Tascam 42B play back heads and IEC setup

[rbwtapeinterlink-Bob]

I am thinking that when I get my new/old Tascam 42B, and after inspection, I will take it in to my local tech and have him re-wire the playback heads. Can anyone suggest what cables he should use and where can I obtain them from? I will want to have them in hand when I take the deck in.

Also, can anyone who has the Eros or Tube Repro pre amps tell me what impedance they operate at? Are they adjustable and if so, what's the range? Finally, has anyone modified their tape deck with cables from the playback heads, but retained the use of the internal electronics in the tape deck? Thanks for all comments and input.

bob w.

[ironbut]

Hi bob,

I use Cardas 24 ga 2 conductor shielded cables when I do the head out conversion. They're very flexible and I have no issues with the sound. I buy it from Michael Percy Audio. If your tech has never worked with Cardas enameled cables (the enamel is on the bare wire strands) tell him it's best to tin it with a solder pot so the enamel gets burned off quickly.
Ground the shield at the output end only and be sure and put a little heat shrink on the head end to cover any exposed shielding strands.

I believe both the Tube Repro and Eros have a 47kohm input impedance in stock form.
 

[rbwtapeinterlink-Bob]

Good morning Steve and thanks for chiming in for me. In regards to the "heads out" cable, is there a specific length I should be aware of? How much cable can we use before it's too long?

The 47Kohm is similar to that used in most phono pre amps is that not correct? That being the case, why can't I use my upgraded Jolida tube pre amp which permits adjustable Kohms, but not capacitance? Just wondering???? My Jolida JD-9 upgraded has switches to provide (100 ohm, 300 ohms, 1000 ohms, 47,000 ohms, 47 pico Fared, 100 pico Fared, 150 pico Fared and 200 Pico Fared. Is there enough variation here to see if it would work with my Tascam 42B?

I am looking for as much input as I can get here. There must be some reason for not being able to use a tube phono pre amp if we look at the fact that the Seduction had to be upgraded in order for it to work with the various tape decks. I already understand the electronics in most tape decks is not the best. Again, just wondering???

bob w.

[Listens2tubes]

Here's a disscusion of the input impedance over at the Bottlehead forum:http://www.bottlehead.com/smf/index.php/topic,1312.0.html Isn't the Jolida a phone section. If you read the mods for the Seduction http://www.bottlehead.com/et/adobespc/Seduction/bottleheadtapeheadpreamp.htm they involve converting the RIAA equalization to tape eq: NAB and CCIR.

I concur with Steve on the Cardas. Kept as short as possible.:-)

[rbwtapeinterlink-Bob]

Hello Listens2Tubes and good morning to you. I appreciate your input. What I think I will do, when I take my tape deck into the tech, I will see if he can add the Cardas cables while still letting me use the internal electronics. That way, until I get access to a tape head pre amp I will still be able to use the 42D's internal electronics to listen to tapes. Of course I will have him convert the deck from NAB to IEC which is described in the owners manual and only requires re-routing a cable from one board to another. Thanks so much.

bob w

[Listens2tubes]

Keeping internal playback electronics connected while also having an outboard playback preamp connected is not advisable according to Dan and Co, due to loading interactions between the two. Though in at least one thead I remember someone talking about wiring a switch for this, IIRC it was on a Nagra. That said, I would not want to have all my signal go through a switch before continuing to the electronics. Wiring direct from the headblock plug is as direct as I will get and that works for me.

[ironbut]

I agree with Neal. I would avoid adding a switch to such a tiny signal. It doesn't take much to loose high frequencies between the heads and the amplification.
Regarding the length of the cable needed, you won't really know that until you get in there and find the best way to route it from the headblock connection to the output connection. I would guess that if you were to purchase 4 feet, that would be more than enough.

