experimenting with caps to attenuate bass in my diy phones.
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setmenu

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I have just began experimenting with capacitors in series
with the headphone cable to help control the excessive bass my
diy phones [mk1] have.
Is this approach a real no no for sound quality regardless of the
capacitor used?

At present I have just stuck in some cheap 220uf caps I had lying
around by way of experiment.
This has certainly tamed the bass.
There are also some slight changes in other areas but I won't dwell on that at this stage.
I have also ordered some highergrade black gate items to compare.

Views?

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Budgie

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I would suggest that a series cap is a livable solution. A parrallel inductor would work too, I suppose, but thats kinda tough on the amp. Maybe tone controls in the preamp would be better?
 
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ringtheorist

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I think the Blackgates should do wonderfully. Of course, they will take an eternity to break-in and one problem is that they need to stay broken in.

If I recall correctly, the impedance of those ribbon transducers was awfully low.. something on the order of 2-3 ohms correct? If that's the case, you'd need an awfully big capacitor to get reasonable -3dB points. What size did you order? I would think that something like 1000uF would be a more ideal value than 220.

-b
 
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setmenu

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Thanks for the responses.
The reason I first wished to try an 'inline' attenuation approach is
so I would be able to mess around with various available amps
before taken the plunge at doing one of my own [this is now looming ever closer!].
I have considered inductors but for the reasons mentioned and the fact I would probably have to make them I thought the
capacitor approach the best starting point.

I am pleased with the bass attenution I get with the 220uf caps
a value of 1000 with my 5ohm impedence[or dc resistence to be more correct] would not offer the reduction i need.

The cheapo caps I am using work in bass terms but in overall
sound mmm, not sure about that the top end seems a little more 'congested'.
Also a they are rather a blunt instrument.
But it is a positive start I feel.
I DO hope the blackgates [standard model,but if encouraged will opt for their top model that suits] will be an improvement over the
cheapos.

I have read that caps in the signal path are not a good Idea,
vieled sound etc.[hence post question]
But It seems that with filters crossovers etc they cannot be avoided.

Also am I right in thinking that the AKG 1000 model uses some sort of filtering to control their bass?

Anyway with this start I can begin to address the fact that the amp driving these is the [a] weak link.

I am ever keen to get the MK2 versions of these phones
completed , I am hoping these will be a big step forward but feel
bass is still likely to be an issue with these,so all I learn now will
come in handy with those.

Oh and boy did the new cables I made up make a big difference!
The stuff is Van Den Hul Flexicon B4.

Ringtherorist
What about your electrostats,have you had any time to work on
those?


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setmenu

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WOW
Those Blackgates are good!



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setmenu

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I have upped the attenuation with a 147uf value now.
Things have definitely gotten better!
Infact the best they have sounded ....woohoo!
Getting rid of all that excess energy has tightened things up and
generally opened things up.
Listened to Don Giovani,very yummy.
Then Bjorks vespertine,also yummy.
And then Nirvana unpluged in New York,great acoustic,real sounding clapping audience etc[+great music].
+ more stuff too.

Also have an sacd player now as well,,interesting......but not enough material for that medium yet to comment.

All said and done I am really chuffed with the results I am getting
at the moment[bearing in mind the amp needs a serious upgrade
here!] and I am now finding myself actually listening to these things for pleasure rather than just testing,that said once a certain level of acceptable fidelity is reached testing and listening
can be difficult to divide.
I do try to keep my feet on the ground by having the stax 4040
system warmed an ready just to shatter any illusions[delusions]
I may be developing,but the gap is closing.

Roll on the MK2s
[and a decent amp!]


Setmenu

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Tomo

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Hey,

You use BG? I sorta don't recommend because it takes longer to burn in. But that doesn't mean it is a bad cap. It just mean it gets even better over time. Oh yes, it gets better. Take a time and wait a while.




Tomo
 
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setmenu

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Hi Tomo
Yes Ringtherorist says they will sound better broken in but also
mentions keeping them broken in.
With caps,do they 'break in' with intermitent use or do they
require a constant potential so to speak?

curious.


cheers

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Tomo

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Hey,

That's the problem, you know? You have to have BG subjected to voltage continuously. I have BG in my PSU and I ran it constantly for like few hundred hours, never turning off.

I wonder how would you do so for coupling caps. Perhaps connect it across some voltage source for a week.

BG is quite different from other electrolytics. I know all electrolytics require burning in, because you have to reform the cap after heating the leads when you solder. But BG's internal is quite unique and takes a little longer to burn in. And I also hear rumors that if you leave BG unused you will have to burn in again. Intermitent use is probably not favorable for BG.

I chose ELNA Cerafine over BG for that reason ... like 2 years ago when I was building Szkeres amp when Cerafine costed like pennies. (A figure of speech)

Tomo
 
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setmenu

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Tomo
If this 'burn in' is a chemical change or whatever and takes
some considerable time to happen I wonder how long the effect
would then take to reverse.

If for arguments sake a cap took 50 hours of continuous use at
a given signal strength would it take the same 50 hours to
revert to the new state if unused?

If this were the case pherhaps an 'artificial' burn in circuit [bit extreme I know] to get them up to speed followed by a minimuim
daily usage to maintain their 'state' would suffice.
???

Interesting stuff eh.

I am dying to get a good amp sorted for these phones..but spose
I should get the Mk2s up and running first as they will have different needs.
Patience,Patience



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Tomo

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No idea,

Chemical Effects and Natural Duration stuffs tends to be non-linear and crazy. But it does seem to happen for some people.

BG, I used with my solid amp with a hyper-spec opamp. It has so little quescent current that I can keep it on all day and have that reverse effect out of my mind.

I guess you can't do that with class-A amp, huh? But then it sounds good as it is now right? It just gets better with use and if it goes "reverse," it still sound awesome anyways. I guess it isn't much of problem to begin with. [shrug]

Tomo

P.S. By the way, my BG is in my PSU. Usually I use a lot of HFQ Panasonics because it is really high performance of really low price. I parallel a lot of them. Oh yeah, I almost forgot that I have loads of 10,000uF caps some place ... Yeah used to be a cap crazy.
 
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Jupiter

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Quote:

Originally posted by setmenu
If this were the case pherhaps an 'artificial' burn in circuit [bit extreme I know] to get them up to speed followed by a minimuim
daily usage to maintain their 'state' would suffice.
???


Somebody already thought of designing a burn-in circuit for caps: http://www.geocities.com/rjm003.geo/.../diy_rack.html
 
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setmenu

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Hehe
Pherhaps their would be a market for a mini gym [in this place anyway
]to train up out discretes before putting them to work




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