DIY audio: what are you building?

[Guest Muon N']

5 hours ago, andyr said:

Hugh Dean has come up with a new Class A amp - the Alpha Nirvana ... 40w into 8R (with +/-27v DC rails).  There is also a 4R version (with +/-20v DC rails), which I  am going to build - to see whether it sounds better driving my mids & ribbons than my current NAKSA 80s.  (Mids are 3.2 ohms; ribbons are 2 ohms.)

 

He has made the design open-source ... so you can buy the PCBs from the guy who started this thread on DIYAudio:  https://www.diyaudio.com/forums/solid-state/344540-alpha-nirvana-39w-8ohm-class-amp.html

 

Hugh has also further developed the design ... this will be his next commercial amp (the 'Omega'), with slightly more power.

 

Andy

 

"and of course, always dominant H2 and a monotonically decreasing higher order harmonics."

 

 

Cool, love his work 

[Batty]

Well, it is Hugh

[Red MacKay]

On 18/12/2019 at 8:51 AM, MarcAL said:

Flaring is not absolutely necessary if you you go with a larger diameter.

 

Maybe not, but flaring if possible on both ends is better  (imo)

 

On 18/12/2019 at 8:51 AM, MarcAL said:

To test your port you can have it protruding your cabinet then fix it permanently once you have the correct length.

Just to be different, I ran the ports for my Tannoys external.  I guess that is not for normal people though...  Three ports that I ran, I ran at different lengths too.  Does port length sum, or does it set up different resonance points for the speaker I don't know.  But going from SS to valve amps I needed to change the length of any one port 25mm to get the same tone.

 

No, nothing was measured and say what you like - but it sounded pretty good to my ears and that is all that counts as I was tuning my system for me.

[RankStranger]

 

the good folks at Plyco we’re nice enough to push my cutting job through before they started their Xmas break so I spent some of Boxing Day making boxes (appropriate, no?). I’m very happy with how they went together and they shouldn’t take much sanding to get them nice and flat. I’ll pick up some 12mm for the bracing tomorrow and special order the black mdf for the baffles next week. Trim, veneer and hardware will have to wait for the next injection of cash but I have plenty to be going on with in the meantime

 

it feels really good to finally get a start on the real things. I have next week off work so I should be able to make a pretty good dent in them

[mwhouston]

3 minutes ago, RankStranger said:

 

the good folks at Plyco we’re nice enough to push my cutting job through before they started their Xmas break so I spent some of Boxing Day making boxes (appropriate, no?). I’m very happy with how they went together and they shouldn’t take much sanding to get them nice and flat. I’ll pick up some 12mm for the bracing tomorrow and special order the black mdf for the baffles next week. Trim, veneer and hardware will have to wait for the next injection of cash but I have plenty to be going on with in the meantime

 

it feels really good to finally get a start on the real things. I have next week off work so I should be able to make a pretty good dent in them

Got a drawing or a image of a similar finished unit. 

[andyr]

2 hours ago, Muon N' said:

 

"and of course, always dominant H2 and a monotonically decreasing higher order harmonics."

 

 

Naturally, Ian! 

 

The monotonically decreasing harmonic profile is what is special about Hugh's later amp designs.  However, it seems the Class A design - as distinct from his prior AB designs - has resulted in a better-sounding amp. 

 

Hence, I am trying it out!

 

Andy

 

[Guest Muon N']

Should be something special for sure, Andy 

[RankStranger]

1 hour ago, mwhouston said:

Got a drawing or a image of a similar finished unit. 

it’s the fern and Roby-style full-ranges I’ve been planning for months

[btd]

On ‎25‎/‎12‎/‎2019 at 6:57 PM, RankStranger said:

Merry Xmas to me. Santa bought me a shiny new replacement for my crappy $2 shop multimeter. 
 

 

Now I just need to learn to use the damn thing properly. 
 

While I think of it, Merry Xmas to you lot, too  

I have had the same unit for a couple of years now. It has lasted well and works fine. From memory the leads may have been a bit stiff to begin with but are quite flexible now.

