OT Tube & spkr advice on fixing up my SF Deluxe Reverb

[Johnny Guitar]

Hello,

I recently used my 78 Deluxe Reverb and jammed with a drummer (I haven't been jamming much in recent years) and I noticed I couldn't compete with his volume. This has happened when a bass player was involved, and often with another guitar player.

So I want to put a new speaker in it. I replaced the old (with a ceramic magnet I think) original speaker with a very old Jensen Special Design which I loved but blew out too many times. I still have the speaker but don't want to recone it again until I can figure out if it is severly under powered for a Deluxe (?) or if something else is causig it to blow out constantly (maybe the AlNiCo magnets are going bad?). Eventually that was replaced with a Celestion 25W 16 ohm greenback. I really like the sound on my Strat (fierce) but I lose the definition with my Les Paul (it has those reissue PAF HBs).

I'm hoping that when I go back to an 8 ohm speaker I will get more volume and better definition at higher volume. I have this same problem with one of my SF Champs. It (obviously) has an 8 ohm ceramic magnet speaker. My other one, with a "Fender" Special Design (obviously a rebranded Jensen), really kicks ass.

So I'm looking at two speakers from Antique Audio. One is a Celestion:

http://www.tubesandmore.com/new/scripts/silverware.exe/moreinfo@d:/dfs/elevclients/cemirror/ELEVATOR.FXP?item=P-A-VINT30

The other is an AlNiCo Jensen Special Design:

http://www.tubesandmore.com/new/scripts/silverware.exe/moreinfo@d:/dfs/elevclients/cemirror/ELEVATOR.FXP?item=P-A-P10Q

I was also going to give my amp a retube. I'm thinking of using Groove Tubes in the preamp section (12ax7s and 12at7s) and Fender tubes for the rectifier and the 6v6s ( a matched pair -- so I don't need to worry about rebiasing)

Anyone have any opinions on speakers and tubes?

Let me know!

Thanks as always.
John

[jasonober]

this is a great place to buy tubes IMO:
http://eurotubes.com/index.htm

[bwanasonic]

I really like the Weber Alnico BLue Dog, but that might not be the best match for a Deluxe. Spend some time at the Weber site, and I'm sure you could get an idea of which model best suits your amp. As for tubes, there are a number of good suppliers of new and NOS tubes. Check out:

Lord Valve-

http://www.nebsnow.com/LordValve

KCA NOS Tubes-

http://www.kcanostubes.com/index.html#index

For new JJs, Bob at Eurotubes-

http://www.eurotubes.com/index.htm

I'm curious to try the Groove Tubes 12AX7-M (the one they actually make), but as for the rest of the rebadged chinese/russian/yugo stuff they offer, I usually opt not to pay the premium they charge for printing their logo on the tube.


Kerry M

[Nasse]

Somebody recommended Eminence Red Fangs, almost similar to Celestion Blue bulldogs but cheaper

[Fret Wire]

I'd go with the Jensen Alnico, the Vintage 30 is a nice speaker, but may sound too bright in your Deluxe.

For tubes, I'd go with NOS JAN 6v6's, along with JAN 12ax7's/at7's. Be aware, some so called "matched sets" aren't that well matched. You can usually score NOS Jan's relatively cheap on Ebay. Before you spend too much money on pre-amp tubes, remember that the reverb tubes and tremolo tubes need not be low noise or non-microphonic, just rugged. If you don't want to go NOS, try the new JJ (Telsa) 6v6's, they have a good tone and reliability for new production tubes.

