It is currently Mon Mar 16, 2020 10:06 am

All times are UTC - 7 hours



Post new topic Reply to topic  [ 277 posts ]  Go to page Previous  1, 2, 3, 4, 5 ... 19  Next
Go to page Previous  1, 2, 3, 4, 5 ... 19  Next
Author Message
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Tue Nov 20, 2012 1:43 pm
Offline
Roadie
Roadie

Joined: Sun Aug 02, 2009 6:55 pm
Posts: 297
Location: Warren Mi
The only 50 legend is the GB speaker, hmm wonder if i get more head room with a 75 watt or more


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Tue Nov 20, 2012 4:05 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
Ok. Time to talk about speakers. But first, let's talk about speakers in general and some common terms.

Speaker diameter: Overall diameter of the speaker basket, not necessarily the speaker cone itself.

Impedance: This is a complex value made up of a magnitude and phase angle that represents the resistance of a speaker to alternating current (I am using "resistance" here as a generic term). Most speaker manufacturers only provide the magnitude of the speaker impedance expressed in ohms, typically 4, 8, or 16 ohm.

Power Handling: Usually the maximum power that a speaker is rated to handle before self destruction. :shock: A good rule of thumb is to use a speaker, or combination of speakers, rated to handle twice the rated power of the amp. It has been my experience that most good speakers are typically underrated by their manufacturer and most amps are overrated by theirs. :lol:

Sensitivity or efficiency: How loud a speaker will play given a certain level of input, usually 1 watt, and measured at a certain distance, usually 1 meter. It is expressed in dB SPL (Sound Pressure Level). Typical loudspeakers range in sensitivity from about 95 dB SPL to 105 dB SPL.

Magnet type and weight: Most modern and vintage speaker magnets are made with ALNICO or ceramic magnets. Several modern speakers are now being made with neodymium (Neo) magnets. For any given magnetic field strength, ALNICO magnets are the heaviest, followed by ceramic, with Neo magnets being the lightest.

Resonance and overall frequency response: The resonance of a speaker is the frequency at which the impedance magnitude is the greatest. Typical guitar speaker resonance is around 90 Hz. A bass speaker typically has a resonant frequency around 50 to 60 Hz. Below the resonant frequency, frequency response drops off drastically. Overall frequency response is usually expressed as the frequency range between the -3 dB points from the midrange response. Typical values are from about 70 Hz to a little over 5 KHz.

There are other speaker parameters, but they are of more concern to speaker cabinet designers than the average guitarist.

So, how does all of this apply to the BDRI and how do you choose a good speaker? Well, here is the order in which I look at things.

1. You have to choose a speaker that fits. Ok. This is a no brainer. :lol: The BDRI uses a 12" diameter speaker. I have seen plans (Sorry, but I lost the link) to put two 10" speakers in a BDRI. Obviously a new baffle must be made and the speakers are mounted on the diagonal like a low power Tweed Twin. It was pretty cool looking and the clip sounded great. Don't know if a 15" will fit, but I bet someone has tried.

2. The BDRI is rated to handle an 8 ohm speaker load or a 4 ohm speaker load if a second 8 ohm speaker is plugged into the extension jack at the same time. The owner's manual has a nice little chart showing acceptable combinations.

3. Choose a speaker with appropriate power handling capability. Since the BDRI is rated at 40 watts, a good choice would be in the 75 to 100 watt range. But, remember what I said about underrated speakers and overrated amps earlier? There are plenty of speakers that work well with the BDRI and sound good that are rated in the 50 to 60 watt range.

4. The BDRI can be a very loud amp. To counter this, some people may want to choose a speaker with a lower sensitivity rating to bring the volume down. The stock speaker is probably rated around 100 dB SPL so a speaker rated at 95 dB SPL would be a good choice. Keep in mind that for a speaker to sound half as loud as another, there has to be a 10 dB SPL difference between the two.

