SWR Bass 350 Fan Defeat

**lowfreqgeek** · #1 08-26-2010, 12:08 PM

I've got an older Bass 350 with a fairly loud fan and I'm curious about doing a defeat switch on it. I know how to do it - no problem there - but I'm not sure want to risk stressing it with the fan turned off.

Here's my situation: I have a session with a high-profile engineer on Monday and I'd really like to use the Bass 350 for it's really sweet DI and simplicity. The plan is to mic a cab and run a DI simultaneously, but the fan on the SWR can get loud. I'd like to defeat the fan for the session, but I don't want to risk blowing the amp, either. I'm not gonna run it loud, but I also know that fan will turn on after an hour of just being on - let alone doing any work.

My other, more complex option, is to use my Avalon U5 and my Epifani UL502 (dead quiet). While that sounds like a sonically better plan, the SWR DI is extremely clean and would work great for this particular band. I'll also be running a VT Bass post-DI/pre-cab, and the Aural Enhancer on the SWR is bypassable, so the cab sound will be more "Ampegish" than SWR.

Why am I doing all this if we have a hot-shot engineer doing the session? Cause he's flying in from L.A. with no gear and the studio does not have a bass amp of any kind. I've consulted with the engineer, who wants to use the U5 or SWR AND mic my Epifani cab. Would be nice to just use the SWR for everything and save time on setup - but only as long as the fan doesn't come on, or the amp doesn't blow without the fan.

I guess my other option is to just use a long speaker cable and set up the SWR in the control room and the mic'd cab in the live room.

bwest9 · #2 08-26-2010, 12:12 PM

One option: go to a computer store and replace the internal fan with a quiter one of the same output.

**lowfreqgeek** · #3 08-26-2010, 12:32 PM

Quote:

Originally Posted by bwest9

One option: go to a computer store and replace the internal fan with a quiter one of the same output.

Good option - but will it be quiet *enough*? If so, then it's a done deal. If not, well...

BigOldHarry · #4 08-26-2010, 12:36 PM

Quote:

Originally Posted by lowfreqgeek

Good option - but will it be quiet *enough*? If so, then it's a done deal. If not, well...

Well, if your fan has gotten *loud*, then it's shot.

I wouldn't check a computer store (unless it's Frys - they have lotsa stuff) - - I'd look on line. Newegg might be a good place to look... but you need some info first: The exact size of the fan, the voltage, the CFM. Oddly, fan technology has impoved quite a bit since your amp was made (due to the whole computer heat thing). You can probably find a better fan that is quieter than the original if you look around a bit...

And that amps is a keeper - Those are good, solid heads that deliver a nice tone - better, if you ask me, than the SM400 or 900.

**lowfreqgeek** · #5 08-26-2010, 12:42 PM

Quote:

Originally Posted by BigOldHarry

Well, if your fan has gotten *loud*, then it's shot.

I wouldn't check a computer store (unless it's Frys - they have lotsa stuff) - - I'd look on line. Newegg might be a good place to look... but you need some info first: The exact size of the fan, the voltage, the CFM. Oddly, fan technology has impoved quite a bit since your amp was made (due to the whole computer heat thing). You can probably find a better fan that is quieter than the original if you look around a bit...

And that amps is a keeper - Those are good, solid heads that deliver a nice tone - better, if you ask me, than the SM400 or 900.

I probably have something here at work... I may look around and see. The fan should be replaced anyway, but I recall that some versions of the SWR amps had fan defeats. Or was that just speaker defeats? Oh well... I've got some local electronics parts suppliers to check, too.

I was blown away by the DI last time I did an A/B test against the U5. The U5 is excellent and will remain in my stable for a while, but the SWR DI sounded more natural, less hyped to me than the U5. Clean, quiet, and big, but not overdone. Coupled with the AE bypass, it's a great sounding piece of gear for the studio, IMO. Eventually I'll get around to replacing the active op-amp DI with a Jensen xfmr, but it's good for now.

KramerBassFan · #6 08-26-2010, 12:45 PM

Get a newer, quieter fan.

If SWR decided that their amplifier needed a fan, who are you to say that it does not?

ahc · #7 08-26-2010, 01:13 PM

Quote:

Originally Posted by lowfreqgeek

I recall that some versions of the SWR amps had fan defeats.

Yes, my Bass 750 (black face/chrome lettering) has one. The fan is pretty darn quiet, so I never turn it off. The first series of the Bass 750 did not have a fan, so when I bought this one, I made sure that it did. GC ordered it for me after I turned down the one they had in stock without a fan. My Redhead (first evolution - gone but not forgotten) and Electric Blue head do not have fans.

Al

Jim Carr · #8 08-26-2010, 01:24 PM

Don't replace the fan, and don't do anything except defeat the fan. Be sure it is easy to activate between takes or if the amp gets hot.

But it won't. My 2000 vintage chromeface pre-fender 350 has a fan defeat. I have played entire sets with the fan off due to pilot error--no problems--and I was pushing a 410 + 115 (4ohm total load) at a pretty high volume.

I would worry more about being musically prepared and being sure the signal from the SWR DI is not too hot.

**lowfreqgeek** · #9 08-26-2010, 02:44 PM

Thanks, Jim.

The signal from the SWR is definitely on the hot side. Fine when I'm using a Jazz, but not so fine when I'm using a G&L (which I'll be using...). So we may have to pad it, but that's what the engineer is for.

I'll probably just throw a fan-defeat on it for this session and then deal with the fan later. It is old - 1994 vintage burgundy face. I know I can get a quieter BLDC fan that pushes more air, but I probably won't worry much about it right now. The amp does get really hot, but it's never shut down on me. I usually push 2 Epifani UL112s (4 ohm total) with it. One night after 3 hours of constant playing at a loud volume, the face was almost too hot to keep my hand on. Still sounded great, though. For the session, I'll just use one cab - and just loud enough to get a good signal at the mic.

I'm looking forward to working with this engineer. His list of credits range from Rod Stewart to Marilyn Manson. Classic rock, punk, alternative, movie soundtracks... He's done it all - and he's buddies with our guitarist and drummer (and working for free...), so the sessions should be a lot of fun. But I also want to be prepared and make a good impression as a player and fellow gear-head. Last thing I want to do is ruin a good take with a loud fan or a blown amp.

BTW - almost every session I've ever done (not that many) has been direct, which is why I own the U5.

Quote:

Originally Posted by Jim Carr

Don't replace the fan, and don't do anything except defeat the fan. Be sure it is easy to activate between takes or if the amp gets hot.

But it won't. My 2000 vintage chromeface pre-fender 350 has a fan defeat. I have played entire sets with the fan off due to pilot error--no problems--and I was pushing a 410 + 115 (4ohm total load) at a pretty high volume.

I would worry more about being musically prepared and being sure the signal from the SWR DI is not too hot.

BassmanPaul · #10 08-26-2010, 03:57 PM

Quote:

Originally Posted by bwest9

One option: go to a computer store and replace the internal fan with a quiter one of the same output.

That is if the fan is actually a computer fan. Some are definitely not.

It's also a terrible idea to stop the fan on a fan cooled amplifier. You are just asking for trouble.

Put the amp itself in another room from the miced cabinet.

Paul

Jim Carr · #11 08-26-2010, 10:23 PM

Quote:

Originally Posted by BassmanPaul

...It's also a terrible idea to stop the fan on a fan cooled amplifier. You are just asking for trouble.

Put the amp itself in another room from the miced cabinet...

Paul, your suggestion to use isolation was my first thought, too, and it is a good one. However, I have run a slightly newer revision of this amp without a fan for over an hour with no problems, so while your warning is valid, I think for a limited time, it will be safe with no fan, especially if it is not being driven hard and is checked now and then.

IMHO, the producer is likely to ask for the Avalon anyway! I went through an Avalon AD2022 for three day long recording sessions two years ago, and I must admit I was blown away by how gorgeous my Sadowsky sounded through it.

The artist I was working for decided to redo some tracks with upright once he heard my lovely old bass on one track, so I redid a number of the same tunes on upright. The mic that was on my upright for those redo sessions (wish I knew what it was) also went into the same Avalon pre-amp.