HF loss - general

[vince666]

IMHO, there is also wear on those heads.

point is that the heads in such Technics decks aren't exactly the hardest permalloy around and it's very unlikely to find them without some considerable wear... the deck should be used very little by the previous owner to get heads in really good shape.

 

[WOPL Sniffer]

IMHO, there is also wear on those heads.

point is that the heads in such Technics decks aren't exactly the hardest permalloy around and it's very unlikely to find them without some considerable wear... the deck should be used very little by the previous owner to get heads in really good shape.

the deck should be used very little by the previous owner to get heads in really good shape.


REALLY??????

 

[vince666]

the deck should be used very little by the previous owner to get heads in really good shape.


REALLY??????

I do understand what I stated above is just very obvious... but if I wrote that post is for two exact reasons:

first, there are heads made of (relatively) soft permalloy. (easy to realize how much a head is soft or hard just by the time and effort needed while relapping it)

second (and most important), if our friend will show a picture of such heads also here, it will be easy to see why I posted the above.

Cheers,

Vince.

 

[Alex SE]

the deck should be used very little by the previous owner to get heads in really good shape.


REALLY??????

No need for such reaction, he is pionting that permaloy heads don't need lot of use to get wear. We are all here to talk, share opinions and knowledge and to learn. No reasaon to criticize each other We don't want people to leave Phoenix, but to say whatever they think and want.

 

[Alex SE]

I do understand what I stated above is just very obvious... but if I wrote that post is for two exact reasons:

first, there are heads made of (relatively) soft permalloy. (easy to realize how much a head is soft or hard just by the time and effort needed while relapping it)

second, if our friend will show a picture of such heads also here, it will be easy to see why I posted the above.

Cheers,

Vince.

Nothing but agree. Besides, I like when people are explaining detailed. Some of us sometimes don't understand something that is obvious for a professionals.

 

[vince666]

No need for such reaction, he is pionting that permaloy heads don't need lot of use to get wear. We are all here to talk, share opinions and knowledge and to learn. No reasaon to criticize each other We don't want people to leave Phoenix, but to say whatever they think and want.

but I don't think WOPL wanted to be negative about my post (he isn't, actually)... and, after all, what I posted is just obvious and he did put this in good evidence.

and... it's well known that the permalloy heads used into RS-B / RS-BX series decks are quite soft...
go figure, when I had got my first RS-B965 like a dozen years ago with the intention of getting it modified by our dear Alex, before sending him the deck I had happened to send him a picture of the transport and heads...
My heads had quite some wear (but they could still be successfully relapped, in fact he relapped them just nicely) but I simply was unable to see it, not having any true experience about the "heads" matter back then...
Nevertheless, by simply giving a look at the picture, Alex immediately told me my head had considerable wear and, of course, he was right.

Obviously, nowadays, after relapping several heads by myself, I am able to "see" the wear a lot better than before.

And your head has wear on it... cannot know exactly how much wear but, for sure, that wear groove you have there will just work like an unwanted pressure pad lifter, making overall performance worse.

 

[Alex SE]

but I don't think WOPL wanted to be negative about my post... after all, what I posted is just obvious and he did put this in good evidence.

and... it's well known that the permalloy heads used into RS-B / RS-BX series decks are quite soft...
go figure, when I had got my first RS-B965 like a dozen years ago with the intention of getting it modified by our dear Alex, before sending him the deck I had happened to send him a picture of the transport and heads...
My heads had quite some wear (but they could still be successfully relapped, in fact he relapped them just nicely) but I simply was unable to see it, not having any true experience about the "heads" matter back then...
Nevertheless, by simply giving a look at the picture, Alex immediately told me my head had considerable wear and, of course, he was right.

Obviously, nowadays, after relapping several heads by myself, I am able to "see" the wear a lot better than before.

And your head has wear on it... cannot know exactly how much wear but, for sure, that wear groove you have there will just work like an unwanted pressure pad lifter, making overall performance worse.

