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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Thu Dec 27, 2012 10:45 pm
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I made another simple mod to the BDRI tonight. I decided to try shimmilou's mod of increasing the B+ supply's filter cap size by adding a 20 mfd, 500 VDC cap to the stock 47 mfd, 500 volt cap for a total of 69 mfd.

CAUTION!!! Tube amps contain high voltages that can be lethal. Be sure to check the power supply caps with your DVM prior to working on your amp and drain the caps if necessary. Make sure your amp is unplugged and never stick both hands inside a live amp.

Although the mod is super easy, you MUST make sure the power supply caps are completely drained as you will be soldering the 20 mfd cap directly to and in parallel with the 47 mfd cap.

Take the 20 mfd cap (or slightly larger if you choose) and lay it alongside the 47 mfd cap. Make sure you have the polarity matched or you may have an unpleasant experience when you power up. :shock:

Bend the leads of the 20 and make a single tight wrap around the leads of the 47. Crimp the leads tight and solder. Trim the excess leads off the 20. Lift the 20 slightly and shoot some silicone or hot melt glue under the cap and press the cap down into the goop. You are done. It will look like this when you are finished:

Image

I did this mod to see if it would help lift my plate voltage and hold it up better as I biased the amp. It didn't. Oh, well. Still, I biased the power tubes at 53 mA cathode current (about 50 mA plate current) per tube with a plate voltage of 403 VDC average per tube. This gave me an idle plate dissipation of about 20 watts or about 67% of max plate dissipation (30 watts for a 6L6GC).

The next obvious question is, does the amp sound any different?

This is a little harder to answer. The bass does seem a little tighter. It might be easier to tell with the addition of a larger cap, say a 47 mfd instead of a 20 mfd. But it definitely doesn't sound worse, which is a good thing. :lol:

Yes, I know that I owe everyone a sound sample. Things have just been kind of hectic lately and I start my new job on Monday (I had been laid off in August and was unemployed for the last 5 months). I'll try and get one posted as soon as I can.

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Dec 29, 2012 3:34 am
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bill, first off i'm glad to hear you are working again. i hope it's a job you enjoy. second, i think i have found a combo of caps in my tone stack i like. .0068uf on the bass and .022uf on the mid with a 56k resistor in place of the 100k. i like the "tweed" sound i'm getting. the amp seems to almost breakup earlier and it has a nice lower note growl almost like the speaker is now trying to breakup (sort of Clapton/ Cream 2005 sound). again thanks for the ideas.


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Dec 29, 2012 9:17 am
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Glad you are happy with that combo. :D

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Jan 12, 2013 7:24 pm
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So my tubes finally came in..
V1 = 12AY7
V2 = 12AX7
V3 = 12AX7
V4/V5 = 6L6GC

Nothing spendy, an EH 12AY7 and a set of matched JJ's 6L6GC's.
Big difference in the tone though.
Thanks for the pointers.

I had already switched the speaker to a C-Rex awhile back and now it is really working well with those new tubes.
Since my Blues Deluxe Re-Issue is still under warranty I probably will not do any of the pcb mods, but I have a 1995 Blues Deville 4 x 10 that I am starting to work on.
Switching out the pots and jacks first, new tubes and maybe make some of the pcb mods.
I switched the speakers to 2 Ragin Cajuns and 2 Eminence Legends sometime ago and that made some improvement. After I get the insides done I am gonna shellac that thing up and make it shine...

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Jan 12, 2013 8:10 pm
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Excellent! :D

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Fri Mar 01, 2013 7:17 am
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bluesky636 wrote:
OK. As I promised last night, here is my adventure swapping tubes around in my BDRI. Note that I am not going to recommend specific tube brands, just identify what I have been using. Tube brands are a very personal thing and everyone has their favorites. I like JJ tubes and use them in all three of my tube amps, but we're primarily going to talk about tube types. If you want more information about JJ tubes for the BDRI, check out

https://www.eurotubes.com/cart/index.ph ... ory_id=122

My BDRI came equipped with Groove Tubes in the following configuration:

V1 = 12AX7
V2 = 12AX7
V3 = 12AX7 (Balanced for PI use)
V4/V5 = 6L6R (Actually SOVTEK 5881WXTs).

The tubes sounded OK, but a couple things I noticed were the highs were somewhat piercing and the clean sound was kind of thin and harsh. I play (or at least try to play) Blues and prefer a thicker, warmer sound. The drive channel I did not like at all (I currently use a Full Tone FD-2M through the clean channel for overdrive).

