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Post subject: Speaker swap for Blues Deluxe
Posted: Sat Jun 04, 2011 1:20 am
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I have a Mexican Blues Deluxe that is, on the whole, a good little amp but I feel the tone is lacking in some ways. I've yet to find a Fender amp that couldn't be improved with a speaker swap, so that's what I'm thinking of. I generally favour Celestions and am thinking probably either a Vintage 30 or one of the chinese G12-H's. The question is which variant, and specifically what impedance? I know that 8 ohm is "correct" but...

I used to have a Silverface Twin Reverb (100w master volume model) that had a pair of Celestion G12-H's in it - that was an awesome amp, but not very practical. I didn't have a car at the time, and a Twin is heavy enough before you stick about 10kg's of speakers in it, so it had to go. That was about 15 years ago, I still miss it and am still searching for something with comparable tone... I'm sure there was a crazy combination of all sorts of voodoo that contributed to the tone of that amp, but I suspect the speakers were a big part of it - not least because they were 16ohm speakers, giving an 8 ohm load overall. I think this resulted in the power amp getting worked a bit harder and overdriving earlier than would be the case with a pair of 8 ohm speakers to give 4 ohm overall. Whatever, it made glorious noises, especially with guitars with fat single coils - which is still my preference where pickups are concerned.

Has anyone any comments on this? I appreciate that it will put additional stresses on components, etc. but would replacing the 8ohm Eminence with a 16 ohm Celestion be a totally stupid idea?

Thanks in advance,

G


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Post subject: Re: Speaker swap for Blues Deluxe
Posted: Sat Jun 04, 2011 9:48 am
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A Blues Deluxe Reissue is not going to sound like a Silverface Twin Reverb no matter what you do to it. They are completely different amps.

What tubes are you using? Have you tried adjusting the bias on the power tubes? Fender sets them to be very cold stock. That tends to sound sterile and brittle. I am running a Phillips JAN 5751 in V1, a JJ 12AX7 in V2, a JJ 12AT7 in V3, and JJ 6L6GCs in V4/5. My power tubes are biased at 38 mA cathode current (36 mA plate current) at 413 VDC plate voltage. This equates to about 83 mV at the Fender bias test point. I am running the stock speaker and with this tube setup have no desire to change speakers.

If you do decide to replace speakers, the Eminence Cannibus Rex is a common choice. Stick with an 8 ohm speaker no matter what.

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Post subject: Re: Speaker swap for Blues Deluxe
Posted: Sat Jun 04, 2011 10:15 am
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bluesky636 wrote:
A Blues Deluxe Reissue is not going to sound like a Silverface Twin Reverb no matter what you do to it. They are completely different amps......Stick with an 8 ohm speaker no matter what.


+1, +1

Arjay

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Post subject: Re: Speaker swap for Blues Deluxe
Posted: Sat Jun 04, 2011 1:25 pm
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Hi hopkinsgm,

You have an external speaker jack that you can connect to another 8 ohm speaker cabinet. The HRDlx extension cabinet comes with a Celestion G12 P80 and when used with the BDlx will give you much more tight/bassy sound from the amp. The closed back of the ext cab will also do wonders for the Eminence speaker. I put the Celestion from the ext cab into the BJr, and put the Eminence speaker from the BJr into the ext cab and the Eminence sounds much better in the cab than it does in either amp (HRDlx or BJr). Now I sometimes use the HRDlx with the internal Eminence speaker and the cab with an identical Eminence speaker and the two combine very well. Just another option for you. :idea:

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Post subject: Re: Speaker swap for Blues Deluxe
Posted: Sat Jun 04, 2011 11:05 pm
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Retroverbial, bluesky636 - I appreciate that the Blues Deluxe is not a Silverface Twin Reverb and will never recreate that sound. For the record, my old Silverface Twin Reverb sounded nothing like a typical Silverface Twin Reverb either... :wink:

The reason I mentioned the old Silverface Twin Reverb was to illustrate the point of hanging a bigger speaker load off the power amp. What I was pondering was how big an impact this had on the sound of the amp (I suspect that it contributed to a power amp that would slip into overdrive at relatively sensible - i.e. less than ear-splitting - volume levels). I was wondering whether it would be worthwhile trying this on my Blues Deluxe as I am looking to change the speaker anyway.

