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Old 6th May 2012, 11:06 AM   #1
Plado is offline Plado  United Kingdom
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Default Here's a weird enquiry

I need some expert guidance here please.
My system which comprises Rotel Pre-amp RC-972 into a John Shearne Power Amp and on to a pair of Bowers Wilkins CM1 speakers, has excellent power and sound quality but there's a new problem. I've had a hearing-loss due to damage and that has sent my own frequency response curve into a very ragged shape. Running the Pre-amp with Flat response is simply not suitable for what I hear with my natural remaining hearing modified by two digital hearing aids.

OK so what I want to do is tweak the system by adding a Graphic Equalizer with at least 5 channels so I can re-model the shape to one of my own personal preference so it sounds "flat response" to me.

Can I simply buy a Graphic EQ and put between the Rotel and the Shearne?
There is no EQ Bypass or Cancel switch to my knowledge on the Rotel.
Only one spare phono socket pair, on the back marked VIDEO all other inputs and outputs are occupied. I'm not even sure if placing a Graphic EQ would seriously degrade the signal. Currently there's a thick gold plated phono lead connecting into the J Shearne.

What are my options in this - anyone got any clues?
Thanks in hope !
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Old 6th May 2012, 11:18 AM   #2
AndrewT is offline AndrewT  Scotland
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Your brain has already inserted your "graphic equaliser".

What you hear as "normal" sound has been interpreted by your brain to sound like what your best memory has of what it should sound like.

You hear a bell ring, you recognise that as a bell ringing.
You hear a car door slam, or you hear a house door slam, you hear a big dog bark, or a bird sing. They all come across as recognisable signals/sounds.

You don't need a contraption to confuse what your brain is already doing rather well.

It's when the sound is too quiet to be heard that some form of support may be required. That is a quite different requirement from EQ.
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Old 6th May 2012, 11:24 AM   #3
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Yes you can place a line-level graphic equaliser between your power amp and your pre-amplifier.

Just ensure that the equaliser will not clip with the possibly higher level output of the pre-amplifier.

i.e. Ensure that the equaliser can cope with a 2V or more level input signal.

If your hearing is that badly impaired, and integrating what AndrewT is saying above, you wouldn't need a HQ equaliser to see what effect it would have on your listening experience.

Last edited by KatieandDad; 6th May 2012 at 11:28 AM.
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Old 6th May 2012, 12:04 PM   #4
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Also worth considering anyone else living with you.

If you modify the sound to suit you it might sound horrible to any one else.
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Old 6th May 2012, 01:46 PM   #5
Plado is offline Plado  United Kingdom
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Well a big thank you to Andrew and Katie and Dad,
You all make some very interesting and appropriate comment on this.
I have indeed got to consider that if I re-shaped the sound, my wife would then find it sounds ragged and probably not sweet or musical.

My digital hearing aids have a setting for music and for when I'm sitting at and playing my grand piano. Set to normal shape the piano sounds 'wrong'
Set to Musical shape and it sounds much more natural. I'm surprised that it doesn't take me a month to habituate the switchable shape the way it did when I had a new model of hearing aid with 10 channels adjustable instead of the previous one with just 4.

Anyhow be that as it may, I do take your point that my problem is more the reduced dynamic range as I can no longer hear very quiet sounds. That is I can hear nothing quieter than about 30db whereas 15 years ago before the damage when I was a full time Piano Tuner, I could hear down to about 5db and from a Frequency point of view I was about 20 hz - 17,500Hz - now I can hear nothing above 10k Hz and at the loudness end I can't bear anything much above 90db - even 85db is uncomfortable. So you see I have a grossly reduced Dynamic range and though my B&W CM1 Speakers have a lovely smooth sound I'm in trouble with CDs and digital broadcasts because I have to turn it up to hear the quiet passages in any detail and then when the music goes loud, I have dive and turn it down so as not to stick us both to the walls!

It's a horrible affliction and added to 65dB approximate Tinnitus at 8000hz whistle 24/7 you can imagine how I find that headphones creating the sound close up to the entrance to my ear canals allows me to hear much more detail in the quietest parts of music and they prevent it having to blow me to worse damage when the music gets louder as I can run the headphones at a realistic level without them ever being horribly loud or dangerous.

So to sum up then, I suppose I could try putting the graphic equalizer in place if they were available without huge expense, but I'm a bit loathe to because it could be throwing money away and I might wreck the present very beautiful sound for anyone else.

Thanks very much to both of you for your comprehensive response, and give my regards to the lovely Scottish Border country.
--
Plado

Quote:
Originally Posted by AndrewT View Post
Your brain has already inserted your "graphic equaliser".

What you hear as "normal" sound has been interpreted by your brain to sound like what your best memory has of what it should sound like.

You hear a bell ring, you recognise that as a bell ringing.
You hear a car door slam, or you hear a house door slam, you hear a big dog bark, or a bird sing. They all come across as recognisable signals/sounds.

You don't need a contraption to confuse what your brain is already doing rather well.

It's when the sound is too quiet to be heard that some form of support may be required. That is a quite different requirement from EQ.
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Old 6th May 2012, 01:50 PM   #6
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Have you considered headphones ?

Might sound daft but it is much easier to control enormous hearing aids (headphones) than a whole Hi-Fi system (Room)

Pop along to your local CashConvertors, you should be able to pick up an equaliser for a few quid. At least it will prove to you that you are working in the right direction for your hearing.

Alternatively ask your Audiometrist to provide you with an audiometry test chart. We could reverse engineer a PLADO equalisation curve, similar to an RIAA curve to correct for your hearing.

