VHS modified as high quality audio recorder part 2
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- Опубліковано 12 січ 2024
- Best to look first at part 1: • VHS modified as high q...
After part 1 there were many remarks and questions, some of them - in technical terms - require an ‘in depth answer’. So stay with me in part 2, I try to keep it as simple as I can. Some questions are understandably, because there is little ‘real’ technical details to find about HiFi VHS. Mostly because different brands use different standards. Also there ia a difference between NTSC and PAL.
This is really cool. I always wished people or a company made a new 4 track or 8 track recorder that used VHS tapes so people could record songs analog much easier. I use an 8 track cassette recorder currently.
Outstanding work. I have bought VCR HIFI, just to have a "deck" relying on vhs. Those tapes are 3 hours long, not like standard tapes...60, 90 or 120 minutes.
I used to dream with a day, when good old analog equipment could be modded and upgraded easily. With all the buildup knowledge and extensive components market. Unfortunately, this kind of electronic nirvana, became impossible.
You keep showing us that it is possible, but engeneers like you are rare.
I love those vintage tape formats, always will.
Cheers 🇵🇹
Thanks for the nice words...!
There is even a digital emulator of the dbx process, it is a plugin called "Satin" , i think the name is chosen because of that silky quality we associate with analog hi-fi. Congratulations on your custom VCR , it's impressive you did that at home. Cheers !!
Plugin for what, please?
@@colloidalsilverwater15ppm88 tape and analog noise reduction emulation
For a moment I thought you had crossed a Fostex A8 with a VHS into a hifi 8 track recorder (Not the US 8track!) That brings back many memories! I used to work with the A8 as a multitracker, synced to a Roland W30 sampler / MIDI sequencer and then used a Sony PCM 501 converter combined with an Akai VHS video recorder for digital mastering. The 501 was the “consumer” version of the PCM 701. I actually bought that before DAT was even available. Believe it or not but the PCM 501 tended to produce dropouts during recording at 16 bits. They were rare but mixing long tracks could be a bit hit and mis in a time of non-total recall mixing (Those where NOT the days, eh?). No complaints about the audio quality us such though. The 14 bit option was less prone to dropouts but had a clearly audible loss in sound quality. More comparable with good MP3. I still own all that stuff but obviously do not use it anymore. Nowadays my main recording axe is a Roland VS 2480 16 to 24 track total recall system. Also already ancient compared to the latest technology but I never felt the need to upgrade after that. So stable! Best mix of hard- and software.
Isn't this just what the Alesis ADAT was?? 8 tracks..? 🤔 but the fact that you did this at home is incredible!!❤
Thanks... no ADAT was a digital system, and special on this modification - it's fully analogue!
fantastic
Это лучшая вещь для записи звука!
I masterd to VHS back in the 90s. Before DAT tapes where affordable.
Made many mix tapes on my Sony Beta hifi in the 1980s. Yes, that AFM pumping distortion was audible.
I did't know that audio-only AFM-based hifi stereo was avail for the commercial sector -- back in 1982!
In a way, the Mhz AFM recording system reminds be of DSD (also MHZ based).
No it was not available. This VCR was my own design and modification. It was a 'standard mono VCR!' Many af the recorders had a 'pumping' audio, not because of the compressor, but due to the automatic volume control. NOTE: that the first Betamax(en) worked completely differed from VHS.
@@TheoFaber As far as I know only the NTSC Beta Hifi recorders worked different. The PAL Beta Hifi had separate hifi heads in the drum. The NTSC models used the video heads for the hifi audio signals as well. The European SL-HF100 had 2 video and 2 audio heads (and a stationary audio and erase head)
You are (partly?) wright, only the first NTSC Beta's where different. To my info: the later models NTSC and the PAL versions had 4 heads. Much later Sony build the VHS models, the same as the other brands (depth modulation).@@KR1275
@@KR1275 Yes the NTSC Betamax had enough spectrum space to squeeze in four AFM carriers. That's right four carriers for stereo. The problem is that the head azimuth was set to cancel track to track crosstalk at the video FM carrier frequency. Therefore it did not work in the AFM area around 1mhz. So they needed a separate AFM carrier for each channel AND each head. The color under in NTSC Betamax was 688khz so that gave them the needed spectrum space without resorting to depth recording with separate heads. But both Betamax and VHS also needed phase trickery to get around the head azimuth problem for color under. The major advantage here besides saving the cost of two extra heads was interchange. When you optimized Betamax playback for maximum video RF, the AFM was optimized as well. VHS with separate AFM heads has an issue where you could track good audio OR good video, but not both from a third party tape.
