Search found 1000 matches

by Max N
Tue Aug 22, 2017 10:57 pm
Forum: Speakers
Topic: OB with Alpair 12P and Eminence Beta 15
Replies: 95
Views: 4204

Re: OB with Alpair 12P and Eminence Beta 15

I think the Basta baffle model is probably accurate, it's been around for a while and it's quite widely used. Remember you don't get complete cancellation, it's a 6db/octave roll off. And the pressure wave is propagating from the driver in all directions, so only a very small part of the wave sees t...
by Max N
Tue Aug 22, 2017 9:55 pm
Forum: Speakers
Topic: OB with Alpair 12P and Eminence Beta 15
Replies: 95
Views: 4204

Re: OB with Alpair 12P and Eminence Beta 15

Excellent Max. There's just something about the sound of OBs. I'm struggling to get my head round how they produce deep bass though. Doesn't the sound cancel around the relatively small baffle quite high up? Or is that what the miniDSP does, shape the bass somehow? Depends what you mean by deep I g...
by Max N
Tue Aug 22, 2017 9:37 pm
Forum: Buying and Selling
Topic: Wanted - designing power supplies for valve amplifiers by Blencowe
Replies: 2
Views: 162

Wanted - designing power supplies for valve amplifiers by Blencowe

Does anyone have a copy of this book they want to sell? Edit, just seen that Jack has been looking for a copy, so I take it they are hard to come by. Never mind. I didn't realise I had been away from this hobby long enough to a new book to come out and go out of print before I even heard of it. :) F...
by Max N
Sun Aug 20, 2017 5:52 pm
Forum: Assorted Stuff
Topic: Dacs, kits or bought?
Replies: 33
Views: 1137

Re: Dacs, kits or bought?

The AK4396 kits that some of us bought were a surprisingly good starting point, but they didn't have optical.
Ebay now has DACs using AK4490 ('premium' 'flagship') which do have optical in. I don't know if anyone has tried them?

Edit: I think Ray has had a play with the AK4490?
by Max N
Sun Aug 20, 2017 2:26 pm
Forum: Speakers
Topic: OB with Alpair 12P and Eminence Beta 15
Replies: 95
Views: 4204

Re: OB with Alpair 12P and Eminence Beta 15

What was the cap mod on the pse's Max? Must drag mine out for a listen sometime. If you have the WAD circuit diagram to hand, on the 6AU6, C4 AC-couples the screen grid to the cathode, and the standard value was 0.47uF. Morgan Jones's book contained a worked example of how to determine the size of ...
by Max N
Sun Aug 20, 2017 2:09 pm
Forum: Speakers
Topic: OB with Alpair 12P and Eminence Beta 15
Replies: 95
Views: 4204

Re: OB with Alpair 12P and Eminence Beta 15

Good news that it works ok max open baffles are a really good way of doing things Nice we300b valves by the way... Mrs N bought me the 300Bs when they went back into production in the early noughties. I'm a very lucky man :) They don't do everything well, but the midrange is lovely. In this applica...
by Max N
Sun Aug 20, 2017 1:57 pm
Forum: Speakers
Topic: OB with Alpair 12P and Eminence Beta 15
Replies: 95
Views: 4204

Re: OB with Alpair 12P and Eminence Beta 15

ed wrote:
Sun Aug 20, 2017 11:55 am
awesome Max, awesome!

how big is the room?
Cheers Ed. Room is 4.5m x 9m, angled ceiling 2.8m high.
by Max N
Sun Aug 20, 2017 10:59 am
Forum: Speakers
Topic: OB with Alpair 12P and Eminence Beta 15
Replies: 95
Views: 4204

Re: OB with Alpair 12P and Eminence Beta 15

I am really liking these speakers. :) As well as sounding great, they make it easy to hear the differences between different power amps. On Friday I dug out some old Meridian power amps and gave them a listen. Yesterday I got the 300B PSEs hooked up. I have to say I think this is the best sound I ha...
by Max N
Sun Aug 20, 2017 10:39 am
Forum: Speakers
Topic: OB with Alpair 12P and Eminence Beta 15
Replies: 95
Views: 4204

Re: OB with Alpair 12P and Eminence Beta 15

Max, what are the benefits of having the Alpair central rather than on top of the two Betas ? I have a theory, but its just a theory because I haven't experimented (although it would be very easy to do so may well try it) My theory is that the two Betas are acting like a D'Appolito or MTM. From an ...
by Max N
Sun Aug 20, 2017 10:33 am
Forum: Speakers
Topic: OB with Alpair 12P and Eminence Beta 15
Replies: 95
Views: 4204

Re: OB with Alpair 12P and Eminence Beta 15

Ant wrote:
Thu Aug 17, 2017 10:19 pm
They are really rather shoddy max
Cheers Ant :)
by Max N
Sun Aug 20, 2017 10:33 am
Forum: Speakers
Topic: OB with Alpair 12P and Eminence Beta 15
Replies: 95
Views: 4204

Re: OB with Alpair 12P and Eminence Beta 15

BTW, if you do decide to stick with active, the miniDSP 4x10hd is considerably better than the basic unit (assuming that's what you are using). Gives you remote volume control too. :D Yep, I just went for the basic version, but am now considering sticking with active so may well upgrade. Was lookin...
by Max N
Sun Aug 20, 2017 10:28 am
Forum: Speakers
Topic: OB with Alpair 12P and Eminence Beta 15
Replies: 95
Views: 4204

Re: OB with Alpair 12P and Eminence Beta 15

Ali Tait wrote:
Thu Aug 17, 2017 10:14 pm
Nice work Max. Try crossing at 200hz, that sounded best to me.
Thanks Ali. I'm working my way down, currently at 300Hz and sounding better than 500...
by Max N
Sun Aug 20, 2017 10:27 am
Forum: Speakers
Topic: OB with Alpair 12P and Eminence Beta 15
Replies: 95
Views: 4204

Re: OB with Alpair 12P and Eminence Beta 15

You've ran out of fruit BTW. Otherwise, shoddy +1! Like. Mrs N says she still finds me plenty fruity thank you very much Actually the fruit basket has been appropriated by Cocoa the cat as a bed, which tended to make the fruit a bit hairy, so nowadays its just a cat bed...... There's a joke in thei...
by Max N
Sun Aug 20, 2017 9:58 am
Forum: Speakers
Topic: OB with Alpair 12P and Eminence Beta 15
Replies: 95
Views: 4204

Re: OB with Alpair 12P and Eminence Beta 15

Very good effort - not to say, perhaps, even ... shoddy :!: Cheers Mark. Very happy I went with the Betas now. Interestingly, Basta allows you to include the output impedance of the amp, and the effect it has on the Qts of the speaker drive unit. When I enter a typical SET output impedance on a par...