I pm-ed Alex today, asking about relapping. We'll see if he have a time for such things. And yes, I want that one as a spare part. And yes, it would be great to try amorphus one on 965

 

[vince666]

And yes, it would be great to try amorphus one on 965

of course!

that NOS amorphous heads you have there (identical to the ones I also have here) are of really GREAT quality and a noticeable improvement over the original permalloy ones... and they are mechanically compatible with the RS-B965.

till now, I've put those nice amorphous heads into my Technics RS-M260, in place of its original sendust heads (which are some quite bad sounding ones!) , with lots of modifications to make these amorphous work properly in this deck, and now it sounds like a totally different (and MUCH better) deck.
Those original sendust heads in the RS-M260 were quite good in recording and very bad in playback (in fact, the tapes recorded with those heads sounded a lot better when played on another deck than on the same deck where they were recorded)... but these Canon amorphous heads are even better in recording mode (I have measured impressive MOL and frequency response on just any tapes) and they sound just excellent on playback.
Go figure... going from those original sendust heads to these amorphous heads, on the RS-M260, I've gained about 7Khz of treble response on just any tapes... i.e. , while doing REC/PB sweep tests, a (decent) Sony HF from 1986-87 showed the -3dB point at about 16Khz on the original sendust heads and now it shows the -3dB point at about 23Khz... and a BASF chromdioxid super II from early-mid 80s showed -3dB point at about 19Khz on the original sendust heads and now it shows the -3dB point at around 26Khz.... but, in general, i've noticed treble bandwidth improved by about 7Khz on just any tapes.
And just a couple data about the measured MOL at 315Hz on these amorphous heads...
I've measured MOL of about +9 dB VU on TDK D from 1982 and on TDK SA... and +12.7 dB VU on Sony Metal ES from 1985...
Then, I'd say those amorphous heads are just NICE and, maybe, they might shine even more on a modified RS-B965, after applying further needed mods to match these new heads, of course.

 

[Alex SE]

of course!

that NOS amorphous heads you have there (identical to the ones I also have here) are of really GREAT quality and a noticeable improvement over the original permalloy ones... and they are mechanically compatible with the RS-B965.

... with lots of modifications to make these amorphous work properly

Thats why it is unusable to me

a (decent) Sony HF from 1986-87 showed the -3dB point at about 16Khz on the original sendust heads and now it shows the -3dB point at about 23Khz...

23kHz sounds great but I'm not sure that I can hear difference between 20 and 23. To be honest, I have never tested. Just want my tapes to sound as close as possible to source, while listening on regular speakers. Have no intention to take a headphones and look for a difference You know what I mean.

 

[vince666]

23kHz sounds great but I'm not sure that I can hear difference between 20 and 23.

it's not about directly hearing the frequencies between 20 and 23 Khz (which aren't hearable, and especially at our age)... but, hey, think about it this other way...
if the deck can reach higher frequencies, then I expect the transient response and/or the treble details would improve in precision so there might be some kind of hearable effect not just in terms of pure frequencies but in the way the better treble response would positively affect the sound about these other kinds of details...

and, btw, a deck which can exceed 20Khz on a basic ferric tape (together with high MOL) is a sign of a deck with NICE performance.

after all, while measuring the actual performance of a deck, you go and check also what's not directly hearable but which is still measurable (and, btw, there are lots of other things which aren't measurable but they are easily hearable and then also the evaluation by ears is important, not only the measurements).

 

[J!m]

The more response that exists in the machine, the limitation becomes the tape only.

Having more frequency response than audible allows it to remain (ideally) dead flat to 20k and not already beginning the roll off.

 

[Alex SE]

The more response that exists in the machine, the limitation becomes the tape only.

Having more frequency response than audible allows it to remain (ideally) dead flat to 20k and not already beginning the roll off.

Was it something about my deck? LOL

 

[vince666]

Was it something about my deck? LOL

LOL.

anyways, your deck should be suppoused to show very nice extended treble, surely rolling off past the 20Khz point... and if it doesn't happen then there is a reason (or more reasons together).
which is why this thread does actually exist: to try to find the reasons and fix the problem.

 

[Makymak]

The problem with head wear isn't only the depth of the groove. It's also the condition of the gaps. Depending on the situation, the edges of the gap are getting eroded, scratched or anomalous without a significant groove presence. These anomalies affect the quality of the sound and definitely the frequency response. You can't examine the gap condition with naked eye or with your finger. You need a means of magnification to see it. I had a case with a deck with almost groove-less heads. But it sounded awful. It was the gaps...

And yes, these b and bx heads are soft enough and easy to lap, although RS-B965 and RS-B755 have quite harder heads (esp the recording part) than the permalloy BX heads.