Here's good source for the JAN's, and the new JJ 6V6's:

http://www.thetubestore.com/

[Lonestarjohnny]

yo!
You will still need to have your bais checked, just because a set of tube's are matched does not mean diddly, each set of groove tube's are supposed to be gain matched, that's what all the write'in on the tube base is about, Gain, if you had a set of GT's in your amp and nuthin has changed from vibration, and your old GT's were graded with a 7 on the tube base, then you might get away with buying a new set with the # 7 grade on the box and if all's well they should work with out changeing the bais,
I just checked a new Quad of matched GT KT66's on my Hickok tube tester and guess what, we had to take them back and get them exchanged, they were 35 Microhm's apart, not good, could'a caused a problem being that far off, the exchanged set was better, only 5 microhm's apart and they sounded pretty good running the bais at 47 1/2 neg. V. DC.
Johnny

[Johan]

Hello,


I'm hoping that when I go back to an 8 ohm speaker I will get more volume and better definition at higher volume. I have this same problem with one of my SF Champs. It (obviously) has an 8 ohm ceramic magnet speaker. My other one, with a "Fender" Special Design (obviously a rebranded Jensen), really kicks ass.

John

if you are using a 16ohm speaker on that Deluxe's 8ohm output, you only get about 12-15 watts out when maxing the volume.
if you have a lot of bass in you sound I would go with a speaker with a little stiffer cone. many of the new reissue alnico speakers have very thin cones that, to me, doesnt seem to like too much bass when pushed. resulting in muddy mids and almost out of tune lows ( just an opinion...)
if you decide on Celestion, you can never go wrong with the classic G12T75..or if you are on a budget, the low cost "Super-65" is much better than most people expect...

Johan

[Johnny Guitar]

Wow! As always, a lot of great help here .

As far as a speaker, I'm now leaning toward that Jensen Special Design since it's cheaper and I did like the sound of my other old one (until I realized I needed to recone it every six months  :evil: -- I wonder if I can see a power rating on it if I pull off the bell cover, maybe it's only a 15W speaker?). The other reason is that everyone mentions it may be too bright, but I really love a rather piercing sound. As long as it isn't too piercing with my Strat (I used to have major problems with my Strat into a Marshall Super Lead 100). It's a bit of a balance to get it set up to work well with both Gibson HBs and a Strat.

As far as tubes, I clearly have a lot to learn :oops: . There are a lot different tube places and prices and a lot to think about.

Since the amp has *never* be re-biased for the power tubes, I'd hoped that if I put in a pair of matched Fender tubes they would be close to the original spec. Given what's been said (especially by Lonestar Johnny) I guess I have WAY too much faith in any of these mfg. quality control houses. I don't want to learn how to re-bias an amp at this moment. Though I do want to get into this this comming year -- as well as building a couple of tube amp kits.

But I appreciate the links and the insights -- keep 'em coming if you have any more!
Thanks!
J

[ErikMiller]

My recommendations are as follows:

Definitely go to an 8 ohm speaker for the Deluxe and a 4 ohm for the Champ.

Go to Antique Electronics Supply and get either Electro-Harmonix 12AX7EH's or JJ ECC83S's for the 12AX7 positions, a JJ ECC81 for the 12AT7, and a matched pair of Electro-Harmonix 6V6's for the output. In my listening tests, the EH 6V6's are closest to old RCA's in tone. The EH 12AX7's have the most gain; the JJ's sound a touch less aggressive.

As for what brand of speaker, I like Weber VST speakers, but the Jensens or Sicas they sell at Antique Electronics will probably sound pretty good in there, too. Sica is the company that manufactures the Jensen reissues.

It's the impedance mismatch that is probably responsible for your loss of volume.

Have the amp biased by a pro. Call around and ask what they charge in your area.

[Johnny Guitar]

The Weber speaker prices are more than I'm wanting to pay right now, but as I looked around on the site I saw the "Bias Right kit" to bias output tubes.

I've been reading the GEO tube faq and a few other things -- I think I will probably get two of the Bias Right kits and learn to do it myself.

