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Post subject: some new tubes for a BDRI
Posted: Fri May 27, 2011 1:23 pm
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I just put an electro-harmonix 12AY7 in V1, and a Eurotubes JJ ECC81 (a balanced 12AT7) in V3 of my Blues Deluxe Reissue. Changing these two preamp tubes made a tremendous difference in the gain of the amp; now it is usable at apartment volumes. The clean channel also sounds richer; all in all, a very good tube swap.


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Post subject: Re: some new tubes for a BDRI
Posted: Fri May 27, 2011 5:26 pm
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Hi teleman2009,

bluesky636 did a similar lower-gain tube change in his BDlx and reported the same improvement. Amazing what a couple of different tubes can do. :)

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Post subject: Re: some new tubes for a BDRI
Posted: Fri May 27, 2011 9:51 pm
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Yep. Phillips JAN 5751 in V1 (a little more gain than a 12AY7) and a JJ 12AT7 in V3. V2 has a JJ 12AX7 and power tubes are JJ 6L6GCs. Depending on what power tubes you have, you may want to look at upping the bias. Fender biases the amp way too cold. I'm running 38 mA cathode current (about 36 mA plate current) at 413 VDC Plate voltage. Works out to be in the neighborhood of 83 to 85 mV at the Fender bias test point. Sounds great.

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Post subject: Re: some new tubes for a BDRI
Posted: Tue Feb 05, 2013 6:06 pm
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Hi,

I know this post is rather old, but I'm hoping to get some advice. I'm in the middle of doing the research and I'm thinking of replacing the master pot on my BDRI and I'm also intrigued by this tube replacement as well. I too suffer from the excruciating volume level at 2.

I have everything I need to do the volume pot (except the part, which I'll order) and I am very comfortable with doing the job, but what I don't have is the specialized equipment to do the biasing of the tubes. from my research, I understand that there are self biased tubes. Is it possible (or advisable even) to use these in my BDRI to avoid having to purchase an expensive piece of equipment that I may only use once or twice in my lifetime and if so, any idea which tubes I would use? If I find out that I can get a reliable bias meter for fifty bucks or so, I don't mind getting the tool, but I'm seeing prices of $250+.

I thank you all in advance for any light you can shed on this for me. In the meanwhile, I will continue to do my research.

Thanks,

Mike (Shakey)


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Post subject: Re: some new tubes for a BDRI
Posted: Tue Feb 05, 2013 6:11 pm
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Hi bernard-shakey,

Preamp tubes are plug and play, no biasing required. Only output tubes need a bias check/adjust. :)

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Post subject: Re: some new tubes for a BDRI
Posted: Tue Feb 05, 2013 6:25 pm
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oops (red face). I guess my research fell short. I should have dissected this further.

Thank you so much for the reply shimmilou. Really appreciate that. It makes it seem more doable.

OK, so these are the preamp tubes that are being replaced. So do you think I can keep my 6L6's and replace the preamps, do the pot mod and I should have a more realistic volume?

Mike


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Post subject: Re: some new tubes for a BDRI
Posted: Tue Feb 05, 2013 6:53 pm
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Here is the procedure for properly biasing the power output tubes:

In order to properly set the power tube bias, you need to measure both the plate current flowing through the tube as well as the plate voltage present at the tube for the measured current You then multiply those two values together and compare the result to the rated maximum output for that tube. In the case of a 6L6GC, 30 watts is the maximum rated output for a single tube. In an amp like the BDRI, you adjust the plate current so that the product of plate current and plate voltage is between 50% and 70% of the max power.

However, it is not easy to measure the plate current. The best and safest way is to measure both cathode current and plate voltage using a bias probe and a DVM. A good bias probe (the one I use) is this:

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

Weber sells a bias probe that includes the meter:

https://taweber.powweb.com/biasrite/br_page.htm

Using cathode current is close enough for government work and actually gives you a little safety margin to avoid biasing the tubes too hot.