@@TheoFaber Yes, that's correct about ALC, but there was also a recording compressor and playback expander in the AFM processing chain on both VHS and Betamax HiFi. But I agree it worked very well although some picky audiophiles claimed to hear it. But those people also claim to hear differences in power cords and now even Ethernet and USB cables as well. LOL!
love the picture in the background lol
There is more than electronics that keeps us buzzy... 🙂
I also use my PANASONIC NV-HD660 to record music and it sounds AMAZING .
VHS machines and tapes are superior to classic audio cassettes and decks but i do love then too .
Even more superior than most reel recorders! DAT recorders were the best, when they were working!
@@batmandestroys1978
Maybe in low speed 3' 3/4 but superior than 15 inches and especially 30 i don't think so .
But Do you have any proof of that ?? anyway ?
Pretty sure hifi-decode can decode a rf capture of it!
Thanks for the update!
Wow. I did something similar to a type C 1 inch reel to reel broadcast machine. Now as you may know the type C format is direct color recording with an FM band of 7 to 10mhz. So there is very little side band energy below 1mhz and no color under signal. I used the AFM audio card form a Sony Betacam (not Betamax) professional VTR. These have two linear audio tracks and two FM audio tracks, channels 3 and 4. The AFM frequencies are 310khz and 511khz. Note that the type C machines must have the optional sync head to maintain continuous RF recording and playback. The sync head is optional because the TBC can recreate the missing vertical interval from the servo signals but that won't work for AFM audio.
Worked for years with C format (Sony) technical and video-production. But never in my wildest dreams i had the nerve to modified it (it was the master machine). So my deepest respect for your modification. Never knew that the AFM frequency's where so low?
this is so amazing, i would love to purchase one of these from you asap
Thank you, the video is not yet in HD, so quick you are. Unfrt nothing is for sale. They are 1 of a kind, last one is not fully operational. The small one is.
nice work,
curious to hear an rock song on that
very impressive
Great project, i wonder if it would B easier to record (playback) a video-signal made with PCM coding. A Composite AD-DA converter.
No, it's quit difficult because of the switchover at the and of a frame (head a and head b). And it's digital. Diff systems exist like DV and DVCam....
Your English is excellent
Thank you... but it can be better!
Really impressive work. Have you very closely compared the resulting waveforms of this analog system compared to a digital recording? I would be very curious if there is any difference. The specs seem to be better with a digital system, no?
No - not compared. But digital will be even more steady than analogue on a oscilloscoop. And yes; a digital system can have even better spec's. But the modification is from 1982 and meet even today wonderful spec's. The people how love analogue, will be in heaven with this. And when you use something that makes you happy, measurements do not matter, unless you own a studio.
...i was talking about this with my dad the other day! This is absolutely amazing!!! Sir, is there a way that i can get ahold of you and talk to you about this 8 track audio recorder?!?!
Note: this machines are the only (proto) examples and are not for sale. With country are you in? You can give me your e-mail adres or a temp one, i wright back in my beste English :)
Nice subject (and Nice poster)
We like to put energie in both...
Makes me wonder if using a similar process to record onto compact cassette would firstly work and secondly have any improvement in the reproduction of sound....
Not sure how DCC works but it's probably similar? Maybe?
My thought process is that by using a carrier signal to record audio on a compact cassette, you are moving away from amplitude modulation which can give you dropouts to frequency modulation which theoretically should make dropouts a non issue....
It would possibly need a good and strong carrier frequency somewhere between 20-20khz although I'm thinking that there's probably a relationship between what the carrier frequency is and what the audio signal has to be on top of it?
Yeah I don't know much about it, I sort of understand the basic properties of it's workings but that's about it....
Very nice thoughts ! for only it was possible. DCC used a special head with 8 (?) tracks, to record a digital stream in parallel. And the other answer is more technical. To deviate a carrier FM you need at least 5-10 times the highest audio frequentie. Mostly in use is 75 - 150kc. VHF walky tolky's (speech only) use about 25kc. To have a reasonable relation between the carrier and the deviation you need to go in to the hunderts of kc. Best is above 500kc. All this is not possible on a audio cassette. But the thought is beautiful and proofs that you have the fantasie and curiosity to go far in electronics!
I also watched video 1 and don't understand if all of this is the exact system of VHS hi-fi applied to a VCR that did not had it in origin (maybe took from another vcr), simply disabling video heads, or you have designed a YOURS system which is superior to the one anyone knows. In any case, if the video heads do not record, how can the vcr correctly remain in synchronism joining signals from audio heads A and B with precision, avoiding a buzz sound??
