Graphic Equaliser

[toshiba tony]

Sin upon sin, I've added a graphic to my gear. It's a Sony TA-F7b jfet amplifier.
Yes, I need shooting but it improves poor room acoustics, but my problem is this. It has in\out for two tape decks,(the equaliser), one of which I want to use my reel to reel on and the other the Sony tc-k7 cassette deck. There is no way I can adjust the volume on the two tape inputs on the equaliser as the volume gain on the amp is inserted before the split phonos on the back of the amp.
If the outputs from the reel to reel and cassette deck were volume controlled this wouldn't be an issue. The TA-F7b has provision for two decks but these are occupied with other inputs. Being Bank Holiday I took a day off work to think it out but nothing has come to me. If only the volume control on the amp was after the stages where you break the amplifier chain everything would be OK. But as far as I know a lot of power amps without a preamp don't have gain controls.

[toshiba tony]

As an after thought, I don't use either phono input on the amp. Anyone know if an r\c network could work to allow me to use those for line level inputs?

Sin upon sin, I've added a graphic to my gear.

Not a sin at all, if I could tell the difference between one of those properly set up and tone controls I would use one too.

Line to Phono, search for "Inverse RIAA" and you get lots of very similar circuits.

[Radio Wrangler]

To quote the great Rowan and Martin's Laugh-In.... "If it feels good, do it!"

You could take a moment to consider how many mixing desks have extensive equalisation available on an each channel basis, and so every purist ought to eschew listening to anything ever recorded in a studio.

Besides, they have another use: Better than garlic for vampires, it will scare away audiophiles and allow you to enjoy your music undisturbed.

Don't go too far, though. A pair of **** speakers would have all the sane people laughing.

David

it will scare away audiophiles and allow you to enjoy your music undisturbed.

Brilliant!

[toshiba tony]

Cheers Merlin and David, knew what I wanted. Didn't know what to ask for. If that makes sense. We once spoke about Levell's David. In the days of DIN4500, was it called? Did my time there. Forgot more than I knew. Thanks both.

[paulsherwin]

Originally Posted by Radio Wrangler

You could take a moment to consider how many mixing desks have extensive equalisation available on an each channel basis, and so every purist ought to eschew listening to anything ever recorded in a studio.

While this is true, domestic and stage PA graphic equalisers are quite simple designs which can introduce phase errors, so their use isn't normally a good idea if maximum fidelity is important and there is an alternative solution. Most studio equalisation is done in the digital domain nowadays.

[toshiba tony]

Mine has a switch and it switches something in. presumably some sort of sum and difference idea and it sounds like a teenage ghetto blaster. REVOLTING

[teetoon]

Hi Tony. I seem to remember discussing this with you before.
The type of graphic with tape inputs is not designed to be connected between the pre and power amp. It only works properly if you connect it to one of the tape loops.
Pre-power sockets on domestic amps were there so you could use the preamp with a bigger power amp or a different preamp feeding the power amp.
If you look at a professional graphic they do not have tape inputs.
If you could find your old thread on this I'm sure we found a solution to your input requirements using the equipment you have.

David.

[toshiba tony]

Thanks David, I will search my posts.

[toshiba tony]

Thanks, found it, even though I lose one of the rec\play inputs on the amp I gain two back on the graphic. You nailed when you told me why the links were provided on the amp.

[teetoon]

Glad to hear you found it. Hopefully you will have enough inputs as I seem to remember the sony already has 2 tape inputs and they can be switched to send signals from and to each other so you should have 3 tape loops with the graphic connected.

David.

[mhennessy]

Pretty sure that if you wish to change level according to frequency, you're going to introduce phase shifts, whatever fancy circuitry you use. Exactly the same thing happens in the acoustic domain, which is lucky because we can model loudspeaker enclosures using electrical theory

The reason tone controls were removed from hi-fi amplifiers is to sell more speakers and accessories like cables. Terms like "phase error" - whatever that actually means - are designed to fuel audiophile nervosia.

Many excellent loudspeaker designs have the tweeter in reverse-phase relative to the woofer. And of course, crossovers contain tone controls - albeit fixed in the design. Don't tell anyone!

I have no problem using both a parametric and 3rd-octave equaliser in the hi-fi, and for R&D work.

Glad you've figured out how to connect it. I started explaining it, then saw that David beat me to it. So now, just enjoy it! Though resist the temptation to go mad. Pro gear has a bypass switch to let you refer back to the original - I assume yours does?

[paulsherwin]

Tone controls were removed because the hifi market had become increasingly obsessed with accurate reproduction and the 'length of wire with gain' model. It wasn't some sort of corporate conspiracy. If you look inside many 90s amps you will find the PCB has been drilled and printed for tone controls, but the controls have not been fitted. My well regarded Marantz PM66SE has this arrangement, even retaining a largely pointless 'tone bypass' switch presumably carried over from the original design.

Most hifi amps do have tone controls nowadays, even ridiculously esoteric models bought by wealthy crackpots: http://hifilounge.co.uk/devialet-expert-1000-pro

[dtvmcdonald]

Originally Posted by Radio Wrangler

To quote the great Rowan and Martin's Laugh-In.... "If it feels good, do it!"

