Author Topic: Help a Newbie with Tube Amp  (Read 16264 times)

Offline Response Audio

  • Industry Participant
  • *
  • Posts: 1003
  • Build your system for yourself, not the critics
    • Purity Audio Design
Re: Help a Newbie with Tube Amp
« Reply #15 on: May 26, 2012, 05:03:01 PM »
Hello Deepak,
 Sorry I was not around to answer your questions. Things have been a bit touch and go around here with my mom in a hospital 2-1/2 hours away.

 Thanks to all those who chimed in to help out.

 For tube rolling, I would suggest waiting till the amp breaks in and you have a better idea of "where you are" before making changes. One you have a feel for the amp's sound, you will have a better idea of what dirrection you will want to go in should you decide to make any tube changes.
Design Engineer
Purity Audio Design www.PurityAudioDesign.com
Purity Foundation Streaming Pre, Foundation DAC, Purity Foundation Hybrid GaN 200, Pure Audio Project Trio 15 Classic, Sony SACD Player, Nakamichi tape deck,

Offline sleepyguy24

  • Obsessively Audiophilic
  • ****
  • Posts: 904
Re: Help a Newbie with Tube Amp
« Reply #16 on: June 09, 2012, 07:06:25 PM »
Evening everyone.

If you are really on a shoestring budget I got this pocket multimeter just for biasing my Jolida JD 502P and for checking batteries.



http://support.radioshack.com/support_meters/doc72/72438.pdf

A word of caution though. If you are crazy enough to put the taller Tung Sol KT-120 tubes in your Jolida along with Pearl PCF tube coolers checking the bias with this kind of meter can be a finger tip burning experience. ;)


Offline sleepyguy24

  • Obsessively Audiophilic
  • ****
  • Posts: 904
Re: Help a Newbie with Tube Amp
« Reply #17 on: June 20, 2012, 02:12:34 PM »
Sorry for the stupid question.

If one has speakers with a 6 ohm nominal impedance which tap do you use if your tube amp has 8 and 4 ohm taps only? Is this one of those situations where you try each tap and see which one you like? The amp in question is a Jolida JD-502P. I'm just concerned because I don't want to damage my gear.

Thanks in advance.

Offline Putz

  • Obsessively Audiophilic
  • ****
  • Posts: 330
Re: Help a Newbie with Tube Amp
« Reply #18 on: June 20, 2012, 03:23:02 PM »
Sorry for the stupid question.

If one has speakers with a 6 ohm nominal impedance which tap do you use if your tube amp has 8 and 4 ohm taps only? Is this one of those situations where you try each tap and see which one you like? The amp in question is a Jolida JD-502P. I'm just concerned because I don't want to damage my gear.

Thanks in advance.

I used the 4 ohm tap on my Jolida running my Salk Songtowers. Many speakers that report 6 ohm impedance will dip down to 4. It's usually not a flat curve. Might want to check with the speaker manufacturer to confirm.

Offline richidoo

  • Out Of My Speaker Cabinet
  • ******
  • Posts: 11144
Re: Help a Newbie with Tube Amp
« Reply #19 on: June 20, 2012, 03:44:20 PM »
You can try both, it won't hurt anything. You will find that the bass is tighter and overall sound is cleaner, deader, softer on 4 ohm tap, which has more leverage to convert voltage into current. 8 ohm tap is more open and alive sounding, and a few dB louder, but bass will be "warmer" (looser and less controlled) and probably more pleasant tubular colorings in the midrange too.

My preference is for the highest tap that the speakers will allow, but rock and bass heavy music will prefer more damping from the lower tap.

Offline rollo

  • Industry Participant
  • *
  • Posts: 6982
  • Rollo Audio - Home demo the only way to know
Re: Help a Newbie with Tube Amp
« Reply #20 on: June 25, 2012, 08:07:52 AM »
  Exactly. No harm to try both as Rich suggested. The load is not constant meaning it will go above and below [6] Ohms. Our Pipedreams speakers are [6] Ohm as well and the [8] Ohm tap works best overall for us. Have fun trying.


charles
contact me  at rollo14@verizon.net or visit us on Facebook
Lamm Industries - Aqua Acoustic, Formula & La Scala DAC- INNUOS  - Rethm - Kuzma - QLN - Audio Hungary Qualiton - Fritz speakers -Gigawatt -Vinnie Rossi,TWL, Swiss Cables, Merason DAC.

Offline sleepyguy24

  • Obsessively Audiophilic
  • ****
  • Posts: 904
Re: Help a Newbie with Tube Amp
« Reply #21 on: June 27, 2012, 07:47:49 AM »
Many thanks gents for the help. I've made note of the info in the posts above. If I do use the 502P with the 6 Ohm nominal KEF speakers I will try both taps. I really had no idea using different taps could really change up the sound. Good to know.



Offline sleepyguy24

  • Obsessively Audiophilic
  • ****
  • Posts: 904
Re: Help a Newbie with Tube Amp
« Reply #22 on: October 31, 2014, 06:18:22 AM »
I could have sworn there was a thread for general tube gear hints but I can't find it. I'll just post this hear in the hope that someone finds this thread.

In another thread these words of wisdom were written:

"First thing you look at when having a problem with a tube product is the tubes."

It reminded me of what happened with my Jolida JD-502P amp. I paid a pretty penny for a matched quad of JAN GE 6550 cryo tubes. One morning I turn on the amp I see a flash and the amp shuts down. I thought it was something else and turned the amp back on. It turns on and then shuts off again. I'm pissed and freaking out thinking something has blown up inside because the fuse was ok. So I call my tech and he tells me to relax and change the tubes first before I head over. Luckily I had a spare set of power tubes that I know worked and the amp was back rocking and rolling. I then started yelling out profanities because my matched quad of cryoed JAN GE 6550 had just become a trio and no replacement tube could be found.

Moral of the story. Check the tubes first. If my tech wasn't cool I could have been out at least $50 to have it reviewed.

Offline tmazz

  • Out Of My Speaker Cabinet
  • ******
  • Posts: 12088
  • Just basking in the glow of my tubes.....
Re: Help a Newbie with Tube Amp
« Reply #23 on: October 31, 2014, 07:31:33 AM »
Dean, you are lucky it was just the tube. A similar thing happened with my VT-200 except the short in the brand new tube also took out 4 bias resistors. Tube amps sound great but when something goes bad in a circuit with 400-500V plate rails it usually goes bad in a big way.  :shock:

But if you want the tube sound that is kind of the cost of admission. like they say, "nothin for nothin".  :roll:
Remember, it's all about the music........

• Nola Boxers
• Sunfire True SW Super Jr (2)
• McIntosh MC 275
• ARC SP-9
• VPI HW-19 Mk IV/SDS/SME IV/Soundsmith Carmen Mk II ES
• Pro-Ject Pre Box S2 DAC/Rasp Pi Roon Endpoint
• DigiBuss/TWL PC&USB/MIT Cables