You are partly wright, the recorder had no HiFi audio, only (low quality) video. I used (1982) a pcb from a scrab HiFi VCR, but only the audio part. Disconnected in my machine the original video part and used the rotating head to record audio. So the original video heads are used for audio. That was my idee, leave the video part out and use the entire bandwidth of the tape for audio. There is space for more channels. Also the audio will not be partly erased by the video, as in the original HiFi designs. And indeed, when I measured the RF (audio) output from tape, the level was enormous and turning the tracking control gives no effect. So a great improvement on the original HiFi recorders.
But than (you wright again) there was the problem of tracking / synchronization. I know that from the start. So I started developing a stable (X tal) signal for the servo systems. In this machine, only the frame synchronization is compared with a pulse, deriving from the video drum. From my x-tal and divider a pulse is written - in rec - by a stationary head (original design) like the stationary audio head. And also in playback used to synchronize the servo’s. So in playback the pulse from tape is compared with the pulse from the video head.
The problem of ‘buzzing’ is not there. By correctly adjusting the take over point from head A and B AND using the same video drum for record and playback, buzzing is not measurable or audible. But another reason is the absence of erasing by the video head, like in a original HiFi machine. In all the years I never heard anything disturbing like drop-out’s or so. Only with complete damaged tapes from defective machines.
All this was done, because in 1982 going digital mend a lot of money. And designing / building something yourself - out of the question. Hope this story helps?
@@TheoFaber All understood! So in practice you have built a circuit to drive the fixed head (which normally manages mono audio track and sync track) to have a very precise synchronization between tape position and rotaring heads. Also not partly erasing audio with video heads like original design helps to have a strong and stable signal. All clear!! Uhmm I am very curious to the quartzed synchronization circuit :) I am sure a great difficulty is to integrate it with servomechanism of vcr, to let them work normally without a video input. But I also think that hi-fi audio tapes recorded will be playable with perfect quality only in the same machine: in another one maybe the distance between rotating drum and fixed head is different, so the synch has to be regulated...
@@PuccaLover83 No - I am not clear. The existing audio / ctl head (stationary) is used. Only it’s driven by an extra pcb (see film) of my own, how has a standard video proc IC (verry cheap) that produces a standard bl/w video sign. That is connected to the video in port - that’s all. I good have made special modifications to the servo systems, but I did not (verry buzzy in 1982). So synchronization of the servo systems, is reassembly standard. In rec and play back. Sorry but I do not remember the type number of the IC(s). Also the schematic’s I draw, are lost in time. But every stable 50 / 60 hz pulse can be used, by simply inserting the pulse on the wright point(s) in de servo circuitry.
You are correct, by stating that every recorder you want to reform, will need it’s own solutions. So knowledge and schematic’s are necessary. Some measurement equipment will be helpful. A scoop will bring some light in the dark.
The old audio track is also still in use and the quality is terrible. Wow and flutter (and noise) are going to the sealing, see film 1 at the end. But still, after all these years, the HiFi specifications are a dream.
@@TheoFaber yes I did understood that your special circuitry drove the fixed head of vcr! I have seen also first video. A question: why have you also transplanted the fm modulator of hifi audio from another vcr to this one? Did not was simpler to modify directly that vcr? Maybe its servo system was more complicated to work? Or maybe because you wanted a small, portable machine?
@@PuccaLover83 I used an existing pcb from a scrap recorder, because from audio to video head is a long way. First there is a low pass filter (30kc) then a measured level control (manual with meter) a noise reduction (like Dolby), then a pre emphasis, so the audio level has to be correct. I did not have the time to design all that in 1982 incl the play back with all the filtering. I did design the rec / playback amplifier for the video drum, see film. That was necessary, because the extra pcb did not have one. After the fact, it was stupid, because the rec/playback amp from the original rec is now unused. And was absolute useable for the purpose.
Now I have time to spare, and maybe I built another one, with more channels, just for fun. And do the entire design. Maybe … because it serves no purpose, unless you are a audio analogue enthusiast. Which I am not.
Could this be made in a modern PCB with schematic?
Yes - if you take the time for it, Specially if you want more than 2 channels... from this machines, there is no PCB or schematic for publication. Sorry...
@@TheoFaber I can make a PCB from a schematic and send it for production but I'm in no level of knowledge to design a HiFi schematic from scratches, it is not my field of expertise.
Again thanks for your kind offer, but there is no complete schematic available. Most of it, is in my head🥳@@Capturing-Memories
Great video thank you :)