Ampeg SVT-VR Fan Replacement

[PolkaHero]

While I'm replacing preamp tubes and modifying circuits to eliminate the dreaded not powering up under lower voltages, I guess I'll ask if anyone has replaced the noisy fan in their SVT-VRs. Not really that big of a deal live, but kind of annoying when practicing/testing it out with different cabinets. Can anyone here recommend a model that is much quieter than the original, seems like a pretty easy replacement. It's still under warranty, but it will cost a mint to ship it (plus I don't trust FedEx or UPS), probably much less to purchase a fan and install myself. Thanks!

[Tim1]

I have never found the fan on my VR to be particularly noisy. It seems to be a bit of pot luck whether you get a quiet one or otherwise.

[beans-on-toast]

For your reference, this is the fan (Jamicon JA1225H1SON) that came with a Vietnamese VR that I had: http://www.jamicon.com/spec/AC/JA1225-0N.pdf

You can compare the specs with other models. Basically it is an AC fan, sleeve bearing, 120X120X25mm(4.75x4.75X1") dimension with 4.125" mounting centres, 60CFM air flow rate, 41.8 dbA noise rating.

You want to look for something with a ball bearing as opposed to the sleeve bearing, similar CFM flow rate, with a lower noise spec.

I haven't tried this one but it looks good: part number 670-OA125AP112TB (http://www.orionfans.com/112007/m0_oa125_series.pdf) at www.mouser.com.

Note that there is a difference in 120 vs 220 VAC specs. The 50 HZ 220 VAC models tend to be a bit quieter. They turn a little slower.

[coreyfyfe]

Fliptops has a replacement fan for vintage SVTs which might work, not entirely sure if the mounting is the same on the newer ones. They have the model number blocked out but it appears to be the second one down on this page:

http://www.midwestsurplus.net/contents/en-us/d240.html

which has a ball bearing according to these specs:

http://dkc3.digikey.com/PDF/T083/P2302.pdf

[PolkaHero]

Originally Posted by beans-on-toast

For your reference, this is the fan (Jamicon JA1225H1SON) that came with a Vietnamese VR that I had: http://www.jamicon.com/spec/AC/JA1225-0N.pdf

You can compare the specs with other models. Basically it is an AC fan, sleeve bearing, 120X120X25mm(4.75x4.75X1") dimension with 4.125" mounting centres, 60CFM air flow rate, 41.8 dbA noise rating.

You want to look for something with a ball bearing as opposed to the sleeve bearing, similar CFM flow rate, with a lower noise spec.

I haven't tried this one but it looks good: part number 670-OA125AP112TB (http://www.orionfans.com/112007/m0_oa125_series.pdf) at www.mouser.com.

Note that there is a difference in 120 vs 220 VAC specs. The 50 HZ 220 VAC models tend to be a bit quieter. They turn a little slower.

Wow, thanks for all of that helpful information! I checked out that link and it says these fans have "4x" leads. My SVT fan has only a 2-lead connection. Will I be able to connect one of these fans to my amp?

[PolkaHero]

Originally Posted by coreyfyfe

Fliptops has a replacement fan for vintage SVTs which might work, not entirely sure if the mounting is the same on the newer ones. They have the model number blocked out but it appears to be the second one down on this page:

http://www.midwestsurplus.net/contents/en-us/d240.html

which has a ball bearing according to these specs:

http://dkc3.digikey.com/PDF/T083/P2302.pdf

Thanks for that link. At 53 CFM, do you think the air flow would be sufficient compared to the stock which is 65 CFM? I don't want to sacrifice component life for lower noise.

[coreyfyfe]

Originally Posted by PolkaHero

Thanks for that link. At 53 CFM, do you think the air flow would be sufficient compared to the stock which is 65 CFM? I don't want to sacrifice component life for lower noise.

If Bruce at fliptops is recommending it (at least for the vintage amps) I'd say it's probably ok. He seems to know his stuff pretty well.

[PolkaHero]

Well, I emailed Ampeg to see if this is covered under warranty. I still have two years yet remaining on my warranty, so we'll see how the current staff at LOUD Technologies handles this! BTW, my amp is a US model made by LOUD.

[beans-on-toast]

Originally Posted by PolkaHero

Wow, thanks for all of that helpful information! I checked out that link and it says these fans have "4x" leads. My SVT fan has only a 2-lead connection. Will I be able to connect one of these fans to my amp?

The fans can be ordered with different configurations. They can have wire or terminal connectors. The SVT-VR has a terminal type connector. The fan power cord plugs into this. The model that I referenced, the TB in the part number indicates "terminal connector" and "ball bearing".

For the fans with wires, the dual voltage models have 4 wires (4X), the single voltage models have 2 wires (2X). That is what they were referring to on the spec sheet.

I haven't been able to determine if the Orion terminals are the same size and spacing as the Jamicon terminals. They probably aren't. Perhaps someone here knows. The Jamicon terminal spades are 7.8 mm apart and each spade is 0.5 mm thick. If the two terminals are not the same size you would also need order an Orion terminal cord (for example C45-24, 45 degree angled head, 24" cord) with the fan and splice it in to the old one or get a new power connector where it connects to the amp. If you don't want to use a cord with a terminal plug, you can use spade connectors that push onto each terminal. A lot of amps are done this way. I've seen SVT's done both ways.

As I said in my last post, I haven't tried this fan in the VR. It will fit and be quieter than the old one. The power connection issue is something that you will run into when replacing a fan.

[PolkaHero]

As I figured here is the response from LOUD that I received today:

Hello,

If the fan is unusually loud, check to see if it’s dirty, as an unbalanced fan will be noisy.

Sadly, the apparent ‘loudness’ of a cooling fan is not a warrantable item, unless it is due to a manufacture defect.

Commonly, with most tube heads at least, the amp is not on top of the speaker cab but on a table or something similar. Tubes heads can pick up the vibrations of the cab, and may affect the signal (physical movement, translated to ‘noise’).


Well, the fan has been loud since it was new so I know it's not dirty. I don't agree with the last paragraph as my amps are always on top of the speaker cabinets, and I'm sure most bassists set their rigs up this way also. Great company running Ampeg nowadays, huh?

Looks like I'll have to make the change myself. I think I'm going to order one of these fans posted and splice the existing connector and wire with the new fan's wires as I'm sure any fan I order won't have connectors that fit the amp's connectors. Thanks again for the input and feel free to post anymore fans that might work.

[stingray56funk]

Wow...the last bit of their response is pretty ridiculous. Someone had not drank all of their coffee yet when they responded to your email. Sheesh!

[PolkaHero]

Not satisfied with Ampeg's email reply I called their service center today. Talked to a gal who was really helpful and knowledgeable about the amp, and she recommended taking it to the nearest service center as the fan may be covered under warranty. I also have a bit of 60 cycle hum in channel 2 which she said may be an open ground or bad solder joint so I'm going to have that looked at as well.

Okay, off to the service center! Hope it's not on the bench for too long. . .

[BassmanPaul]

Be aware that if you change the fan yourself then your warranty will in all likelihood be voided.

Paul

[johnk_10]

channel two has more hum than channel one, and IME, it is completely normal for this amp. i have noticed this on every VR that i've tried (including mine), and i've played thru more than eight of them.
and IMO, the fan's noise it also fairly loud on them if you're not used to playing thru an SVT, but it doesn't bother me at all, and its no louder than the 13 vintage SVT's that i've owned

[beans-on-toast]

Originally Posted by johnk_10

channel two has more hum than channel one, and IME, it is completely normal for this amp.

I don't know if this is the same hum you are referring to...

I have some notes somewhere that I just can't find. They are related to a fix for the hum in channel 2 on the SVT-VR. As I recall, it was in the early models and Ampeg had a fix.

I did find this (http://music-electronics-forum.com/t15670/). You have to register to see the images. They discuss how to fix a ground loop related to a voltage regulator.

[johnk_10]

nice link beans!

[BassmanPaul]

There's no need to replace the regulator - just install an insulator kit.

Paul

[beans-on-toast]

As Paul said, a mica insulator is a lot easier to install than replacing the regulator.

If the heatsink grounding on the chassis is the problem, I don't see why one couldn't grind it down or install a smaller heatsink.

I guess you have to be looking at one to really see what is going on and what the best fix would be. I don't like cutting traces unless it is really necessary.


David

[BassmanPaul]

Originally Posted by beans-on-toast

As Paul said, a mica insulator is a lot easier to install than replacing the regulator.

To be clear on this, it's not just the TO220 insulator (mica with heatsink compound or the better grey thermal ones), you also have to use the isolating hardware or the ground will remain.

Paul

[PolkaHero]

Got my amp back from the shop today (just in time for tomorrow's gig!). Unfortunately, the fan was not covered under warranty and the tech couldn't find a suitable replacement. He was able to cure the hum in channel two by shielding components in the preamp from the standby switch at no charge.

I ordered an Orion fan from Mouser Electronics that is 20 CFM better airflow and is 9 dB quieter than the stock one. My tech said that he will wire the fan into the amp for no charge and while I wait at the store, good deal. He said it also won't void the remaining warranty on the amp.

I asked if he noticed the Hammond organ tubes I had installed in the preamp to replace the stock Sovtek/EH Tubes. He hadn't (he's also a Hammond organ tech), but said he replaces all of his tube amps with old tubes and pretty much said the newer China/Russian tubes are junk. Guess that doesn't void my warranty either; glad he didn't open up the main board and see my standby relay modification!