The first thing I did was learn about biasing the amp. After doing some research, I learned that Fender has a tendency to bias their amps pretty cold, primarily to extend tube life. The Fender spec for the BDRI is 60 mV at the bias test point with a plate voltage of about 430 VDC. I learned that this equates to an idle power of about 12 watts. I have read, but not confirmed that the stock power tubes are only rated at 25 watts. This would translate to a bias setting of about 48% max plate dissipation. Way cold! If the stock tubes were 30 watts, they would be even colder at that setting. Anyway, I tried increasing the bias voltage at the test point to 70, then 75, and finally 80 mV. The amp probably sounded best at about 75 mV. What I didn't realize at the time was that you also have to measure the plate voltage as it will decrease as the bias is increased and vice versa. Oh, well. Nothing blew up. Yet.

Still not happy, I decided to change tubes.

My first crack at different tubes was the JJ "Blues Option" from Eurotubes. That set consists of:

V1 = 12AX7
V2 = 12AT7
V3 = 12AX7 (Balanced for PI use)
V4/V5 = 6L6GC.

12AT7? Now I had to learn more about different "gain factors" for preamp tubes. Turns out a 12AX7 has a gain factor of "100" and a 12AT7 has a gain factor of "60". Here's a good explanation of gain factor:

http://thetubestore.com/gainfactor.html

So, what this all means is that the amp now has a little less gain from input to output. It will still play plenty loud, you just have to turn it up more or hit it with a bigger input. How did it sound? Pretty good. I also learned that the JJ 6L6GCs could be biased hotter for a thicker, more driven tone. By this time I learned that you had to measure plate voltage too. So, I set out to increase my bias when things blew up.

Well, they didn't really "blow up", but there were a lot of sparks and a small fire. :shock:

While I was measureing the plate voltage with my DVM on pin 3 of V5, the probe slipped and momentarily connected pins 3 and 2 (the heater). There was a big spark and a tiny fire on the PCB. Naturally I jumped back, pulled the probe out, blew out the fire, and turned off the power. There was a small charred area on the PCB between the two pins. How do I clean that up? Well, I took my electric toothbrush, and old brush attachment dipped in alcohol, and scrubbed the charred spot. It actually cleaned up quite nicely. There is a small depression where the fire burned the PCB, but very little residue. Amazingly, there was no damage and everything worked afterwards. I never told my wife what happened. :wink:

Following that episode, I invested in a bias probe:

http://www.amp-head.com/product_info.ph ... ucts_id=70

Now I could safely bias the amp to my heart's content.

The amp was sounding pretty good, but there was one issue I had that I had been reading about others complaining about. That was the fact that volume on the clean channel jumps significantly between "1" and "3". The common fix is to suggest replacing the volume control with an audio taper pot. That is wrong, by the way, as the clean volume control is already an audio taper pot. My research led me to believe that the problem was too much gain in the preamp stage. What to do? :idea: Swap the 12AT7 from V2 with the 12AX7 in V1. So now my tube configuration was:

V1 = 12AT7
V2 = 12AX7
V3 = 12AX7 (Balanced for PI use)
V4/V5 = 6L6GC.

Hey. That works! The volume didn't jump as much and you had to turn the clean volume up a little higher to get things loud like before. But it didn't sound good. With the original configuration, the clean channel was a little thicker sounding. This setup sounded too thin, almost as bad as the original tube set did. So I changed things back to the origninal JJ setup and searched some more.

I then discovered NOS tubes and the 5751.

I buy all of my NOS tubes from here:

https://www.kcanostubes.com/

The owner, Mike K is a nice guy (I got to meet him) and lives only about 20 minutes from me.

Anyway, after reading about SRV and others using a 5751 in V1 to bring the gain down a little I bought a couple. The 5751 has a gain factor of about "70" a little more than the 12AT7 but still less than the 12AX7. And the sound? Fantastic. Warm and thicker with no harshness. But the amp was still a little too loud for home, so I decided to try a balanced 12AT7 in the PI like Fender uses in some of their other amps. So this configuration was:

V1 = 5751
V2 = 12AX7
V3 = 12AT7 (Balanced for PI use)
V4/V5 = 6L6GC.

The 12AT7 in the PI position seemed to tighten up the bass a bit. Volume was now at a more resonable level for home use (but still capable of being quite loud), and the clean channel voume control was, well, more controllable. :lol: The amp sounded great.

