Which tube to swap in VAC25 due to noise?

[gorch]

My VAC25 became noisy for a while. So, I came to swap the JJ 6V6 S to a premium selected pair of  TAD 6V6GT-STR. However, although felt not as much as before, noise remains persistent that makes me ask the experts which other tube might be required to be swapped.

List:

• V1: JJ ECC83S
• V2: Ei ECC 83
• V3: JJ ECC81 (reverb)
• V4: Ei ECC83
• V5: TAD 6V6GT-STR (prior: JJ 6V6S)
• V6: TAD 6V6GT-STR (prior: JJ 6V6S)
• V7: 5U4GBEH

[Dutchman]

Try swapping the ECC83’s with another ECC83. Go from V1 thru V4 If you swap and it quits thats the tube. I don ‘t know if the reverb tube is shared on that amp but you can pull it to see if that’s the noisy one. 

[seeker]

22 hours ago, Dutchman said:

Try swapping the ECC83’s with another ECC83. Go from V1 thru V4 If you swap and it quits thats the tube. I don ‘t know if the reverb tube is shared on that amp but you can pull it to see if that’s the noisy one. 

This.  Most of the time a V1 swap will drop it a lot.  Haven't followed tubes in a while, but if you end up needing a new one, imagine a TAD ECC83 would be worth a look.

One thing I can't remember is the class for the VAC25.  If its AB, then the V4 is most likely the phase inverter with the 2 triodes balanced, which would be best to remain as the V4.

[gorch]

A TAD 7025 Mullard style TAD tube now is in  V1. The amp sounds nice and clean. I will see if it removed the noise finally. However, the swap was already worth it. The VAC25 sounds very balanced, clear and warm now. Definitely an overall improvement. It's a shame the amps are not produced anymore. They are just great!

#https://www.tubeampdoctor.com/7025-s-premium-selected-mullard-style-tad-tubes

[Hfan]

Had something similar on a Deluxe Reverb type recently. I went to the pre amp tubes (V1 and V2) first. The noise was pretty loud but would settle down after it was powered up for a bit.

I removed the V1 and swapped in the V2 from channel 2 and kept the guitar plugged into channel 1. Just ran the one channel for a while and the problem was 90% better, The other pre amp tube probably is on it's way out too.

So yes I'd try the pre amp tubes, one at a time.

Do power tubes ever cause noise or just power issues?

I love my tube amps but tubes are a pain in the butt. I see Fender has some new SS amps out ..Twins Deluxe and Princetons that are getting good reviews.One day maybe.

[tbonesullivan]

JJ tubes are Ok, but I feel that there are just better options out there. Even the Electro Harmonix 12AX7s are richer in harmonic content.

I haven't been tube swapping for a bit now. Kinda got it out of my system, but I have a few amps I want to swap things around in again.

[gorch]

On 10/18/2019 at 4:28 AM, tbonesullivan said:

Electro Harmonix 12AX7s

As part of the overall activity I swapped a EA 12AY7 for a 12AX7S into my pico plexy pedal. Gave it more head room and more flexibility to play with compressor or treble booster. There are few TAD tubes in both my VAC25 and AC15 now. They had been an improvement so far.

I still love tube amps. They sound full and warm in a way I have never heard from digital units. However, I don’t have to move them around normally. For frequent stage playing, I would certainly consider another route.

[joshoowah]

1 hour ago, gorch said:

As part of the overall activity I swapped a EA 12AY7 for a 12AX7S into my pico plexy pedal. Gave it more head room and more flexibility to play with compressor or treble booster. There are few TAD tubes in both my VAC25 and AC15 now. They had been an improvement so far.

I still love tube amps. They sound full and warm in a way I have never heard from digital units. However, I don’t have to move them around normally. For frequent stage playing, I would certainly consider another route.

This is something I encourage everyone to do if they have an amp that is too harsh or just lifeless, whether its shrill on the top, too little headroom, or just not providing the warmth and dimension they expect.

A 12AY7, 6072/6072A (JAN-spec 12AY7) or 5751 in V1 can make all the difference, and you can still get good NOS varieties for not much more than a modern Chinese or russian repro. I have those in V1 of my Bassman (Kendrick 2410) and Assman (Kendrick 2210), and they provide all the warmth and harmonic content you could ever want. The Brownie (Princeton) has all it's original 1962 tubes, though I sometimes put a Telefunken ECC803 in V1 to change its flavor.

[Jakeboy]

JJ 12ax7s are good but can bring the sizzle in some amps....V1 is always where you should start because any noise it has is amplified throughout the rest of the circuit. Dutchman gave good advice. Go one at a time until you locate the problem.

[gorch]

As it reads, that is what I like with tube amps. You can flavor them to your likes. There’s always an option. It’s about haptics too.
How could you do that with a modeling amp other than loading a template? It just doesn’t provide the haptics.

[Jakeboy]

2 hours ago, gorch said:

As it reads, that is what I like with tube amps. You can flavor them to your likes. There’s always an option. It’s about haptics too.
How could you do that with a modeling amp other than loading a template? It just doesn’t provide the haptics.

Had to look up the word “haptics” as it is new to me...but not the concept. That touch sensitivity and interplay between a player and a really good tube amp is the thing that modelers HAVE to conquer in order to truly take over the amp world. I do think they are certainly close...especially with a good JFET pedal in front that reacts to the players touch in an amp-like manner .

[gorch]

12 hours ago, Jakeboy said:

Had to look up the word “haptics” as it is new to me...but not the concept. That touch sensitivity and interplay between a player and a really good tube amp is the thing that modelers HAVE to conquer in order to truly take over the amp world. I do think they are certainly close...especially with a good JFET pedal in front that reacts to the players touch in an amp-like manner .

The musical behavior is another feature of tube. However, I rather meant haptic in the way, having an item in hands like a LP vs. mp3 or a guitar vs. a virtual instrument.

[tbonesullivan]

On 10/19/2019 at 10:59 AM, Jakeboy said:

JJ 12ax7s are good but can bring the sizzle in some amps....V1 is always where you should start because any noise it has is amplified throughout the rest of the circuit. Dutchman gave good advice. Go one at a time until you locate the problem.

They can, but they also can be kinda dark and brittle. I know that Eurotubes is HUGE on all JJ all the time, and that Mesa Boogie currently uses the JJ ECC83S as their preamp tube of choice, but I just feel that using ALL JJ isn't good. I do use them in some positions, mainly for their resistance to high heater to cathode voltages, as found in Cathode Follower positions.

I just make sure to go through a dealer and/or relabeler such as Ruby, as JJ is not very good about culling out the bad ones at the factory, per my tech and lots of other people (myself included).  Too tired of dealing with JJ tubes that go bad.

Right now though I've gotta do some speaker swapping, which is slightly more involved.