[Silent One]

Quote:

From WA5 manual:
 
SPK – Speaker output
K1K – AKG K-1000 headphone output
HPL – Headphone Low impedance headphone jack output (8 to 40 ohms)
HPH – Headphone High impedance headphone jack output (41 to 600 ohms)
 


 

Originally Posted by Xcalibur255 






In regards to impedance ranges, it is 8-99 ohm for low and 100-600 for high, at least it is for my WA6.  Many amps use 100 ohm or whereabouts to draw the line between "low" and "high" impedance.

__________________________________________________________________________________________________________
 
 
by Silent One
 
 
To contribute further, from the WA6SE manual:
 
HIGH: High impedance outputs for headphones that are above 70 ohms. 
LOW: Low impedance outputs for headphones that are below 70 ohms.

 

[nututubes]

 
Quote:

Quote:

X2. Anyone spending serious money on tubes should also invest in a tube tester. I've sent tubes back to on-line retailers as well. I would never had known they were bad if it wasn't for my tester. I would say the money I've saved by returning the tubes has paid for the tester. 
 
 

You can get decent testers for reasonable prices, too. There is one on Audiogon right now for about $200. That's the price of one TS BGRP 6SN7GT

Hello Rob, can you tell us about some tube testers that we should keep on the short list?
 
 

 

[sillysally]

This is a copy and paste from the WA5LE owners manual.
High – for high impedance headphones such as 80+ ohms
Low – for low impedance headphones such as 8 to 100 ohms

 

[spagetka]

seems that manual should be revised too

 

[grokit]

Seems like the impedance cutoff changes by the model. I wonder what the spec'd cutoff is for the WA22, are these manuals online? I can't find it.

 

[brink]

When I purchased my WA22, I received a "WA22 Quick User Manual" by e-mail:
 

 HI is high impedance output for 60 ohms or above. LO is for low.

 

 

[Clayton SF]

Does anyone know the cutoff for the WA4? I guess my ears would be the best judge but it's good to know. Like the WA5 and WA5LE it's spec'd at 8-800 ohms.

 

[2359glenn]

 
Quote:

Can you elaborate a bit on why using high impedance with low impedance phones is not ideal?  It seems to be the better option in my case for the K701 (62 ohm).  Running the amp on low results in a flat sound with no drive or PRaT, it feels much more at home with the amp set to the high impedance setting even though the K701 is outside of the ideal load range.  Many users have reported the LCD-2 behaves this way as well at and it too is a low impedance load (50 ohm).
 
This is one of those things where I always believed in just trusting your ears and going with whichever seems to sound better, but I'm curious to know the technical/electrical reasoning behind why one should be a better choice than the other. 

Trusting your ears is the way to go using the amp one way or the other is not going to heart the output transformers or 6AS7s. I don't know why there is no standards with
headphones like there is with speakers 4 , 8 , or 16 ohm. It would be expensive and a PITA for a manufacture to make output transformers with all the proper taps for all the
different impedance headphones out there. I don't know what the impedance of the taps on the output transformers on the Woo amps are but I can explain with the transformers
in my 300B amps.
  A transformer has a ratio the transformers in my 300B amps are 2500 ohm to 4 , 8 , or 16 my speakers are 8. If I have my 8ohm speakers hooked to the 8ohm tap
the 300Bs will see a impedance of 2500ohms on the plates. if I hook the 8ohm speakers to the 4ohm tap the 300Bs will see 5000ohms on the plates this normally reduces
the distortion but lowers the power output. It also changes the operating point of the output tubes that will change the sound.
 By hooking your 62ohm phones to the high impedance you will be getting more power to the phones and you prefer the sound with the 6AS7s running at a lower impedance
on the plates.
  I hope this explains what is happening.
 
    
 
 

 

[Skylab]

Quote:

 

Hello Rob, can you tell us about some tube testers that we should keep on the short list?
 
 

I can really only comment on the two I have - a B&K 650, which is a big, full mutual transconductance tester, and the B&K 606, which is a very compact, emissions tester.  I get very similar results from both.  I bought the 650 calibrated, for about $300.  The 606, which is not as old, I bought for $125, and I use it a lot since it is so compact, and will test some tube types like the 6BQ5, 5670 and 6AS7 that the 650 will not test.
 
There is a LOT of great info on tube testers here:
 
http://www.tone-lizard.com/Tube_Testers.html
 

 

[dminches]

Quote:

 

Hello Rob, can you tell us about some tube testers that we should keep on the short list?
 
 

 
I would highly recommend speaking to Bob Putnak at Tubesound.com.  Bob has spent countless hours with me going over various tube testers and finally helping me decide which one was the best for my purpose.  Bob is a tube tester wiz and sells these fully calibrated and in great condition.  I would not recommend buying one from someone you don't know because you have no idea if it is working or calibrated.  The extra amount you may pay is well worth it in the end.

 
 

 

[Clayton SF]

Quote:

I would highly recommend speaking to Bob Putnak at Tubesound.com.  Bob has spent countless hours with me going over various tube testers and finally helping me decide which one was the best for my purpose.  Bob is a tube tester wiz and sells these fully calibrated and in great condition.  I would not recommend buying one from someone you don't know because you have no idea if it is working or calibrated.  The extra amount you may pay is well worth it in the end.

x2
 
I got my tube tester PACO 10-12 from Bob as well. I am very pleased with this tester but what is front and foremost about Bob Putnak is his excellent customer service.
 

 

 

[Skylab]

Definitely good advice. Buying a calibrated tester is important.

 

[dannie01]

Quote:

x2
 
I got my tube tester PACO 10-12 from Bob as well. I am very pleased with this tester but what is front and foremost about Bob Putnak is his excellent customer service.
 

 

The tube tester looks very nice so do the 6F8G, Clayton. No way to find any in the place I live, sigh.

 

 

[Clayton SF]

No tube testers in Hong Kong? WHAT??? In your neck of the woods you can find a whole slew of NOS, Mullards, and GECs but no tube testers?

 

[dannie01]

Should have but never seen any for sale in the market. And I think what they got are mostly from US, too. I've tried to grab one from Ebay but it's too heavy for shipment and not sure if it is well calibrated.