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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Sep 14, 2013 7:06 am
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Aspiring Musician
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BMW2002Ti wrote:
KC9SYJ,

Actually subbing one tube in for another is not that sinful. Leo experimented with several combinations of gain stage and output tubes --- plus the voltage parameters around those tubes --- before coming out with production models.

It's all for the sake of tone. Empirical testing is often the best way to fine tune.

:D :mrgreen: :D


It was either Forrest White's book 'Fender;The Inside Story" or some other Fender related book where I read that Leo would often go out on the production line and make a change in an amp in mid production without informing Forrest or QC,and REALLY mess up the readings at final 'end of line' test,or something like that,...and Forrest and the QC person would be 'up in arms' so to speak. And I can understand why Leo would try several combinations of tubes and the voltage parameters around them before coming out with production models.

_________________
If it aint' broke,...don't fix it! I like to keep my amps and guitars factory original,...no mods necessary,...don't want them,...don't need them!

My gear as of now;
Standard Strat
Hot Rod Deluxe III amp
Champion 20 amp
'59 Bassman LTD Reissue


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Sep 14, 2013 7:16 am
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Joined: Mon Apr 05, 2010 2:37 pm
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Location: Natural Bridge, Virginia
KC9SYJ wrote:
Not taking what Bill said wrong at all,and nor am I taking it harshly. I am well aware of the fact Leo didn't design the BDRI,however,I was only thinking that had he done so,he may or may NOT have approved. As I pointed out in one of my posts in a
different thread,I am still learning about this stuff,and that is really the main reason why I
questioned Bill's modifications and as to why he done them. Guitar amps are QUITE different than a radio transmitter,that's for sure. We hams experiment,too,but it's mainly when we are building an antenna(I have done that with help of another ham radio operator,...he helped me build my first antenna,...a 50 mhz five element beam),or building a CW transmitter from a kit(something I have yet to do) among other things. I am one of those types of people who go by the owner manual and what it says to do or NOT do,and do all I can to follow them to the letter. So again,...I am not taking anything wrong at all nor am I taking it harshly. Heck,...if I built my own amp,...with help of one of my radio buddies who is more experienced at electronics and building projects than I am,I might gain some knowledge of amp design. But until then,I will stick with using genuine replacement parts in my equipment. Now I can understand one thing about amps,...and tube type radios as well,...that if it calls for a particular tube and it's no longer available,I can see subbing it for an equivalent tube type,...that would be the ONLY time I would use a different tube type than what the amp,...or radio,...called for! Again,that's just me and how I operate. I am reading about tube amp design,so I still have LOTS to learn. Can you REALLY tell a difference in sound with different tubes? Like,...if I were to pull the GT technology tubes out of my HRD III and replace them with say,...JJs,E-H,or Tung-Sol tubes. You know me already,...I'd replace with same tube type,of course. :) I have,..BTW,..checked out some of those amp kits on Tube Depot,and they look quite interesting,...something I would not mind trying,with help of a ham radio buddy,or someone far more familiar with amp design than I am! :)


You seem to be hung up on the idea that once an amp has been designed and built that that is it; end of the road, end of story, done. What you don't seem to realize is that the general topology of a tube amp is very flexible. Minor changes in component values can make big changes in sound. As long as the changes remain within the operating parameters of the tubes and circuit, you will not damage anything. Sure, if you bias a tube too hot, you risk burning it up or if you use too large of a grid stopper, you may kill all high frequency response in that stage, or if your wiring is not neat and clean you can end up with uncontrollable oscillations. I have direct, personal experience with the latter item when I built my Wrecking Ball amp.But with careful layout and suggestions from others, the amp is now stable with all controls dimed and it is a VERY high gain amp.

I am now thinking about changing the feedback resistor in the power stage to give me a little more loop gain which will allow the power stage to break up more. Also, changing the screen grid resistors for a little more compression. Yes, using too large a value of screen resistor may result in starving the screens and ending up with a bad sound. But that is way beyond what we are talking about.

I have formulas and on-line calculators (that I have referenced before) that I use in my designs and mods. Application of these calculators allows me to see the theoretical impacts to the amp and determine if the change may be useful or not. Implementing the change is the next step.

If you are uncomfortable with making changes, that's fine. I was the same way at first, but as I learned more about tube amps, I learned what works and what doesn't. I am still learning. Maybe someday I will know as much about these things as Arjay, shimmilou, and BMW2002Ti. :D

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Sep 14, 2013 7:20 am
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Rock Star
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Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
KC9SYJ wrote:
BMW2002Ti wrote:
KC9SYJ,

Actually subbing one tube in for another is not that sinful. Leo experimented with several combinations of gain stage and output tubes --- plus the voltage parameters around those tubes --- before coming out with production models.

