Subway Blues Combo

[Baldy]

Anyone know how to quiet the hum these things have going on??? I bought one on the cheap today in great shape. It sounds great but is too noisy for me to use in my studio. It has new Mesa tubes and is great other than the noise.

Thanks for the info.
John

 

[carlsoti]

As I've been told, my Rocket 44 uses (essentially) the same pre-amp circuit as the Subway series. It has the same hum you're describing; mainly on the clean channel? I've asked around and have been told that it's something you have to learn to live with, as the hum is inherent in the arcitechture of the design. I have pondered what it might be like with lower gain preamp tubes, like a 5751 or one of the tubes fender uses. I rarely, if ever, use max gain on either channel, so I could probably make it work, though I haven't bothered yet, as I'm not in a position that it's critical. (gigs or studio)

 

[Baldy]

Anyone know how to estimate when these were made????

 

[igfraso]

The Subway amps had originally 2 versions:
- Subway Blues
- Subway Rocket

I guess they were put in production in 1995.

Later in 1998, the Subway Rocket was joined by the Rocket 44 (change in the power amp section) and the 440 (presence added).
Regards

 

[igfraso]

The Subway amps had originally 2 versions:
- Subway Blues
- Subway Rocket

I guess they were put in production in 1995.

Later in 1998, the Subway Rocket was joined by the Rocket 44 (change in the power amp section) and the 440 (presence added).
Regards

 

[Zoner]

These had a know issue that produced the "hum". Here is one thread addressing it:

http://forum.grailtone.com/viewtopic.php?t=14425&highlight=subway+hum

Mine does not hum. It is my second favorite amp after my MK and is SOOOO much easier to tote around. The hum really sucks, though, and is well worth vanquishing. Good luck.

Z

 

[Ken j]

The later version of these did not have the potted section on the circuit board. Also they did not have the hum problem. I have been playing with tubes in a Subway Blues I purchased last year. I don't have any hum but found that the Eletro-harmonix preamp tube were noisy (not a hum) also I wanted to cut the gain down so that there was a little more clean head room and have the ability to play at bedroom levels. Although I am still experimenting I have tried NOS RCA 12AT7's in both V1 & V2 with the AX's in V3 (inverter) and V4 (reverb). This quieted the amp right down (no noise what-so-ever) and increased the clean headroom but kind of lost its tone. I then tried all 12AX7's except for V3 I put an AT. This wasn't much different for low volume than the stock configuration. Yesterday I tried 2 JJ ECC83S's (12AX7's) in V1 & V2 with the Eletro 12AX7's in V3 & V4. This was very musical but not able to acheive low bedroom volumes. I then tried 2 JJ ECC83S's (12AX7's) in V1 & V2 and a JJ ECC82 (12AU7) in V3. This stayed musical and allowed me to turn it down to the lower volumes I want. The JJ's are much quieter than the Elctros. When diming it I was still able to get the EL84's to overdrive. For the record I put a new matched set of Boogie branded EL84's in about six months ago. My amp is a later version amp without the potted cicuit board and with the half power jack. I am still not sure I will keep this amp but I am more impressed with it now that I put the JJ's in it. I may need to revisit the RCA's again with the 12AU7 in the inverter.

This amp has 4 gain stages in the preamp, so if you do not have quiet tubes in V1 and V2 you will really amplify the noise. I also received the noise mod direct from Boogie when requesting schematics from them. The mod is also posted on schematicsheaven.com.

Remember, amount of gain: 12AX7=100, 12AT7=60, 12AY7=45, 12AV7=41, & 12AU7=20

 

[Baldy]

I spoke with the Boogie people yesterday and they said that a board needed to be replace to eliminate the noise. The cost is $100. Does the Schematic Heaven mod accomplish the same thing or nearly the same thing? It doesn't have to be perfect, I would just like to eliminate [/i]some of the noise.
John

 

[Ken j]

The mod shown on schmatic heaven is the same one emailed to me by Mesa. It is discussed in full detail with some excellent pics in the thread in the modern section that was noted above in this thread. Link: http://forum.grailtone.com/viewtopic.php?t=14425&highlight=subway+hum If you get the board from Mesa it is the same as the later version. I attached a link to a pic of the later board in that thread.

 

[Baldy]

Looks like we'll start with changing the part as shown on schematic heaven. If that don't do it, off to Petaluma.........