[kranky]

Andy, I have built Hugh's earlier version the Alpha 20 and to my ears is by far the best amp i have built to date, and i have built my fair share of amps.

No need for exotic fairy dust parts and no adjustments (bias or dc offset) just build as per instructions and enjoy.

I have all the parts and pcbs to build the 55 watt version (Alpha BB) but the 20 watt version is more than enough for my needs, until i feel the need to scratch that itch one day.

Good luck with the Alpha Nirvana build.

Steve.

 

[andyr]

22 minutes ago, kranky said:

 

Andy, I have built Hugh's earlier version the Alpha 20 and to my ears is by far the best amp i have built to date, and i have built my fair share of amps.

No need for exotic fairy dust parts and no adjustments (bias or dc offset) just build as per instructions and enjoy.

I have all the parts and pcbs to build the 55 watt version (Alpha BB) but the 20 watt version is more than enough for my needs, until i feel the need to scratch that itch one day.

Good luck with the Alpha Nirvana build.

Steve.

 

 

Thanks - good to hear, Steve. 

 

Andy

 

[mwhouston]

10 hours ago, RankStranger said:

it’s the fern and Roby-style full-ranges I’ve been planning for months

The first time you mentioned this it got me interested. I was thinking  60ltr same design for a BG20-8 and their port.

 

https://www.visaton.de/en/products/fullrange-systems/bg-20-8-ohm

 

 

 

[Red MacKay]

Is there any technical reason for having a port on the front of a box, rather than the rear?

 

To my ears, speakers with rear ports always sound cleaner, better.  Is this because the box still works as a ported design, but the main sound you hear is more direct only off the cone, and the sound out of the port is more like room filler/ atmosphere?

 

And what of phase response differences of the sound off the cone compared, to that after it has bounced around inside the speaker enclosure and finally makes it to your ears?

 

Just asking here - don't crucify me please.

[RankStranger]

50 minutes ago, mwhouston said:

The first time you mentioned this it got me interested. I was thinking  60ltr same design for a BG20-8 and their port.

 

https://www.visaton.de/en/products/fullrange-systems/bg-20-8-ohm

 

 

 

That looks like a promising driver. I went with the Seas because the F&R uses one (albeit a much more expensive one) and I managed to source a lightly-used pair locally for an affordable price.

[mwhouston]

1 hour ago, Red MacKay said:

Is there any technical reason for having a port on the front of a box, rather than the rear?

 

To my ears, speakers with rear ports always sound cleaner, better.  Is this because the box still works as a ported design, but the main sound you hear is more direct only off the cone, and the sound out of the port is more like room filler/ atmosphere?

 

And what of phase response differences of the sound off the cone compared, to that after it has bounced around inside the speaker enclosure and finally makes it to your ears?

 

Just asking here - don't crucify me please.

Not sure which is best and it may vary from design to design and driver to drive. With the port at the rear you may have to watch rear wall proximity where at the front that is not an issue. With the port at the back any chuffing will be lost. My ports on my boxes are ugly so they always go to the rear. 

[mwhouston]

56 minutes ago, RankStranger said:

That looks like a promising driver. I went with the Seas because the F&R uses one (albeit a much more expensive one) and I managed to source a lightly-used pair locally for an affordable price.

In the online modelling I use the driver and port combo in 60ltr works very well. Really just playing it safe here. My big problem is space in the house with three systems all with speakers plus spare Altec horns I’d like to sell there is just no room for more speakers. As much as I want to build them.  

[RankStranger]

15 minutes ago, mwhouston said:

In the online modelling I use the driver and port combo in 60ltr works very well. Really just playing it safe here. My big problem is space in the house with three systems all with speakers plus spare Altec horns I’d like to sell there is just no room for more speakers. As much as I want to build them.  

Oh, I have absolutely no room for these. I have no idea what I’ll do with them once they’re finished. But it’s the journey that counts, right?  