It's all for the sake of tone. Empirical testing is often the best way to fine tune.

:D :mrgreen: :D


It was either Forrest White's book 'Fender;The Inside Story" or some other Fender related book where I read that Leo would often go out on the production line and make a change in an amp in mid production without informing Forrest or QC,and REALLY mess up the readings at final 'end of line' test,or something like that,...and Forrest and the QC person would be 'up in arms' so to speak. And I can understand why Leo would try several combinations of tubes and the voltage parameters around them before coming out with production models.


Fact of the matter is that Leo based his designs on available tube designs of the day. He certainly did not invent anything new in amp design. He took the designs that were documented and tweaked and modded them to achieve what he wanted. They are certainly not the be all and end all of amp design. Many amp designs today are based on the early Fender design. I hate to say this, but Leo is long dead. Time to move on and not worry about "What would Leo do?"

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Sep 14, 2013 7:27 am
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Aspiring Musician
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Joined: Sun Jan 27, 2013 3:44 pm
Posts: 366
bluesky636 wrote:
KC9SYJ wrote:
Not taking what Bill said wrong at all,and nor am I taking it harshly. I am well aware of the fact Leo didn't design the BDRI,however,I was only thinking that had he done so,he may or may NOT have approved. As I pointed out in one of my posts in a
different thread,I am still learning about this stuff,and that is really the main reason why I
questioned Bill's modifications and as to why he done them. Guitar amps are QUITE different than a radio transmitter,that's for sure. We hams experiment,too,but it's mainly when we are building an antenna(I have done that with help of another ham radio operator,...he helped me build my first antenna,...a 50 mhz five element beam),or building a CW transmitter from a kit(something I have yet to do) among other things. I am one of those types of people who go by the owner manual and what it says to do or NOT do,and do all I can to follow them to the letter. So again,...I am not taking anything wrong at all nor am I taking it harshly. Heck,...if I built my own amp,...with help of one of my radio buddies who is more experienced at electronics and building projects than I am,I might gain some knowledge of amp design. But until then,I will stick with using genuine replacement parts in my equipment. Now I can understand one thing about amps,...and tube type radios as well,...that if it calls for a particular tube and it's no longer available,I can see subbing it for an equivalent tube type,...that would be the ONLY time I would use a different tube type than what the amp,...or radio,...called for! Again,that's just me and how I operate. I am reading about tube amp design,so I still have LOTS to learn. Can you REALLY tell a difference in sound with different tubes? Like,...if I were to pull the GT technology tubes out of my HRD III and replace them with say,...JJs,E-H,or Tung-Sol tubes. You know me already,...I'd replace with same tube type,of course. :) I have,..BTW,..checked out some of those amp kits on Tube Depot,and they look quite interesting,...something I would not mind trying,with help of a ham radio buddy,or someone far more familiar with amp design than I am! :)


You seem to be hung up on the idea that once an amp has been designed and built that that is it; end of the road, end of story, done. What you don't seem to realize is that the general topology of a tube amp is very flexible. Minor changes in component values can make big changes in sound. As long as the changes remain within the operating parameters of the tubes and circuit, you will not damage anything. Sure, if you bias a tube too hot, you risk burning it up or if you use too large of a grid stopper, you may kill all high frequency response in that stage, or if your wiring is not neat and clean you can end up with uncontrollable oscillations. I have direct, personal experience with the latter item when I built my Wrecking Ball amp.But with careful layout and suggestions from others, the amp is now stable with all controls dimed and it is a VERY high gain amp.

I am now thinking about changing the feedback resistor in the power stage to give me a little more loop gain which will allow the power stage to break up more. Also, changing the screen grid resistors for a little more compression. Yes, using too large a value of screen resistor may result in starving the screens and ending up with a bad sound. But that is way beyond what we are talking about.

I have formulas and on-line calculators (that I have referenced before) that I use in my designs and mods. Application of these calculators allows me to see the theoretical impacts to the amp and determine if the change may be useful or not. Implementing the change is the next step.

If you are uncomfortable with making changes, that's fine. I was the same way at first, but as I learned more about tube amps, I learned what works and what doesn't. I am still learning. Maybe someday I will know as much about these things as Arjay, shimmilou, and BMW2002Ti. :D


:lol: :lol: I'm still learning,too! Even in my radio hobby,...I'm still learning,...so much to learn about both tube amps and radio gear! Being new to tube amps,...I am leary about those changes,but like you,...I am sure as I move along,...I'll get a better understanding of what is going on inside that amp of mine.

