[audiotone]

I got the idea on this forum...

B200 single driver seemed ok.
Spruce seemed a good material...

I gave it a shot:




more over here: http://picasaweb.google.com/tony.de.lobelle/20080526VisatonB200SpruceBaffle

[ghpicard]

Nice !
Why did you make the baffle start above the floor instead of from the floor ?

Gastón

[Dmason]

Hi Tony

Interesting. Give us your assessment of what it sounds like to you, your ears, room, system, etc. I think Spruce and Balsa stringers are the way to go for a more complex baffle design. "Sympathetic resonances" is what is attributed to the use of Spruce, in the sounding board of most pianos.

[audiotone]

Nice !
Why did you make the baffle start above the floor instead of from the floor ?

Gastón

No special reason...I had this baffle made some time ago but was not shure yet how to use it...

Tony

[audiotone]

Hi Tony

Interesting. Give us your assessment of what it sounds like to you, your ears, room, system, etc. I think Spruce and Balsa stringers are the way to go for a more complex baffle design. "Sympathetic resonances" is what is attributed to the use of Spruce, in the sounding board of most pianos.

first impressions after only a few days:

nice tone....very nice tone.
piano gets a body, so do singers and cello's, violins etc...

tried it open en closed.
for the moment only 2 screws are holding the back cover in its place.

Bass is with some notes a bit to much, but I saw I need some extra bracing on the back cover and more screws.

about 50L closed baffle with 2 sheets of rockwool inside.

I still have some violin lacquer to paint the box.

I have IMF TLS 80 and Jordan VTL as reference...this one is the most natural sounding with good room impact...

I did not like the open baffle so far...no bass.

I also use a subwoofer (reckhorn speaker and amplifier) to make it very life like. (Subwoofer comes in at around 45 Hz/24dB/oct not to much level, just a little to give that extra room information)

No tweeter needed: everything is there (TLS 80 has supertweeters, so I know what should be there to hear)

I could live with this...

[tanchiro58]

Tony,

What kind of material is the phase plug? Do your speakers sound little bright in the top end before or after installing phase plugs? Did you insert the phase plugs all the way in?

Thanks,
Tan

[audiotone]

Tony,

What kind of material is the phase plug? Do your speakers sound little bright in the top end before or after installing phase plugs? Did you insert the phase plugs all the way in?

Thanks,
Tan

Tan,

I am still getting used to the sound...
indeed the top end is not yet 100% to my likings...with or without the phase plugs.
I sometimes try a helper tweeter on top (B&C DE25 in a ME45 horn, 1mF cap and an autoformer: this is really good!)
I have no idea what the plug is made of...it seemes a bit hard to me, maybe I will try to make one myself from spruce...

I think I will try the Supravox RTF64 (without the wizzer) with the B&C combo...(still have to order them)
no correction needed for the Supras they say...have to find out for myself.

kind regards,

Tony

[kyrill]

hi Audiotone

It has been some time now. You still have the B200?

[audiotone]

hi Audiotone

It has been some time now. You still have the B200?

Yep.
but in NoBox now...this really lifelike!
http://picasaweb.google.be/tony.de.lobelle/20080526VisatonB200SpruceBaffle#

also have some Saba greencones...but for the moment I prefer the B200...

it is nice to try all these drivers...they all have their qualities and shortcomings...

I am just enjoying music....

[kyrill]

hi
can you hear a transparency difference between B200 and Saba green cones?

[Paul Hynes]

Hi Tony,

How are you keeping.

I notice you are experimenting with the B200 at the moment.

What effect does the phase plug have on the sound quality?

Regards
Paul

[audiotone]

hi
can you hear a transparency difference between B200 and Saba green cones?

the sabas sound is very direct and bright, but they need the woofer at around 150 Hz...do not like that.
the B200 goes all the way down, plays beautiful even without the woofer. Full and rich with the woofer set to 65-70 Hz.
Cellos and voices are magical! Rock is powerfull... in short: everything is well balanced.

[audiotone]

Hi Tony,

How are you keeping.

I notice you are experimenting with the B200 at the moment.

What effect does the phase plug have on the sound quality?

Regards
Paul

Hi Paul,

should have listened to you in the first place...
the digital equalising adventure was not what I was looking for: flat response is not what I hoped it would be.
I am still considering 2 x 8 B200: do you still use them? (lost that picture, I had a hd crash)

about the sound plug:
I prefer the sound without the phase plug, but with the plug the image is unbeleavable wide and deep...always compromising.
I also think the plug is made from the wrong material (Hard wood and it sounds hard) I will make some in spruce when I have some time.

regards,

Tony

[kyrill]

maybe you can use spruce and coat it with a sound absorbing material. the thin layer means only higher freqs will be "absorb" a bit

[audiotone]

maybe you can use spruce and coat it with a sound absorbing material. the thin layer means only higher freqs will be "absorb" a bit

Hi Kyrill,

thanks for the tip.
I will try colophony resin first because I had good results in the past and I have everything in house to do that.

