Hello people, first of all I'm not sure where the TC-D5M fall into as of categories, so if this is in the wrong place I do apologize. I can't keep my self from fiddling with things that are probably perfectly fine as is. I keep trying to find ways to improve something, even if it's not necessary (I know it's a problem), it's just that I'm a modification maniac. Now, onto the question at hand. What is the head that's in the TC-D5M? From what I've read it seems that it's sendust. How is the frequency response of this head? How does it compare to a ferrite head from the Sony TC-158SD? I had the chance to buy some NOS heads and one of those is a Sony PF145 3602 A Ferrite head. I compared the two heads and they seems to have pretty similar dimensions and it seems it will fit int he D5M pretty nicely. My question is would it be worth it to try to do it? Or is the only way to find out is to do it and do some measurements? If this is a stupid question I am sorry, it just seems possible.
Thanks man. I appreciate the support. I'm just wondering if there's any reasons NOT to do this. Cheers!
The unit would be classified as a field recorder but we mostly put them in the Walkman Section of this forum. This is from the TC-D5M user manual: From the TC-158SD Manual Maybe one of the better portables for Frequency Response and it was aimed as a somewhat affordable high-end unit. I don't pay close attention to FR but it's two closest competitors might be the WM-D6 and Marantz PMD-430, I can't think of another off the top of my head. Yea a fun project but I'm not sure your going to see much upward difference.
Oh wow, this is great information, thanks! However, is it the head that's limiting the FR or the electronics inside? Again I'm sorry if this is an amateur question. Because the head on my D5M looks to be quite worn, and the ferrite head is brand new. Also, this is for playback only. Not planning on doing any recording with it.
Good question, I don't know but the sonics will suffer with a worn head. From what I remember, advertising was more for "less head wear with our new heads" than our heads deliver the best FR. Outside of audio geeks, I don't think head swapping for better sonics was ever a thing. Nortronics used to be huge for replacement heads, there's a ton of information on this website, they bought up the remnants of the Nortronics years ago. https://www.jrfmagnetics.com/index.html?JRF_mainframe=/JRF_nortronics.html
This is wonderful. These type of niche information is very hard to find and usually only known to those who has been in this hobby for very long. Thanks for sharing! If there's any more informations like these please I would appreciate it a lot of you are willing to share!
HF response limitation is from the head, specifically how fine the gap is. Electronics have HF response that goes significantly above 20kHz. In order to keep the response flat at 20kHz, the -3dB point is moved further away. Low frequency response is a combination between the head (how good tape/head contact is) and electronics (FR of preamplifier). As far as TC-D5 series go, the TC-D5M sendust head is a bit better (30Hz - 17kHz) than the ferrite heads used in TC-D5, D5 Pro and Pro II units (40Hz - 16kHz), although difference isn't that significant. The actual FR obtained will depend a lot of more on wear and proper alignment than one head or another. Here it's to be kept in mind ferrite heads DO wear and they're much harder/impossible to re-lap when it happens. In your particular case, it makes sense to swap a worn head with a new one, assuming you can't re-lap the old one. Do keep in mind there is an adjustment shim under the right screw, which is used to set the head height. This should be checked when installing the new head.
We were lucky in the early days of the internet when small companies and retired people would fill it with great information. (This next part actually made my computer freeze and I had to reboot!) The "internet overlords" have deemed these sites unindexable and we've seen the disapperence of a ton of info. Luckily I've kept most of my stereo bookmards through the decades, some sites are still on The Wayback Machine but a lot of them are gone forever. It's nice seeing some of the old places like GeoCities being rebuilt but searching them is as hard as searching old websites on archive.org. You might find more head info on www.worldradiohistory.com or www.archive.org but searching is a pain, I'll find veins of information and roll with it. Good luck with your project!
A little update. Here is something very odd. Before changing the heads, after running Azimuth, head height and level checks, azimuth and level checks are good, but getting no signal from left channel when using head height test tape. Odd. After changing head(ferrite head), head height and level are good, but azimuth looks like this. What could this mean? Measured from line out.
