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Topics - bobschneider

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Reel to Reel Tape Machines / Borbely tape preamp
« on: August 13, 2010, 04:47:49 PM »
After a long time on hold, I've finally finished my project to build a high quality solid state tape preamp.  The basis of my design is a phono preamp kit sold by the well known designer Erno Borbely.  www.borbelyaudio.com.  I used his EB804/419 All JFET MC/MM phono preamp as my starting point.  This is the simplest and least expensive of the RIAA preamps he offers.  I used it because it could be set up for either active or passive EQ, and because I already had one I was using as a phono preamp.  The articles on his website (originally in AudioXpress in 2005) give a lot of explanation of how the preamp works, including the information needed to design either an active or passive EQ version.

Dr. Borbely was extremely helpful in helping me work though what I needed to do.  I bought a pair of surplus silver/ceramic 4P5T rotary switches (genuine Red Army surplus!) off fleaBay, since I wanted to be able to switch between tape and phono.  One switch switches between the 3 pairs of RCA jack inputs on the back panel: MC, MM and Tape Head. One pair of switch poles changes the RCA jacks (with associated input loading), the other pair changes the feedback resistor which changes the gain of the input stage (I ended up with the gain for the head on my Otari MX-5050 close to the MC gain).  The other switch changes the passive EQ network between the two stages of the preamp (a series R and a shunt RC network, except for RIAA which needs a second C shunt in parallel with the RC) - I can switch between IEC 15ips, NAB 15ips, IEC/NAB 7.5ips (those curves are identical), and RIAA.  I could have set it up for old LP curves as well, but all my LPs use the RIAA curve.

I am very pleased with the sound of this, using my Otari MX-5050 with the Tape Project transport mods.  The sound is much clearer and more vivid than the stock playback electronics, which I have extensively upgraded (Burr Brown op amps, modern capacitors including Blackgate bipolars in the coupling positions, etc).  Cymbals sound like metal (I'm listening to Waltz for Debbie as I type).  This is the best sound I've ever had in my system!

Unfortunately, Dr. Borbely is retiring, and shutting down his kit business later this year, so if you want to build one of these you should act soon.  If anyone's interested in building one of these, I'm happy to let you know the values of the parts you need to modify Dr. Borbely's phono preamp kit.  His "starter" phono preamp with the power supply is Euro 380 plus shipping (about $500), the additional caps and resistors might run $50 more, I paid something like $20 for the switches, and the case and RCAs are whatever you want to spend.

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Suggestion Box / Zappa
« on: March 30, 2010, 05:43:43 PM »
How about some Zappa?  I believe his widow Gail has the rights to most of his music.  I'd vote for Hot Rats or Overnite Sensation, but any Zappa would make me happy...

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Brilliant Corners / Why so much leader on Brilliant Corners?
« on: December 14, 2009, 09:05:48 PM »
I just received my copy of Brilliant Corners today (forwarded from Chicago to Houston), and I have to say I agree with all the raves.  I have this on CD, and know what good music it is, but the sound quality on the tape is just fantastic!  Another home run for the TP guys.

But one thing that struck me as odd was how much blank tape there was after the end of the actual recording, before the leader (i.e., on the outside of the reels when stored tails out).  There must be 10 minutes of blank tape at the end of each reel.  That certainly isn't the case before the start of the tape - that amount of blank tape looks like no more than a minute or two.  And I never noticed so much blank tape on my other TP tapes. 

There must be a reason for this, but I can't for the life of me figure it out.  Can someone enlighten me?

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Tape Tech / Odd alignment issue
« on: January 20, 2009, 07:24:06 PM »
Last night I finally finished recapping and aligning my Otari MX5050 Mk3.  So after listening to the Dave Alvin TP tape I recently received (which sounded great), I decided to try the 7 1/2 ips Ampex copy of Sgt Pepper I bought on eBay a few months ago.  For the first couple of minutes on side 1, the tape kept popping in and out of the slot in the right side guide arm.  It was also wavering back and forth between the capstan and pinch roller.  This didn't seem to affect the sound too much (the tape stayed put in the guides in the headblock), and it stopped after a couple of minutes, but it does concern me.  I tried different take up reels, and rewinding the tape on the Otari to get a better tape pack, but it's still doing this.

Is this something I should be concerned about, and is there anything I can do to stop this?  The Otari's guide arms don't appear to be adjustable (and I replaced the soft stock Otari arms with hard stainless steel aftermarket arms), and I haven't encountered this with any other tapes, so I suspect it has something to do with the Sgt Pepper tape.

Thanks!

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Tape Tech / Head Marker Ink?
« on: August 01, 2008, 09:30:57 PM »
Hi.  I just joined the forum, and subscribed to the Tape Project tapes.  I'm really looking forward to hearing these.

I have two Otari MX5050s, an early MX5050B-2HD I'm rebuilding, and a later MX5050B-III.  The service manual for the B-III says that, to align the heads, you mark the surface of the heads with "Head Marker Ink" or a Marker Pen, and observe the wear patterns after running 10 secs of (disposable) tape. 

Does anyone have any suggestions as to what kind of marker pen is suitable for this use.  Obviously I want something that won't harm the heads.  Presumably I want something that can be cleaned off when the heads are aligned with a normal head cleaner such as alcohol.  I don't expect to be able to walk into my local art supply store and get Head Marker Ink, but if there's something I can ask for there that will work to align the heads without wrecking them, that would be great.

TIA.

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