But could it sound better? :?:

By this time I had learned about the real "tweed" amps from the 50's. Hey, the BDRI looks like a tweed amp. Can it be made to sound like one? Well, no. But I did learn that several tweed amps used a 12AY7 (gain factor of about 40 - 45) in V1. Why not. First I tried a EH 12AY7. I was not impressed. Then I said to myself "The 5751 is an NOS JAN tube. Maybe an NOS JAN 12AY7 would sound better". So, back to Mike K I went for some NOS JAN 12AY7s. Now my amp looked like this:

V1 = 12AY7
V2 = 12AX7
V3 = 12AX7
V4/V5 = 6L6GC

I have found sonic heaven. :mrgreen: :mrgreen: :mrgreen:

Well, that's a little bit of an exageration, but the amp did sound darn good. Oh, I briefly tried a 12AT7 in V3 but that made the amp too quiet for me. Overall loudness is about the same as the previous configuration but the clean volume had an even better sweep than the 5751 provided. So, that is my final tube configuration. Does it sound better then the 5751/12AX7/12AT7 combination? Its a bit of a toss up. Both are very smooth and thick sounding. Very nice cleans and capable of a nice "Bluesy" tone. I think it would boil down to personal taste, but you can't go wrong with either combination in this amp.

A couple of things to note. Most of what I have talked about was the effect on the clean channel. Using lower gain tubes in V1 or V2 will reduce the amount of gain available from the drive channel. You can still get a bit of drive, but you have to turn the drive volume up higher. Some may like it, or not. Another personal taste thing. I don't use the drive channel myself as mentioned previously. Also during this time I was experimenting with biasing the power tubes. That will be a separate subject, because I discovered some very unusual things about the bias circuit in my amp.

Tomorrow night: "Speak up. I can't hear you". Yes, we'll talk about speakers for the BDRI. :lol:


Okay,...question regarding replacement tubes. When that becomes necessary for my amp,if I don't want to use Groove Tubes and choose NOS tubes instead,which RCA or GE tubes would work as subs(provided I stay with the 12AX7 and 6L6 tubes platform)and not have to have my amp re-biased? I would not want to use tubes of a different type(12AT7,for example) than what the amp calls for,...if it calls for 12AX7 tubes in the preamp stages,...that's what it will get,...same with the 6L6 power tubes in the power amp stage. I clicked on the link to the kca site! Are NOS tubes more expensive than the factory installed Groove Tubes or is it the other way around?

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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


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Fri Mar 01, 2013 9:09 am
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NOS tubes are very expensive, and anytime that you change output tubes brands/type you need to re-bias. Changing preamp tubes does not require a re-bias.

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Fri Mar 01, 2013 11:40 am
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Aspiring Musician
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Joined: Sun Jan 27, 2013 3:44 pm
Posts: 366
shimmilou wrote:
NOS tubes are very expensive, and anytime that you change output tubes brands/type you need to re-bias. Changing preamp tubes does not require a re-bias.


That being the case,...I'll stick with the good ole Groove Tubes when tube changes are needed. I checked the prices on NOS tubes and yeah,...VERY expensive as you indicate.

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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


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sun Mar 03, 2013 8:02 am
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KC9SYJ wrote:
shimmilou wrote:
NOS tubes are very expensive, and anytime that you change output tubes brands/type you need to re-bias. Changing preamp tubes does not require a re-bias.


That being the case,...I'll stick with the good ole Groove Tubes when tube changes are needed. I checked the prices on NOS tubes and yeah,...VERY expensive as you indicate.


The only NOS tube I use is the 12AY7 in V1, about $40 from Mike K. Electro-Harmonix makes a decent 12AY7 for about $20. The rest of my tubes are modern JJ from www.eurotubes.com which are far superior to the GTs that came stock in the BDRI. If you don't experiment with tubes, you will never know just how good the BDRI can sound. Even GT sells tubes that are better than the stock BDRI tubes.

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sun Mar 03, 2013 10:32 am
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bluesky636 wrote:
KC9SYJ wrote:
shimmilou wrote:
NOS tubes are very expensive, and anytime that you change output tubes brands/type you need to re-bias. Changing preamp tubes does not require a re-bias.


That being the case,...I'll stick with the good ole Groove Tubes when tube changes are needed. I checked the prices on NOS tubes and yeah,...VERY expensive as you indicate.