5. The tone of the speaker can only be truely evaluated with your own two ears. What sounds good to me may sound like crap to you. But, pretty much all manufacturers provide frequency response graphs of their speakers that can help you decide on a speaker. Keep in mind that most guitar amps don't really have a flat frequency response setting. Most guitar pickups are fairly midrangey in their output, so most amps typically have elevated bass and treble to try and smooth things out. Speakers are the same way. Here are the frequency response curves of two commonly used Eminence speakers:

http://www.eminence.com/curves/curves.p ... &width=580

http://www.eminence.com/curves/curves.p ... &width=580

Notice the difference in the upper midrange dips. The Private Jack has a deeper upper midrange dip than the Cannabis Rex. But the Cannabis Rex has a slightly higher and smoother treble peak than the Private Jack. The speaker sound descriptions are also telling.

Private Jack: Thick and smooth, with lots of mids and extended highs. Very will balanced speaker. Classic British flavor.

Cannabis Rex: Clean and full, with lots of body and sparkle. Smokey smooth with high-end definition.

6. Magnet type can play a big part in the sound of the speaker along with cone material. Personally, I find both to be of lesser importance than the other speaker concerns, but people do have their favorites.

So how do you decide? Well, like I said, the final decision should be made with your ears. Two common choices for the BDRI that I have seen mentioned time and again are the Celestion Gold,

http://celestion.com/product/6/celestion_gold/

and the Eminence Cannabis Rex,

http://www.eminence.com/speakers/speake ... nnabis_Rex

I use a Cannabis Rex in my BDRI and find the sound to be very smooth and perfect for Blues. Note also that both the C. Rex and Celestion Gold are only rated at 50 watts. However, I have yet to hear about anyone blowing these speakers up with a BDRI. They are both well built, very stout speakers.

Now that we have the big stuff, relatively speaking, out of the way, tomorrow we'll start talking about circuit mods.

_________________
Bill

Image


Top
Profile
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Tue Nov 20, 2012 4:09 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
ken361 wrote:
The only 50 legend is the GB speaker, hmm wonder if i get more head room with a 75 watt or more


Headroom is dependent on several factors, power handling being only one of them. How the cone is designed and its breakup modes will have a greater effect on headroom. It is possible to have a low power rated speaker breakup later than a higher power rated speaker and vice versa, given the same signal input.

_________________
Bill

Image


Top
Profile
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Tue Nov 20, 2012 4:56 pm
Offline
Aspiring Musician
Aspiring Musician

Joined: Fri Mar 16, 2012 12:49 pm
Posts: 838
This is a great thread, Bill :!:

Although most of what you're presenting is way above my knowledge base, I am trying to follow the flow and pickup as much as I can along the way.

Any chance you'll do a similar thread for the HRD? :wink:

Cheers and thanks!
BM

_________________
This is the Blues. Are you listening?


Top
Profile
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Tue Nov 20, 2012 5:07 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
Bluer Monkey wrote:
This is a great thread, Bill :!:

Although most of what you're presenting is way above my knowledge base, I am trying to follow the flow and pickup as much as I can along the way.

Any chance you'll do a similar thread for the HRD? :wink:

Cheers and thanks!
BM


You're welcome. Feel free to ask questions about anything I say. Its gonna get a little deeper from here on out.

Sorry, but I don't have a HRD and there are a number of significant differences between it and the BDRI. In general, most of what I talk about could be applied to the HRD like tube and speaker choice, but the the sound and intended uses of the two amps are different. Some of the circuit changes I will be discussing could be applied to the HRD but there are differences in the circuits, component values, and part identifiers. You would have to compare the schematics to really figure out would would work and what wouldn't.

_________________
Bill

Image


Top
Profile
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Tue Nov 20, 2012 5:59 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
Great posts Bluesky!

In addition, IME... headroom can be also how the input and gain stage (and PI) tubes are setup. How much clean voltage they can "swing." Fender tends to run them on the conservative side (esp in vintage amps). This yields a wider swing before going into cut-off and OD.

Other vintage amps, like some Marshalls and Voxes run them a bit harder to get earlier compression, cut-off, and OD.

Front-end tone shaping --- along with tone-stack setup. :D is becoming a bit of a lost art. But, really that's all a lot of pedals are doing. Though, digitally, in most cases. There is a difference.