All the links and suggestions are really helping me!
J

[Fret Wire]

If you don't mind a brighter sound, the Jensen C12-Q or C12-N are very affordable ceramic choices. They are usually on the bright side till they break in.
http://www.tubesandmore.com/new/scripts/silverware.exe/catalog@d:/dfs/elevclients/cemirror/ELEVATOR.FXP?PAGE=SUBCAT&SEARCH_TREE01=SPEAKERS&SEARCH_TREE02=01JENSENVINTAGE&SEARCH_TREE03=CERAMIC

It's all subjective to your ears. Take tubes, the EH 6v6 has always been advertised as being close to the "RCA" sound. They've never sounded that good to me. With 21 amps that take 6v6's, I've tried more than a few. And as I'm sure Lonestarjohnny (JD) will tell you, the plate voltages Champs and Deluxe Reverbs run at will quickly weed out less rugged tubes. Of course, I don't want to pay RCA blackplate, grayplate, Mullard, or Brimar prices either. The JAN's offer a good price to tone ratio.

As everybody else pointed out, you definately need to rebias. Your resistors and caps have drifted to some degree with age, and newer production tubes make it wise to check bias always. Back when tube production was domestic and high quality, re-biasing or matching when changing tubes wasn't as important, reliability wise. Once bias was set by the factory, re-biasing was more fine tuning for tone. Biasing and Matching is always important tone wise. The amp factories never really bothered with closely matching tubes. Ask anyone who worked at the amp factories during that time. Most all tubes would fall in the acceptable plate voltage and bias range. Not so in new production tubes. The Deluxe can smoke many new production 6v6's in short order.

[ErikMiller]

The Weber speaker prices are more than I'm wanting to pay right now, but as I looked around on the site I saw the "Bias Right kit" to bias output tubes.

I've been reading the GEO tube faq and a few other things -- I think I will probably get two of the Bias Right kits and learn to do it myself.

All the links and suggestions are really helping me!
J

If you have a DMM, all you need is one of the Bias Rite "head only" things to properly set your bias. Especially if you use matched tubes, you only need to have the thing plugged into one tube socket at a time.

Weber sells their "Sig 12" for $50. I have a "Sig 8" and really like it.

[Johnny Guitar]

If you have a DMM, all you need is one of the Bias Rite "head only" things to properly set your bias. Especially if you use matched tubes, you only need to have the thing plugged into one tube socket at a time.

Well now I'm thinking about permenantly adding the cathode resistor to the output tubes (which would be much cheaper and make for quicker re-biasing). This is mentioned at GEO in the Tube FAQ and a diagram appears here:

http://www.diyguitaramp.com/bias.html

I'm wondering if many people do this or if people advise against it?

Thanks!
John

[Fret Wire]

It's a common method. The Bias Rite is convenient, and safe for people who don't have much experience. And, if your amp has external access to the bias pot, the whole procedure can done without any dissassembly. They sell kits to measure both voltage and current.

If you want to do the cathode resistor method, there's a few things to remember. First, drain your electro caps before working on the amp!! Don't use the screwdriver-shorting method, if you can solder enough to work on your amp, you can solder well enough to make your own cap-drain tool. Use metal film for the cathode resistor, your calculations will be more accurate. If the output tubes share a cathode resistor, remember to divide the current reading by the number of tubes.

The basic formula for biasing is:
class AB1 =  (max plate dissipation x 700) / plate voltage = mA

class A  = (max plate dissipation x 900) / plate voltage = mA

That gives you the 70% dissipation for AB1 and 90 % for A. They are basic starting points. You can go a little up or down in search of the sweet spot. Never exceed the max plate voltage rating for the tubes you're using. Many of the  newer production 6v6's can't handle the plate voltages the NOS tubes could. You Deluxe runs pretty high plate voltages.
So you can't just say, "I'll set my DR at 25ma", and be done with it. The current changes with the plate voltage.

Also, if it hasn't been done, your 78' DR needs a cap job. Sometimes they die slowly, but if they go completely, it's a disaster. You could lose your transformer. If your gonna re-tube and get a speaker, you might as well make sure the amp is up to snuff. If you re-cap, try to keep as close to original uf values. It doesn't hurt to up the voltage rating, and if you study the schematic, you'll see a few caps that Fender cut it close with the voltage rating, raise the rating on those.