There are many You Tube videos available that show the proper way to bias amps in general and for specific amps. Although specific to the Hot Rod amps, this video is a good one and the basic principles are the same:

http://www.eurotubes.com/eurotubes-Hotr ... lts-mA.htm

Finally, you might want to read these to learn more about amp biasing:

http://www.aikenamps.com/WhatIsBiasing.htm

http://www.aikenamps.com/Why70percent.html

Keep in mind that while biasing an amp, the amp is powered on and you are exposed to high voltages which can injure or kill. This is a good read also:

http://www.aikenamps.com/SafetyTips.html

Good luck, have fun, and be careful if you decide to do this yourself. With the proper tools and procedures as outlined, biasing an amp is very safe.

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Last edited by bluesky636 on Tue Feb 05, 2013 10:10 pm, edited 1 time in total.

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Post subject: Re: some new tubes for a BDRI
Posted: Tue Feb 05, 2013 6:56 pm
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I did not find it necessary to replace the master volume pot on my BDRI. If you are interested in making additional mods to your BDRI, you might want to read this thread of mine on all the changes I made to my BDRI:

viewtopic.php?f=13&t=80142&p=911995

It's 8 pages long. :wink:

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Post subject: Re: some new tubes for a BDRI
Posted: Tue Feb 05, 2013 7:26 pm
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Wow! Thanks for all that great info bluesky636. I got some reading to do. I have bookmarked your forum page with all your mods and I'm about a page into it already. Add me to the list of extremely thankful peeps for your precious time and loving care that you put into that commentary. It is invaluable and I will definitely read through it and use it a tool to help me through this process.

Unfortunately some of your links have truncated in your first reply. I'm sure I will be able to figure them out with the site's URL conventions. I think it's a cut 'n paste thing. Just lettin' you know in case you have to post it again.

I like the probes you posted, but as I said for the one or two times that I'll ever use it, that's a little rich for me and I don't want to go out and get a $50 makeshift unit and be disappointed. I'm sure you get more use out of yours than I ever will.

As for the master volume pot, the reason I was sold on that was because I did a search for "volume to high" on my amp and a bunch of results came up saying that Fender uses a "linear-taper" volume pot as opposed to a "log/audio-taper" (i.e. http://guitarless.com/2011/07/how-to-fe ... olume-mod/). I was getting this crazy jump in volume from 1 to 2. Even on stage, I couldn't go past 3. As I understand it, the tubes don't even start to crunch at that level. I've been relying on my effect pedal for all that. I'd like to use the amp more for drive like Neil Young does (I'm in a Neil Young Tribute band, thus the reason for the natural overdrive).

Anyways, I'll try the tubes first and see how that goes. If I need further control, I'll go for the pot mod. My local shop (Long and McQuade http://www.long-mcquade.com) doesn't have the JAN 5751 so I may have to go with the 12AY7/12AT7 tubes, unless I can find an equivalent through them (or order cross border from the US, which is a bit of a pain - I'm in Toronto, Canada).

Thanks again for all the help.

Mike


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Post subject: Re: some new tubes for a BDRI
Posted: Tue Feb 05, 2013 7:31 pm
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OK, so I see that the one you use is $85. that's doable (was looking at the taweber ones @ $250+). I just gotta check with the vendor to see what the shipping implications will be.


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Post subject: Re: some new tubes for a BDRI
Posted: Tue Feb 05, 2013 10:08 pm
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bernard-shakey wrote:
OK, so I see that the one you use is $85. that's doable (was looking at the taweber ones @ $250+). I just gotta check with the vendor to see what the shipping implications will be.


You'll need a DVM too. The Weber Bias Rite for the BDRI is the BR-2 (octal) for $120 which includes a meter. There is no Weber bias probe listed for $250. Don't know where you got that from.

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Post subject: Re: some new tubes for a BDRI
Posted: Tue Feb 05, 2013 10:35 pm
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bernard-shakey wrote:
Wow! Thanks for all that great info bluesky636. I got some reading to do. I have bookmarked your forum page with all your mods and I'm about a page into it already. Add me to the list of extremely thankful peeps for your precious time and loving care that you put into that commentary. It is invaluable and I will definitely read through it and use it a tool to help me through this process.