_________________
If it aint' broke,...don't fix it! I like to keep my amps and guitars factory original,...no mods necessary,...don't want them,...don't need them!

My gear as of now;
Standard Strat
Hot Rod Deluxe III amp
Champion 20 amp
'59 Bassman LTD Reissue


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Profile
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Sep 14, 2013 8:01 am
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Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
KC9SYJ wrote:
:lol: :lol: I'm still learning,too! Even in my radio hobby,...I'm still learning,...so much to learn about both tube amps and radio gear! Being new to tube amps,...I am leary about those changes,but like you,...I am sure as I move along,...I'll get a better understanding of what is going on inside that amp of mine.


Review this site:

http://ampbooks.com/

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Bill

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Sep 14, 2013 11:14 am
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Aspiring Musician
Aspiring Musician

Joined: Sun Jan 27, 2013 3:44 pm
Posts: 366
bluesky636 wrote:
KC9SYJ wrote:
:lol: :lol: I'm still learning,too! Even in my radio hobby,...I'm still learning,...so much to learn about both tube amps and radio gear! Being new to tube amps,...I am leary about those changes,but like you,...I am sure as I move along,...I'll get a better understanding of what is going on inside that amp of mine.


Review this site:

http://ampbooks.com/


I'll do that! Thanks!

_________________
If it aint' broke,...don't fix it! I like to keep my amps and guitars factory original,...no mods necessary,...don't want them,...don't need them!

My gear as of now;
Standard Strat
Hot Rod Deluxe III amp
Champion 20 amp
'59 Bassman LTD Reissue


Top
Profile
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Sep 14, 2013 1:25 pm
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KC9SYJ wrote:
...Can you REALLY tell a difference in sound with different tubes?...


Yes, we all have our favorites, and there are very spirited debates over brand choice. Some differences are with tone, harmonic content, breakup point, smoother breakup, and sometimes even all of the above.

Keep in mind that there are some serious considerations when switching to a different type, such as from 6L6 to 6V6 and vice-versa. The amp must be able to handle the tube and the tube itself has to be able to handle the application, not just any 6V6 or 6L6 will work in any amp. You must consider Plate voltage and current, screen voltage, and even heater current draw.

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---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Sep 14, 2013 3:36 pm
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Aspiring Musician
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Joined: Sun Jan 27, 2013 3:44 pm
Posts: 366
shimmilou wrote:
KC9SYJ wrote:
...Can you REALLY tell a difference in sound with different tubes?...


Yes, we all have our favorites, and there are very spirited debates over brand choice. Some differences are with tone, harmonic content, breakup point, smoother breakup, and sometimes even all of the above.

Keep in mind that there are some serious considerations when switching to a different type, such as from 6L6 to 6V6 and vice-versa. The amp must be able to handle the tube and the tube itself has to be able to handle the application, not just any 6V6 or 6L6 will work in any amp. You must consider Plate voltage and current, screen voltage, and even heater current draw.


Over on the "Tube Knowledge" thread,I told Bill(Bluesky636) that I had been in contact with Tube Depot and they have actually recommended I try the Tung-Sol 6L6 STR tubes in my HRD III. When I was thinking about going with a BDRI like Bill has before I chose the HRD,Tube Depot even recommended the same Tung-Sol tubes for that one as well. Must be a good tube otherwise they would not have recommended it,and as you have said,shimmi,...everyone has their favorites and may I add,...their preferences. You bring up an interesting point in your statement when you say that with the differences between a 6L6 and 6V6,that the amp has to be able to handle the tube and the tube itself has to be able to handle the application because you have to consider plate voltage and current,screen voltage,and even heater(filament)current draw. I say that because in comparison,...when we ham radio operators are dealing with tubes in a linear amp designed for an 811A tube,and if you try and sub a 572B tube in it's place,you had better be sure the power supply can handle the 572B(or vice-versa). If not,you risk damage to the power supply and that has been known to happen. I was told that by a fellow ham. When I was questioning Bill's mods to his BDRI,I was thinking of that scenario with the linear amp. I should have pointed that out in the beginning and I failed to do that! :oops:

_________________
If it aint' broke,...don't fix it! I like to keep my amps and guitars factory original,...no mods necessary,...don't want them,...don't need them!

