Technics RS-B965

[scan80269]

Alex, thanks for all your help with my RS-B965. It has benefited tremendously with the ANT4066 switches and the muting transistor removal.

My latest acquisition is not a cassette deck (!), but rather an RME Fireface 400, which I plan to use as a high-quality headphone amp, as well as ADC & DAC. Since I don't have any decent analog source (other than perhaps my Sony TC-KA3ES decks), I am going to explore the possibility of using the DAC in the Fireface 400, along with high-resolution digital content such as 24/96 recordings (HDtracks.com, etc.) Listening to good CD recordings with a pair of headphones plugged into the front of the FF400 has yielded a level of sonic clarity I have never experienced. I used an old Sony DVP-NS999ES DVD/SACD player to play CDs over Toslink S/PDIF, and the FF400 cleans up the clock embedded in the S/PDIF stream, and does a clean DAC to drive the headphones output. I also have an OPPO BDP-83 Blu-Ray player that can play DVD-A & SACD discs to use as a high-res digital audio source. I intend to feed the FF400 analog outputs to my decks, as soon as I find some TS to RCA phono adapters.

The FF400 is also useful with AudioTester. I think I'll keep busy using the FF400 as a high-quality external sound card to do measurements on my various decks.

BTW, here's a discovery that an audiophile colleague and I made recently: A good PC can serve as an audiophile quality digital sound source! Yes, I know PCs have never come close to being considered hi-fi in sound quality, but here are a few tricks to get the best audio out of a modern PC:

* Use Toslink optical S/PDIF output (can be from sound card or motherboard)
* Use Windows 7 OS
Win7 supports the latest implementation of Microsoft's WASAPI (Windows Audio Session API), with ability to bypass the kernel mixer to deliver low-latency audio streaming. Without WASAPI, the PC sound is arguably NOT audiophile quality
* Use an audio player with WASAPI support, e.g. Foobar2000 with WASAPI plug-in
* Uninstall non-essential HW and their device drivers to help cut down on DPC latency spikes, which can cause drop-outs in real-time audio/video streaming
* Optional: use clock-jitter reducing devices such as Apogee Big Ben to clean up clock jitter embedded in S/PDIF
* Optional: use high-quality standalone DAC (Benchmark 1, etc.)
* Use high-resolution audio content, e.g. 24/96 recordings

The FF400 is really versatile, and can be easily moved from PC to PC. I'm probably going to build a small PC dedicated to being an audio source to use with the FF400 and my decks.

Cheers!

[A.N.T.]

Originally Posted by scan80269

Alex, thanks for all your help with my RS-B965. It has benefited tremendously with the ANT4066 switches and the muting transistor removal.

My latest acquisition is not a cassette deck (!), but rather an RME Fireface 400

Sam, thank you for a good feedback. I think that modified RS-B965 is a great deck. Re. RME - I like their products, actually I am using 3 RME Digi 96/8 PAD/PST cards in my computers. After some mods these work very well in hi-res audio (24/96), the sound quality is comparable to a good tape deck. However it is a complete off-topic here!

Cheers

Alex

[scan80269]

My RS-B965 started giving me fits the other day. It chewed up a TDK D and a Sony UX-Pro. Since I was watching the deck closely while it played the UX-Pro, I was able to stop the chewing before it got too bad.

I had to use my Sony mirror cassette to help with adjusting the lateral position of the supply-side roller/tape guide assembly. After fiddling with this a bit, the deck has managed to play through a few different tapes without chewing them, and even the previously chewed tapes can now play through, after a bit of help to flatten the wrinkled areas. This deck apprarently suffered from the same ailment as my Sony dual-capstan decks: shifted supply side roller/guide assembly causing the tape to slip off the guide.

This RS-B965 also sometimes fails to open the cassette compartment on eject. When I first got the deck, there was a thin spring loose at the left side of the cassette compartment and interfering with compartment motion. I couldn't figure out how to latch it back in place so I removed it. Now, the left-side hub of some cassettes can get a little stuck during eject and the compartment would not swing open. If the spring is supposed to provide additional eject force to help the compartment swing open, then the next time I work on the RS-B965 I'll look into putting the spring back.

This unit is also in need of major azimuth alignment work.

[A.N.T.]

Originally Posted by scan80269

My RS-B965 started giving me fits the other day. It chewed up a TDK D and a Sony UX-Pro. Since I was watching the deck closely while it played the UX-Pro, I was able to stop the chewing before it got too bad.

I had to use my Sony mirror cassette to help with adjusting the lateral position of the supply-side roller/tape guide assembly. After fiddling with this a bit, the deck has managed to play through a few different tapes without chewing them, and even the previously chewed tapes can now play through, after a bit of help to flatten the wrinkled areas. This deck apprarently suffered from the same ailment as my Sony dual-capstan decks: shifted supply side roller/guide assembly causing the tape to slip off the guide.

This RS-B965 also sometimes fails to open the cassette compartment on eject. When I first got the deck, there was a thin spring loose at the left side of the cassette compartment and interfering with compartment motion. I couldn't figure out how to latch it back in place so I removed it. Now, the left-side hub of some cassettes can get a little stuck during eject and the compartment would not swing open. If the spring is supposed to provide additional eject force to help the compartment swing open, then the next time I work on the RS-B965 I'll look into putting the spring back.

This unit is also in need of major azimuth alignment work.

Yes, that spring is a nuisance - I had to remove it on my RS-B965 as well and now cassettes (mostly Metal) sometimes stuck. I think about adding a spring somewhere to fix it.

Re. chewing tapes - if you have a tension measuring cassette - use it and see if the back tension is correct (about 8-10g on my deck) - sometimes left reel becomes loose and tension goes down - that in itself is enough in a dual capstan configuration to mishandle the tape. The position of the tape guide on the left may affect few things, including REC/PB phase response (which looks like an azimuth misalignment between REC and PB heads), but it should not affect the tape travel unless it is way off. Something else is wrong and I would not consider fiddling with the tape guide as a fix.

Alex

[A.N.T.]

I've spent all day today servicing, modifying and aligning my own RS-B965. It came from Germany in a pretty good condition some while ago however I didn't have time to do anything with it. Now I did all the mods and also found that the last bit that spoils the sound is the output "Class AA" amplifier stage. When I took it out the impression was like a last veil was removed from the soundstage, everything snapped into focus. Now I have to do something about boosting the output (the amp had a gain about 3 and I took it out (IC5 and IC6 near output sockets) and replaced each with a wire link between pins 5 and 7. Which means that I have 1/3 of the output voltage and level meters do not work properly . But the sound is just great .

Alex

[scan80269]

RS-B965 appears to make liberal use of "Class AA" amps. In addition to IC5 & IC6 (M5218L) driving the line outputs, the headphone outputs are driven by IC701 & IC702 (another pair of M5218L) also in "Class AA" configuration connected to line-out. Does this mean the headphone outputs should sound even worse than the line-outs?

There is also an IC10 (M5218L) in the voltage-controlled amp section of the recording-equalizer amp, though the current drive stage is built with discrete transistors.

The RS-B965 operating manual has a section dedicated to "Linear Magne-Field Class AA", talking about the design of the recording-equalizer amp. I suppose this is largely marketing hype, and such designs do not necessarily translate to better sound.

Regarding the tape chewing, I have a mirror cassette but not a torque cassette. I need to be on the lookout for one of the latter. My RS-B965 has stopped chewing tapes, but I'm keeping a watchful eye on it.

[Dave Cawley]

I am the friend Alex originally talked about. It's a great deck and I'm waiting for the final mod from Alex!

Regards

Dave

[A.N.T.]

Originally Posted by scan80269

RS-B965 appears to make liberal use of "Class AA" amps. In addition to IC5 & IC6 (M5218L) driving the line outputs, the headphone outputs are driven by IC701 & IC702 (another pair of M5218L) also in "Class AA" configuration connected to line-out. Does this mean the headphone outputs should sound even worse than the line-outs?

Yes, the headphone output does sound worse than the line output. What I would like to try is just to cut resistors to the second amp (in case of the line output I'll cut R31, R32, R37 and R38, leaving the second amp as just a follower with the output disconnected). Perhaps even for the headphone amp just cutting R721/R722 and R725/R726 may do the same trick.

Originally Posted by scan80269

There is also an IC10 (M5218L) in the voltage-controlled amp section of the recording-equalizer amp, though the current drive stage is built with discrete transistors.

The RS-B965 operating manual has a section dedicated to "Linear Magne-Field Class AA", talking about the design of the recording-equalizer amp. I suppose this is largely marketing hype, and such designs do not necessarily translate to better sound.

At the moment I am considering changing all remaining opamps in the signal path - IC1, 2, 3 and 10. For a start I will just install sockets for all of them.

"Linear Magne-Field" is a separate issue from "Class AA" and is a good thing for a change - it is a current output stage for the recording head. It does reduce the distortion, especially at high levels with CrO2 and Metal tapes. On the SONY UX-S 3% 1kHz THD reached at +6.5 dB from DIN level (i.e. +10.5 dB on VU scale ! ) - as good as most Metal tapes. And, obviously, Technics did not invent this - same technique was used as early as in Nakamichi 1000 and Sony TC-229SD.

Alex