Vintage Products

Re: Replacing Cassette Tape head

Eugenio Colazzo — Sun, 27 Jul 2008 08:48:08 GMT

If you tried to set the azimut whitout success try to use another head (even if a different quality) and check if there is a signal quality improvement, maybe the problem could be a defective cap.... I have a Beocord whit same problems, louder bump when play start and low quality signal.

Re: Replacing Cassette Tape head

yachadm — Sun, 27 Jul 2008 05:57:38 GMT

Hi Dave,

Thanks for your clear and well-written reply!

I now understand that a substitute head should have very similar (if not identical) electrical characteristics, in order to do the job smoothly.

I already have a donor machine, and its head is in worse condition than mine.

The original head (even brand-new) wasn't a great performer. I remember when I bought the BeoCord new in 1976, thinking to myself - an Aiwa deck in the dealer had better sound! But I wanted a BeoCord to match my BM3400!

I emailed B&O customer support for help in getting the Electrical Characteristics, to see what I can find on the open market. Let's see how they reply. I always enjoy a challenge, and maybe this the time for me to learn something new!

Menahem

Re: Replacing Cassette Tape head

casdave — Sat, 26 Jul 2008 15:27:42 GMT

Magnetic materials exhibit a behaviour called magentic hysteresis.

It takes a certain amount of energy before you can even begin to impose changes in the magnetic layout of the tape, and if you tried to put a an analogue signal onto this tape, then you would slice off part of the signal and it would sound distorted.

What you do is to sit your analogue signal onto another signal that is much higher in frequency(this is called the bias signal). The higher frequency signal is a sinewave, crossing zero, and it takes the place of the analogue in the part of the tape that does not respond properly. The analogue signal is superimposed upon this bias, and gets put onto the tape undistorted.

The high frequency signal, what remains of it, is easily filtered out.

The problem is that heads tend to not be exactly the same, and so the bias signal needs to be changed to match it, and there is a variable resistor inside for this purpose.

Now the heads can be quite variable, good quality control and they can be similar enough not to need much change, and B&O heads are prety tightly specified.

If you try some other non- B&O head, you may be able to get it to work, but it will very likely ned to be set up. It may also have a differant amount of signal pick up ability too, and that is less easy to sort out because you need to change the gain of the head amplifier to suit.

I would recommend that you find a donor machine.

First though, you may need to look at more than just the azimuth, check out the height of the head relative to the tape as this can have a big effect, it could be that the tape path is not quite right and the tape itself does not line up properly with the head.

Re: Replacing Cassette Tape head

yachadm — Sat, 26 Jul 2008 13:40:21 GMT

Hi Eugenio and Dave,

I have already aligned the azimuth to the best possible sound - still not what I'd expect.

What do you mean by setting up the head bias? I'm not familiar with tape-terms at all?

Menahem

Re: Replacing Cassette Tape head

casdave — Sat, 26 Jul 2008 05:11:50 GMT

If the heads are of very tight specifications, so that the quality is uniform, then you can get away with taking one from another similar machine.

I expect B&O tape heads to be good quality and so have a uniform operation, but I would still be inclined to set up the head bias - but for most folks it probably would not be too important.

If you go for some other head, you almost certainly will have to set up the head bias and there may be issues with the output/input characteristics - in older equipment you just try it and see, unless you can get your hands on the data sheets.

Re: Replacing Cassette Tape head

Eugenio Colazzo — Fri, 25 Jul 2008 18:55:48 GMT

Hello

Before replacing the tape head try to realign the azimut, take a good tape with a good music and try to find the correct head alignment. If you don't solve let us know

Replacing Cassette Tape head

yachadm — Fri, 25 Jul 2008 10:28:31 GMT

Hi all,

I have completed a restoration of my Beocord 2200 (Type 4601) - 1976 vintage.

The tape head is the last remaining piece of equipment which needs taking care of.

Even before the restoration, the sound was pretty muffled, with reduced frequency response, and very muted highs.

Wear grooves (very undesireable) are visible on the head.

Unlike a phono cartridge, which can be swapped, until the right combination is found, I understand (correct me if I'm wrong), that choosing a new tape head is a little more complicated.

Can the more knowledgeable here give me some pointers on what to do?

The original part number is 4B19A, but I'd like to consider a much higher-spec one, which will show off the upgraded components now, to their best ability.

Menahem