Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 7th April 2005, 07:37 AM   #31
diyAudio Member
 
rcavictim's Avatar
 
Join Date: Jun 2004
Location: Next to an open wormhole NW of Toronto
Default Re: Using 6N1P etc.

Quote:
Originally posted by gingertube
I have a preamp which has a cathode follower output.
I have found that I can drop 6DJ8, 6N1P, 6922, 6ES8 into the socket and they all work nicely at very similar operating point.

So which do I prefer?
Depends on which power amp I'm driving - with most of my valve amps I like the 6DJ8 best.
With my good solid state power amp I definitely like the 6ES8 best. This is definitely a variable mu tube and you get a SET like characteristic that as you increase the volume (signal level) you get increasing asymetrical distortion (due to the variable mu) and the sound "warms up" or "wets" or whatever description you like to use with increased signal level (as 2nd Harmonic distortion is added). This despite it being in a cathode follower (ie 100% feedback).

For those MANY of you who say you don't like the sound of a cathode follower in your preamps - bung in a 6ES8 (ECC189) and have a listen.

Cheers,
Ian
Ian,

I have a whole whack of NIB old stock 6ES8's, so I did try them in the MingDa MC34B. It played, and the variable mu was readily apparent, but it did not sound good. It is interesting to leave stock tubes in the one channel while you make tube changes in the other. That would be a nice tube (in part because it is a triode) I think for a dynamic expander.
  Reply With Quote
Old 7th April 2005, 03:39 PM   #32
diyAudio Member
 
rcavictim's Avatar
 
Join Date: Jun 2004
Location: Next to an open wormhole NW of Toronto
Default 6BK7B's on ebay

Earlier in this thread I noted the magic I got from using 6BK7B's in the long tailed phase splitter of my MingDa MC34B amp. No socket rewiring is necessary, just drop these in. I just saw that five NIB GE's are being offered on ebay in case anyone is interested. This is not my auction and I make this post as a public service announcement. http://cgi.ebay.com/ws/eBayISAPI.dll...765575505&rd=1
  Reply With Quote
Old 7th April 2005, 11:45 PM   #33
diyAudio Member
 
Join Date: Oct 2004
Location: Adelaide South Oz
RCAVictim,
Im not familiar with the MingDA MC34B. Is the spot you tried the 6ES8 a cathode follower or a common cathode stage?

The preamp in which I did like the 6ES8 was definitely cathode follower, 150V rail, running at 8mA. That is, operating well up into its linear mu region at low signal level but traversing into the variable mu part of the curve on larger positive signal swing (less current) all mitigated and made more subtle by the 100% feedback of a cathode follower.

However we all have different tastes - hence the question, to resolve if we are comparing apples with apples.
Thanks
Ian
  Reply With Quote
Old 8th April 2005, 06:31 AM   #34
diyAudio Member
 
rcavictim's Avatar
 
Join Date: Jun 2004
Location: Next to an open wormhole NW of Toronto
Quote:
Originally posted by gingertube
RCAVictim,
Im not familiar with the MingDA MC34B. Is the spot you tried the 6ES8 a cathode follower or a common cathode stage?

The preamp in which I did like the 6ES8 was definitely cathode follower, 150V rail, running at 8mA. That is, operating well up into its linear mu region at low signal level but traversing into the variable mu part of the curve on larger positive signal swing (less current) all mitigated and made more subtle by the 100% feedback of a cathode follower.

However we all have different tastes - hence the question, to resolve if we are comparing apples with apples.
Thanks
Ian

Ian,

Oranges, pears and apples I'm afraid. One socket I tried it in is a long tailed pair phase splitter, the other was a line preamp, plate coupled. No local FB, just global.
  Reply With Quote
Old 8th April 2005, 03:08 PM   #35
DanTana is offline DanTana  United States
diyAudio Member
 
Join Date: Nov 2004
Location: Illinois, USA
I wish I had a chance to try those out before I wired my socket for 12v just to compare. I'm not sure how it would compare to the 6N1 or 6DJ8 I had in that position. I found the 6N1 better than the 6DJ8, but I now find the ECC99 better than both of those tubes. I suppose I could rewire it back to 6v but now I have a ton of more options than I did with it at 6v. When you get tired of playing with those 6v tubes, rewire it for 12v and stick an ECC99 in there.
  Reply With Quote
Old 8th April 2005, 04:42 PM   #36
diyAudio Member
 
rcavictim's Avatar
 
Join Date: Jun 2004
Location: Next to an open wormhole NW of Toronto
Quote:
Originally posted by DanTana
I wish I had a chance to try those out before I wired my socket for 12v just to compare. I'm not sure how it would compare to the 6N1 or 6DJ8 I had in that position. I found the 6N1 better than the 6DJ8, but I now find the ECC99 better than both of those tubes. I suppose I could rewire it back to 6v but now I have a ton of more options than I did with it at 6v. When you get tired of playing with those 6v tubes, rewire it for 12v and stick an ECC99 in there.

DanTana,

You keep talking about 12 volts. Since there ain't no 12 volts in this amp did you add an additional xfmer for a 12 volt filament supply or are you merely referring to rewiring the filament pins so that center tapped 12 volt filament tubes like 12AX7, etc. will work in there on the existing 6.3 VAC?
  Reply With Quote
Old 8th April 2005, 07:21 PM   #37
DanTana is offline DanTana  United States
diyAudio Member
 
Join Date: Nov 2004
Location: Illinois, USA
I'm referring to 12 volt filaments. By rewiring the 4, 5, and 9 pins you are now able to use 12v filament tubes.
  Reply With Quote
Old 17th April 2005, 11:46 AM   #38
diyAudio Member
 
Join Date: Dec 2003
Location: earth
I have aan mc34b and am using 12ax7 as the input and 12at7 as the phase splitter, the 12at7 imo is better here than the 12 au7.

I noticed no difference at all between the cheap 12at7 and a mullard cv4024, so that was a total waste of cash

didn't like ecc99 myself.

I suppose that means my heaters are 12 volts?

I traced the circuit out.

Its an ultralinear design, grid biased.

Input stage is an anode follwer directly coupled to a cathode follower,

direct coupled to the cathode coupled phase splitter.

very nice design, lovely build, and great sound. these are superb amps.
  Reply With Quote
Old 17th April 2005, 12:44 PM   #39
DanTana is offline DanTana  United States
diyAudio Member
 
Join Date: Nov 2004
Location: Illinois, USA
Nice to hear from other fellow MC34B owners. The hardest thing is to fight the stigma of it being a "cheap" Chinese made amp. The input and phase splitters circuits are just the classic Mullard circuit. Nothing new there either, I'm glad the Chinese probably realised it's hard to improve on old tried and true designs. Very simple and "elegant" and sounds fantastic.

I recently purchased a pair of the new Groove Tube Mullard 12AX7M tubes. These are suppose to be reversed engineered from the original Mullards, piece for piece. I can say so far these are my favorite 12AX7 tube. Just a hint of warmth compared to EH or JJ 12AX7's, but a very good sounding tube, not forward like the EH is, better bass than the JJ, better highs than either.

I would love to try some of those Russian teflon coupling caps in it, they will be a tight fit, but it can be done.
  Reply With Quote
Old 20th April 2005, 02:19 PM   #40
DanTana is offline DanTana  United States
diyAudio Member
 
Join Date: Nov 2004
Location: Illinois, USA
Give you guys the latest in my escapades. Now using the ECC99 as phase splitter and a 12AV7 as input. I find the sound very neutral and uncolored with good detail. I'm considering ECC99's in both spots, but gain is an issue. Now, I've swapped the "Ming-Da" capacitors for "Orange Drops" a bit of a squeeze since these are about twice the size, but well worth it for only $2.00 each. Then I reduced the amount of negative feedback by adding a resistor in series with the current one. I simply put another 100K resistor in there. I would of probably never of believed those two things would make that much difference soundwise, but it did. Almost as drastic as tube rolling, but with much better overall results. The detail and clarity sounds much improved, I can now hear lyrics that before I was struggling to figure the words out. The highs and lows also are much better, more control probably and tighter sounding. Since I put the EL34's in triode mode I was very happy with the sound, but I hadn't realized until now what I was missing.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Stereo Buffer with a single twin triode Brit01 Tubes / Valves 43 29th July 2009 02:32 PM
question about twin triode tubes Nihilist Tubes / Valves 2 19th February 2009 04:39 AM
Best/favorite CF NOS noval twin triode? leadbelly Tubes / Valves 34 19th April 2008 04:37 PM
What can i do with 805 triode valves( NOS) TugaTweaker Tubes / Valves 24 20th October 2003 07:16 PM
mmm.... zero-bias class B twin triode amp Circlotron Tubes / Valves 6 5th March 2003 12:49 AM


New To Site? Need Help?

All times are GMT. The time now is 02:43 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2