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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sun Sep 08, 2013 5:08 pm
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BMW2002Ti wrote:
Bluesky,

You might need to change either the dropping resistor or the inline resistor to ground, in the bias supply. What I do is either run a resistor in-parallel or series (depending on which resistor) --- then you can easily go back to 6L6GC parameters.


Back on page 3 of this thread I discussed changing R77 from 68K to 56K.

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Wed Sep 11, 2013 4:29 pm
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My E-H 6V6GTs arrived today from the Tube Depot. I'll probably install and bias them this weekend. Should be interesting. 8)

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Wed Sep 11, 2013 4:48 pm
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Cool. I'm anxious to hear your impression, and I hope that you can bias them without the need for further modification to your amp.........since you've already done your "final" mod. :lol:

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Wed Sep 11, 2013 4:57 pm
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shimmilou wrote:
Cool. I'm anxious to hear your impression, and I hope that you can bias them without the need for further modification to your amp.........since you've already done your "final" mod. :lol:


I think I will have my tombstone say: "Hey, I can make it better". :lol: :lol: :lol: :lol:

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Wed Sep 11, 2013 5:08 pm
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Looks like the E-H 6V6GT is a 14 watt tube:

http://www.newsensor.com/pdf/electro-harmonix/6v6eh.pdf

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Fri Sep 13, 2013 5:11 pm
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Just finished installing, biasing, and playing the amp wit the E-H 6V6GTs installed. All I can say is ....... WOW! These tubes sound really nice.

They biased right up to 23mA cathode current (22mA calculated plate current), at 424 VDC plate voltage for an idle plate output of 9.3 watts/67% of max output (14 watt tube). No mods had to be made to my bias circuit and the pot is right about in the middle of its travel. According to my bias probe, the tube are matched almost exactly, maybe 0.5 mA difference. No evidence of red plating (at least for the time and volume I was playing at :lol: ).

How do they sound? Very different from the JJ 6L6GCs I had in the amp. With the clean volume set to 8 and the other controls set to T=6, B=4, M=8, and P=6, and the guitar volume (I tested with a two humbucker equipped guitar) set to 6, the tone was very clean and much more chimey than with the bigger bottles. Turn the guitar up to 8 and the tone starts to thicken. With the guitar at 10 the amp is nicely breaking up (I still have the 12AY7 in V1. I tried a 5751 in V1 and didn't like it. Gainier and not as smooth.).

Switching to the drive channel with the drive volume on 8, master on 10, and other controls set the same, there is a really a good overdrive. VERY thick and crunchy. The tone also brightened up some (which caused me to cut the treble and boost the mids as noted above).

I can say that so far am very pleased with the tone, but will be playing more to see how it sounds.

I'm contemplating increasing the feedback resistor to maybe 88K for a bit more loop gain in the power stage. I may also try upping the screen resistors from 470 ohms to 1K or 1.5 Kohms for more compression.

Stay tuned for more. :D

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Fri Sep 13, 2013 5:34 pm
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Bluesky, glad you like the switch in output tubes. Many do. The 1k-ohm screen grid is a very good one. Not only for tone, but keeping the 6V6GT more stable at high volumes. Some ppl play with the grid-to-ground resistor values. But, I'd prolly just keep the 200k-ohm.


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Fri Sep 13, 2013 7:31 pm
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Aspiring Musician
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bluesky636 wrote:
Just finished installing, biasing, and playing the amp wit the E-H 6V6GTs installed. All I can say is ....... WOW! These tubes sound really nice.

They biased right up to 23mA cathode current (22mA calculated plate current), at 424 VDC plate voltage for an idle plate output of 9.3 watts/67% of max output (14 watt tube). No mods had to be made to my bias circuit and the pot is right about in the middle of its travel. According to my bias probe, the tube are matched almost exactly, maybe 0.5 mA difference. No evidence of red plating (at least for the time and volume I was playing at :lol: ).

