Fender Twin Amp Pro Tube Series - Whats the next upgrade?

[my7of9]

I have a new Fender Twin-Amp Pro Tube series and I like it a lot but when I put all new JJ's in it got even better! That was 12 tubes total then of course a Bias and Balance.
What is my next best upgrade? I have 2 concern areas.

Here is an official link to my amp: http://www.fender.com/products/searc...tno=0215700000

Aside from the complete tube refitting it is stock.

1. I never use my gain channel because I do not like it at all on any setting even with the new tubes. I have got very much used to using pedals for that.

2. I was thinking a speaker upgrade might be nice and something I could do myself but there are so many speakers out there I thought maybe someone could point me in the right direction to narrow it down a wee bit.

I like a classic rock sounds from 60's and 70's and also like newer stuff too. I like a good tight warm clean punch to start with without losing that bit of jangle and the adding pedals to my taste from there.

Overdrives I use a silicon fuzz and a muff type fuzz as well as a more hot rod marshall type pedal. I use a BD-2 modded pedal as a booster and a vibe and a wah and an analog delay mostly

Can anyone throw some advice, wisdom or experience way please?

I am not unhappy with my sound just wondering if it gets any better yet!

Barry

[pdf64]

It's your call, but changing out all tubes in an amp is rarely justifiable, even if JJs / whatever sound a lot better than what's in there. Reason being most of the preamp tubes in your amp are working in circuits with a lot of negative feedback, which tends to even these things out. Use the V1 slot to demo tubes, it's run flat out with no audio negative feedback so the tube's characteristics stand out, and put your favourite tube in there when you're done to get the most benefit from it.
V6 is just the trem oscillator, it's not in the audio path, anything basically functional will do, there is no tonal impact.
Can you describe what it is about the drive channel that you don't like? Maybe the stock circuit is filtering out too much of the top end, smoothing it out too much?
The stock GT sovtek 6L6s are not the best, I'd imagine that the JJs there helped a lot.
Re bias, the recommended 60mV (0.06V) is very cold, it sounds a lot better to my ears, and looks better on the scope, at 80mV.
The stock speakers are very trebly, it's useful to change at least one of them with something which has more mids and lows. Speakers are very subjective, so try you amp plugged into the speakers of some other amps to get an idea of your preferences. 2 possibles are Celestion V30 or Jensen C12N, they sound very different but both have more lows than the stock PTTA. Peter.

[my7of9]

It's your call, but changing out all tubes in an amp is rarely justifiable, even if JJs / whatever sound a lot better than what's in there.

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The main reason I did this is because I bought it from a store and it had been sittiing there a long time maybe 2 years?? Every time I flipped the standby on I got an scary bzzzztt sound flying at me. Then it occurred to me I should have some backup tubes as spares so I thought what the heck.
Well I am no electronics expert but once it was biased and balanced I heard delicious tube warmth that it never had before! That was a huge pleasant surprise! Also the scary bzzzztt sound was gone as well! I would love to hear any expert opinion on this!!
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Reason being most of the preamp tubes in your amp are working in circuits with a lot of negative feedback, which tends to even these things out. Use the V1 slot to demo tubes, it's run flat out with no audio negative feedback so the tube's characteristics stand out, and put your favourite tube in there when you're done to get the most benefit from it.
V6 is just the trem oscillator, it's not in the audio path, anything basically functional will do, there is no tonal impact.
Can you describe what it is about the drive channel that you don't like?

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It sounds sterile and no matter what I do I cant work it out. Not warm at all. The actual overdrive is unpleasant the way it breaks up. Sounds like a cheap solid state amp distortion Remeber Sunn SS amps! YUK! I do not understand why this is but after much reading here I am not the only one with this problem however no biggie for me since I use pedals.
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Maybe the stock circuit is filtering out too much of the top end, smoothing it out too much?
The stock GT sovtek 6L6s are not the best, I'd imagine that the JJs there helped a lot.

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Wow! Did they ever!!!
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Re bias, the recommended 60mV (0.06V) is very cold, it sounds a lot better to my ears, and looks better on the scope, at 80mV.

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I am going to try this I will report back!
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The stock speakers are very trebly, it's useful to change at least one of them with something which has more mids and lows. Speakers are very subjective, so try you amp plugged into the speakers of some other amps to get an idea of your preferences. 2 possibles are Celestion V30 or Jensen C12N, they sound very different but both have more lows than the stock PTTA. Peter.

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I feel a more Mid Bass responsive speaker would work well too. I agree the stock speakers are very trebly.
Do you have any links to refer me too specifically in this area??

Thanks a lot for your wisdom!!

Barry

[pdf64]

Hi Barry, I only had an hour or 2 with a buddy's PTTA to check it over, and he's a loud and clean player, so didn't spend too much time on the drive channel. Looking at the schematic, V2B is operating in a current starved mode, with a 470k plate resistor and 10k cathode, but the 5150 has a similar stage and that's a popular distortion channel. I would bridge the 470k with a 150k and 10k with a 2k2, which will make the resulting circuit equivilant to the regular values, to see if that helped.
As for the speakers, see
http://www.watfordvalves.com/cgi-bin...treport_40.pdf
There's a second report
http://www.watfordvalves.com/cgi-bin...treport_43.pdf
but that page is dead, which is a shame as it's a good review.
Start a new thread on this and other boards to get peoples experiences
try the fenderforum.com
http://www.fenderforum.com/forum.htm...-10-2716:03:33
thegearpage.net
and plexipalace.com
Also see
http://www.webervst.com/bt9908.htm
which has links to many manufacturer's sites, which will have sound samples etc. Peter.

[my7of9]

Re bias, the recommended 60mV (0.06V) is very cold, it sounds a lot better to my ears, and looks better on the scope, at 80mV.

I have tried bias at 80mV and that definitely was not good for my amp. Took me a little while to dial it in bias and balance. Once there it was warmer at lower volume settings but once I brought it up to normal stage or practice volume it was having a hard time spitting out my notes with clarity and seemed to emphasise the harshness which seems to be coming from the speakers that I mentioned before that I did not like.
Sorry I am no expert on explaining what I hear.
I put it back to 60mV and it immediately sounded better to me.
While I have you hear I thought I would mention that although I do not use the Send and Return on the back of this amp it does affect the sound regardless depending on where you dial it in at least volume wise.
Is this affecting my tone as well and could this be a reason for the gain channel not sounding proper? Just a stab.. I have been keeping both controls set on 5 or half way.

Thanks again for your support! Any additional comments related to what I have been saying are most welcome!

[pdf64]

You should be able to switch the effect loop off, and when off the send/return levels shouldn't make any difference? There's a button on the footswitch to do that, and I think there's one on the amp also. My buddy uses the loop footswitch and send/return controls to get a boost for lead breaks.
Another thought - you need to keep the trem intensity control at minimum. It's a bias vary type trem system, and even with the trem switched off, the intensity control affects the bias. Or if you do use the trem, set the bias with the trem intensity control where you would normally have it, with the trem switched off.
If you prefer the tone with stock bias settings then that's good, your 6L6s won't wear out as quickly as at higher settings. Peter.

[darrellcheng]

one more thing about those amps. Be sure to check your plate and tube type and use a bias calculator to set the bias, dont trust the numbers on the back!