Onken - will Altec 420A work???

[atilsley]

I'm interested to know if the 420A will work in the big Onken?

I understand the 420A is close to the 416

http://www.greatplainsaudio.com/vint...spec_sheet.pdf

T/S specs here -

Xmas inches 0.15
Re 4.6
Vd 19.2
Fs 22.6
Vas 28.2 cu ft
Ref 1.7
Qts 0.47
Qms 6.59
Qes 0.51
Vid 0.20

I'd appreciate any advice on this.....for example, is it best to stick with standard 416?

If going down the Onken path, I'll use the Gene Hiraga design...and use Azura 340Hz on top, crossed around 700Hz, using quality 2nd order xover and mosfet amp.

Andrew

 

[S4m]

Don't know if this is a good recommendation but on this page: mh-audio.nl - Home you find a calculator for Onken enclosures. Maybe it will help you...

 

[atilsley]

Thanks S4m, I've seen that. Then, I saw on some other thread that to one should be careful about online calculators.

 

[Inductor]

Did you measured the specs?
Original Fs from literature (Altec 419-8B, 420A Biflex Speakers) shows Fs being 27 Hz (15") and 39 Hz (12").

 

[kevinkr]

Qts is probably too high, for Onken really low qts drivers are de rigeur, probably under 0.25.. I have Iconic 165-8G in mine which is very very similar to a late 515-8G.

The Marc Cyr Debien/Jean Hiraga spreadsheet calculator is pretty reliable and what I used to design mine.

 

[Pano]

Well.... that is one way to find out.

If it does not, then you go get that pair of 416s.

 

[atilsley]

Thanks guys

I haven't measured the 420's yet...I collect them in two days.

I took the t/s data from here -

Altec Thiele-Small Parameters

 

[Inductor]

Fanny, that was the same source of t/s data, same website.
Altec BIFLEX Loudspeakers
Only that maybe there is a difference in time (years?). One is the manufacturer data, maybe was measured in the factory and the other one maybe was measured after (database?, what drivers?). The Fs getting lower from breaking in, who knows?!
Speaker Break In: Fact or Fiction? | Audioholics

 

[Inductor]

Andrew, why would you use the Altec 420A in a big Onken??
What's the size/volume net?
Well this driver (Altec 420A) has the same behavior (very close graph of output data in frequency) or is ideal for a sealed speaker, of large dimension ~300L, Qtc = 1.00. It needs very large enclosures and very low tuning, comparing with the Altec 416-8B, making it unsuitable for an Onken with same standard dimensions. It needs different volume and alignment.

 

[atilsley]

Andrew, why would you use the Altec 420A in a big Onken??
What's the size/volume net?
Well this driver (Altec 420A) has the same behavior (very close graph of output data in frequency) or is ideal for a sealed speaker, of large dimension ~300L, Qtc = 1.00. It needs very large enclosures and very low tuning, comparing with the Altec 416-8B, making it unsuitable for an Onken with same standard dimensions. It needs different volume and alignment.

Hi, I have (had) three reasons for thinking this.

1. I thought the 420A had similar specs to the 416 specs (I could be wrong, happy to admit error etc)

2. I love the Onken...and wanted to give it a go

3. I have access to some pristine 420A's within a moderate budget

The question is now a little academic, as I'll build a smaller ported box of 250 liters (8.5 cubic foot) first...then make a decision on the Onken/416 down the track.

With the various options for the 420A (from OB to sealed to ported), what would be your pic to get deep bass...?

Kind regards.

 

[GM]

You can use a basic program to calculate a T/S max flat vented or sealed alignment, though Altec recommended > 4 ft^3 sealed and AFAIK always used ~4 ft^3 sealed for its catalog products since it best overall controls the driver's separate mids cone, but it is capable of making deep bass in up to 30+ft^3 vented cabs tuned to the low 20s or even to 16 Hz if corner loaded, though ~20 ft^3 tuned to Fs was Altec's max recommended vented alignment IIRC, but a 511, 811 or similar horn was usually added due to the large cab's inability to damp the mids cone well enough.

Anyway, loaded in the 416A Onken, it may have too much bass 'bloom' due to being too small and maybe tuned too high, especially if driven with a high output impedance, but stuffing all of the vents with the same amount of your favorite damping material to 'taste' will theoretically work well and if not, then swap in 416s and make small > 4 ft^3 cabs for them.

GM

 

[atilsley]

Thanks GM

Today, I picked up my 420A's, they look great.

I knocked up a 90cm x 90cm open baffle unit today..and waiting for glue to go off before trying the 420's.

Planning on using either the Faital Pro tweeter horn or large Azura 340 horn for HF.

Stay tuned.

In the meantime, I'll buolding a 250 liter (8.5 cubic foot) birch ply ported cab to better test the 420.