[glynnw]

My Don Sachs preamp has a JJ rectifier so I decided to waste more money and upgrade to a Linlai tube since I already had a couple of Linlai 6SN7 tubes in the preamp.  As soon as I put it in, the highs disappeared.  Like all of you, I have several test passages I use.  For highs I use a Van Morrison piece, Madame George, which has a triangle struck several times.  With good electronics you hear the decay and notice the different sound as the triangle is struck hard, then softer.  When I put in the Linlai 274B-D there is simply no triangle sound at all.  I had no idea the rectifier could change sound like this.  I bought the tube on Alibaba, so it may be a fake, but it sure looks good and the seller included his contact data like a legitimate business.  Now the JJ tube is back in and the joint us jumpin'.  Any comment on how the rectifier could do this?

[Markwatkiss]

This may sound academic but it will require an average of 50 hours to burn in if you haven’t already done so.

[Early B.]

One question and one comment --

Comment -- yeah, rectifier tubes can significantly alter the sound. No surprise there.

Question -- are you sure you can substitute a 274B tube for the stock rectifier without modification? 

[opnly bafld]

Can you check voltages with each rectifier?
B+
plate on the various tubes

[FullRangeMan]

This new Lin Lai tube needs any break-in?

[musicdre]

rectifier tubes often change the sound a lot.   

your experience sounds frustrating.  patience for break in time is hard to muster - but definitely give it some time before final judgment

good luck!

[glynnw]

I have now read several articles which say the 274B is a substitute and others which say the opposite.  I just looked at both - the Linlai 274B-D has 4 pins while the JJ GZ34S has 5.  I think they are not the same and I should stick with the JJ and consider myself lucky I didn't blow anything up.  The Linlai is gorgeous though.  Maybe I'll use it as a Christmas ornament.

[opnly bafld]

Only 4 pins are used, 1 is not connected.
Obviously any tube that affects a circuit as much as stated in the OP is not a good fit.

[Early B.]

I think they are not the same and I should stick with the JJ and consider myself lucky I didn't blow anything up.

Yep. I was worried there for a moment. If you're itchin' to upgrade your preamp, send Don some pics of the innards so he can recommend some things to do. 

[FullRangeMan]

Sounds like this equip are new or so, the electronics parts may last 10 years or more before anything broke, in these conditions the most effective upgrade I can see are change the cheap ceramic sockets for Teflon sockets that always increase the sound quality IMO and in an pre-amp they will lasts many years.

[Rusty Jefferson]

From his website:

"NOTE: I have modified the preamp to take a 6BY5 rectifier because it sounds better and you can source 6BY5 tubes for $12 or less.  If you own one of my preamps and pay the return shipping I will modify it for you and provide a 6BY5 tube for $75.   If you own an SP14 kit or any other version of this preamp please DO NOT JUST PLUG A 6BY5 TUBE INTO YOUR PREAMP AS YOU WILL DAMAGE IT AND IT WILL NOT WORK!   This modification is something I developed for my customers only.  I will NOT share the details and I will NOT modify any preamp that I did not build.  Sorry, but this is what sets my gear apart from the kit versions."

Any idea if yours has been modified for this rectifier?

[glynnw]

no idea

[Rusty Jefferson]

no idea

Okay. What rectifier are you using and do you have any confirmation (a manual perhaps?) it's the correct type?

[FullRangeMan]

Wow... $12 for a 6by5 is a bargain, fantastisque deal 

[morganc]

From his website:

"NOTE: I have modified the preamp to take a 6BY5 rectifier because it sounds better and you can source 6BY5 tubes for $12 or less.  If you own one of my preamps and pay the return shipping I will modify it for you and provide a 6BY5 tube for $75.   If you own an SP14 kit or any other version of this preamp please DO NOT JUST PLUG A 6BY5 TUBE INTO YOUR PREAMP AS YOU WILL DAMAGE IT AND IT WILL NOT WORK!   This modification is something I developed for my customers only.  I will NOT share the details and I will NOT modify any preamp that I did not build.  Sorry, but this is what sets my gear apart from the kit versions."

Any idea if yours has been modified for this rectifier?

I owned three of these Preamps and they all used the 6BY5.    Only the very old ones do not. And I think you’re lucky you didn’t blow anything up! 

[JackD]

Based on some correspondence I had with Don several months ago I think he did make a few preamps that took 5 volt rectifiers like the 5AR4.  I thought I had lost the manual to my D2 and asked him to see me a .pdf of the manual.  The one he sent me did in fact show the rectifier as a 5 volt tube rather than the the 6X5 or 6BY5.  So it is possible that Glenn has one of those units.  Doesn't mean the tube he bought will sound "right" to him but if he has one of those units it may technically work.  Best bet is to contact Don direct either through e-mail like I did or through PM. If he has one a better bet may be to try a NOS 5 volt 5AR4 from Andy or Brent.  The Matsushita from the Mullard tooled Japan factory might be the best bet or even the Sylvania if the Mullard and Amperex tubes are too pricey. Don would have naturally supplied a New Stock tube.

[FullRangeMan]

It was a nice gesture from Mr.Don Sachs propose modify his pre-amps even at a charge, very different from other manufacturers who take a week to respond an email.

What are important at Don notice at his site mentioned above is that the 6BY5 are the best tube to use with this pre-amp, by what I understand.
https://www.radiomuseum.org/tubes/tube_6by5g.html

https://vinylsavor.blogspot.com/2012/01/tube-of-month-6by5.html

[theflattire]

From what I understand about rectifiers is that they do alter the sound by increasing/decreasing voltage to the power tube.
You usually don't mess with them unless you can confirm that enough capacitance has been built in to handle the voltage changes.
My Modwright PH9.0 can use like 4-5 different tubes while my other amp is only recommended for 1.
You need to read up for even similar named tubes like 5U4's have different specs, ie, 5U4 vs 5U4GB, etc.
The 274a and 274b I think are different also.