Regarding your Jolida, you would need to re-design the filter circuit from the RIAA phono standard to the NAB and/or IEC standard as is done with the Eros or Seduction Phono stage to use it with tape. Of course you may not be able to use it with a phono cartridge.
BTW The adjustments you mentioned are for loading the cartridge and aren't really a part of the RIAA filter.

[docb]

The issue with the switch is that one might be tempted to throw it without turning everything off first and waiting for maybe 30 seconds, which we have proven to be a great way to seriously magnetize a playback head in some decks.

The optimal input load will be somewhat different for different heads so it's difficult to give an exact value. One can install a 100K or 150K trimpot in place of the fixed resistor and adjust it as necessary for the best high frequency response. This will be a moot point if the head cables have too much capacitance per foot, so use short low capacitance cables from the heads to the preamp.

[rbwtapeinterlink-Bob]

Good evening guys and thank you so much for this great advice. Please know that I value your advice and understand what you are saying. I will abide by your suggestions fully. By the way, the 42B was delivered a little while ago and appears to be in great shape and was well taken care of. Everything seems to work and work well. I did notice that playing back a tape, it did not seem to pack smoothly as it should. I have only played part of one tape so don't know if it's the tape or what. After playing another tape, I will have a better idea what's happening. I am going back up to my music room and listen some more. I will be back in touch and thanks again my friends.

bob w.

[docb]

Try cleaning the heads, rollers and guides scrupulously with alcohol. That might help the tape pack.

[rbwtapeinterlink-Bob]

Thanks DocB,

Guys, where can I get alcohol that does not contain additives that won't harm the tape heads and other delicate parts?  I don't want to damage anything now.

Bob w.

[rbwtapeinterlink-Bob]

Good morning forum friends,

I have decided to go ahead and have my Tascam 32-2B setup with cardas from the playback heads since it's IEC ready.  Plus it's about 15 to 20 lbs lighter than the Tascam 42B, so I won't have to try and lug that beast to the tech. At 70 plus years old I had some difficulty getting the 42B up on the record cabinet. Thank God I have continued to lift weights (on and off) over the years but it wasn't easy.

I am going to spend lots of time cleaning all of the areas where the tape travel through the 42B since it has been stored for a year. The 42B was setup for use with Quantegy GP-9 which I don't think is being produced anymore. Is there an equivalent to the GP-9 tape? So, as much as I dread having to lift this beast again, I will have to get it to the tech and have is setup for a more modern tape.     Thanks all.

bob w.

[docb]

Thanks DocB,

Guys, where can I get alcohol that does not contain additives that won't harm the tape heads and other delicate parts?  I don't want to damage anything now.

Bob w.

Any kind of high percentage (low water content) alcohol will work. The highest percentage stuff I have seen was something I picked up at Fry's that was specifically for cleaning electronic components. I think it was 94% or so. But a bottle of Everclear works just fine, and is of course a bit more versatile in its range of application.

Just stay away from "rubbing alcohol", which is often only about 70% alcohol.

The one place you might want to use something besides alcohol would be the pinch rollers. There is some conjecture that over a long period of time the alcohol may cause deterioration of some rubber rollers. Formula 409 seems to work very well on rubber tires and seems to have less ill effect. That said, I think maybe the later decks are less affected by this than the really old ones so it may be unimportant on your decks.

[rbwtapeinterlink-Bob]

Hello again Dan, Doc B,

You and all the forum members are truly a blessing when it comes to responding to questions and my questions in particular. I will try the local CVS and see what they have. I will also check out Radio Shack. I think I can get the Formula 409 from the food shop or auto shop. Thank you so much.

bob w.

[Topper]

Doc B. said "Any kind of high percentage (low water content) alcohol will work."

Try automotive diesel gas line antifreeze. I have Berkebele 2+2 here that says 99% pure isopropyl.  I called them a couple of years ago and was told off record that they can't say 100% because as soon as it is opened it will start to absorb a bit of moisture. I transfer quickly from the bottle to another container to limit exposure. Maybe pointless but it makes me feel better.

Walter