Thanks for the tips on valves and bias bluesky 636 - something else to try. I thought I'd read somewhere that bias on the Blues Deluxe is not adjustable though. If this is true, presumably there are some additional tweaks required?

Thanks also to shimmilou for the thoughts on speakers. I don't really need an extension cab though, so this would be quite an expensive way of swapping the speaker unless a s/h extension cab comes up cheap (though I suppose I could sell on the surplus cab with the unwanted speaker). I will try to find some additional info on the Celestion G12 P80 though.

Oh, and why so much concern about sticking with an 8 ohm speaker? My understanding is that it will make the coupling less efficient, but that's not exactly the end of the world. Or are you concerned about reliability from stressing components in the power amp? My old Twin ran for many years with a bigger speaker load attached whilst in my ownership, and I never noted an reliability issues. And who knows how long before that the speakers had been swapped (or indeed how long it continued with its' subsequent owners).

Cheers,

G


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Post subject: Re: Speaker swap for Blues Deluxe
Posted: Sat Jun 04, 2011 11:59 pm
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If you have a Mexican built Blues Deluxe, it is a Blues Deluxe Reissue, in which case it has an adjustable bias pot. If you have an original issue (from the 90s), American built Blues Deluxe, it does not have an adjustable bias pot.

The Blues Deluxe Reissue is designed to handle a 4 or 8 ohm load. It is not designed to handle a 16 ohm load. Although it may work with a 16 ohm load, I do not beleive is stressing an amp in a way it is not designed for. If you want to run a 16 ohm speaker, be my guest.

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Post subject: Re: Speaker swap for Blues Deluxe
Posted: Sun Jun 05, 2011 1:03 am
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Thanks for clearing up my confusion on the biasing arrangements bluesky636 - it is a Mexican built Blues Deluxe (as stated in my initial post), so will look into biasing next time the amp, a test meter and I are all in the same room. Improving the sound with zero outlay would be ideal!

I will also look into alternative valves as you suggested in your earlier reply - I've dug up a little info about the Philips JAN 5751, and that sounds a particularly interesting valve. I used to read a lot of comments about various valve manufacturers with frustration as there was so little choice readily available in the UK. Thankfully, that seems to be changing as a lot of the specialists suppliers in the UK are more actively marketing their wares. It's also become *much* easier to source what we can't find in the UK from the US these days.

Will start with valves and biasing before worrying about speakers if I have to. Thanks for your valued thoughts and advice.

Cheers,

G


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Post subject: Re: Speaker swap for Blues Deluxe
Posted: Sun Jun 05, 2011 1:13 am
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SRV used to play a lot of games with mismatched loadings vis-a-vis output trannies and speaker impedances. But he was a star -- with a substantial budget for gear (including plenty of spares should one of his amps fail) and one of the most legendary amp techs to ever hotrod a Fender chassis on staff to keep his rigs tuned and running.

If you have that kind of logistic and tech support, use any speaker you care to. But keep this in mind -- your 100-watt Twin Reverb was designed by Leo Fender personally and built by trained technicians using mostly mil-spec components. You labor under false pretenses if you think the amps of today can withstand the abuse heaped upon the Fender amps of yore and survive.

Arjay

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Post subject: Re: Speaker swap for Blues Deluxe
Posted: Sun Jun 05, 2011 6:36 am
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hopkinsgm wrote:
...Oh, and why so much concern about sticking with an 8 ohm speaker? My understanding is that it will make the coupling less efficient, but that's not exactly the end of the world...


That's it exactly. The amp will not magically produce more power just because the impedance is other than "matched". If fact, more or less impedance will result in less power produced as the "matched impedance" will allow the amp to produce the most power.

The real danger is to have too high an impedance, an "open" being the worst case. At some point the impedance can be high enough that the output transformer can fail, but the number isn't exactly definable as to what is too high. Stick within the range of 2 to 1 on any mismatch and the amp will be fine. Example, an "8 ohm" amp can easily handle a 4 ohm or 16 ohm speaker load.

