Heretic Loudspeaker A612 Clone

[Lojzek]

This design demands significantly more complex filter network than assumed as per x/o photo. I have checked simming it. I would not bother cloning it.

 

[rickmcinnis]

It was made clear in Reichart's article that it was trial and error as all series crossovers are. Lots of measuring and even more listening. It is a long and frustrating process. I know I never succeeded in getting one to work well.

 

[ChrisABC]

The OP wants to make a clone of a (Heretic A612), which is a clone (facsimile/ sort of-dif driver) of a (orig Altec 612).
Another option get a different driver. Then it would also be a facsimile of a clone(facsimile) of a Altec 612.

That's a Big box
https://hometheaterhifi.com/reviews...the-heretic-ad612-monitor-loudspeaker-review/

Similar(maybe)-dimensions (35x22x19) vs Heretic 30.25 H x 25.5 W x 17.75 D
https://www.amazon.ca/Freestanding-Chest-Freezer-Adjustable-Thermostat/dp/B08543GYMS/ref=sr_1_5?crid=1MQ21DQW16338&keywords=4+cu+ft+freezer&qid=1685813092&sprefix=4+cu+ft+freezer,aps,135&sr=8-5

Adjust the box to your liking, (Important) have the front baffle to look like the Altec 612, some other driver examples-

https://celestion.com/blog/?fwp_blogcat=cab-designs,crossover-designs

https://celestion.com/wp-content/uploads/2021/10/FTX1530-Crossover-datasheet.pdf

https://celestion.com/blog/ftx1225-suggested-crossover-and-cab-alignment/

a recent thread-large woofer, box

https://www.diyaudio.com/community/...wideband-cabinet-conception-crossover.398348/

 

[planet10]

@DaveR?

Perhaps the 200% Norwegian who is a series XO star can have a look at the problem.

What kind of amp do you have?

dave

 

[planet10]

Another crossover photo from the Heretic Facebook page. Can anyone read the resistor values?

It is clear they buy all their parts from Solen.

dave

 

[planet10]

A first pas slook suggests an 80 litre box tuned to 50 Hz, a 6x8,5 cm vent 18mm long (material thickness (the Heretic Designer in his verbage forgets the walls have thickness).

utside cabinet dimensions are 30.25” x 25.5” x 17.75” and made from are 3/4” birch plywood

Note first that there is no ¾” BB. It is 18mm.

So, about 185 litres if no bracing. Let’s give him the benefit of the doubt and say there is some, so 180 litres. Unles syou have a high output impedance amplifier this will be a bad alignment (but seen too often)

dave

 

[A1008]

Could it be something like this?

 

[raymondj]

I think you can tune on L2 to give you what sound you prefer maybe take it a lower in value?.

 

[Rob7]

Has anyone designed a proper box for this driver yet?

 

[raymondj]

Not yet.

I am thinking about giving them a try.
I cannot confirm but i remember that 60 to 80 litres maybe for reflex with QB3 alignment. 40 litres for a sealed design with limited bass capability. A sealed design could still be a valid compromise for some users in small space especially somebody using a 1 -3 watt SE Valve amp who need the sealed box to control the bass aspects but providing adequate volume with the limited power

For the larger Reflex cabinets I was thinking maybe a traditional Tannoy Chatsworth type cabinet (840 x 395 x 260mm) , or maybe a JBL100 box shape scaled up to give the necessary box volume and fine tuned by tilting backward as needed using small wedges between the speaker and the stand.

Needless to say my wife is not overly keen on the large box sizes.

 

[Rob7]

Needless to say my wife is not overly keen on the large box sizes

Ha! my wife long ago, kicked me and my equipment out of the living room! In a back bedroom and can do as I please… But there are size constraints.

 

[ChrisABC]

Perry Marshall- open baffle 12HX230 Digital Crossover
post#55, 60
https://www.diyaudio.com/community/threads/open-baffle-bass-reflex-hybrid.393837/page-3
post#61
https://www.diyaudio.com/community/threads/open-baffle-bass-reflex-hybrid.393837/page-4

https://s3.amazonaws.com/psma-website-assets/Faital_Coax_Dipoles_Plans.pdf

 

[raymondj]

I have been playing a bit I have them on a 18mm MDF Baffle. H 65cm and W 40cm. N.B. Only one baffle so no stereo listening achieved yet.

I need to check my smaller inductor as it is old and is marked as 0.7mH it could be a little bit different once re meaured.

I have one resistor at the R1{}R2 position of 11ohms. Additionally as attenuation between C1 and the negative of the tweeter I have 18ohms.

L1 is 1mH, L2 0.7mH as mentioned capacitors are both 8.2uF Mic was at approx. 20 degree horizontal offset> will do more investigating and refining.

My first impressions is that I should be able to do this passively using the serial crossover topology.

Obviously component values will change and I have the impression that I will have to go ahead and build the box in the Tannoy Chatsworth style. The reason for this is that I do have some 12" Tannoy reds and the cabinet with a detachable front baffle should allow me to work with either. It will be interesting to see how these tune further. Obviously the box and the effect of its stuffing still need to be worked with. The 4-5Khz bump looks a bit high but I may leave it or have to address it but at the same time not killing the higher frequencies.

I see that at the Heretic website that they have too gone to something approaching the slimmer taller tannoy box design. Which probably means more sales for them as its slightly less imposing

Graphs:
Response
Red / blue is response 20 degree of axis. blues being 4mS window. Green is reverse connection.
Impedance
Red impedance, Green phase.