Unfortunately some of your links have truncated in your first reply. I'm sure I will be able to figure them out with the site's URL conventions. I think it's a cut 'n paste thing. Just lettin' you know in case you have to post it again.

I like the probes you posted, but as I said for the one or two times that I'll ever use it, that's a little rich for me and I don't want to go out and get a $50 makeshift unit and be disappointed. I'm sure you get more use out of yours than I ever will.

As for the master volume pot, the reason I was sold on that was because I did a search for "volume to high" on my amp and a bunch of results came up saying that Fender uses a "linear-taper" volume pot as opposed to a "log/audio-taper" (i.e. http://guitarless.com/2011/07/how-to-fe ... olume-mod/). I was getting this crazy jump in volume from 1 to 2. Even on stage, I couldn't go past 3. As I understand it, the tubes don't even start to crunch at that level. I've been relying on my effect pedal for all that. I'd like to use the amp more for drive like Neil Young does (I'm in a Neil Young Tribute band, thus the reason for the natural overdrive).

Anyways, I'll try the tubes first and see how that goes. If I need further control, I'll go for the pot mod. My local shop (Long and McQuade http://www.long-mcquade.com) doesn't have the JAN 5751 so I may have to go with the 12AY7/12AT7 tubes, unless I can find an equivalent through them (or order cross border from the US, which is a bit of a pain - I'm in Toronto, Canada).

Thanks again for all the help.

Mike


Links fixed.

In my opinion, people who complain about the master volume taper and the amp being too loud don't know how to use a master volume amp. In a non-master amp, you must turn the volume control up quite high to get any overdrive from the amp. Once you do, you get a combination of preamp overdrive (mostly even harmonics) and power amp overdrive (mostly odd harmonics). Depending on the speaker, you may also get some speaker breakup.

In a master volume amp, the best procedure is to just open the master volume control a little bit. Then you turn up the gain/drive volume to get the amount of preamp overdrive that you want. Once that is done, you turn up the master volume to the overall loudness level that you want. Master volume amps are designed primarily to provide mostly 2nd order/preamp overdrive. In order to get power tube overdrive you have to turn the master volume way up to the point that the amp behaves like a non-master amp. The BDRI does not have as much preamp gain as a Hot Rod Deluxe and many people don't like the sound of the BDRI drive channel. I don't use the drive channel at all, just the clean channel with a Fulltone FD-2M pedal in front of the amp.

Also keep in mind that when you replace the 12AX7 in V1 with a 5751 or 12AY7, the decrease in preamp gain will make the drive channel even less useful. With a 12AY7 in V1, depending on the guitar pickup output, I have to turn the drive volume up almost all the way to get any preamp gain .

JJ makes a 5751 tube (available through Eurotubes and others), and Electro-Harmonix makes a 12AY7 tube so you don't have to go to the expense of a vintage NOS tube if you just want to experiment.

I'm sure you know that Neil Young uses a vintage Fender Tweed Deluxe with the 6V6 power tubes replaced by 6L6GC tubes. He runs a fan on the amp to cool the transformers as the amp is set to maximum explode level. :lol: You won't duplicate that sound with a BDRI.

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Post subject: Re: some new tubes for a BDRI
Posted: Wed Feb 06, 2013 5:12 am
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Thank you!!

Ya, I don't know where I got the $250 from either. I must have confused it with another site I looked at. It was a flurry of link clicking and research last night :).

I do have a pretty descent DVM which I believe reads milliamps as well.

I shall give your tips a try with the levels. I guess I should have started out by warning the forum that I am not a proficient guitar player. I have been just learning enough to get by, which includes my understanding of the gear that I am using. We have a lead player in the band that covers all the Neil leads, I'm just the singer/Neil guy :). All this stuff is great for my learning curve. I really need to spend more time on my equipment.

Also, I totally realize that the modded '59 tweed deluxe that Neil uses is a totally different animal than the BDRI. The only reason I got the BDRI in the first place was because it was at the store when I was out on on impulse buying spree and it "looked" like the Neil amp (tweed). Because I wasn't really contributing much to the sound of our band back then, it served well as a prop more than anything else. But now that I am building my skills on guitar, I'm actually turning up the volume a bit and now I am wishing I could get more out of the amp and less out of the Digitech effect pedal. Hopefully with your tips I can do that in my jam room. With whatever I was attempting, The walls are shaking when I have the master @ 2 and the drive channel volume @ 2.