The impedance rating on a speaker is a "nominal" value after all, as the impedance of speaker and amp are dependent on the frequency being produced. :idea:

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Post subject: Re: Speaker swap for Blues Deluxe
Posted: Sun Jun 05, 2011 8:02 am
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After a merry day of surfing, I've read an awful lot of info - some of it possibly total tosh, but that's the joys of the internet for you. I've also seen an awful lot of references to Blues Deluxes that completely ignore the existence of the Mexican made Blues Deluxe Reissues which has, at times, confused and confounded me. Hopefully I've managed to get the differences clear in my head. And hopefully I'll get over it... :wink:

Anyway, back to my original query - I've seen a few sources saying "don't", but very few that could offer a reasoned technical argument why not. The best (most plausible) technical reason I have come across for not trying to drive too big a load (i.e. 16ohm load when expecting 8ohm) is that it will result in overvoltage at the anode of the power amp valves. It seems that the quality of the power amp valves (specifically how good the vacuum in the valve is) will play a major part in determining what happens. In an ideal world, the HT fuse *should* do it's job and keep things safe, but if it doesn't, there's a rather more elaborate fuse called an "output transformer" :!:

Retroverbial's comments about build quality of modern amps noted - I was aware that these days everything is built down to a price, but hadn't realised the extent to which this had affected valve amps. Well, if I'm honest, it's not that I hadn't realised, as that would suggest I'd actually thought about it previously... :oops:

Anyway, looks like I've got some valve shopping to do - Watford Valves seems to be the UK supplier I've seen mentioned in a positive light most frequently. Thanks to everyone who has contributed for all your thoughts and advice, and for making this a noob-friendly forum!

Cheers,

G


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Post subject: Re: Speaker swap for Blues Deluxe
Posted: Sun Jun 05, 2011 8:19 am
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Here is a site with a great explanation of tube amp transformers and impedance. Just scroll down about half way on the page to:

"Q: What does the "impedance" of my output transformer mean?"

http://www.geofex.com/tubeampfaq/tubefaq.htm#transformers

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Post subject: Re: Speaker swap for Blues Deluxe
Posted: Sun Jun 05, 2011 12:34 pm
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hopkinsgm wrote:
After a merry day of surfing, I've read an awful lot of info - some of it possibly total tosh, but that's the joys of the internet for you. I've also seen an awful lot of references to Blues Deluxes that completely ignore the existence of the Mexican made Blues Deluxe Reissues which has, at times, confused and confounded me. Hopefully I've managed to get the differences clear in my head. And hopefully I'll get over it... :wink:

Anyway, back to my original query - I've seen a few sources saying "don't", but very few that could offer a reasoned technical argument why not. The best (most plausible) technical reason I have come across for not trying to drive too big a load (i.e. 16ohm load when expecting 8ohm) is that it will result in overvoltage at the anode of the power amp valves. It seems that the quality of the power amp valves (specifically how good the vacuum in the valve is) will play a major part in determining what happens. In an ideal world, the HT fuse *should* do it's job and keep things safe, but if it doesn't, there's a rather more elaborate fuse called an "output transformer" :!:

Retroverbial's comments about build quality of modern amps noted - I was aware that these days everything is built down to a price, but hadn't realised the extent to which this had affected valve amps. Well, if I'm honest, it's not that I hadn't realised, as that would suggest I'd actually thought about it previously... :oops:

Anyway, looks like I've got some valve shopping to do - Watford Valves seems to be the UK supplier I've seen mentioned in a positive light most frequently. Thanks to everyone who has contributed for all your thoughts and advice, and for making this a noob-friendly forum!

Cheers,

G


Blues Deluxe (and Deville) Reissue service manual:

http://www.blueguitar.org/new/schem/fen ... eissue.pdf

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Post subject: Re: Speaker swap for Blues Deluxe
Posted: Sat Aug 06, 2011 5:38 pm
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Damn, they make the BDRI's in Mexico :shock: ? I have got to get on this forum more often...

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Post subject: Re: Speaker swap for Blues Deluxe
Posted: Sat Aug 06, 2011 6:40 pm
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ny_byooboy wrote:
Damn, they make the BDRI's in Mexico :shock: ? I have got to get on this forum more often...


These amps (and the companion HR's) used to be billed in the catalog as "All-American Tube Amps" but that was quite some time ago -- like eight or nine years now. Today, they all come from Ensenada.

Arjay

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