Electrical Issues... and Misc questions.... Tubes, ICs, etc.

[NOSValves]

Tube question..... I have a TAD-150 signature preamp here. Says it takes 12ax7, 12at7, 12au7. I think it has 2 stock tubes of 12at7. My Jolida CDP takes 12ax7... as does the VRDs.

Can I take those 12at7 tubes out of the TAD and use them in the VRDs and/or Jolida CDP? I don't understand this interchangeablity of tube numbers. But it would be fun to be able to try other tubes for free if they work.

Lisa,

Real busy on my end right now give me a day or two and I will retest what effects the 12At7 has on the circuit. I did try it out but honestly I just don't remember what my thought or testing recovered. I know it will lower the gain in the front end of the amp for sure which will in turn lower the effect that your noise being fed into the VRD's produces at the speaker. But just let me confirm a few things before you go swapping if you don't mind. Not that the amp is going to blow up mind you. In fact that is pretty much impossible.

Craig

[SilverSport]

whenever my parents said "We'll see..." while I was growing up it meant "No!"...[] []

Bill

[SilverSport]

...many times when it comes to being the "test bed" I prefer to let the other lab rats have a go at it...it beats the pop sounds and the whiff of smoke...[li] [um] []

Bill

[meagain]

Craig - thanks... the changes in numbers sort of worries me. As you know, I'm overly paranoid about damaging something with my actions so maybe I should just stick with not being a tube rebel.

Canyon - I got your PM but simply forgot to respond. I do like this Amperex German tube no matter what it's erroneous origins. Tho' I've not had the opportunity to try many.

I got this powervar gadget fully out of the system with only the Jolida on a simple powerstrip (with a few sundries on it) so I need to pare that down more to see if noise is better. Seems I'm getting more hum again though so I still have to play around.

I'm more excited that the music is sounding better. But I heard some 'jumble up' the other night and need to sort out if it's the recording or the room. Going back to the behringer DEQ. Then address shielding, etc. cuz I bet my gear (esp. video stuff) is all secretly talking to each other thru wires & such. I figured most all ICs had such shielding but maybe not and I took it for granted. Also speaker wire. Maybe that pulls in some leaks, etc. I have monster cable. Old monster cable.

[NOSValves]

Craig - thanks... the changes in numbers sort of worries me. As you know, I'm overly paranoid about damaging something with my actions so maybe I should just stick with not being a tube rebel.

Canyon - I got your PM but simply forgot to respond. I do like this Amperex German tube no matter what it's erroneous origins. Tho' I've not had the opportunity to try many.

I got this powervar gadget fully out of the system with only the Jolida on a simple powerstrip (with a few sundries on it) so I need to pare that down more to see if noise is better. Seems I'm getting more hum again though so I still have to play around.

I'm more excited that the music is sounding better. But I heard some 'jumble up' the other night and need to sort out if it's the recording or the room. Going back to the behringer DEQ. Then address shielding, etc. cuz I bet my gear (esp. video stuff) is all secretly talking to each other thru wires & such. I figured most all ICs had such shielding but maybe not and I took it for granted. Also speaker wire. Maybe that pulls in some leaks, etc. I have monster cable. Old monster cable.

Lisa,

I like rebels!! As long as they stop and think before they jump. You're doing just that. Trust me if ill effect could possibly be the results I would never advise you to try it. I would not ratehr have to fix it. You knwo just for your own piece of mind. Not a single thing that you could possibly do to your amps would be none repairable. You know those maybe you amps but they're my babies so no matter what happens or how frustrated you make me at times. I would never refuse to not fix them. I get attached to things like tubes, amps and many other belongings. Heck at least with wood, steel, wires, resistors, caps and glass you know where you stand. It's probably the cave dweller in me []

Craig

[Erik Mandaville]

Meagain:

I'm sure someone in all these pages has already answered this, but I'm too tired to read through all of it to see right now. So, at the risk of being redundant, If you have a DSP or other processor very close to the VRDs or preamp, you might just try moving them (the amps or preamp) a few feet away from the processor. The nature of lots of tube equipment (high impedance) can also sometimes be a really frustrating source of noise in the form of buzziness more than hiss.

This IS NOT in anyway something against the VRDs or Peach, but it may be that if there is a slight lack of full-armor sheilding on either of those (Please note, I have the same situation here with my Moondogs), there is the chance of some infiltration of EMI/RFI that's finding its way into the audio. I just can't remember if the Peach is fully-shielded inside the wood outer-chassis or not. The VRDs are just like my Moondogs and former Horus amps in that they have metal top and bottom plates with unshielded wooden sides. It works just the same as poorly shielded (or badly grounded) cables, and has nothing to do with the quality of your components, which are super. Maybe some distance will help.

Also: I think you said something about a Radio Shack Gold Series cable (?). Most of those are decent cables, but I have had a couple in the past where the shield was very poorly connected inside the jack housing. Until I cut that end off and installed a new jack, it was the source of buzz that bugged me for months.

