Altec 604 build

[radarek]

What’s the internal volume?

 

[radarek]

Little update on the progress so far...

Crossovers are under construction now by Tony of Humble HiFi. Caps to be used are Jantzen superior and wax coil inductor, pathaudio resistor and tyco potentiometer- that one maybe changed later to solid values when setting are find. Wired with duelund tinned wire.

As for the boxes... open baffle for now as work gets busy and no time for major project. Will wait till winter.

 

[radarek]

Pic to show current setup

 

[GM]

What’s the internal volume?

The big ones? Depends on its Vas spec: ~16-27 ft^3.

GM

 

[radarek]

New crossovers almost finished. Cant wait to heard them in the system. May add MF section as per J. Markwart if needed. Don't want to modify much before new cabs will be done.

 

[ICG]

Some might be interested in this, the German DIY hifi magazine Klang + Ton built in 2014 an Altec 6xx alike speaker. They used a 12" Celestion TF1225CX coax driver and kept the enclosure extremely close to the Altec cabinet. With just over 300€ per side rather affordable and it sounds excellent.

Celeste K+T

 

[luxwinter]

As for the boxes... open baffle for now as work gets busy and no time for major project. Will wait till winter.

I've been running Tannoys open baffle for similar reasons - cabinets would be a big project. Nice bass, but not enough of it, so I gave them some help.

 

[radarek]

I've been running Tannoys open baffle for similar reasons - cabinets would be a big project. Nice bass, but not enough of it, so I gave them some help.

Nice... im not as huge fun of bass so no tears here. Im in for vocals and acoustic guitars. Waiting for some free time for the cabinets build but to be fair Im happy with what i have now.
Now need new Dac and finish up the room so i can start on some room treatment

 

[luxwinter]

Good luck. The Twisted Pear DACs sound great... but that's another project. The Tannoy Golds taper off a lot in the bass, so they need a ported enclosure to sound balanced. So on an open baffle you need to equalize them or add a second driver, otherwise they sound very lean.

 

[dotneck335]

Some might be interested in this, the German DIY hifi magazine Klang + Ton built in 2014 an Altec 6xx alike speaker. They used a 12" Celestion TF1225CX coax driver and kept the enclosure extremely close to the Altec cabinet. With just over 300€ per side rather affordable and it sounds excellent. Celeste K+T

Quite a bit less sensitive than an Altec 604E, however---about 5 db. Huge difference!

 

[radarek]

Crossovers arrived. Nice work Tony. Thanks a lot.
Sounds better already. More mid bass especially more noticeable over 63.5hz, have used my analyzer to check it, not bad for open baffle I think, at least good for me/ rookie. Clean and smooth. Now only 200 hours of burning in haha.

Reagards

 

[ICG]

Quite a bit less sensitive than an Altec 604E, however---about 5 db. Huge difference!

The high spl 'advatage' back then was because of the lower available power. The 'huge difference' there is, the 'Celeste' DIY kit goes down to 35Hz while the 'original' speaker does only 70Hz!!!

 

[GM]

thanks for the help. really appreciated.


Darius

Just now seen this...... not a good plan to embed responses within responses since they don't copy in a reply.........

GM

 

[GM]

Originally Posted by GM View Post
You're welcome!

I got an acoustically better plan



Messing with my plan is always a good plan



Skip the <sub>bass robbing stands and make the cabs a full sheet [~60" o.d./58.5" i.d.] high with a double plate top [one flush, the other a full size 'cap' since this is where its 1/4 WL TL pipe modes are highest amplitude, with just a single flush bottom plate since it will be setting very near/on the floor.

This will put the driver 38" up from the floor within the optimal ~0.349-0.424 line offset for smoothest overall response, minimizing the need for internal damping beyond the pioneer's covering the top, one side and back plate.

Ideally, the baffle needs to be > 30" wide to minimize the need for trading efficiency for bandwidth [BW] to tonally balance the lows to mids [baffle step compensation/BSC].


I didn't plan to do baffle any wider then 24-26"

Vent centerline ideally will be height [i.d.] x ~0.848 on down. Note that unless simmed using MJK's or similar software, vent will be [much] shorter than predicted by a vented box program. Side vented like Billfort's is a good plan.


What would be the size of the vent( if sided one or two)?

Cab stresses are all vertical, so vertical boards on edge spanning ~70% of length with some on edge boards to tie all six sides together along with a couple of boards on edge to brace the bottom plate is sufficient.


what would be the depth of the box ~ 18"?
for the box construction _ mitre corners or just butt edge with some jointers? does it matter? is 3/4" plywood still ok?

IOW, keep obstruction to vertical airflow to a minimum to maximize TL pipe action damping the vent.

Recommend skipping double baffles unless you plan to very heavily chamfer the opening [> 45 deg] and recommend > 12 deg included even if just a single baffle.

For heavy, deep drivers and especially duplex, best to use a full cradle to both take the stress off of its baffle mounting and provide additional damping: 6moons audio reviews: Stephæn's Altec 604 Dream
Speaker


I was planning those cradles too...


GM</sub>

<sub>OK, 26" is considered the minimum for ~adequate baffle step compensation [BSC].

Need to know cab volume to calculate vents and ideally need actual driver Fs if driven with a high output impedance.

Box depth of course depends on its volume, so for 25 ft^3: 12"^3 = 1728"^3*25 ft^3 = 43,200"^3/[58.5"*24.5"] = 30.14" i.d. deep and of course bigger will be deeper still.

3/4" [1.8-1.9 mm] is the norm, but ideally needs to be void free, so Baltic Birch, Apple, marine grade or similar.

Miters are nice if you can do them 'right n' tight', but the vast majority of DIYers just do lap joints, though in either case, glue blocks should be used and should span ~71% of the joint length, i.e. don't block the corners, it just creates stress/resonant 'hot spots'.

Cool! Well worth the effort!

GM</sub>

 

[radarek]

Bit of update... Joe of Stewartspeakersystems made a set of nice, slightly modified 620 cabinets. There are on the way to me. In meantime I have been working on the SET amplifier. Z1kit from Dacware with little upgrades...
All should be ready for xmas ...

 

[radarek]

And here they are... new cabinets. Just finished the transplant last night. Will play them over the xmas and new year and then start to finish the surfaces. Front and back Duratex paint, top and sides walnut veneer.
More dynamic, more direct, cleaner then my open baffle.

 

[radarek]

And both...

 

[GM]

 

[Cal Weldon]

Nice.

 

[John Busch]

Sweet! Thanks for sharing!