Failing this, I'm considering trying my hand at building a 5e3 from a kit. Originally, I had this hair-brained idea to build a secondary circuit right in the case of the BDRI with some sort of multi-contact, compound switch (a hack of sorts) to switch the amp between the BDRI circuit and the 5e3 circuit, sharing whatever components that they have in common (of course, not at the same time) - two amps in one cabinet. But I had an email exchange with a guy at TubeDepot and although he thought it was an intersting idea, he dismissed it saying there wasn't enough room in the cabinet. The switch I was thinking of would have been a rotary 5 position (standby for amp1 / amp1 power / off / amp2 power / standby for amp2). That way you would never be able to switch directly to the other amp without having to go through a standby toggle, then a power toggle. Stupid idea?

Anyways, thanks again for all the input.


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Post subject: Re: some new tubes for a BDRI
Posted: Wed Feb 06, 2013 5:20 am
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oh, and on replicating the Neil sound, even if I cloned all of his gear, I probably still couldn't come close to sounding like him :D . You know that saying about the quality of the gear doesn't make up for lack of skill - that applied to me (but I'm working on it).


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Post subject: Re: some new tubes for a BDRI
Posted: Wed Feb 06, 2013 4:49 pm
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bernard-shakey wrote:
Thank you!!

Ya, I don't know where I got the $250 from either. I must have confused it with another site I looked at. It was a flurry of link clicking and research last night :).

I do have a pretty descent DVM which I believe reads milliamps as well.

I shall give your tips a try with the levels. I guess I should have started out by warning the forum that I am not a proficient guitar player. I have been just learning enough to get by, which includes my understanding of the gear that I am using. We have a lead player in the band that covers all the Neil leads, I'm just the singer/Neil guy :). All this stuff is great for my learning curve. I really need to spend more time on my equipment.

Also, I totally realize that the modded '59 tweed deluxe that Neil uses is a totally different animal than the BDRI. The only reason I got the BDRI in the first place was because it was at the store when I was out on on impulse buying spree and it "looked" like the Neil amp (tweed). Because I wasn't really contributing much to the sound of our band back then, it served well as a prop more than anything else. But now that I am building my skills on guitar, I'm actually turning up the volume a bit and now I am wishing I could get more out of the amp and less out of the Digitech effect pedal. Hopefully with your tips I can do that in my jam room. With whatever I was attempting, The walls are shaking when I have the master @ 2 and the drive channel volume @ 2.

Failing this, I'm considering trying my hand at building a 5e3 from a kit. Originally, I had this hair-brained idea to build a secondary circuit right in the case of the BDRI with some sort of multi-contact, compound switch (a hack of sorts) to switch the amp between the BDRI circuit and the 5e3 circuit, sharing whatever components that they have in common (of course, not at the same time) - two amps in one cabinet. But I had an email exchange with a guy at TubeDepot and although he thought it was an intersting idea, he dismissed it saying there wasn't enough room in the cabinet. The switch I was thinking of would have been a rotary 5 position (standby for amp1 / amp1 power / off / amp2 power / standby for amp2). That way you would never be able to switch directly to the other amp without having to go through a standby toggle, then a power toggle. Stupid idea?

Anyways, thanks again for all the input.


The DVM will be set to read volts when used with a bias probe. The probe contains a precision 1 ohm resistor in the cathode circuit that you measure the voltage across. One volt measured across a 1 ohm resistor equals 1 amp. The probe also has circuitry to allow a direct reading of the plate voltage .

I considered building a 5E3 clone. Instead I built a 5F6A 1959 Bassman clone:

viewtopic.php?f=13&t=65668

I also converted a modern Champion 600 to a 5F1 Champ circuit using the stock PCB:

viewtopic.php?f=13&t=63259

I'm a better amp builder/modder/repairer than I am a guitar player. :lol: :lol: :lol:

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