SAT bass trap 2- diy bass trap

Update SAT bass trap

Somkeone ask me why you use 6 ply of carpet instead of 5,7 or 8 ply. Good question,actually it need a mass of 1.49kg/m2.
Here is the calculation:
The panel surface

1.74 x 0.29 = 0.5046 m2,
1.49 x 0.5046 = 0.75kg



I have weight 1 ply of carpet is around 145gram(less10% to minus the excess)=130.5 gram

So 750 gram/130.5 = 5.74 ply,
So round it up around 6 ply.

I have try out 3 ply carpet at first and it is not working.6 ply give me more satisfactory result. Sometimes we really need to do calculation to cut down the trial and error.
On the 1st version i can varying the depth of the bass absorber panel.
I found that the result is close what i have calculated out.

KLau

SAT bass trap-diy bass trap

Simple as this (SAT)  baSS trap

Last year Koo come and visit me and taught me how nasty my room acoustic is. There is a lot of boom. Last week Koo inform me that he will be coming soon. So during this year I have employ 9 pieces of Helmholtz and 3 panel of bass absorber.The helmholtz will take care of the 120hz and below.

I only manage to finish the last piece of panel absorber last week. Before I make this last pieces of panel actually I have make another 2 pieces bass panel that can be adjustable. This is the simpler version.
The targeted frequency is 148hz.
The dimension of the panel is 174.38cm x 29.14cm x 11cm (internal)
1.49 kg/m2 panel mass.

This is the frame.I just use a few pieces of salvage wood.

After much consideration, i use carpet.The type of carpet we call in punch needle carpet.Rock wool is the best material but beware it may cause rashes.

I use 6 layer.I use staple .Now is 5 layer and later wrap the whole panel with another layer.If you worry the carpet is not strong enough you can put in wire mesh.But 6 layer of carpet might even put off a bullet.

This is the rear side.Just cover with a thin layer of plywood and done!

This is the 1st version oif panel absorber.This design is much more complicated with adjustable depth.

What is the result?

Before I employ any panel absorber, I can detect mid bass boom. At first I put 2 pieces, boom is disappear but there is mid coloration especially male voices. It is easily detectable when playing the Amos lee album.

When I added the 3rd panel the low mid coloration, high and dynamic is gone. So one must take care when we added something to our room it might disturb the whole acoustic sound balance of the room. We must be very careful when doing absorber for frequency more than 100hz. The range of the absorber range is too big and it might hinder the dynamic of a system
Koo, you can come now..

KLau

Jadis Pre

A Jadis jp80mc is having some problem and open up for health check. I took the opportunity to take some photo. The jadis jp80mc is separate into power supply and line.Show here is the power supply.This power supply is said universal to Jadis other pre amp like the JPS2.

KLau

What are you talking about

Many people talking about mid bass, mid high and etc but are they referring the same frequency that they are talking about?

To cut the confusion, here is the refer frequency range:

KLau

Speaker Maintenance

Can you see how delicatel this person pamper the speaker. Actually there is story behind this.This actually happen while we are trying to “poison” a guy into ls3/5a. After letting the guy listen to 11 and 15 ohm black tag rogers. We just show the guy how to take care of ls3/5a.

A english lemon oil is the recommended to rub on the speaker cabinet. You can use other natural oil but it might further make your speaker darker especially walnut. This English lemon oil is not so oily compare to others and according to Bluesea:

1)Rub off any dust and then use a fine cloth and apply the oil to the cabinet.
2)After this rub it with your bare hand and this will let the speaker cabinet soak more.

 
 
Klau

Which power tube?Shuguang EL34B,Electro Harmonix EL34,Reissue MULLARD EL34,Reissue Gold Lion KT88,Treasures 6ca7-z,Ei KT90 ,Groove Tube EL34m , 6CA7

Shuguang EL34B

Electro Harmonix EL34
Reissue MULLARD EL34
Reissue Gold Lion KT88

Treasures 6ca7-z

Ei KT90 (Not in production)
Groove Tube EL34m , 6CA7(no longer listed on groove tube webpage).


First i have to say i have tested or listen to the above tube either in my own system, friends or in dealer system and not the result is not conclusive.
I would categories them under 2 batch distinctively by the origin of the tube.
I found even with the claim of different design I still find the sound characteristic is almost the same.
The first batch will be from China Shuguang that are more tonally pleasant but with bloated bass and sound “dirty” at the high.
This category of power tube is more suitable for small speaker or speaker with tight bass.In my system base on ls3/5a, i tends to favour this group.
This including the:
Treasures > GT 6CA7 = > GT EL34m(1ST BATCH)  => SHUGUANG EL34B

The second category will be from Russia.The sound is thin withn tight bass.Full range or big speaker tends to favour this group of power ube.
I also put the EI kt90 under this category as the sound is much closer to this category:

Ei   >    Gold Lion   =>   mullard   >     EH


>      BETTER
=>    EQUAVALENT OR BETTER.

I found that more better i rank  is usually improve on the dynamic and sound less "dirty".
This might lead to improve imagimg , soundstage and etc.Tonality is usually the same even with the claim of different design.


KLau

Power tube saga.Treasures 6ca7-z,Gold lion reissue KT88,Ei KT90,GE 6550A

Power Tube.


Last week was a very interested week where 4 type of power tube been tested on Marantz 8b.To make this possible the bias is been modify to accomodate the 6550 and kt88 tube. The sequence tested is as follow;

TREASURE 6CA7-7, Shuguang celebrate make this to celebrate 50th anniversary.

Treasures 6ca7-z

Gold lion reissue KT88

Ei KT90

GE 6550A.

At that night I rank them as follow

1ST GE6550A

2ND Ei kt90

3rd treasures 6ca7-z and reissue kt88.(Both have their own sound characteristic that may appeal to different user)



As time is not permitted we have not tested the Sylvania and telefunken metal base EL34 that in the owner collection.

I still say NOS tube still rule.Even  Marantz 8b that been optimise for EL34 i still prefer  the NOS GE 6550A 


*More picture will be add later.


KLau.