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  #1  
Old 01-19-2011, 10:39 AM
vidguy's Avatar
vidguy vidguy is offline
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BIAS EQ settings for LPR35

So I've got myself 1 reel of LPR35 to play with.
What are you guys doing with your EQ and Bias settings.

I've been going back and forth between "Normal" and "LH"

I've yet to get this deck biased, so I know I'm not optimal.

Maybe the best bet is to leave everything at normal and adjust the Bias/EQ internally?
  #2  
Old 01-19-2011, 12:45 PM
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Skywavebe Skywavebe is offline
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Hi Vidguy,
The proper calibration is done by starting at the beginning in the service manual. In the first part they want you to calibrate the playback section and set the output controls for Specified Output level. This is done using an AC millivolt meter such as the Leader LMV182A. The thing you are going to be using in this setting is an alignment tape from Teac, STL or Magnetic Reference Laboratory which is currently available from many sources such as US Recording Media. Once all the playback settings are correct and the Playback EQ is set then only after that can you start to do the record level setting and bias and all modern day tapes will be set to high or the upper switch settings. The lower setting result in lower print level and a secondary bias offset from the main high bias setting. The deck is expected to be set up at the highest speed and highest bias setting- all other settings after that are a compromise from that. The record setting will require an sine wave oscillator and a form of attenuator to set levels to the correct amount while in the calibration procedure. Many people do not have the equipment, experience or alignment tapes required to do this work and often times rely on a Technician to do this work for them. I am one such person and having been in the repair business for 38 years and having worked for Teac at the Chicago Factory service, many tape deck owners have had me set their machine up. I can also assist you in doing it if you do have the equipment but fall into a place that you do not understand.
There are some requirement as to alignment tapes and equipment that you simply can not do the job without these items. This is the simple truth to this part of tape deck maintenance. Calibrating record as in starting in the middle of a procedure will result in error and a waste of time.
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Skywave Tape Deck Repair- Chicago area
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Past Teac/Tascam Lead Service Technician at Chicago Factory Service, Sony too still doing repairs.
http://s609729863.onlinehome.us/tape...uipment-repair
  #3  
Old 01-19-2011, 04:51 PM
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Thank you for that very detailed explanation.
I have no intention of calibrating the deck myself.


I was just wondering if I should set my bias & eq switches to LH on my rt701.
  #4  
Old 01-19-2011, 06:08 PM
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Arnold_Layne Arnold_Layne is offline
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LH stands for Low noise High output tapes. Most tapes will fall under that category. LPR35 is a better than consumer grade tape and your Pioneer's default bias and eq settings may not give optimum results. The deck should be calibrated and biased to the LPR35 tape by a professional for best results.

A_L
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  #5  
Old 01-20-2011, 05:14 PM
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ti-triodes ti-triodes is offline
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Quote:
Originally Posted by vidguy View Post
Thank you for that very detailed explanation.
I have no intention of calibrating the deck myself.


I was just wondering if I should set my bias & eq switches to LH on my rt701.


On the oft chance that you may not want to get your deck calibrated for the 1 tape you want to try , why don't you try doing what Pioneer suggests in the manual. Change the settings and see what sounds best. The machine isn't going to explode if you change the bias and eq.


