the same units (with 1.5db steps) and have asked him also for bass inductors. To my ears his units sound more open than either the Klipsch autoformer or solen air core inductors. I am a very satisfied customer indeed.

 

Tanks by the way for elaborating a bit on the Jentzen wax coils - it was a useful description.

 

Wolfram

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Those autoformers are sold by a gentleman called Werner Jagusch. They can be either purchased off ebay, or from him directly (which might influence the price slightly). I use the same units (with 1.5db steps) and have asked him also for bass inductors. To my ears his units sound more open than either the Klipsch autoformer or solen air core inductors. I am a very satisfied customer indeed.

 

Thanks by the way for elaborating a bit on the Jentzen wax coils - it was a useful description.

 

Wolfram

It was my pleasure Wolfram - glad to help another enthusiast

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  • 2 weeks later...
  • 2 months later...

Hi folks

Just another quick update -

As its been previously posted about the custom crossover build I have decided to make one small but expensive change on the capacitors

I have decided to change over the Sonicap capacitors (white) and replace them with Jentzen Superior Z caps

In this crossover build design , the Sonicaps feed the mid and tweeter.

So in effect their about the most critical caps in the whole xover.

This is the size difference of the two prior to fitting

post-57741-0-76320000-1432984660_thumb.j

And this after

post-57741-0-85760000-1432984757_thumb.j

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I have made several observations after a break in period between the two capacitor types

I have had two good listening sessions since the Jantzen capacitor change

However about 40 hours of music has gone through the system to settle in the new capasitors

Fortunately the crossovers are fitted with attenuation in the mid range and tweeter section so I can tweak the db output to suit my room acoustics ect

So on to a description of my listening experience

Finally attenuation set on

- Tweet on -5 db

- Midrange - 11 db ( it sounds nice from 9 db to 12 db )

These atenuator settings have just the right and pleasing mix I like best for the room the system is set up in, but I change them to suit the material I am playing

Bass - Apart from the defined sound that we can hear - The bass presentation is fast and defined and also fuller longer notes at the same time, Bass also acts like a vibrating wave machine, the sound waves just bore into the body , furniture and walls ect

Mid Range - This section has had the biggest perceptible change

The soundstage is more expanded and I explain it in this way -

Notes start sharply and finish when the sound wave energy is depleted - drums, triangles , guitar strings, violin, piano, horns, breaking glass sounds ect - the notes just hang there if they are in the recording

Tweeter - Top end at first was not as clinical as before but as the caps have settled in the top end is now very sharp and subtly more musical kinda fuller but very sharp at the same time ( hard to find a word of explanation for it )

If one could see the sound waves you could describe them as hugging the listener

That's al I have in my report as I have written it as I was listening and describing my impressions for you as I listen in real time

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  • 5 months later...

Use Google books, and read about how coils used to be made and why. Most modern coils skirt the wax because it's a pain to work with and adds cost. Most coils aren't dipped in anything, which is imbecilic. This relates to electrical and mechanical integrity. The audible difference is very subtle, hardly worth getting excited about. However, the pursuit of audio "perfection" mostly involves a long list of subtle improvements that add up to monumental improvement. Some things are less subtle than others. With that said, I'm working with Universal Transformer to have all of my parts impregnated with wax. Next in line is the 2.5mH coil, which is also getting the same wire/core/frame upgrade as the autotransformer I use.

 

Agree, if you are starting with a good product like the LaScalas, it's a game of 1-2% improvements.

 

Out of many, One unified

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When you have time, can you list your system components on the LaScalas and update your component and cost list on the crossovers.

 

Looks like JBL tweeter, Altec 802 mid driver and Crites woofer?

 

Did you take any measurements along the way for comparison purposes?

 

Very cool project!

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When you have time, can you list your system components on the LaScalas and update your component and cost list on the crossovers.

 

Looks like JBL tweeter, Altec 802 mid driver and Crites woofer?

 

Did you take any measurements along the way for comparison purposes?

 

Very cool project!

Firstly speaker drivers and cabinet construction

Heavily modified Klipsch La Scala's

Double thickness sides and back with added braces

Bass bin extension - https://community.klipsch.com/index.php?/topic/108425-la-scala-bass-reflex-mod/

Drivers

Crites CW1526C 15 inch cast woofers.

Great Plains Audio 399 A mid compression drivers, fitted to -

Elliptrac 400 timber mid range horns with adaptors to suit 1”, 1.5” & 2” horn drivers

JBL 2404H “Baby Cheeks” tweeters.

Component cost

That may not be easy as parts were sourced at various times from various parts of the world, some were pre loved and some I already had on hand

Also my purchases are in Australian dollars so the ever changing exchange rate will create havoc with correct pricing

I have posted in the thread all the components used so it is still correct to the last post of changes / tweaks

We did some sweeps and will add a seperate post on that with photos

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This post are impressions from 2 persons during the measurement tests but mostly my mates impressions as my personal impressions are noted above on post # 48

Please note that we are novices at taking measurements and microphone positioning was troublesome but we gave it a go :)

It was an interesting day for my mate and I ( we built the crossovers together but he solders better than me )

Completed over 20 sweeps, didn't record some of them as they were just, 'hey lets try this', sort of deal.

We did record I think something like a dozen sweeps. some are presented below.

The first sweep is Full Range's preferred attenuator settings as I walked in. And I agree, it has the best overall presentation.

We upped the mid and tweeter levels just to try it, and in someways it sounded better, in others not so great, not bad, just not as good as it could be.

The bass near field, well I've no idea where to measure that with his speakers. We tried various positions for the mic.

Not one made any difference, so the one here is in the middle of the bass horn cabinet, 20mm from its front 'edge'.