How do they sound? Very different from the JJ 6L6GCs I had in the amp. With the clean volume set to 8 and the other controls set to T=6, B=4, M=8, and P=6, and the guitar volume (I tested with a two humbucker equipped guitar) set to 6, the tone was very clean and much more chimey than with the bigger bottles. Turn the guitar up to 8 and the tone starts to thicken. With the guitar at 10 the amp is nicely breaking up (I still have the 12AY7 in V1. I tried a 5751 in V1 and didn't like it. Gainier and not as smooth.).

Switching to the drive channel with the drive volume on 8, master on 10, and other controls set the same, there is a really a good overdrive. VERY thick and crunchy. The tone also brightened up some (which caused me to cut the treble and boost the mids as noted above).

I can say that so far am very pleased with the tone, but will be playing more to see how it sounds.

I'm contemplating increasing the feedback resistor to maybe 88K for a bit more loop gain in the power stage. I may also try upping the screen resistors from 470 ohms to 1K or 1.5 Kohms for more compression.

Stay tuned for more. :D


Why and for what reasons would you even want to do what you have done,Bill? That amp was NOT designed to run on 6V6 tubes,...it was designed for 6L6 tubes in the power section,...or "finals" was we hams refer to them. Tell me why,...other than for more compression as you claim,...would you want to increase resistance in a circuit designed to run 470 ohm resistors to now run on 1k or 1.5K resistors. That kind of modification is just asking for trouble in an amp that was not even designed to run on them. :shock: :roll:
I read about you all doing these mods and to me you are doing more harm than good to an amp that most likely wasn't even broke in the first place. If Leo Fender were alive and reading about what you have done,...he would PROBABLY have a cow,...especially if he himself designed that amp to run on the components best suited for it. I'm not real sure about what Leo would be thinking,...but if I were in his shoes and seen what you had done,..I would be asking 'Why in the heck did you put 6V6 tubes in an amp designed to run on 6L6 tubes,and further more,don't even think about putting those 1K ohm resistors in where 470 ohm resistors are supposed to be. I did NOT design that amp to run on those components!" :x
Just my five cents,...but again,,,why? If the amp wasn't broke in the first place,don't fix it :!: I would NEVER even consider any such mods and change of components to my HRD III,...especially if it wasn't designed for them. 1K ohm resistors in where there are suppose to be 470 ohm resistors and 6V6 tubes in where 6L6s are supposed to be? Nope,...not in my HRD III! Ain't happening! Only genuine Fender parts in my amp,...if she calls for 470 ohm resistors,that's what she gets. If she calls for 6L6 tubes in her "finals",...that's what she gets,...12AX7s in her preamp,...what she gets,...nothing else :!: I enjoy reading the forums on the amp boards,...but I tend to question some of the modifications you guys perform at times! Myself,...really the ONLY time I would consider a change in components would be,for example,if the speaker were to fail under warranty for some reason or a tube would fail,...BUT,...I would replace with same tube type and/or speaker.