Top
Profile
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Tue Nov 20, 2012 6:06 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
BMW2002Ti wrote:
Great posts Bluesky!

In addition, IME... headroom can be also how the input and gain stage (and PI) tubes are setup. How much clean voltage they can "swing." Fender tends to run them on the conservative side (esp in vintage amps). This yields a wider swing before going into cut-off and OD.

Other vintage amps, like some Marshalls and Voxes run them a bit harder to get earlier compression, cut-off, and OD.

Front-end tone shaping --- along with tone-stack setup. :D is becoming a bit of a lost art. But, really that's all a lot of pedals are doing. Though, digitally, in most cases. There is a difference.


Thanks.

All true. I was just addressing speaker headroom/breakup. The 6" speaker in my 5F1 modded Champion 600 reissue breaks up a lot sooner than the 12" cab I normally plug into. :lol: :lol: :lol:

_________________
Bill

Image


Top
Profile
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Tue Nov 20, 2012 6:22 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
Great thread bluesky636

_________________
---> "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.


Top
Profile
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Tue Nov 20, 2012 6:57 pm
Offline
Aspiring Musician
Aspiring Musician

Joined: Fri Mar 16, 2012 12:49 pm
Posts: 838
bluesky636 wrote:
You're welcome. Feel free to ask questions about anything I say. Its gonna get a little deeper from here on out. ...
Thanks, Bill. Well, before we dive into the deep end, I'd like to ask about the tubes.

  • Apart from the differences in gain, are there other differences between the various 12AX7 compatible replacement tubes such as the 5751, 12AT7, 12AY7?
  • From what I recall from a chart on the tubestore website, 12AX7 are 100 gain and 12AY7 45 gain. Does this translate to about a 50% drop in volume? (I'm probably not using the correct term here, but I hope you understand what I'm asking)

Thanks & Cheers!
BM

_________________
This is the Blues. Are you listening?


Top
Profile
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Tue Nov 20, 2012 9:37 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
shimmilou wrote:
Great thread bluesky636


Thanks, shimmilou. :D

_________________
Bill

Image


Top
Profile
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Tue Nov 20, 2012 10:21 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
Bluesky, Oh boy! :lol: :lol:

What was the name of that mind exercise program to help slow down Dementia?


Top
Profile
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Tue Nov 20, 2012 10:27 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
Bluer Monkey wrote:
bluesky636 wrote:
You're welcome. Feel free to ask questions about anything I say. Its gonna get a little deeper from here on out. ...
Thanks, Bill. Well, before we dive into the deep end, I'd like to ask about the tubes.

  • Apart from the differences in gain, are there other differences between the various 12AX7 compatible replacement tubes such as the 5751, 12AT7, 12AY7?
  • From what I recall from a chart on the tubestore website, 12AX7 are 100 gain and 12AY7 45 gain. Does this translate to about a 50% drop in volume? (I'm probably not using the correct term here, but I hope you understand what I'm asking)

Thanks & Cheers!
BM


There may be physical differences between the construction of the various tubes that account for differences in noise level, tone, etc. Otherwise, the 12AX7, 12AY7, and 5751 are direct replacements for each other and do not require any changes in bias or circuit design for good performance. The 12AT7 is compatible but may require a change in bias level for optimum performance. For the most part, it really doesn't matter though.

However, the big thing to watch is the current drive capability of the various tubes, particularly when used as a phase inverter. A 12AX7 is capable of a plate current of 1.2 mA, a 12AY7 of 3.0 mA, and a 12AT7 of 10 mA. I don't have the specs handy for a 5751 but I believe it is in the range of the 12AX7 and 12AY7. In the Tweed era, Fender used the 12AX7 as the PI. The Blackface/Silverface amps use a 12AT7. If an amp is designed to use a 12AX7 as a PI, you can generally substitute a 12AT7. The higher plate current capability of the 12AT7 is of no consequence as the power amp stage will only draw what is needed and it was designed for the 12AX7 current output. However, if the PI is designed for use with a 12AT7 in mind, the power amp stage may draw more current than a 12AX7 could provide. You would not get optimum performance in that case. In fact, the amp might not even work or sound very good it it did.

