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FDP Forum / Amp Mods, Repairs, and Projects / Speaker and/or tube upgrade?

Contributing Member

Vero Beach FL

Tbird Greg
Dec 14th, 2016 05:54 AM   Edit   Profile  

I have a new HRD III. It is all stock. I like the sound of it as is, but I am influenced by all FDP'ers who replace the speaker and tubes. I would consider upgrading, but without being able to hear the differences between stock and replacements, I wouldn't know what speaker or tubes I would go with.

I'm an old-school guy who wants sweet chimey cleans with a bluesy OD sound. That's about as definitive as I can get, yet those terms mean something different to everyone. But I would like to hear what speakers and/or tubes you've upgraded to and the reasons for your choices.

Contributing Member

Northern VA

The Fine Line Between Clever & Stupid
Dec 14th, 2016 01:49 PM   Edit   Profile  

I have a '96 HRD and changed out the speaker to a Mojotone 70w Greyhound and the tubes with JJ's:

V1: 12AY7, those have a gain factor of 45. For comparison the 12AX7's that come stock in the HDR have a gain factor of 100.

V2: 12DW7, it's a dual triode tube with gain factor of 100 on one side like the HRD stock 12AX7, but the other triode has a gain factor of only 20

V3: 12AT7, those have a gain factor of 60.

2 6L6's
Biased to 67. If you don't know how to bias, it's VERY easy on the HRD...just follow the instructions very closely.

It really made the volume far more manageable. It's still loud...but not the nothing to ground shaking volume with nothing in-between like before. You can actually play it in a living room, still not the best choice of an indoor amp but it is possible now.
The lower gain tubes made the drive channel a little more usable...to my ears. The clean channel is better than before with very, very slow break up...it becomes too loud at home before that happens. I'm not a high gain type of guy, old blues and Stones' OD is my choice.

(This message was last edited by daveg at 05:41 PM, Dec 14th, 2016)



Dec 15th, 2016 02:16 PM   Edit   Profile  

Jensen C12N

Contributing Member

I say 'no' to drugs

They never listen
Dec 15th, 2016 04:59 PM   Edit   Profile  

Speaker type totally depends on how you like the amp to respond.

Ceramic-mag speakers are a bit "faster" than Alnico. They are generally punchier because they damp faster. Ceramic magnet properties are fairly unaffected by the AC current in the voice coil.

Alnico-mag speakers generally slur the notes a bit as you crank up the volume past 7 or so because they compress a bit. This is due to the alnico's magnetic properties that cause it to demag and remag as AC flows through the voice coil. This is huge if you're going for an old-school blues tone and response.

It's also the reason why 99.9% of all speakers used for bass amplification are ceramic or neodymium--they're punchier and more crisp.



Dec 19th, 2016 04:01 AM   Edit   Profile  

My understanding is that it takes a lot of energy to demag / remag permanent magnets, and that it's not feasible for guitar amps to do that to the magnets in their speakers.
So Weber's explanation of alnico magnets demagnetising and remagnetising with the ac in the voice coil is not technically correct.
See link

External link

Contributing Member

Irishman in Paris

It's just a guitar, not rocket science.
Dec 19th, 2016 05:34 AM   Edit   Profile  

First let's just make clear that the compression that Peegoo is taking about occurs when the AlNiCo speaker is driven close to it's power handling limit. With a HRD running at home volume levels it'll react just like a ceramic magnet and the onset of any compression will be gradual as you turn up the volume. And if you run a 35 Watt speaker in a 15 watt amp, the amp might never generate enough output current for it to occur.

As an ex-physicist I simply cannot say if the compression in AlNiCo speakers is a myth or not, I just don't have the expertise in magnets to look at the data and tell you if it's true or not. I am open to the idea that it's a myth (because the guitar industry is full of very pervasive misunderstandings). I do note that Celestion and Weber refer to it on their websites, Eminence simply says AlNiCo has a "reputation for sounding compressed" and Jensen and avoid the subject.

Contributing Member

Vero Beach FL

Tbird Greg
Dec 19th, 2016 05:37 AM   Edit   Profile  

I'm just going to use the amp stock until I hear one that has been modded with different tubes or different speaker. Maybe then I'll decide if I like that sound and make changes. Until then, I like the sound as is. Some people are just tinkerers who enjoy swapping out parts and such, but I'm not one of them.



Dec 19th, 2016 11:13 AM   Edit   Profile  

DrKev, I can't find anything on the Celestion site regarding the dynamic demag/remag hypothesis?

Also note that all the 12" Celestion alnico speakers look to use a similar weight magnet, so it seems likely that they have a broadly similar mag strength, flux density etc.
Yet the VC ratings range from 15 to 90 watts.
So I don't see that the magnet in a Blue could the demag/remag thing at ~12 watts, whereas the Cream magnet would hold off until the power level hit 85 watts; it just doesn't seem feasible.
I suspect that Ted was just trying to explain the BH curve in layman's terms, and in doing so, unwittingly started an internet myth.

Contributing Member


I like guitars and amps
Dec 19th, 2016 06:35 PM   Edit   Profile  

I have a Weber 12F150 8 ohm in Ft Laud if you want to consider it. we can meet for lunch somewhere in the middle.(Maybe on a golf course) for a handoff

Contributing Member

Irishman in Paris

It's just a guitar, not rocket science.
Dec 21st, 2016 11:09 AM   Edit   Profile  

@pdf64 - the blurb for the Celestion blue speaker says...

"When coupled with a suitable amplifier it evokes rich definition and develops beautiful musical compression when pushed."

That may be the only mention though!



Why do I keep fixing things that work?
Dec 21st, 2016 12:51 PM   Edit   Profile  

On my Hot Rod Deluxe, the best change I have done is: Eminence Texas Heat speaker, which keeps all the Fender vibe but doesn't flub out on the low frequency, tubes: JJ 6L6GC, 1st preamp tube is a JJ hi-gain 12AX7, next are old RCA 12AX7's. When I had the RCA in the first position, it gave me a really nice dimensional tone that was beautiful but lost some of distortion characteristics, so I went back to the hi-gain 12AX7's there and the other tubes allowed it to perform better and translated the distortion nicely without any harsh characteristics. After trying many combos of tubes, I settled on this. But the first thing I did was the speaker upgrade and it was the most significant thing I did to improve the overall response and sound quality, the tubes helped to define what I was looking for in my sound.
Be careful, once you start the more you can't stop yourself!
Best regards, Woody

(This message was last edited by Cal-Woody at 03:23 PM, Dec 21st, 2016)

FDP Forum / Amp Mods, Repairs, and Projects / Speaker and/or tube upgrade?

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