You could take a moment to consider how many mixing desks have extensive equalisation available on an each channel basis, and so every purist ought to eschew listening to anything ever recorded in a studio.

David

I actually more or less do! I try to listen to things recorded in
concert halls. Unfortunately some labels used serious eq on concert hall recordings too. I just checked what I am listening to at the moment,
and it was recorded in a concert hall in 1956. Sounds great.

[toshiba tony]

Think your'e a bit of a whizz kid do you, Teetoon Well, I took your advice and it was spot on, to the letter. Been in the repair field all my life and I couldn't suss it. Used tape I for the graphic, put both cassette decks through the graphic and the reel to reel on tape 2. Thought I would have to put one of the decks connected to the graphic on record to send audio through from the other inputs, but no. Just de-select both decks and the selected input come through the graphic. And the links on the amp are back in place, star guy, I mean that. Thank you.
Tony Walker

[Hartley118]

Sin upon sin, I've added a graphic to my gear. It's a Sony TA-F7b jfet amplifier.

A graphic can be useful for correcting a few dB here or there in speaker/room response. I use one permanently in my Quad 33/303 system feeding a pair of Goodmans Maxim speakers. My 50 year old Maxims benefit from a permanent lift below 100Hz and also a bit of a dip to correct their over-prominent upper midrange.

Graphics became popular in studio monitoring systems in the 1970s. I suspect that it started with a worthwhile desire to soften the mid-range prominence of some American monitor speakers, but they soon began to drive studio managers to despair as they went overboard and tried to compensate for every room resonance and found they got a different result every time, depending on the measurement mike position

In general, the human ear seems rather good at ignoring room resonances at mid-high frequencies and hears the actual characteristic of the speakers, 'listening through' the room acoustic. At lower frequencies on the other hand, a graphic can provide helpful room correction: for example to suck out a frequency band that's subject to a boomy resonance.

So, I find a graphic can give useful improvement, but beware of turning those sliders to extremes. Odd stuff can then happen at those steep band boundaries!

Martin

[Edward Huggins]

Originally Posted by paulsherwin

My well regarded Marantz PM66SE has this arrangement, even retaining a largely pointless 'tone bypass' switch presumably carried over from the original design.

Most hifi amps do have tone controls nowadays, even ridiculously esoteric models bought by wealthy crackpots: http://hifilounge.co.uk/devialet-expert-1000-pro

That "Source Direct" feature on your very nice Marantz PM66SE does bypass the tape in/out looping and balance circuitry so as to avoid any possible insertion loss therein. But then I am a fan of the "straight wire with gain" model!

[Radio Wrangler]

The straight wire with gain is indeed generally laudable, but it is an easy place to put some compensation for the less-perfect parts of an audio system. It seems less wasteful than the pundit-required method of having to keep buying new pieces of equipment to get one item to compensate for the failings of another.

£22,900, and other models and things not far off that price... and they keep it in a farm... and they've included a map of its location?

Does anyone have a scan of "1001 burglar alarm circuits used in farms" that they could email?

P.T. Barnum said that 'there's one born every minute' and William of Occam reckoned that the simpler explanation was more often the right one. Hmmm.

David

[mhennessy]

The "straight wire with gain" is really an earlier thing, from Peter Walker originally. What I'm referring to came later, and is generally known as "flat earth". Happily, not all companies played along, but a notable handful did - the history is plain to see, even from outside of the industry...

Even today, tone controls are very much in the minority, although rather more sophisticated conceits - for example, Devialet's "SAM", and Linn's "Exakt" - exist as alternatives to traditional tone controls that are currently non-toxic in the eyes of the audiophile. At a recent show I did, the adjacent stand had $$$$$ valve amps with adjustable amounts of 2nd and 3rd harmonic distortion - literally "niceness" knobs on the front panel! OK, user choice and all that, but I did get a bit agitated when the salesman claimed that adding just the right amount of harmonic distortion in the amplifier will cancel out the harmonic distortion in the speakers!

Originally Posted by Douglas Self

Tone-controls cause an audible deterioration even when set to the flat position.
This is usually blamed on phase-shift. At the time of writing, tone controls on a pre-amp badly damage its chances of street (or rather sitting-room) credibility, for no good reason. Tone-controls set to flat cannot possibly contribute any extra phase-shift and must be inaudible. My view is that they are absolutely indispensable for correcting room acoustics, loudspeaker shortcomings, or tonal balance of the source material, and that a lot of people are suffering sub-optimal sound as a result of this fashion. It is now commonplace for audio critics to suggest that frequency-response inadequacies should be corrected by changing loudspeakers. This is an extraordinarily expensive way of avoiding tone-controls.

Luckily for me, the hi-fi industry is not my primary income, so I can be choosy about who I work with. There's no shortage of "sane" companies out there, fortunately. They tend to have much smaller marketing departments than the giants, but they make an honest living nonetheless.