 

[ChrisABC]

Last resort crossovers- (not series though)

Econowave

https://projectgallery.parts-express.com/pro-audio/faitalpro-based-econowave/

Faital 12pr310
https://www.usspeaker.com/faital pro 12pr310-1.htm
Selenium D220Ti CD
https://www.parts-express.com/pedocs/specs/264-270-d220ti-spec-sheet.pdf

Heretic driver
Faital 12hx230
https://usspeaker.com/faital pro 12hx230-1.htm
---

uhhh

Faital 6hx150-6
https://www.parts-express.com/FaitalPRO-6HX150-6-Neodymium-Coaxial-Driver-8-Ohm-294-1192?quantity=1

see the 3rd question...

"Hi. I have two of these drivers but no crossover. Is there a PE assembled crossover that I can use?
A shopperOct 3, 2019

Best Answer: A 1,700 Hz, 12 dB/octave crossover is recommended, the closest i would have to those specs would be the 2000 Hz model below.

Greg T.STAFFOct 3, 2019ReplyInaccurate

Dayton Audio XO2W-2K 2-Way Speaker Crossover 2,000 Hz

 

[raymondj]

I need to carry on understanding the serial Xover topology. It should be intuitive , but it isnt as yet to me.

My mouse wheel finger is plum tuckered out with all the wheel rolling in the simulation. Plus youngest son here with his partner and they were out till late this morning so I don't think there will be any major measurements today. When the index finger signals he is good to go I may look at backing off the attenuation and using a very small capacitor in front of the tweeter. That may give a reasonable response, but then when i go and have a look at the directivity it will be poor.

I will also have a look at a series crossover in the coming days.

 

[Zoran]

Agreed! So what is the guess as to what these are? Two resistors in parallel on the tweeter? 0.9 ohms attenuation is only about 2db on the tweeter.

An L-Pad seems unlikely to me given the values. Any thoughts on this?

The diference in SPL LF/HF is about 9db that is huge... So it is not lightly that 0.9ohm is the serial value? Simply it is not enough.
More ligtley is that they are in serial OR even configured as L-pad...
To remainf You -6db is a 1/2 of voltage value. Another -6db will be 1/2 of 1/2 (1/4). So -12db is 3/4 : 1/4 toatal level...
cheers

 

[Zoran]

scale these graphs in photoshop and blend to have more clear insight what is happening?

Please take a look in the crossover plate, the places for coils are predicted to be bigger. So that can lead to usage of inductors with much "fatter" wire, with low Rdc specially on bass unit...
img_8267-jpeg.1179898

 

[mattstat]

I need to carry on understanding the serial Xover topology. It should be intuitive , but it isnt as yet to me.

And that's one of the major issues with series crossovers. The basic function is reasonably straightforward, but once you get into trying to shape response and deal with real-world speakers you run into constraints all over the place and resorting to circuits that get complicated and tend not to perform exactly like the simulators say. If you're picky about the result and don't have speakers that posses the desired frequency response inherently, series tends to be a lot harder than parallel. So far I haven't pushed a series project to completion due to their rising complexity and inherent limitations. With a parallel crossover it's much easier to beat frequency response into submission. With series it seems like sometimes you just can't get there from here.

But I also don't think I'd be happy with the drooping upper end of the 12HX230's tweeter, so maybe I'm just too picky for series in this application. I haven't seen a frequency response plot of the Heretic speakers, so I don't know if they're mostly settling for the native response of the tweeter or if they found a way to shape it. Or if it doesn't sound like it looks in the Faital plots. Assuming the crossover shown earlier in the thread depicts the full circuit, the part count seems low to be doing much shaping, but maybe they're better at it than I am.

These pages on series crossovers cover a decent amount of ground:
https://www.tubecad.com/2017/11/blog0402.htm
https://www.tubecad.com/2017/11/blog0403.htm


This quote seems like a bit of an exaggeration, but I think the gist is right:

https://www.stereophile.com/content/gramophone-dreams-71-heretic-ad614-loudspeaker
Gaboury: "Another aspect that tickled my mind was that serial crossovers are almost impossible to model in software, which is probably the reason nobody is crazy enough to dig into them. Designing a second-order serial crossover is something that, to do right, requires a lot of time spent doing trial-and-error listening. That amount of time, plus the uncertainties involved, cannot be justified in a mainstream corporate environment."

 

[raymondj]

Thanks for the reminders about the information over at Tube cad.

I think your descriptions sums the situation up well.

I thought it was more intuitive by doing the tuning real time. establish basic values then measure and tune by changing a value. Wago connectors are great for that. Once the response is beginning to look reasonable carry out some more measurements at 30,45.60 degrees etc.
Holidays coming up will be a bad time for measurements as the house will be full.

I would like to redo my measurements phase wise and maybe try the driver front mounted, see if that gives s different profile of wiggles.

In some respects they sound more than passable. Possibly in a large space nobody would question them. But up close and personal taking measurements, the time alignment and response graphs look poor. When Mr Gravesen measured some Tannoys he was shocked by the wayward response, but still admired the sound!
I think?

Strangely, listening to the radio three stream didn't seem such a dynamic experience as yesterdays session with the big Co Ax. A bit like having the amp on quarter volume and the DAC output attenuated at 50% as well. Slightly muted something missing.

As to the Co Ax tweeter lack of extreme top end response in my graphs, please bear in mind that the measurement wasn't the best. When I redo them I will be more precise and use the laser for alignment , and i can check its alignment/mounting to the rest of the chassis

 

[planet10]

Series XO can be special.

Where is our series XO expert to weigh in... @DaveR?

dave