[mwhouston]

56 minutes ago, RankStranger said:

Oh, I have absolutely no room for these. I have no idea what I’ll do with them once they’re finished. But it’s the journey that counts, right?  

I’m all for the journey but the destination is another issue. 

[planet10]

14 hours ago, RankStranger said:

Similar shape but smaller can be found in any of the wide Classic Golden Ratio miniOnkens. Here a visualization of the ig one for the Alpair 10p.

 

https://frugal-phile.com/boxlib/P10free/fatCGR-MK10p-0v92-280418.pdf

 

dave

[TMM]

Drummed up enough motivation to continue work on some bent lamination cabinets (5 of them; two towers, a centre and two bookshelves) that have been sitting untouched for at least a year. The last done to them was finishing gluing the sides, so now the overhangs need to be trimmed flush.

 

First I needed to make a bigger DIY router table


Then made a heck of a lot of dust machining the front and rear overhang of the laminations

Still plenty of work to do, maybe I'll be finished by 2021... 

[Red MacKay]

12 minutes ago, TMM said:

Drummed up enough motivation to continue work on some bent lamination cabinets (5 of them; two towers, a centre and two bookshelves) that have been sitting untouched for at least a year. The last done to them was finishing gluing the sides, so now the overhangs need to be trimmed flush.

 

First I needed to make a bigger DIY router table


Then made a heck of a lot of dust machining the front and rear overhang of the laminations

Still plenty of work to do, maybe I'll be finished by 2021... 

Love the table!  That's fantastic thinking. 

 

...And that does look like about the angryest router cutter I have ever laid my eyes on!!!

 

[TMM]

That's a 2inch planing bit. It's scary looking but not so bad to use as it's a good quality cutter (sharp carbide tips and well balanced). I have my router set on 2 out of 6 for speed, and feed it slowly only taking off 2-3mm at a time. The table and the cabinet are each too heavy for anything to kickback, so the biggest problem is feeding it too quickly and bogging down the router, or if there's an issue with the jigging and the cabinet drops down, causing the depth of cut to be more than expected.

[audiohippo]

4 hours ago, TMM said:

Drummed up enough motivation to continue work on some bent lamination cabinets (5 of them; two towers, a centre and two bookshelves) that have been sitting untouched for at least a year. The last done to them was finishing gluing the sides, so now the overhangs need to be trimmed flush.

 

First I needed to make a bigger DIY router table


Then made a heck of a lot of dust machining the front and rear overhang of the laminations

Still plenty of work to do, maybe I'll be finished by 2021... 

Very impressive. What drivers are you using in the design?

[Red MacKay]

>Very impressive. What drivers are you using in the design?

 

Click on the blue link at the bottom of TMM.  I think it is all there.
 

[My electronics, programming and audio blog]

[TMM]

The towers are going to be a 3.5-way with 2x Usher Audio 8945A 7" woofers, Dayton Audio RS52A 2" dome mid and Usher 9950-20 tweeter.

The centre will be a W-TM-W 3-way with 2x Scanspeak 18W/8545K00 7" woofers, Dayton RS52A 2" dome mid and Dayton ND20FB-4 tweeter

The 'bookshelves' I haven't decided yet - I'm just building them because it isn't much more effort to do 5 cabs of the same curved profile versus 3. The cab size and tuning can suit a lot of different drivers. I'd like to try my hand at a waveguide design, perhaps Vifa NE180W-08 7" woofer and a 1" tweeter in a Visaton WG148R waveguide. Probably a SEAS tweeter, they have perfectly flat faceplates so they interface well to a waveguide. 

 

As a teaser here's the last set of speakers I finished almost 2 years ago using the same construction, with Dayton DA175 woofer + Tang Band W3-1335SB mid + SB Acoustics SB29 tweeter. They were the proof of concept for the batch of cabinets i'm making now. The new cabs are slightly wider at the front to allow for a larger roundover, slightly deeper to increase the interior volume and the side curve profile is more aggressive (comes out significantly wider than the front baffle width).

Edited December 27, 2019 by TMM