No, a 12AY7 is not half as loud as a 12AX7. The gain of a tube stage is dependent on the circuit design as well as the tube's gain factor. Plate voltage and current, bias level, use of a bypass cap on the cathode, etc. all go into figuring the gain of a tube stage. As an example, a preamp stage using a 12AX7 and no bypass cap on the cathode resistor has a midrange frequency gain of about 25 dB. A 12AY7 with a 22 mF cathode bypass cap (a typical value used in Fender amps) has a midrange frequency gain of about 30 dB. 5 dB greater than the 12AX7. I used this calculator to come up with those numbers:

http://ampbooks.com/home/amplifier-calc ... capacitor/

Even more interesting is the fact that a 12AX7 configured as a cathode follower (as used to drive the 12AX7 PI in teh 5F6A Bassman) has zero gain: output voltage = input voltage.

http://ampbooks.com/home/amplifier-calc ... -follower/

You just dove into the deep end of the pool. :lol:

_________________
Bill

Image


Top
Profile
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Tue Nov 20, 2012 10:28 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
BMW2002Ti wrote:
Bluesky, Oh boy! :lol: :lol:

What was the name of that mind exercise program to help slow down Dementia?


Uh, I forget. Seriously. :oops: :lol:

_________________
Bill

Image


Top
Profile
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Wed Nov 21, 2012 6:20 am
Offline
Aspiring Musician
Aspiring Musician

Joined: Fri Mar 16, 2012 12:49 pm
Posts: 838
bluesky636 wrote:
... You just dove into the deep end of the pool. :lol:
Indeed. You lost me a little with "bypass capacitor", "cathode resistor", and "cathode follower" so I consulted with our friend Google and was able to put some of the pieces of the puzzle together. It's still fuzzy but slowly coming into focus. :lol:

Thanks for taking the time to write such a detailed reply. Looking forward to future episodes.

Cheers!
BM

_________________
This is the Blues. Are you listening?


Top
Profile
Post subject: Re: Modifications To The Fender Blues Deluxe Reissue Amp
Posted: Wed Nov 21, 2012 7:31 am
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
Bluer Monkey wrote:
bluesky636 wrote:
... You just dove into the deep end of the pool. :lol:
Indeed. You lost me a little with "bypass capacitor", "cathode resistor", and "cathode follower" so I consulted with our friend Google and was able to put some of the pieces of the puzzle together. It's still fuzzy but slowly coming into focus. :lol:

Thanks for taking the time to write such a detailed reply. Looking forward to future episodes.

Cheers!
BM


Yeah, sorry. I'm a systems engineer by profession and an electrical engineer by degree. I have to know why things do what they do. The upcoming discussion will use more of those calculators to explain why the mod does what it does, but I'll also just explain what the mod is and the result so the math can be skipped.

If you want some good books that explain all this in simple terms, these are some good ones:

http://www.amazon.com/Guitar-Amplifier- ... ap_title_0

http://www.amazon.com/How-Hot-Rod-Your- ... ap_title_0

http://www.amazon.com/The-Guitar-Amplif ... pd_sim_b_1

For more detail (and a lot of math!) I recommend these:

http://www.amazon.com/Circuit-Analysis- ... d_sim_b_39

http://www.amazon.com/Vacuum-Tube-Circu ... pd_sim_b_5

http://www.amazon.com/Vacuum-Tube-Circu ... pd_sim_b_5

http://www.amazon.com/gp/product/075063 ... 04_s00_i00

Just for fun:

http://www.amazon.com/Amped-Illustrated ... d_sim_b_17

http://www.amazon.com/The-Soul-Tone-Cel ... d_sim_b_14

_________________
Bill

Image


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 277 posts ]  Go to page Previous  1, 2, 3, 4, 5 ... 19  Next
Go to page Previous  1, 2, 3, 4, 5 ... 19  Next

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: