doubling driver numbers/spl gains?

[SpeakerBob]

the lp12's not too hot at the moment - valhalla ps, basik lvv arm/k9 cartridge

looking to upgrade over the next 6 months...(rega rb250(with origin live mods) dynavector 20x MC cartridge / find out about my bearing and suspension)

I must add, for me this hi-fi stuff is all about the music, and as I try not to buy cd's (also means I cant pirate), I have to go out and buy the stuff.

Also I listen to lots of different types of stuff, and if I was a rock fan, or a jazz fan, or a blues fan, I'd have bought a third of what I have. As it is I'm all 3, plus a dance/hip hop fan....meaning lots of records of different types (have you heard the new Johnny Cash album? - well worth a listen btw)

I listen to music for about 4 hours a day, I watch a dvd once/twice a week..

This shows my leanings for my system I think....

off to bed now, gotta get up in 5 1/2 Hrs for work...

Cheers

Rob

 

[planet10]

the lp12's not too hot at the moment - valhalla ps, basik lvv arm/k9 cartridge

Except fopr the arm (ittok), the same as mine before i twisted the K9s stylus -- now i have a Garrett P77 (a gift from a friend).

rega rb250(with origin live mods)

THE RB250 is a good arm. ChrisB did the mods on his himeself, i'll see if i can get him to tell us what he did.

dave

 

[SpeakerBob]

""THE RB250 is a good arm. ChrisB did the mods on his himeself, i'll see if i can get him to tell us what he did.""

Sounds interesting, AFAIK the mods are silverwire replacement and something to the counterweight..

Rob

 

[planet10]

Sounds interesting, AFAIK the mods are silverwire replacement and something to the counterweight..

Chris got a Rega 3 w RB300 and then replaced the RB300 with the modded RB250. New wire and he is playing with some different counterweights (designed & manufactured locally). I think there were a few other tricks too.

dave

 

[SpeakerBob]

Reply from Design 3DWD :


""Dear Mr. Wells,

Design 3DW3 is a consultancy, having designed for NAD and TAGMcLaren Audio. We are continually involved with hi-fi and will be launching our own speakers in the near future.

We will mainly be stocking drive units which we have tested and incorporated in our designs. Other products will then be obtained for the customer as a special order.

Currently we can supply Monacor speakers.

We are in the process of becoming an Adire dealer with matters to complete before we can import and provide a suitable backup service. Adire have jumped the gun by publishing our details before we are quite ready. However, we anticipate that everything should be in place shortly.

I am only able to estimate the price at the moment, so I have to be cautious:

Adire Shiva Mk.3 ~ £125 inc. VAT plus delivery.

I hope the price will be a little lower and can confirm later.

We will be keeping this driver in stock as we are developing a high-end speaker using the Shiva.
Sincerely,

John Choong ""



Approx $180

Rob

 

[daatkins]

I don't think that charging £125 is a bad price - I was expecting more.

I imported an NHT1259 ($150) in 1997 and 5-day shipping was $40 then I had to pay import duty (about 15%?) and VAT (at 17.5%) on the total. I think £170 was about the final result.

I certainly would be good to have a source of Adire drivers in the UK!

Nice one,
David

 

[SpeakerBob]

I'm kinda looking forwards to the tumult - if it works out to be a good sounding speaker 4 of these could be my answer to A/V nirvana

btw, Dave - any info on the rega mods (maybe should be moved to the analogue section?)

Cheers


Rob

 

[planet10]

btw, Dave - any info on the rega mods (maybe should be moved to the analogue section?)

Post a question on the analogue forum, and you'll get lots of suggestions (and i'll send the URL to ChrisB so he can talk about his)

dave

 

[trespasser_guy]

Ok, so I am somewhat confused. If you add another woofer with its own amplification, you get 6dB gain. If I am building a multi-woofer system with a tweeter, using one amp for the whole thing, what is the gain having the two woofers instead of one, given that the woofers are 94dB sensitivity?

 

[planet10]

Ok, so I am somewhat confused. If you add another woofer with its own amplification, you get 6dB gain. If I am building a multi-woofer system with a tweeter, using one amp for the whole thing, what is the gain having the two woofers instead of one, given that the woofers are 94dB sensitivity?

If you have one amp & one 8 ohm woofer then.

You get 3 dB when you add a 2nd woofer.

If you wire them in parallel and your amp doubles its power into 4 ohms vrs 8 ohms (some real world amps will approach this ideal, some will actually put out less (ie budget AV receiver), and a tube amp will usually put out the same if you change to the 4 ohm taps) you will gain another 3 dB -- Rob carefully avoided this issue by adding 1 amp/speaker (a clever man he).

If you wire them in series (and observe the above caveats) you will lose 3 dB.

So the answer is, by adding a 2nd woofer you will gain between 0 & 6dB.

dave

 

[trespasser_guy]

In my design, I had two 4-ohm woofers linked in series with one another for an 8-ohm load. So, I will lsoe 3dB this way? Or just gain 0?

 

[SpeakerBob]

Post a question on the analogue forum, and you'll get lots of suggestions (and i'll send the URL to ChrisB so he can talk about his)

dave

Will do when I get nearer to attacking the deck. (still trying to finish off my bass cabs!)

Cheers

Rob

I think the doubling driver/6Db is a great way of getting good sensitivity out of standard drivers. (95Db from a pair of 89Db speakers). - Also it's easy to implement if you're x/o is active.

 

[planet10]

In my design, I had two 4-ohm woofers linked in series with one another for an 8-ohm load. So, I will lsoe 3dB this way? Or just gain 0?

Actual implementation will vary somewhat, but to generalize...

if you have SS you gain 0 dB (but you have a happier amp)

if you have tubes (and change taps) you gain 3 dB.

dave

 

[SpeakerBob]

""if you have tubes (and change taps) you gain 3 dB""

I've always wondered, Dave - what do you do with a valve amps output trans when you're using a 6 ohm driver? afaik they're always 4/8

Rob

 

[planet10]

I've always wondered, Dave - what do you do with a valve amps output trans when you're using a 6 ohm driver? afaik they're always 4/8

Actually what you do with any speaker (none of which actually resemble a resistor -- not even a variable one) and choose the tap that sounds the best. The taps are usually configured for max power into those nominal loads.

dave

 

[SpeakerBob]

makes sense - the only valve amp I've ever owned (and still do!) is my selmer "treble 'n' bass combo" - I'm pretty sure thats got 8/16 ohm sockets on the back, and I used to use the 16 with an 18" goodmans driver in its original (selmer) cab. I used to dj with this setup aswell! - those were the days

pretty sure its a 50 watt push pull - uses el34's for the power and ecc 8? pre

Rob

 

[trespasser_guy]

ok, so what if I linked two 8-ohm woofers in parallel for 4-ohm total? Would I get the 3dB gain then?

 

[planet10]

ok, so what if I linked two 8-ohm woofers in parallel for 4-ohm total? Would I get the 3dB gain then?

3 dB over a single woofer plus some more (up to 3 dB) if your amp puts out more power into a 4 ohm load.

dave

 

[trespasser_guy]

ok, I am sooo very sorry for the continual questions...

But, if I link all these in some form or fashion, but the crossover still gives me 8-ohm, then I don't gain anything?

 

[planet10]

But, if I link all these in some form or fashion, but the crossover still gives me 8-ohm, then I don't gain anything?

The XO has to be designed for the speakers and you can mostly ignore it for the purposes of this discussion.

If it is an "8 ohm XO" and you use it with 4 ohm speakers, you will end up with a 4 ohm speaker, but the XO won't be working as designed.

dave