Assuming the unit works perfectly in both playback and record ? Can the bias be set to match input/output levels at 10kHz ? Would also be interesting to see a frequency response measurement with white noise tape.
Thanks for the reply Valentin. The head height is 1khz and azimuth is full track 10khz. I used these tapes, I'm not sure if you are familiar with them. Also, I'm not sure regarding recording, as I've never really tried to record anything with it. Playback however sounds fine, I think. Honestly I have no idea if it's perfect or not but it's good enough that I can't find issues with it. I will give the recording a go and see how it goes. Regarding bias, could you elaborate a bit on that? I think I know what you mean but I'm not 100 percent sure....thanks!
Yes, I am familiar with HPR tapes. There's a thread here about head height one: https://www.tapeheads.net/threads/h...nspeterroth-to-adjust-the-head-height.106958/ Goal of this adjustment is so the outputs are at a minimum. This type of tape has a track in between the 2 normal audio tracks (see picture attached), so fact L channel is higher indicates the head sits a bit high. On the old head it's the opposite: head sits a bit low causing R channel to have high output, while L being very low. However, what I would do before even checking this is check the height of the tape guides: erase head and REC/PB head. You would need an M300-like gauge to do this check. What's important here is not the absolute height (as most cassettes machines tend to be little bit off anyway), but that the 2 guides heights match. Otherwise tape won't run straight. In regard to bias, I mentioned it because when the head height is off you won't be able to adjust the bias correctly on one channel. Like even on the highest setting (only 15pF capacitor connected) the 10kHz recorded level will still be much lower than the input. You need to pick a reference song that you know exactly how it should sound and compare the digital version with the recorded tape. Otherwise it can seem to sound ok even when it's not. And of course a frequency response measurement will tell more than measurements done at a specific frequency. If you get a flat response with no dips or early rolloff you know everything's fine.
Thanks again for the reply. Unfortunately I don't have the gauge as of right now. are there any alternative methods to check? I have tried to fold the shim under the head to increase its thickness thus gaining height, it helped, but i don't think it's quite enough. I don't see a way of adjusting the tape guide heights however, which makes this pretty frustrating...
Ok, after a bit of more fiddling I have found another piece of identical brass shim under the erase head. Reading the SM shows nothing should be there. Should there be another piece of shim there?
So, turns out there were two pieces of shims under the erase head. They are about the same thickness, but around double the thickness of the one under the play head...hmm...
You can check for tape curling at the guides, but that's not very accurate since the guides are usualy a little bit wider than the tape, so there is a certain window where there won't be any curling despite tape isn't running in the middle. To adjust you need more shims, bending the existing one is not an option. You can use pieces of paper (0.1mm thickness - assuming 0.1mm is not too much) cut in that particular shape also. In regard to guide height vs head height, since the guides are attached to the heads, the 2 are the same in this case. There's no way to independently adjust the guide height (apart from removing/re-welding the guide), but you shouldn't need to do it either. Only situation where guide height can be adjusted indpendently is on dual-capstan deck supply pinch roller (which also acts as a guide) or on guides that are not part of heads. Then as far as the record head is concerned, wouldn't assume the distance between the base of the head and guide is the same on both heads. Without a gauge it's hard to compare the height of the 2 guides. But if the unit is erasing the tapes correctly (with no erasing of opposite side), I would assume the erase head height is correct. Case in which I would leave the erase one alone and adjust just PB/REC one. As a sidenote, there's no need to quote previous posts as it adds redundant information. Instead of using the Reply button (which quotes automatically), you can type in box below and press "Post Reply" instead.
Ah, ok, Thanks for the clarification. I did some more fiddling and ended up switching the head to the ferrite one. I found that the Sendust head was unevenly worn, near the left side bottom, there was a ridge that I could feel with my fingernail, that ridge is not there on the right side. That would explain why the sound was odd, because the tape was trapped in the ridge(at least that's what I figured). I installed the ferrite head without any shims, and it performs alright, azimuth and level can be achieved, and height is almost there. If I listen to it, I can't really complain about how it sounds. It was better than before for sure. Thanks again, I will update if events occur. Cheers! P.S. I will definitely get one of those gauges ASAP.
