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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Fri Dec 14, 2012 6:14 pm
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bluesky636 wrote:
Well, there are these little things on the amp called "tone controls" ... :wink:

Yes, I know, and I dialed the treble down and made adjustments to the mids and bass a lot in an attempt to eliminated that quality, but in the end it sounded like a muffled "snappy" sound instead of being smooth. It seems that this is the only Fender that I've tried that generates this kind of transient attack.
I haven't had the chance to try a Blues Deville or Bassman.
Also wondering if a re-biasing would change that attack.


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Fri Dec 14, 2012 6:21 pm
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Mister Mxyzptlk wrote:
bluesky636 wrote:
Well, there are these little things on the amp called "tone controls" ... :wink:

Yes, I know, and I dialed the treble down and made adjustments to the mids and bass a lot in an attempt to eliminated that quality, but in the end it sounded like a muffled "snappy" sound instead of being smooth. It seems that this is the only Fender that I've tried that generates this kind of transient attack.
I haven't had the chance to try a Blues Deville or Bassman.
Also wondering if a re-biasing would change that attack.


I've never experienced anything like that. My BDRI doesn't react like that. The attack depends a lot on the guitar you are using, the pickup, the guitar pick, etc. If I have time this weekend, I'll try and record a short demo.

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Fri Dec 14, 2012 6:44 pm
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bluesky636 wrote:
I've never experienced anything like that. My BDRI doesn't react like that. The attack depends a lot on the guitar you are using, the pickup, the guitar pick, etc. If I have time this weekend, I'll try and record a short demo.

OK, thanks,
I've recently tried various other amps using the same guitar, none of them have that particular transient attack that is very similar to the sound in the YouTube I posted. This was also the second BDRI that I tried, each of which sounded very similar.
Aside from that, it has a much fuller sound than, for example the Blues Jr. The BJ can really rock though with an OD pedal, albeit somewhat boxy sounding.

To be fair though, I'll test it again using some different guitars and compare.

Thanks,
MrM


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Fri Dec 21, 2012 6:07 pm
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hey Bill , i just wanted to say that i went even further with the tone stack and TRIED to get the sound of an original tweed twin. it came out so awesome and close to it that i had to let you know. i know that the circuit is closer to a bassy man amp but i desided to go one further. i focused mainly on the 57 tweed twin and it came out as close as it could. i even discovered a way to make the mids act like a tweed twin (you know have that "cut" as you increase the volume. it is an intresting sound. thank you for all your hard work on this thread. by the way i used to be blackstrat71 but some web site problems made me have to change my user name. god bless.


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Fri Dec 21, 2012 10:46 pm
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shinkicker wrote:
hey Bill , i just wanted to say that i went even further with the tone stack and TRIED to get the sound of an original tweed twin. it came out so awesome and close to it that i had to let you know. i know that the circuit is closer to a bassy man amp but i desided to go one further. i focused mainly on the 57 tweed twin and it came out as close as it could. i even discovered a way to make the mids act like a tweed twin (you know have that "cut" as you increase the volume. it is an intresting sound. thank you for all your hard work on this thread. by the way i used to be blackstrat71 but some web site problems made me have to change my user name. god bless.


Perhaps you could start a thread on that subject. I would be interested in knowing how you did that considering that the tone stack and basic circuit topology of the low power Tweed Twin is nothing like that of a 5F6A Bassman or BDRI.

http://ampwares.com/schematics/twin_5e8a.pdf

The high power Tweed Twin on the other hand, is basically a high power 5F6A Bassman.

http://ampwares.com/schematics/twin_5f8a.pdf

Yes, I saw your post in the Lounge about your identity change. :D

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Dec 22, 2012 6:43 am
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i just changed the caps on the bass and tried to determine what the mid value would be sence as you said these shematics are nothing alike. i settled on a .01uf and changed the mid resistor to a 220k. my next trick is to change the presence and treble pots to the t.twin specs. 1m on treble and 5k on presence. it might get intresting. the mid control dosen't exist on the t. twin. so by moving the resistor to a 220k it made the mids less pronounced but you can turn the dial and it seems to adjust the freq but the mids are not made louder or more or less bassy. the amp sounds better with single coils especially my e.c. strat. less bass in your face. the amp can get a bit twangy but not in a bad way. it gets that growly tweed bass when you push it. i mainly use the drive channel but the normal is nice as well but you still have to back down the bass when you crank it on normal. i guess basicly it a work in progress but so far so good.


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Dec 22, 2012 1:19 pm
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Well, first of all, let me say that if you are happy with the sound, that is all that matters. :D

But, there are several technical considerations about your mods that concern me and would prevent me from recommending them.

Lets look at the BDRI tone stack first. The graph below shows the frequency response of the stock BDRI tone stack (green), my modified tone stack (red) and your modified tone stack (yellow). The component values shown are yours, the graph can't show all three. Bass, mid, and treble are all set to "6" (Yeah, they don't look that way on the graph. That is the result of the different scales. But they represent a value of "6" on the BDRI knobs.)