The only NOS tube I use is the 12AY7 in V1, about $40 from Mike K. Electro-Harmonix makes a decent 12AY7 for about $20. The rest of my tubes are modern JJ from http://www.eurotubes.com which are far superior to the GTs that came stock in the BDRI. If you don't experiment with tubes, you will never know just how good the BDRI can sound. Even GT sells tubes that are better than the stock BDRI tubes.


I will take that into consideration!

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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


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sun Mar 03, 2013 11:42 am
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About speakers,...just out of curiosity,I was nosing around Jensen's website and was just wondering that if I were to decide to upgrade the stock Eminence speaker at a later time with a Jensen unit,which one you think would work best? I looked at the C12N Vintage Ceramic,and the P12N(something or other) Vintage Alnico. Are these good choices or should I look at some of their other speakers as a possible upgrade? One last question regarding that,...would a speaker change void warranty? On the stock Eminence speaker that comes in the BDRI amp,...any idea what model speaker it is? I don't have my BDRI amp yet and was wondering about the stock speaker. I nosed around the Eminence site and I could not find much of anything close to it except for maybe the "Legend" series speakers. Anyway,I am enjoying the post on the BDRI mods,even if I may only upgrade the speaker at a later time,...if at all! Learning quite a bit about the amp just from this rather lengthy post. I'm a ham radio operator(can you tell by my username?) and have some electronics knowledge,...though not a whole lot,..but can understand some of what you're talking about.

73( Best Regards )
KC9SYJ

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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


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Mon Mar 04, 2013 7:37 am
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Posts: 8708
Location: Natural Bridge, Virginia
KC9SYJ wrote:
About speakers,...just out of curiosity,I was nosing around Jensen's website and was just wondering that if I were to decide to upgrade the stock Eminence speaker at a later time with a Jensen unit,which one you think would work best? I looked at the C12N Vintage Ceramic,and the P12N(something or other) Vintage Alnico. Are these good choices or should I look at some of their other speakers as a possible upgrade? One last question regarding that,...would a speaker change void warranty? On the stock Eminence speaker that comes in the BDRI amp,...any idea what model speaker it is? I don't have my BDRI amp yet and was wondering about the stock speaker. I nosed around the Eminence site and I could not find much of anything close to it except for maybe the "Legend" series speakers. Anyway,I am enjoying the post on the BDRI mods,even if I may only upgrade the speaker at a later time,...if at all! Learning quite a bit about the amp just from this rather lengthy post. I'm a ham radio operator(can you tell by my username?) and have some electronics knowledge,...though not a whole lot,..but can understand some of what you're talking about.

73( Best Regards )
KC9SYJ


Last question first: Yes, the stock BDRI speaker is one of the Eminence Legend speakers. I forget which one right now, but I might have mentioned it in my thread.

The biggest complaint with the BDRI is that it is overly bright and can be harsh. That is why the Eminence Cannibis Rex is one of the most popular replacement speakers. The CR is more mid-rangy and helps cut the harshness. I have seen the Celestion Alnico Gold used in the BDRI but it is very expensive. A Jensen C12N might be a little bright. You can try and compare the frequency response graphs and specs of the CR with the Jensen and see how they match up. I talk about what to look for in the speaker section.

Technically, any mod to the amp can void the warranty if you screw up and damage the amp. To replace the speaker you do need to remove the amp chassis from the cabinet (pull all the tubes first and make sure you label which tube came from which socket) which requires discharging the power supply caps for safety. If you are not comfortable doing so, take the amp to a good tech and let them do it. It is really not that hard if you take your time.

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Tue Mar 05, 2013 6:43 pm
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I have a friend who uses one of these and we put a new speaker in (C Rex) and it really helped it out tons. It got rid of that icepick high end.


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Tue Mar 05, 2013 9:43 pm
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fenderfan1988 wrote:
I have a friend who uses one of these and we put a new speaker in (C Rex) and it really helped it out tons. It got rid of that icepick high end.


If you read the speaker selection of this thread you will find that the CR is what I use and included in my analysis and recommendations. :wink:

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Wed Mar 06, 2013 12:12 am
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bluesky636 wrote:
fenderfan1988 wrote:
I have a friend who uses one of these and we put a new speaker in (C Rex) and it really helped it out tons. It got rid of that icepick high end.


If you read the speaker selection of this thread you will find that the CR is what I use and included in my analysis and recommendations. :wink:


Cool. Just sharing my personal experience.


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