My gear as of now;
Standard Strat
Hot Rod Deluxe III amp
Champion 20 amp
'59 Bassman LTD Reissue


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Profile
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Sep 14, 2013 4:02 pm
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KC9SYJ,

The Tungsol reissued 6L6GC-STR is a very good tube. The tone isn't vintage RCA. Lacking the midrange of the classic tube. It is more like the 1990s production Svetlana (St Petersburg made) SV-6L6GC.

Quite heavy designed plates. Looks mil spec tough.


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sun Sep 15, 2013 5:06 am
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KC9SYJ wrote:
...You bring up an interesting point in your statement when you say that with the differences between a 6L6 and 6V6,that the amp has to be able to handle the tube and the tube itself has to be able to handle the application because you have to consider plate voltage and current,screen voltage,and even heater(filament)current draw. I say that because in comparison,...when we ham radio operators are dealing with tubes in a linear amp designed for an 811A tube,and if you try and sub a 572B tube in it's place,you had better be sure the power supply can handle the 572B(or vice-versa). If not,you risk damage to the power supply and that has been known to happen...


Yes indeed, you got it, same with instrument amps, and with instrument amps you also have sound shaping considerations with tube choices.

A point to clarify is that a "filament" is a directly heated Cathode, meaning the filament is the Cathode. A "heater" is for an indirectly heated Cathode, meaning that the heater and Cathode are separate parts. Sometimes though, some will use the terms "heater" and "filament" interchangeably. OK, so I'm nit-picking. :lol:

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Wed Sep 25, 2013 3:49 pm
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Well, after about a week and a half of playing with the E-H 6V6GTs in my BDRI, the shine has begun to fade. Although the tubes sound great from the mids through the highs, the bass is not up to snuff. If the amp volume and/or bass are turned up much, the bass is very farty and flubby with a nasty breakup. I know it is not the speaker, as this did not occur with the JJ 6L6GCs. I need to check the bias as I have not done so since the initial setup. I like to run my bias fairly warm (initially set to about 67% max plate dissipation), so I will check it to see if it has shifted any. Today I ordered a matched pair of JJ 6V6Ss from Eurotubes to try out. If I find I don't like them any better, I may try the JJs in the Wrecking Ball and replace the single JJ 6V6S in my modded Champion 600 with one of the E-H 6V6GTs. Stay tuned.

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Fri Sep 27, 2013 5:26 pm
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Just swapped in and biased the JJ 6V6S power tubes in place of the E-H 6V6GT tubes. Interesting difference between the two pairs.

The JJs biased up at 24 mA cathode current (about 23 mA plate current) and 425 VDC plate voltage for a bias set point of 70%. The tubes appear to be matched within about 0.5 mA and the plate voltage difference was about 1 VDC.

The tone is very different. Played clean, the E-Hs are very bright and chimey. The JJs are a little darker and thicker. Cranked, I think the JJs have a smoother overdrive compared to the E-Hs with very little fartiness when the bass is overdriven. The JJ bass is much tighter than the E-Hs. As others have noted, the JJs do sound more like a less powerful 6L6GC, but they do overdrive easier than the 6L6GCs. They are still pretty loud.

These will definitely stay in for a while so I can check them out. They would probably work really well in the Wrecking Ball

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Fri Sep 27, 2013 5:38 pm
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Bill, I'd expect that result with the JJ 6V6S. Next step between the 6V6S and 6L6GC would be the 5881. If you can find them... the Sylvania 6L6GA or 6L6GB are really nice tubes. Better dynamics than the Tungsol 5881/6L6WGB. Coke bottles, smoked glass. Bias to around 14 watts per tube.

http://www.ebay.com/sch/i.html?_nkw=6l6ga


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Fri Sep 27, 2013 8:56 pm
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BMW2002Ti wrote:
Bill, I'd expect that result with the JJ 6V6S. Next step between the 6V6S and 6L6GC would be the 5881. If you can find them... the Sylvania 6L6GA or 6L6GB are really nice tubes. Better dynamics than the Tungsol 5881/6L6WGB. Coke bottles, smoked glass. Bias to around 14 watts per tube.

http://www.ebay.com/sch/i.html?_nkw=6l6ga


KCA NOS Tubes has a nice selection of NOS 5881s and 6L6GBs. I considered a set for my 5F6A clone. To be honest though, other than my NOS 12AY7s and 5751s, I really don't have much of an interest in NOS tubes. Maybe if I played professionally, but I don't. All of my amps have been tweaked around JJs and have worked out quite well.

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Fri Sep 27, 2013 11:43 pm
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Bill,

I got 15 NOS 1952 Sylvania JAN-JHS 6L6GA for $50 about ten years ago. If you are interested, I can try to find them in my infinite stash.


:lol:


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