Tony

[Paul Hynes]

Hi Tony,

It’s difficult to relate to how something sounds buy word of mouth. You really have to hear the performance yourself to be sure. The frequency response curves do suggest EQ is required but I have resisted this path in an effort to reduce the signal path to the absolute minimum between the music source and the B200. This has paid dividends big-time. I currently use an Altmann Attraction DAC with modified power supplies for digital sources or a two-stage valve phono preamp for vinyl sources. These go to a “Lightspeed” LDR volume control then one heavy-duty depletion mosfet driving the line array. I do not need any additional voltage gain to achieve the SPLs I require for realistic reproduction.

I started my B200 experiments in the same way as you with one pair although I already knew I was going to construct a line source. Their performance on an open baffle was very musically coherent after a period of around a month of running in. It is a well-balanced drive unit. It is also very transparent which can lead one to think the drive unit needs work, if there are problems elsewhere in the system, as it will reveal these problems. The Altmann gear that you have is very musical so I understand why you are having good results with the B200. They go well together.

I am still using 2 x 8 B200 on an open baffle line source array with all 8 drivers wired in parallel.

http://s700.photobucket.com/albums/ww7/paulhynes/th_Picture036.jpg

I have no inclination to change anything with the line arrays, as they sound so good. One pair of B200s sounds good but everything changes for the better once you organise 8 into a line source. You probably won’t need the sub-woofer as the bass extension improves and you can move enough air to reproduce the big drums with full weight and dynamics. Distortion is very low as the drive units are barely idling most of the time (sensitivity 105 dB for 1 watt at on metre). Important attributes like tempo and timbre are excellent. Image size and stability is great as there is very little wall, floor and ceiling bounce to interfere with the leading edge of the wave front. Back wall reflections just sound like hall ambience. The music sounds like a live performance, which is all I want from my system. They also sound very good and still retain presence at low levels. The cost of sixteen B200 drive units is a little daunting but I have helped a friend design and build a 4 unit version, with excellent results. Not quite the power and weight of the 8 unit version, but he is very satisfied with the performance.

It is a shame about the trade-offs with the phase plug. Perhaps the spruce will improve matters. I would be interested to know if you have any success with this.

Regards
Paul

[kyrill]

hi Paul

as the B200 is a 6 ohm driver and you do all yr drivers in parallel..

how can an amp drive so low impedance drivers?

I have a "standard" tube amp ( Jadis Da-5) can tube amps drive so low resistances?

[Paul Hynes]

Hi Kyrill,

I hope you are still enjoying your SB.

You are right that most standard amplifiers would not like to drive the resultant nominal 0.75 ohm load.

Most line arrays are wired in series/parallel to arrive at a reasonable load. Unfortunately this places a highly reactive electrical spring (for want of a better word) between the drive units and the amplifier. Everything goes to hell under these circumstances. The image becomes diffused and unstable and the music is dynamically and rhythmically compromised. Wiring all the drive units in parallel removes these problems.

The only way a tube amp can drive a sub 1 ohm load is if the output transformer has been designed with suitable tapings to match the load.

As luck would have it (well, to be frank, the laws of physics), to deliver power into a sub 1 ohm load you need little voltage swing, just a high current capability. This allows the use of low voltage supply rails, which limits dissipation in the current amplifier, allowing relatively simple class A designs to work well. I have designed two types of output stage for this purpose. They are basically current amplifiers without any voltage gain. One is a single ended pure class A current buffer with a current source bias which is DC coupled. The other is a simple “circlotron” output stage, for balanced inputs, once again without voltage gain, that can be biased in class A or class AB for higher power delivery with less efficient drive units. This is also DC coupled.

Both these amplifiers can also drive low impedance ribbons directly.

Incidentally both output stages can be fitted with a voltage gain stage to make them compatible with normal systems and they also give excellent sound quality under these circumstances. I have driven the single ended output stage with a 300B valve. This was very nice and without the restrictions at the bandwidth extremes when using output transformers.

Regards
Paul

[kyrill]

Ah how nice to make yr own designs

my SB3 modded by Wayne and "Pat" sings happily with yr dual voltage pws

[audiotone]

Paul,

I still have an autoformer at hand...could that solve the low impedance issue?
I like my Byob too much...

Tony