World-Designs-Forum  

Go Back   World-Designs-Forum > For Sale/Wanted > Suppliers
Register FAQ Members List Calendar Gallery Today's Posts Mark Forums Read

Suppliers Recommended Component Suppliers (and the ones to be avoided)

Reply
 
Thread Tools Display Modes
  #1  
Old 25th April 2017, 07:48 AM
bob orbell bob orbell is offline
Senior Member
 
Join Date: Nov 2009
Location: kettering northants.
Posts: 2,731
Default Tad

Hi all, has anyone used Tube Amp Doctor valves, German design made in bloody China , they do seam to get some good review's. BOB
Reply With Quote
  #2  
Old 22nd July 2017, 07:24 PM
Ardee Ardee is offline
Junior Member
 
Join Date: Sep 2006
Location: UK
Posts: 22
Default Re: Tad

Rather a delayed reply but, yes, I have used the 6922. This is Russian, physically identical to EH, but internal matching not as good as the EH Gold.
Reply With Quote
  #3  
Old 22nd July 2017, 10:34 PM
Greg.'s Avatar
Greg. Greg. is offline
WD Archivist
 
Join Date: Dec 2005
Location: Bristol, UK
Posts: 3,582
Default Re: Tad

Quote:
Originally Posted by Ardee View Post
Rather a delayed reply but, yes, I have used the 6922. This is Russian, physically identical to EH, but internal matching not as good as the EH Gold.
.....and your thoughts on the sound, please?
Reply With Quote
  #4  
Old 23rd July 2017, 05:51 PM
Ardee Ardee is offline
Junior Member
 
Join Date: Sep 2006
Location: UK
Posts: 22
Default Re: Tad

Greg,

If you run the valves at low current and low bias voltage, any slight difference in the valve's characteristics is likely to be audible. I am running them with reasonably high current and bias voltage, and with low signal levels. I cannot honestly say that I can hear any difference between two valves which have matching curves, even if they are a different brand.

I plot the curves of any small signal valves I use, so those that are poorly matched or obviously not linear don't get listened to. I find that a good TAD sounds the same as a good EH or a good NOS. NOS are more of a gamble, as TAD and EH Gold are selected, whereas NOS E88CC and ECC88 vary wildly. You need a large batch of these to find a couple of good ones, probably because the same batch has been picked over several times in the last 50 years.

The Russian valves tolerate higher cathode heater voltages than NOS, so are less likely to go noisy.

I think TAD aim to serve the guitar market, where AC gain is more significant than DC matching. EH seem more interested in the HiFi market, and I have not found any bad EH Gold valves, other than one which was clearly damaged by a dealer (Hot Rox) who admitted having no idea how to use a valve tester. I would advise buying from a dealer who does not try to test small signal valves which are already factory-matched.
Reply With Quote
  #5  
Old 24th July 2017, 07:53 AM
bob orbell bob orbell is offline
Senior Member
 
Join Date: Nov 2009
Location: kettering northants.
Posts: 2,731
Default Re: Tad

I don't think that this was the answer that Greg was asking, most members here will want to change one valve for another to see if they get an improvement or not in sound, not rebuild the circuit that the valve is going into , as for Hotrox, I have had only good results from them as have many others. BOB
Reply With Quote
  #6  
Old 2nd August 2017, 07:47 PM
andrew ivimey's Avatar
andrew ivimey andrew ivimey is offline
Senior Member
 
Join Date: Dec 2005
Location: Bedford
Posts: 2,028
Default Re: Tad

Nevertheless I would agree wholeheartedly with Ardee. And as a guitarist too I never buy my valves from Hotrocks who appear to use anything cheap (Chinese, Russian and JJ re-branded) I'm happier taking potluck on eBay myself for e.g. ecc83s and el84s and match them myself and then happy to use Russian valves rejecting a few on the way.

oh yes and EH valves are sovtek - Mike Mathews bought the factory in Russia.

For HIFi although I have a fair sprinkling of Chinese and Russian output valves I try to use ancient english and american valves where I can.
Reply With Quote
Reply


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT +1. The time now is 04:49 AM.


Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright World Designs