It is currently Tue Mar 17, 2020 3:51 am

All times are UTC - 7 hours



Post new topic Reply to topic  [ 11 posts ] 
Author Message
Post subject: Blues Jr pre-amp tubes
Posted: Sat Aug 14, 2010 10:06 pm
Offline
Hobbyist
Hobbyist

Joined: Wed Aug 04, 2010 10:28 am
Posts: 69
Location: Vancouver Is, B.C. Canada
Was thinking of switching my stock pre-amp tubes for two JJ12AX7s (V2,3) and a single 12AY7 (V1) . The JJ12AX7s come regular or gold (twice the price). Are the 12AX7golds worth the extra cost?

cheers


Top
Profile
Fender Play Winter Sale 2020
Post subject:
Posted: Sat Aug 14, 2010 11:27 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
You know, as far as tone goes, I don't find a big difference between the gold plated pins of the JJ 12AX7 & the steel pin variety. What may make a difference is the gold pins maybe first selected for quietness and balance across the two triodes, before plating. Something a seller maybe able to do with the plain steel pin JJ's.


Top
Profile
Post subject: BJr tubes
Posted: Sun Aug 15, 2010 8:01 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
I tried a 12AT7 in the V1 spot and loved the mellowing effect, it sounded better in that position than in the other two (V2, V3). However, having the lower gain tube in there also caused a fairly annoying excess hum/buzz when the fat switch was off. The sound was great as long as the fat switch was on, but as soon as it was switched off the hum became apparent. I couldn't stand the extra noise, so I put the original tube back in (maybe a 5751 would have less noise?). I was able to clean up the sound much more with a few new capacitors, an adjustable bias control, and dressing the leads in the amp. Lowering the idle wattage helped clean up the sound, the new caps opened up the tone and the lead dress practically eliminated the noise. I can still get the same distortion from the amp as before, but now it can also be much cleaner as well. It is still a BJr, but much more versatile now. :D There is no need for matched or balanced preamp tubes in this amp. The gold pins may be a waste of money for the stock amp, they won't affect the tone. The gold coating is better for corrosion resistance and a slightly better electrical connection. :)

_________________
---> "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:
Posted: Sun Aug 15, 2010 9:35 am
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Thu Feb 19, 2009 8:33 pm
Posts: 457
Location: Bushnell, FL
Save your money! Gold pins are not worth the bother! I have bought what is supposed to be same tubes except for gold! I always liked the standard pin tube better for tone! Marketing hype!

_________________
Charlie P 5E3 Build 6-14
2x12 cab Build 16, 5e3 Built 3-4-16
6G3 Head Build 3,3,18
Fend HSS Am DLX Strat 08
Fend MIM Telebot Dlx 11 Tronical Tuner
Fend SupSonic 60 2010
Gibson Robot 08, Gib. Faded Ch LP 07
Gret. G5420 16, Peavey VK112 08,


Top
Profile
Post subject:
Posted: Wed Aug 18, 2010 12:59 pm
Offline
Hobbyist
Hobbyist

Joined: Wed Aug 04, 2010 10:28 am
Posts: 69
Location: Vancouver Is, B.C. Canada
Have just purchased three Electro-Harmo pre-amp tubes and a matching set of JJ El84 power tubes for my new BJr. Is there a recommended bias setting for these power tubes in order to make them run a little cooler in this amp?

Thanx for your help.


Top
Profile
Post subject:
Posted: Wed Aug 18, 2010 1:30 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
canucklehead wrote:
....Is there a recommended bias setting for these power tubes in order to make them run a little cooler in this amp?

Thanx for your help.


About 7.8 to 9.8 watts idle is recommended for the EL84s for class AB (I set mine at about 8.5 watts idle which is right at 70%). The stock setting has the tubes idling at over 13 watts (too hot!). :( However, the stock amp has no bias adjustment, you will have to add one (as I did), or change the power supply bias resistor value.

_________________
---> "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:
Posted: Wed Aug 18, 2010 2:10 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Tue Aug 07, 2007 2:19 pm
Posts: 8827
[quote="Cap47"]Save your money! Gold pins are not worth the bother! I have bought what is supposed to be same tubes except for gold! I always liked the standard pin tube better for tone! Marketing hype![/quot

+1 Cap, I totally agree. I survived for decades without the gold pins. I'd steer clear of Cryogenic tubes too.

_________________
Life...... It's sexually transmitted and always fatal


Top
Profile
Post subject:
Posted: Wed Aug 18, 2010 2:38 pm
Offline
Hobbyist
Hobbyist

Joined: Wed Aug 04, 2010 10:28 am
Posts: 69
Location: Vancouver Is, B.C. Canada
thanx for that, shimmilou. Looking forward to hearing a difference.
cheers


Top
Profile
Post subject: BJr
Posted: Thu Aug 19, 2010 11:00 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
Hi canucklehead, and everyone,

You might find this interesting (BJr Rehab):

http://www.fender.com/community/forums/viewtopic.php?t=42982

_________________
---> "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:
Posted: Thu Aug 19, 2010 9:42 pm
Offline
Hobbyist
Hobbyist

Joined: Wed Aug 04, 2010 10:28 am
Posts: 69
Location: Vancouver Is, B.C. Canada
hey Shimmilou, many thanx for the rehab info. Valuable information. I think i will wait a year for the warranty to expire before proceeding with the mods. What speaker are you using in your BJr?
cheers.


Top
Profile
Post subject: BJr Speaker
Posted: Fri Aug 20, 2010 4:40 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
I still have the stock Eminence speaker, same one as in the HRDlx. "Gold Label Reissue". Sounds fine to me. I think that the mods are more of an improvement than a new speaker would be. :D

_________________
---> "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
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 11 posts ] 

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: