Search the Community
Showing results for tags 'R2R'.
Found 2 results
On the owners thread I was recently very interested in the idea of R2R DAC,s . On the positive side they are almost always described as being musical by those that bother to listen to them . On the downside those that deal in just measurements complain that this type of DAC often have very poor specifications compared to what is possible with todays chips . I have also had explained to me that getting the R in R2R correct and consistent is a major headache and often casue porblems with production of the units in sensible numbers as a result they are often very expensive . Denafrips is a current mfg that favours this type of architecture (I am presuming that R2R is different to NOS) and they seem to be getting quite a bit of praise for the sound of their range of DAC,s . I had wanted to buy one just to see and when a Denapfrips DAC came up on e-bay being both late , me being drunk and the sale in French i made the silly error of buying the DAC only to then find out this was pre the companies switch to R2R architecture. My problem but have to say delighted with the quality and the sound of the none R2R Denafrips DAC . Still want to hear an R2R and see if there is something a bit special about it but will have to leave myself to the possibility of another Wammer having one and being able to get a listen . However did find this listed which is supposedly an R2R DAC but not a huge amount of money . Interested but since I am now retired not able to afford the chance on this but you never know others may well be interested . As always view points both good and bad are always appreciated . If any one is using an R2R at Kegworth let me know and which room you will be in and will have a good listen on the Saturday night . https://www.magnahifi.com/en/webshop/agd-r2r11
After Lodgesound (Stewart Emmings) passed away last summer, I was asked if I might pass on some of his knowledge in due course. I was a complete tape novice before Stewart taught me the basics. I'm sure that there will be some on this forum, who will know far more than I do. Stewart worked in broadcast for his whole career, at the BBC, C4 and then at the BFI, where he was in charge of video and audio restoration. He and his best friend Mike restored the sound tracks and pictures on Hollywood film re-releases, TV programmes and numerous other material. In a standard 3 head machine the tape passes over the erase head, then the record head and finally the repro (replay) head in that order. That means that the repro head monitors the signal, which you have just recorded onto the tape. Hence when lining up a tape deck, you need to set up the repro head first. Equipment needed: you need a test tape, PPM meter, oscilloscope (and a tone generator, plus a new tape - for the record set up, which I'll describe in another post later) Before starting clean the heads and tape guides with a lint free wipe/cotton bud with a small amount of isopropyl alcohol. Demagnetise the heads, if the machine hasn't been demagnetised in recent memory. The first step is to check the repro head azimuth against a test tape. This is really important, as incorrect azimuth cannot be corrected in later adjustments. Incorrect azimuth leads to poor sound quality, esp losing high freq leading to muffled sound. 1) You need a test tape and a scope to set up repro head azimuth, plus a small allen key to alter the repro head azimuth if needed Load the test tape. Connect up the R2R outputs to Ch 1 & 2 of your scope and set the scope to read X-Y (Lissajous). Play the 10 k tone and look at the scope - a perfect azimuth should give you a sharp focused line at 45 degrees (should look like this /) - if the azimuth is incorrect you will have an oval trace - adjust the azimuth on the repro head until you get a perfect 45 degree line Once the azimuth on the repro head is correct, you now adjust the repro output levels to give you a flat frequency response on replay. 2) Adjust the repro levels on playback (repro) head. Load the test tape. Connect up the R2R outputs to an accurate meter, preferably a PPM meter (much better than VUs, which were known in the BBC as "virtually useless"). If you use the internal VUs on the machine, you may find that these are not accurate enough. Play the test tape 1k test tone and adjust the repro level on Ch1 (using a tweaker or small screwdriver on the repro control panel - read your instruction manual to find out where this is) until you get the correct reading on the PPM meter (usually PPM4 = minus 4VU = 0dBu). Do the same for Ch 2. Repeat the process as above for 10k tone on the high freq repro level adjustment on the control panel. Repeat the process again using a 100 Hz tone on the low freq repro level adjustment on the control panel. The repro side of your machine should now be lined up properly with a flat frequency response (if you want, you can repeat these steps on a series of other test tape frequencies and check it with a sweep test tone). I'll do the record section on another day. Charlie PS I specifically didn't make any reference to particular test tapes, as it depends on your machine, the tape speed of the machine and what reference flux you want to set your machine up for. Choosing a test tape is a whole chapter in itself. If you are interested, then the bible on this is the MRL reference guide.