It may or may not sound good, but how will you know unless you try?
  #6  
Old 01-20-2011, 07:36 PM
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Skywavebe Skywavebe is offline
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Hi Vidguy,
I have no problem that a person wants to test their decks by switching around the setting parameters to see what they sound like. However, most technicians will tell you that there could be 100 to 400 settings in the deck that are possible with the use of variable pots and variable capacitors or pots controlling the Bias and hoping that you hit on the exact one by the few possibilities of the combination of the switches or even close to what tape you are using is a bit like playing the lottery. Even if the deck was set up for something close to what you are using, with an amount of hours on the heads from when it was new they are still likely to be yet further off than what you want. If you are not wanting to have the deck worked on by a Technician, then the only thing left is to learn to do it yourself. It is not as hard as some make it out to be but practice makes more perfect and of course an investment in alignment tape and some equipment will be needed.
Many decks on the assembly line were set for a generic range of tape types so that if one was used to testing a deck with a listed tape like XL I, that they should get good results. However, it had been my experience that there were a large variance in what you could expect and some machines were not too close to what they should be. There can be a large variance in the quality of a decks capability which then is indicated why one guy loved his Teac and another says it is OK. All of the clients that I have heard back from after I have worked on a machine have said they sounded very good. Some call it my magic but really all it is is an application of known capabilities of a machine and in some case correction to the circuits to give he best results (the record EQ that I have mentioned before) is an example. LPR35 is an excellent tape and there is no reason a person should not want to get every bit of quality out of that expensive tape of today's technology but it is going to take some effort.
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Sam Palermo, BSEE , ProSquad Member
Skywave Tape Deck Repair- Chicago area
(630)616-0932 Office/ Email skywavebe@sbcglobal.net
Past Teac/Tascam Lead Service Technician at Chicago Factory Service, Sony too still doing repairs.
http://s609729863.onlinehome.us/tape...uipment-repair
  #7  
Old 01-20-2011, 09:10 PM
shawn shawn is offline
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Hi Sam,
Do you think I can get the best out of LPR 35 on a Teac X 2000r? I mean without circuit board modification?
  #8  
Old 01-20-2011, 10:19 PM
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Lance Lawson Lance Lawson is online now
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While I have an uneasy time with 468 I have made a few observations that are worth noting. After I recomissioned my TEAC I went through it and set and balanced all the EQ settings as well as record and output settings. My deck had somewhat poor factory setup I think. Anyway once I had it sorted out I noticed that the RMG 468 displays a very noticeable difference in sound depending on the bias switch settings. On the position 1 settings it has a predictable recorded sound which is very accurate to the source. On the position 2 settings I get a really nice treble boost so if the source could use a hand with the high frequencies it can easily be done with the setting switches. This has always been the case but seems the 468 can deliver 2 worthwhile characteristics. It will be interesting to see how the LPR35 works on my deck.
  #9  
Old 02-03-2016, 09:36 AM
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vladtm vladtm is offline
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Over bias for LPR-35 on ReVox B77

I just got a new reel of LPR35, any experience on biasing this tape on a B77 revox machine ?

I find it interesting, biasing for lowest modulation noise at 20hz, i can get it to almost zero modulation noise. But with that bias, i cannot EQ it for 12Khz response.

The manual for LPR35 gives a 4dB over bias at 10khz. I tried that, but the 3rd harmonic at 1khz and the modulation fuzz at 20hz is not at the lowest.

But yes, using the 4dB over bias, i don't even have to use the EQ, with EQ to minimum, 12k response is on the spot.

Any ideas on the behavior i am observing ?

Best Regards.
Vlad
  #10  
Old 02-03-2016, 09:47 AM
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Skywavebe Skywavebe is offline
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The X1000R can be set up for LPR35 in the LHII position and that is what I have used for many years since the retiring of XL I. The mods done to the X1000R are probably due to EE lack of record level and to allow both tape to record at optimum. If you don't use EE tape then just set up for LHII and be done with it. EE tape was a silly idea anyway.

The adjustment of low modulation noise is one way to do a job but it might not be the way the manufacture suggests. but who am I to quote rules as I adjust my machine at 0 Vu when the book says -20dB. Well my issue is that people never record at -20 so why use that as a reference level.
The lower speeds of course have to be adjusted at -10 or -20dB due to saturation. This usually happens at the 3.75IPS speed which many are finding out is not really all the good for music
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Best regards,

Sam Palermo, BSEE , ProSquad Member
Skywave Tape Deck Repair- Chicago area
(630)616-0932 Office/ Email skywavebe@sbcglobal.net
Past Teac/Tascam Lead Service Technician at Chicago Factory Service, Sony too still doing repairs.
http://s609729863.onlinehome.us/tape...uipment-repair
  #11  
Old 02-03-2016, 01:49 PM
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Zombie Zombie is offline
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Same bias as UD and UDXL Idon't worry
  #12  
Old 02-03-2016, 03:49 PM
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I set up the machine at 257nWb - 0dB , the HF adjustment is done at -10 db , but yeah, looks like there is some compromise, you get near zero modulation or bandwidth for HF with a bit of fuzz in the very low frequencies.
  #13  
Old 02-03-2016, 04:45 PM
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deromax deromax is offline
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I found that the pulsing low frequency sound at the begining of Pink Floyd song "Breathe", on Dark side of the moon, will audibly reveal tape distorsion in a very noticeable way!
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