I found the comparison with the listening position interesting.

Looks like a decent plot to me. But I'm learning so if anyone can shed their thoughts on it, please do, but be nice, I've got training wheels on :D

The sweep pre and post capacitor change (not really shown), supposedly should push the mid section up another 25 hertz. But I can't see any difference at all. ~ 500hz.

Some of the measurements are a bit strange, like the spike at 5khz.

We suspect it might be a combination of mic position and crossover design.

But I'd like to spend another day there playing with ideas and seeing where they lead. (sweep of mid on its own and tweeter on its own would prob be a good start).

Maybe raising the crossover point for the tweeter (~6khz) may help to flatten it out a bit.

The way the crossover is designed, the caps we changed are in series with both the mid and tweeter.

The sonic difference with the change of caps though. Wow.

The caps still need to break in, But its like the system can reveal 4 more layers of detail.

The impact of bass has improved several fold, the ringing on instruments (when its supposed to be there) has grown beyond the confines of the walls.

Theres more detail but a little harshness, I believe that harshness will disappear as the caps break in.

Break in is truely over since the time we did the sweeps in May 2015

post-57741-0-95620000-1446337766_thumb.jpost-57741-0-24980000-1446337798_thumb.j

Edited by Full Range
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Very cool

 

At the end of the day, the designs always come down to bench testing and tweaking.

 

It's good you are keeping score, so you can experiment with changes and measure the effect.

 

I assume you are going for the elusive linearity.....

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In room measurements are always a bit of a shock. The fact that you even cared enough to do them

is admirable.

Anyrhing a new capacitor does, it's done doing by the 20 hour mark. I was told this by Richard Marsh, and while explaining the phenomena to me, I found my eyes glazing over.

If you listen at live levels, the harshness is being caused by the horn. The throat overloads quickly at loud levels.

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  • 5 months later...

A few weeks back I experimented with Paper In Oil (PIO) capacitors in the bass section of the crossover

After living with the PIO capacitors for a while I have decided to go back to the Jentzens

Not that they were bad in the scheme of things - just not to my palate

post-57741-0-68480000-1461480571_thumb.j

So on to another update

Today I was left home alone and decided to get the soldering iron out for another small tweak to the crossover

This tweak was made in the Tweeter attenuator section only

Recently purchased 2 Duelund cast resistors and knowing that the other Duelund resistors I used in the crossover made a noticeable change I decided to swap over the current Path Audio to the Duelund cast resistors

To make a neat and tidy job of it I repurposed and altered some small brackets to hold the much longer Duelund Cast resistor in place

I believe that this particular resistor is called a 'swamping' resistor and in this possition it is used to help linearise the auto-former. ( If I'm wrong I would be happy to be corrected )

Now on to the testing and listening report

Warmed up the DIY First Watt F 6 Class A amp for about an hour then got down to business

First impressions were instant, and a noticeable change for the better was observed, it's as if all the high notes are effervescent with life

I was getting a tingle at the back of my neck to the top of my head from it

Hard to describe the feeling but effervescent is very close

I LOVE MY SYSTEM were my words as I shouted out in delight

Normally one would expect vibrations from the Bass and Mid Range but this change has opened something in the higher octaves that I never knew was missing.

So not only did the system reproduce the high octave sounds much sweeter, I was also getting a tingling feeling as well and that was totally unexpected

FR

post-57741-0-35040000-1461480975_thumb.j

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Props... thanks for the updates. I eagerly await my new AA's

Later on this year I will probably make my final modification

Just saving up several hundred dollars, to change out the Large Air Core inductors to Jentzen Wax 12 awg for the mids and 8 awg for the bass

Will keep the members updated as I make any changes and report my results

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Excellent work on your crossovers I am in the middle of doing new x-overs for my Forte's that will be exposed.

I have learnt and experienced quite a lot in audible changes with component selection

More than subtle changes have been observed with the Deulund resistors.

However keep in mind and have a holistic approach to everything that's connected together as one component affects the other

For most people these changes may not be perceived but for Klipsch Horn owners that have over 100db sensitivity it's noticeable

Keep us in the loop with your build progress

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  • 1 month later...

Some months ago a decision was made to have Jantzen make me flat foil WAX inductors

Money was saved and the order was placed

The change over was for the main inductors

One for the bass - 8AWG L 2.70 mH Rdc 0,14ohm

One that jointly handles midrange and treble - 12 AWG L 2.4 mH Rdc 0,31 ohm

Take Note - that the set of 4 coil units weigh over 30 pounds - that's a workout and a half ;)

Hook up wire is silver plated OFC copper and silver solder was used

post-57741-0-26140000-1466815838_thumb.j post-57741-0-43660000-1466816177_thumb.j

The 2.7 mH inductor is large - the size of a coffee cup saucer @ approx 10 pounds each

post-57741-0-16980000-1466815983_thumb.jpost-57741-0-00020000-1466816011_thumb.j

And the finished job

post-57741-0-11660000-1466816299_thumb.jpost-57741-0-31540000-1466816321_thumb.j

The only thing left was to sit down and have a listen

Listening impressions observed we subtle but in a positive way

Most noticeable in some key areas were -

1) Seamless crossover points

2) Better midrange voice definition and control - but still keeping its sharpness and prat

3) Bass became or seemed deeper to my ears, but also retained its layered effect but most noticed was that these layers were smoothed out making the music meaty in the bass

In saying that I feel that when the First Watt M2 amplifier is installed and connected to the system in a couple of weeks it will be a different kettle of fish

** Will update again with listening impressions using the M2 **

I have one more modification in the works but I'm just waiting for the production of specific values to be made and then move forward with it at some point in the future

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