Erik

[smilin]

LISA

Just stop on by, and I will give you some tubes, I also will trade a little labor for my racks, if you want em, I have 2 new ones, still boxed at my office, since late summer, I would love to have put together. Remember, I have 2 beautiful bellogotti black/glass racks I will give you, or somebody else if you p/u and put my custom racks together. BTW, isolation makes a difference too, I use the Craz 4 rack for my 2 channel, and had timbernation build me a couple maple racks.

[Guest " "]

Tube question.....   I have a TAD-150 signature preamp here.  Says it takes 12ax7, 12at7, 12au7.   I think it has 2 stock tubes of 12at7.   My Jolida CDP takes 12ax7...   as does the VRDs.

Can I take those 12at7 tubes out of the TAD and use them in the VRDs and/or Jolida CDP?   I don't understand this interchangeablity of tube numbers.  But it would be fun to be able to try other tubes for free if they work. 

The tube numbers you posted about have different qualities, tone, and gain.  The gain is the easy one.  Below is a table that captures the MU rating as well as some substitutions for the tubes you refer to.   Changing the MU factor at various stage of audio circuts while changing the gain of that aspect of the circut, can help reduce issues as well, depending on your config.  For example, microphonics is a problem with tubes that have hign MU values.  If you want to reduce microphonics, and can afford lowering your gain, switching to a lower MU tube will do that at the cost of having to turn up the volume a bit to compensate.  A lot of folks prefer whats called unity gain, gradual gain in various stages of different circuts, rather than a large amount of gain in line stage driver circuts.  Which basiclly means sometimes having lower MU tubes thru out sounds better and quiter than having a particular stage that has a high amount of gain, and result is the volume being controls being kept low.  Another issue with high MU stages is what sounds like an ocean sound.....that sound can be eliminated by finding the stage that has a high MU tube, and putting one in that is lower.

Some techno speak, which you can skip over , in the form of a note of caution, there are some tubes, that have the same pin config, and simular MU ratings, but behave differently by design, sometines they can cause problems.  Example a12AU7 and a 12BH7 are same pin config and very close MU rating.  However, the 12BH7 draws more current.  Putting in a 12BH7 in place of a 12AU7 could overheat resistors if the circut uses lower wattage resistors.  On the other hand, putting in a 12AU7 in place of a 12BH7 will result in less power being delivered to the stage that follows.  12BH7's are tipically used in push pull amps as a phase inverter after the line stage driver but before the output tubes.

  MU   Tube     Sub
100   12AX7 - ECC83, 7025, ECC803, E83CC, 6681
  70   5751  -
  60   12AT7 - ECC81, 6201, 6679
  45   12AY7 - 6072
  41   12AV7 - 5965
  19   12AU7 - ECC82, 5963, 5814, 6189



 20  12BH7  (JJ ECC99 or  5814)

[Guest " "]

Tube question.....   I have a TAD-150 signature preamp here.  Says it takes 12ax7, 12at7, 12au7.   I think it has 2 stock tubes of 12at7.   My Jolida CDP takes 12ax7...   as does the VRDs.

Can I take those 12at7 tubes out of the TAD and use them in the VRDs and/or Jolida CDP?   I don't understand this interchangeablity of tube numbers.  But it would be fun to be able to try other tubes for free if they work. 

The tube numbers you posted about have different qualities, tone, and gain.  The gain is the easy one.  Below is a table that captures the MU rating as well as some substitutions for the tubes you refer to.   Changing the MU factor at various stage of audio circuts while changing the gain of that aspect of the circut, can help reduce issues as well, depending on your config.  For example, microphonics is a problem with tubes that have hign MU values.  If you want to reduce microphonics, and can afford lowering your gain, switching to a lower MU tube will do that at the cost of having to turn up the volume a bit to compensate.  A lot of folks prefer whats called unity gain, gradual gain in various stages of different circuts, rather than a large amount of gain in line stage driver circuts.  Which basiclly means sometimes having lower MU tubes thru out sounds better and quiter than having a particular stage that has a high amount of gain, and result is the volume being controls being kept low.  Another issue with high MU stages is what sounds like an ocean sound.....that sound can be eliminated by finding the stage that has a high MU tube, and putting one in that is lower.

Some techno speak, which you can skip over , in the form of a note of caution, there are some tubes, that have the same pin config, and simular MU ratings, but behave differently by design, sometines they can cause problems.  Example a12AU7 and a 12BH7 are same pin config and very close MU rating.  However, the 12BH7 draws more current.  Putting in a 12BH7 in place of a 12AU7 could overheat resistors if the circut uses lower wattage resistors.  On the other hand, putting in a 12AU7 in place of a 12BH7 will result in less power being delivered to the stage that follows.  12BH7's are tipically used in push pull amps as a phase inverter after the line stage driver but before the output tubes.

  MU   Tube     Sub
100   12AX7 - ECC83, 7025, ECC803, E83CC, 6681
  70   5751  -
  60   12AT7 - ECC81, 6201, 6679
  45   12AY7 - 6072
  41   12AV7 - 5965
  19   12AU7 - ECC82, 5963, 5814, 6189



 20  12BH7  (JJ ECC99 or  5814)

[NOSValves]

Fritz your just scrapping the surface. Less gain is just the tip of the iceburg of what truely happens when swapping Mu values. I don't have time to type a long response now. Have to get those Xmas shipments out the door.

Craig