Hi from the UK

[sheriff1972]

Hi All,

I live in Exeter, UK. I have worked with audio for quite some time selling amplifiers to the likes of Abbey Road Studios, Ayr Lyndhurst and a few other well known studios.

I love my music and have some downright silly high end stuff in my home during the last 20 years.

One of the best sounds i had was with a pair of Quad ESL 63's and a pair of Bag End 18 inch sealed box subs. The bass from these cabs was the best i have heard at low level, but the electronic crossover ruined the magic the quads were able to deliver (plus the fact i liked to play louder then the Quads we able so i kept breaking them...).

The more kids my wife and I had the worse my audio system became until recently i decided that i would start again and build myself a better system. One with life-life dynamic contrasts, distortion, using the latest amplitude and phase correction (i will use the Acourate software for measurement and filter creation and JRiver for media playback).

I started searching google for low distortion subwoofers, and found something called the Pi 12, based on a lab horn design - after a bit of poking around i found a link that referred to a BFM design the Tuba 60. The SPL plots looked good, so here i am.

The plan will be to use two subwoofers (starting with one), and build an active system, so i would like to start with the lowest distortion design.

This will be for domestic use, with an occasional garden party thrown in for good measure.

I was thinking that a T30 would do the trick, but happy to receive any advice.

Thanks and looking forward to learning from the experienced guys around here.

Mike

[MissileCrisis]

For someone of your stature I can only recommend the T60. If you only build 2 of them that is. In greater number the T30's work too but if you want to really drop jaws : T60 is your friend. You sir mentioned about high volume low distortion? Well lets just say that my 20 inch T60 can put out 130 dB referenced to one meter (corner loaded) playing real music. And distortion is barely measurable.

THT is a better choice if you want the 22 Hz extension (placed in corner) and don't plan on playing outside much (it's designed for Home theater). T60 is a 25 Hz horn but can be much louder (~6 dB) due to increased power handling and slightly higher efficiency.

You're in the right place bass lover .

Ok so since you have heard such high end gear, I'm expecting a comparison to the Bag End experience after you finish your sub (s). Straight to product page if you're impressed .

[Grant Bunter]

Hi sheriff1972,
Welcome to the forum

Missilecrisis has hit on the requirement you need to know in order to decide a cab build, and that is content. If you don't need less than 35Hz, then the T30 is perfect.
So let us know what you need to cover content wise and we can work from there...

[Radian]

For someone of your stature I can only recommend the T60. If you only build 2 of them that is. In greater number the T30's work too but if you want to really drop jaws : T60 is your friend. You sir mentioned about high volume low distortion? Well lets just say that my 20 inch T60 can put out 130 dB referenced to one meter (corner loaded) playing real music. And distortion is barely measurable.

THT is a better choice if you want the 22 Hz extension (placed in corner) and don't plan on playing outside much (it's designed for Home theater). T60 is a 25 Hz horn but can be much louder (~6 dB) due to increased power handling and slightly higher efficiency.

You're in the right place bass lover .

Ok so since you have heard such high end gear, I'm expecting a comparison to the Bag End experience after you finish your sub (s). Straight to product page if you're impressed .

OP, what do have for a system and room at the moment?

[Charles Jenkinson]

Brilliant!

[sheriff1972]

Hi,

I am no guru! I just sold them the amplifiers.

I have some Tannoy TD10's, some Definitive technology Mythos one tower speakers and a few others kicking around.

I have not set up a system for a few years as i didnt like coming back down the ladder audio wise.

i picked up a pair of motional feedback speakers (Philips) the other day, just for fun. They were.....poor

I am in a rented property currently, about 20 by 16, so pretty small for an audio room.

For DAC duties i will be using a Prism Orpheus.

My currennt amplifier is an old integrated - Chapter Precis.

For sub duties i will pick up a camco Vortex.

T60 in my room would end up in divorce..... I suppose i could always live in it, after my wife kicks me out.....

Cheers

Mike

[MissileCrisis]

No excuses...

Seriously though, build a table tuba or two if WAF is the determining factor. 20x16 isn't too small to have a T60, or two .

PS that amplifier is wayyyy to powerful for a horn loaded subwoofer (any of Bill's designs) you only need 60 v/450 W into 8 ohms per sub max and that would probably end in divorce anyways. The home designs take around 140 W (single driver) and still will be loud enough for you and the neighbors.

[sheriff1972]

The Camco vortex is not about power, its about finesse.

One of the very few pro amplifiers that sound pretty good.

The best sounding amplifiers i have heard have been based on the nCore Hypex technology - and yes you can DIY them too

The Camco also gives me options if i wanted to replicate the Bag End system, as i would replace the cross over with a hand rolled one done in 'Acourate'. I would need some power on tap in this case.

I do like a little overkill, but i unearthed some distortion measurements on another forum where the Tuba did not fair too well.

Having said that - i do fancy a THT - if the distortion measurements from here are to be believed, this should do the trick nicely.

http://www.avsforum.com/t/1194093/myns- ... -vs-tht/30

Post 44 from 'MaxMercy

Cheers

Mike

[Grant Bunter]

In some places/sites there's not a lot of love for Bill's designs.
Call us here the converted lol.

Quite possibly, the telling quote is in post 60 of the thread you linked:
"The facts are my 14 cu foot LLT with a high performance 18" and 1000 watts can't do what my THT can do with a $150 15" Dayton DVC and 28 watts. Not only in output but distortion levels."

The ethos here is to DIY it, to reduce costs in both drivers and amplification.
So, you might find another (commercial) cab or (DIY) design with arguably lower distortion levels, but it will likely come at a significantly higher cost.
And the distortion figures and charts may be just as questionable.
This is not to say Bill's charts are questionable, I'm sure he has no vested interest in making spurious claims.

Plenty of us come here wondering if the claims are true, bite the bullet, build the design(s), and get pleasantly surprised...

[MissileCrisis]

I haven't been able to hear distortion on my T60 playing 25 Hz sine waves. And I'm talking about pegging the thing into the ground. Fact of the matter is your room will distort before the subwoofer and anyone who measures distortion (which there will be below the tuning frequency at insane levels) will not be able to hear it over the massively smooth bass they are getting. Needless to say it kicks the pants off of my dual 15's (MFW-15) which exhibit audible distortion if I push them below 40 hz.

I mean you will have so many rattles past 115 dB that any measurement you get is more likely to be something on a shelf vibrating, walls shaking etc...

[sheriff1972]

Got it - i will give it a try

You can always tell when something is low distortion - when you feel that the music is not loud, and yet you try and talk to someone and they cannot hear you at all...

[88h88]

Got it - i will give it a try

You can always tell when something is low distortion - when you feel that the music is not loud, and yet you try and talk to someone and they cannot hear you at all...

Yup. Last gig I did was just like this, people were claiming it wasn't loud despite having to talk verrrrry loudly next to your ear and the measurement mic saying "IT'S REALLY F**KING LOUD IN HERE!". In testing it was a somewhat 'conservative' 116db but by the end of the evening was cranked.

That was in here this joint. System was 2 subs, 2 tops and a rack containing 1000w of power.



I'm not sure these speakers know what distortion is.

[MissileCrisis]

I'm not sure these speakers know what distortion is.

This is why I grin my head off every time I get to show mine off . Wishing I could afford a second one.