Image

What does the graph show us? Well, first of all, there is about a 10 dB increase in insertion loss below 100 Hz. That is significant in my book. Also manipulating the sliders in the actual program shows that bass varies between -30 dB and -20 dB at 100 Hz, midrange varies only between -22 dB and -18 dB at 800 Hz, and that treble varies between -26 dB and -4 dB ( :shock: ) at 5000 Hz. Not the kind of performance I would look for in a well designed tone stack.

Now, let's looks at your mod to the presence pot.

What you apparently didn't realize is that the 25K ohm presence pot of the BDRI is in parallel with a 4.7K ohm resistor (refer to the schematic referenced earlier). This gives an effective presence pot resistance at minimum presence of about 3.9K ohm. Changing the presence pot to a 5K ohm pot now makes the effective resistance at minimum presence 2.4K ohm. This changes the ratio of the closed loop gain to open loop gain of the PI/power amp feedback circuit from about 60% (stock) to about 71%. This change could have an impact on power amp stability and its ability to resist breaking into oscillation under large signal levels and/or higher levels of presence. The fact that you have not mentioned such a problem is good, but not a chance I would take.

Anyway, that's my analysis of the mods you made. Not something I would do, but if you are happy, who cares what I would do. :lol:

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Last edited by bluesky636 on Sat Dec 22, 2012 2:37 pm, edited 1 time in total.

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Dec 22, 2012 1:47 pm
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Hello Bill,

Is that calculator pictured in your above post something downloadable on the net? If so, where?
Thank you.

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Dec 22, 2012 2:04 pm
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modwiz wrote:
Hello Bill,

Is that calculator pictured in your above post something downloadable on the net? If so, where?
Thank you.


You can get the tone stack calculator here:

http://www.duncanamps.com/tsc/index.html

The Fender stack is a blackface style. I use the Marshall stack as that is the basic 5F6A Bassman stack. You can change the component values to match your stack. You also need to change the source and load impedances to those of your amp to get an accurate graph.

The other calculators I use are found here:

http://ampbooks.com/

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Dec 22, 2012 4:40 pm
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thanks for the heads up on my mod. i guess i overlooked the presence control problem. i deffinately wouldn't want to kill the amp. glad i didn't do that mod. i was just wanting a somewhat brighter amp. right now i have that but as you can see with the graph, a bag of crap for performance. the amp does breakup rather nicely but i have played it a bunch today and think i will try the .022uf cap on the bass and i already switched the mid cap back to a .022uf. and the resistor back to a 100k, the .0047uf on the bass really seems to tighten up the bass and gives it an overall throaty sound. i'm going to play around with it a bit more before i settle. i'm going to take it slow. again thanks for the performance eval.


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sat Dec 22, 2012 8:14 pm
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shinkicker wrote:
thanks for the heads up on my mod. i guess i overlooked the presence control problem. i deffinately wouldn't want to kill the amp. glad i didn't do that mod. i was just wanting a somewhat brighter amp. right now i have that but as you can see with the graph, a bag of crap for performance. the amp does breakup rather nicely but i have played it a bunch today and think i will try the .022uf cap on the bass and i already switched the mid cap back to a .022uf. and the resistor back to a 100k, the .0047uf on the bass really seems to tighten up the bass and gives it an overall throaty sound. i'm going to play around with it a bit more before i settle. i'm going to take it slow. again thanks for the performance eval.


Download the tonestack calculator referenced above and you can see what things look like before making the mods. The source and load impedances I used are for the clean channel. Drive channel values are slightly different but the clean values should get you close enough. The difference usually manifests itself as variations in insertion loss with a slight change in curve shape.

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sun Dec 23, 2012 5:48 am
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thanks bill, i'll download and use it before any mod like this.


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sun Dec 23, 2012 9:21 am
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shinkicker wrote:
thanks bill, i'll download and use it before any mod like this.


Good luck and have fun. :D

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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sun Dec 23, 2012 10:04 am
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bluesky636 wrote:
modwiz wrote:
Hello Bill,

Is that calculator pictured in your above post something downloadable on the net? If so, where?
Thank you.


You can get the tone stack calculator here:

http://www.duncanamps.com/tsc/index.html

The Fender stack is a blackface style. I use the Marshall stack as that is the basic 5F6A Bassman stack. You can change the component values to match your stack. You also need to change the source and load impedances to those of your amp to get an accurate graph.

The other calculators I use are found here:

http://ampbooks.com/


Thanks again, Bill. You are teaching an old dog. No tricks, just good useful information. Just trying to grok much if what you kindly share sends me scurrying for education to make it all useful.

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(Telecaster, Jaguar, Villager 12 String. Mustang l, Bronco, SCX2, Rumble 350, HRDIII, Rumble 2x8 Neo Cab)
http://www.reverbnation.com/modwiz


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Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Sun Dec 23, 2012 12:10 pm
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modwiz wrote:
Thanks again, Bill. You are teaching an old dog. No tricks, just good useful information. Just trying to grok much if what you kindly share sends me scurrying for education to make it all useful.


Just trying to give back for all that I have learned here from others. :D

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