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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: Fri Sep 13, 2013 10:29 pm
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KC9SYJ wrote:
Why and for what reasons would you even want to do what you have done,Bill? That amp was NOT designed to run on 6V6 tubes,...it was designed for 6L6 tubes in the power section,...or "finals" was we hams refer to them. Tell me why,...other than for more compression as you claim,...would you want to increase resistance in a circuit designed to run 470 ohm resistors to now run on 1k or 1.5K resistors. That kind of modification is just asking for trouble in an amp that was not even designed to run on them. :shock: :roll:
I read about you all doing these mods and to me you are doing more harm than good to an amp that most likely wasn't even broke in the first place. If Leo Fender were alive and reading about what you have done,...he would PROBABLY have a cow,...especially if he himself designed that amp to run on the components best suited for it. I'm not real sure about what Leo would be thinking,...but if I were in his shoes and seen what you had done,..I would be asking 'Why in the heck did you put 6V6 tubes in an amp designed to run on 6L6 tubes,and further more,don't even think about putting those 1K ohm resistors in where 470 ohm resistors are supposed to be. I did NOT design that amp to run on those components!" :x
Just my five cents,...but again,,,why? If the amp wasn't broke in the first place,don't fix it :!: I would NEVER even consider any such mods and change of components to my HRD III,...especially if it wasn't designed for them. 1K ohm resistors in where there are suppose to be 470 ohm resistors and 6V6 tubes in where 6L6s are supposed to be? Nope,...not in my HRD III! Ain't happening! Only genuine Fender parts in my amp,...if she calls for 470 ohm resistors,that's what she gets. If she calls for 6L6 tubes in her "finals",...that's what she gets,...12AX7s in her preamp,...what she gets,...nothing else :!: I enjoy reading the forums on the amp boards,...but I tend to question some of the modifications you guys perform at times! Myself,...really the ONLY time I would consider a change in components would be,for example,if the speaker were to fail under warranty for some reason or a tube would fail,...BUT,...I would replace with same tube type and/or speaker.


Sorry if this sounds harsh, so don't take this the wrong way, but you clearly don't understand amp design. There is nothing unique or sacred about these amps (Leo didn't design the BDRI). You don't understand what happens when a component is changed. If you read through this thread, I explained every mod I did, why I did it, and what the effect was. I have a degree in electrical engineering. Tubes were still part of the curriculum when I received my degree. Thirtyseven years after receiving my degree, I am now studying vacuum tube amp design in detail and modifying and building my own amps. I mod my amps because I enjoy it, I learn from it, and (in my opinion) the amps sound better for it. If all you want to do is replace tubes with the same tube or a failed speaker with the same speaker, that's cool. That's your choice. But you will never understand why an amp does what it does or sounds the way it does, or why the sound changes. I won't buy another factory made amp. I will continue building and modding my own and learning from the experience.

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Fri Sep 13, 2013 10:32 pm
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BMW2002Ti wrote:
Bluesky, glad you like the switch in output tubes. Many do. The 1k-ohm screen grid is a very good one. Not only for tone, but keeping the 6V6GT more stable at high volumes. Some ppl play with the grid-to-ground resistor values. But, I'd prolly just keep the 200k-ohm.


Thanks. I will probably give it a try in the near future. :D

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Sep 14, 2013 4:00 am
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Cooler than the other side of the pillow bluesky636. I'm really glad that you like the sound. It's like you have a "Blues, Deluxe Reverb" now! 8)

After experimenting with a few different values, I settled on 2k ohm, 2-watt SGRs in my HRDlx, still with 6L6s. I got just a little more compression, and a little softer drive. So it seems that 1K ohm might be perfect for your 6V6, and would still be good if you switch to 6L6.

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Sep 14, 2013 4:45 am
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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


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Sep 14, 2013 6:54 am
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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! :)

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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


Last edited by KC9SYJ on Sat Sep 14, 2013 7:17 am, edited 1 time in total.

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Sep 14, 2013 6:58 am
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shimmilou wrote:
Cooler than the other side of the pillow bluesky636. I'm really glad that you like the sound. It's like you have a "Blues, Deluxe Reverb" now! 8)

After experimenting with a few different values, I settled on 2k ohm, 2-watt SGRs in my HRDlx, still with 6L6s. I got just a little more compression, and a little softer drive. So it seems that 1K ohm might be perfect for your 6V6, and would still be good if you switch to 6L6.


My Wrecking Ball runs 1K 5W cement resistors on the screens and since that amp is capable of using either EL34s or 6V6s, I though I would try that value. I have 1K 2W metal film resistors that I think should work OK.

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Sep 14, 2013 6:59 am
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BMW2002Ti wrote:
Empirical testing is often the best way to fine tune.

:D :mrgreen: :D


Plus its a fun learning experience. 8)

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