 

[vince666]

The problem with head wear isn't only the depth of the groove. It's also the condition of the gaps. Depending on the situation, the edges of the gap are getting eroded, scratched or anomalous without a significant groove presence. These anomalies affect the quality of the sound and definitely the frequency response. You can't examine the gap condition with naked eye or with your finger. You need a means of magnification to see it. I had a case with a deck with almost groove-less heads. But it sounded awful. It was the gaps...

And yes, these b and bx heads are soft enough and easy to lap, although RS-B965 and RS-B755 have quite harder heads (esp the recording part) than the permalloy BX heads.

nice points there.

yes, on the b965 the REC head is hard permalloy (it has a guard plate, in fact) while the PB head is simple permalloy.
But the pressure pad of the cassettes is mostly on the REC head and then it gets a wear groove just as fast as the PB one which is softer but also not subjected to the pressure pad. I believe that's a reason why they put hard permalloy at least on REC head.

and, yes, gaps conditions are IMPORTANT... i.e., think about those ferrite heads which tend to get fractured without ever making a groove.... they look like new at naked eyes even when they are totally gone.

or, also, i've read on a book in the past that the sharpness of the left edge of the gap of the REC head is important to be able to record high frequencies properly... so, it's not only a matter of wear groove and bad tape-head contact.

indeed, a look of the heads under the microscope helps a lot while troubleshooting.

 

[Skywavebe]

To start with, test tape (ANT is a great choice), gauge for head adjustment and multimeter are ground. Without those 3 tools the one should absolutely not touch a head screws. If a head is not properly adjusted or dirty there is no need to check other things. To say, healthy tape path and mechanics first. So, no discussion about that.
What I'm wondering is, what can be a reason a deck become under-/overbiased, beside heads. Degradation of some components or ...

Well I do know- First the Bias oscillator is powered by a DC supply and as this decays over years with a low grade or cheap electrolytics in the machine it also causes the voltage to go down on the supply of the Bias Oscillator thus a change in performance. This is why Dan and I and my trainees take old power supply section and recap them on old units. Then you can go from there. Then also consider as wear happens and some heads are just garbage as on dual well cassette decks made only for major profit. These soft heads which probably cost a whopping $6.00 are not high end products by any means- that is why fixing such junk like that just goes into more and more repair and higher cost. Then in some models like Nakamichi they had a use of these orange caps that were known to go off tolerance and drift and this was not in the first 5 years but in the years after and some of them like Tri-tracer many years after. Dan is often replacing the orange poly caps in decks with I think he said Wima types. Then there are the do it yourselfers that get into decks to make them better- do you have any idea how they make them better? Moving heads around, turning every pot even if they don't know what it does. This deck will be a real gem after they get done with it and most likely they have a worn out head if they detect any problem. The Akai deck I had here that was -11 dB down at 6.3KHz the guy never said anything about fidelity. This means that a lot fof people never notice and detect any problems clearly when there are. Heads are adjusted with the aid of a M300 gauge and then a scope and test tapes. A multimeter is for DC power supplies and NOT the item to use for heads. A scope will give you amplitude data and phase relationship which is the Azimuth. The levels on a deck are adjusted using a AC Millivolt meter like Leader LMV181A or if the money is available an Audio Precision Test set. I have abandoned the Sound Technology junk a long time ago, Some guys still use that ancient stuff but when I was Chief Engineer at Moody, I could not get rid of a working unit even for free and it probably went into the dumpster by now.

 

[Skywavebe]

Want worn out heads-

 

[Alex SE]

Want worn out heads-

Thanks for so detailed explanation and pictures of course. Those heads are not worn but destroyed. Mine are far away from those but I don't have a microscope to check a gaps but even if there is something, it can be lapped I believe.
Regarding equipment, it would be nice to have Fluke or Leader and one nice oscilloscope, but it would be overkill investment just to adjust 2 or 3 cassette decks.

 

[derek92994]

Is the pressure pad really required for dual capstan decks? It seems to be the number one enemy here. I did a test once on a 3 head which did not have a pad lifter, it seemed to work fine with the pad removed.

 

[J!m]

I would think if the head rose enough it wouldn’t need the pad- just like an open reel deck (although my Kenwood open reel has pads on spring plates)