Last edited by KatieandDad; 6th May 2012 at 01:55 PM.
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Old 6th May 2012, 01:55 PM   #7
AndrewT is offline AndrewT  Scotland
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A compressor/dynamic limiter circuit may improve what you can hear and tolerate.

It will reduce the dynamic range of the signal. That then will allow you to turn up the volume without it becoming "too loud". This might enable you to hear the less loud passages more easily.
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Old 6th May 2012, 03:40 PM   #8
Plado is offline Plado  United Kingdom
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Think I'll reply to both Katie&Dad and AndrewT in this one.
Firstly I must tell you that I have some fantastic Sony cordless headphones already and they don't allow anyone else in the room to hear what I'm listening to at my own volume. They help greatly when listening to Panel Games on the TV as well, so I can pick up speech better as it tends to get drowned out by audience noise and background cruddy music.

But I'm sorry to appear iggerant but Who are CashConvertors and what kind of Graphic Equaliser would I buy if it has to be one that can accept a 2volt input (as per your previous post) Any makes or models? I'm still not sure that I need to go get a graphic eq at all. But one more question a Compressor Dynamic limiter? I've never heard of such a thing. Wouldn't that also affect the way the sound appears to anyone else in the room? Or are you saying I'd put the limiter between the power amp and my headphones?

This is starting to get confusing. Incidentally I already have had many Audiograms done by the ENT dept at the hospital and privately and I've done a lot of tweaking of hearing aids to try to put my hearing back to as close as possible to my natural original hearing. But it will never be possible to simulate my hearing the way it was when I could tell the difference between a Quad Amplifier and a Leak or between Lowther Keff Tannoy and B & W speakers in the days when I bought a pair of P2H B&W Monitors with Ionofane Tweeters. I used those for 30 years!

I am interested in this idea of a compressor Dynamic limiter but I do need a bit more info please if you could furnish it. Ta very mooch.

Quote:
Originally Posted by KatieandDad View Post
Have you considered headphones ?

Might sound daft but it is much easier to control enormous hearing aids (headphones) than a whole Hi-Fi system (Room)

Pop along to your local CashConvertors, you should be able to pick up an equaliser for a few quid. At least it will prove to you that you are working in the right direction for your hearing.

Alternatively ask your Audiometrist to provide you with an audiometry test chart. We could reverse engineer a PLADO equalisation curve, similar to an RIAA curve to correct for your hearing.
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Old 6th May 2012, 05:01 PM   #9
AndrewT is offline AndrewT  Scotland
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The dynamic limiter or the signal compressor would be fitted at line level, i.e. before the power amplifier.

All the quiet sounds would be raised in volume. All the loud sounds would be dropped in volume.
The total dynamic range of the raw input signal would be reduced so that none clipped the amplifier or overloaded the speaker. The wanted quiet signals would be just loud enough to be heard by yourself and any other listening.

There are a few disadvantages to what I just described.
The final output sounds less dynamic. I would expect it sound a little "flat", maybe a bit like modern "pop" radio transmissions.
The range of compression may need to be altered on the fly to suit what you are listening to. This is likely to cost a bit more than a fixed compression ratio.
The noise in the original signal is read as a quiet sound. The compressor will increase the noise and this can be annoying. There is a cure. The compressor has an adjustable cut that removes all signals that are below a certain threshold. Radio Hams and FM radio and similar use these all the time to cut out unwanted noise. Again an adjustable threshold will cost a bit more.

It would be nice if you could borrow a few different types and experiment with them for a few days each.

Edit,
just occurred to me. DJs, using a microphone voice over, will almost certainly use something similar. That way they can shout or talk quietly and the audience hear a similar volume. When the DJ stops talking over, the circuit reads the near zero signal and cuts out, so that the audience does not hear his open microphone bawling out noise at maximum gain.
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Last edited by AndrewT; 6th May 2012 at 05:07 PM.
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Old 6th May 2012, 05:42 PM   #10
Plado is offline Plado  United Kingdom
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Well that's all fascinating stuff but sounds like a rather expensive bit of experimentation and something of that degree of trial and error is likely to end in some rather costly mistakes.

It does sound to me (with my background of 38 years of analytical enforced deep listening doing thousands of piano tunings) that I might find I've messed up beyond retrieval the existing almost acceptable situation. I spent a long time trying to find speakers that were usable and that I could live with, after I'd had to modify my hearing during every waking hour using Digital Hearing Aids.

It's a shame that with all that adjust-ability of the sound at manipulation level - nobody has come up with a filter that can banish background muzak from TV documentaries that swamp the speech to such a degree that I would cheerfully like to throttle and vaporize the Programme Directors and Producers who infest today's serious programme material with their bonkers ideas about enhancing normal linguistics.

If we consider that you're right in your first response about my own habituation and self-regulated Equalization (and I'm sure you are) then I have really already got my own dynamic range limiter in the form of headphones that form the quiet sounds so close to my reception devices ie eardrums and microphones on the hearing aids.
The speakers are too good in quality to monkey about with as it would be tantamount to going to Bowers & Wilkins acoustic chamber and telling them to alter the characteristics of their range of speakers to suit my hearing and thereby completely compromise and wreck the research they did to make them as always highly "musical" speakers. They're also excellent on speech reproduction too. These days speaker technology has moved on so far that even cheap ones are better than some we used to think were wonderful back in the Wharfedale and Bang & Olufsen days !

If I could find a graphic EQ at a reasonable price and one that can accept a 2volt input I might just gamble on trying one but I know of nowhere that will lend me one. We used to have a superb HiFi dealer here for years but the owner retired and my source of Hi Fi paraphernalia disappeared over night.

But thanks a lot anyway for your advice. It's much appreciated and gives me lots to go on when thinking about making adjustments. I think I'm best employed making adjustments to me rather than the system.

Cheers
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