HSU VTF-2 amp repair Options - AVS Forum
Subwoofers, Bass, and Transducers > HSU VTF-2 amp repair Options
HDTBill's Avatar HDTBill 10:38 AM 01-08-2013
Those of us with the classic older Hsu VTF-2 sub-woofers know the story, that the amps tend to go bad over time (burn out or make noise), and as of around 2012, Hsu is no longer offering to repair the amps. Mine is making noise now.

Here is what Hsu Research now offers as a resolution:
"Unfortunately we no longer support that model. If you can enlarge the amplifier cutout about 0.1", you can purchase the VTF-1 MK2 amplifier and use that. It runs $215 plus $25 S/H if you are in the lower 48 states. The other alternative is since we do not support your sub anymore, we will extend you a one-time offer to upgrade to any of our new models at (special pricing)"

The following questions:
(1) Has anyone tried installing the new VTF-1 MK-2 amp? Results?
(2) Is there any 3rd party amp that can be tried?
(3) Hate to throw away the enclosure and speaker, any market for that?
(4) Most folks say it is very hard to repair circuit board even for a shop...it looks fine to the eye, no obvious blown capacitors etc

Now that I got the thing apart, replacing with the VTF-1 MK2 amp sounds workable from a wood work persepctive. The old amp comes out easily in a plastic enclosure, presumably Hsu would replace the whole unit and you would just need to make the hole a little bigger probably with a router. I never used the VTF-2 much over 5% volume but I like to get down to 25 Hz for good sound effects.

Max5150's Avatar Max5150 06:41 PM 01-17-2013
I have the exact situation. I called them yesterday. I would like to fix my older VTF-2 sub if I can and hopefully I can get a free estimate from a shop.

If that doesnt work, I would like to try to replace the amp with another one, but not an HSU. The only problem is I cant find an amp with the same dimensions to fit the cutout.

I dont want to pay for the replacement HSU amp since I can upgrade to the VTF-2 MK4 for a little more than double the cost of the amp and it has a 12" woofer and a 250watt amp vs my existing 10" and 150 watts. Plus I get a 2yr on electronics and 7yr on subwoofer.

If anyone knows where I can find a plate amplifier thats 10" by 10", I would greatly appreciate it. If I repair it with a cheaper amp, maybe I'll move it to the bedroom and buy another one anyway..
ack_bk's Avatar ack_bk 07:28 PM 01-17-2013
Quote:
Originally Posted by Max5150 View Post

I have the exact situation. I called them yesterday. I would like to fix my older VTF-2 sub if I can and hopefully I can get a free estimate from a shop.

If that doesnt work, I would like to try to replace the amp with another one, but not an HSU. The only problem is I cant find an amp with the same dimensions to fit the cutout.

I dont want to pay for the replacement HSU amp since I can upgrade to the VTF-2 MK4 for a little more than double the cost of the amp and it has a 12" woofer and a 250watt amp vs my existing 10" and 150 watts. Plus I get a 2yr on electronics and 7yr on subwoofer.

If anyone knows where I can find a plate amplifier thats 10" by 10", I would greatly appreciate it. If I repair it with a cheaper amp, maybe I'll move it to the bedroom and buy another one anyway..

I don't think you will find a 10" x 10" plate amp to fit the existing one. You could use an external amp like this one:
http://www.parts-express.com/pe/showdetl.cfm?partnumber=302-601

Just bridge it and you have 150 watts.

Or you could buy a plate amp and just hook it up external to the sub.
http://www.parts-express.com/cat/subwoofer-plate-amplifiers/332
HDTBill's Avatar HDTBill 03:45 PM 01-18-2013
Quote:
Originally Posted by ack_bk View Post

I don't think you will find a 10" x 10" plate amp to fit the existing one. You could use an external amp like this one:
http://www.parts-express.com/pe/showdetl.cfm?partnumber=302-601

Just bridge it and you have 150 watts.

Or you could buy a plate amp and just hook it up external to the sub.
http://www.parts-express.com/cat/subwoofer-plate-amplifiers/332

Thanks...hmm this Dayton SA-240 on sale looks like a fit ...looks a lot like the Hsu unit too

http://www.parts-express.com/pe/showdetl.cfm?partnumber=300-805

This model has Boost and there is a similar swicthable boost model.
What do you guys think?
Max5150's Avatar Max5150 02:08 PM 01-19-2013
Thanks guys.. I didnt see the Dayton SA-240.. those dimensions would more than likely fit.
kesando's Avatar kesando 02:58 PM 01-19-2013
I like this model more as the bass boost can be turned on or off and it only a couple bucks more. You also have to be careful when boosting a ported sub as well

http://www.parts-express.com/pe/showdetl.cfm?partnumber=300-803

You may have to build a spacer plate onto the sub box for it to fit
HDTBill's Avatar HDTBill 04:30 PM 01-20-2013
Quote:
Originally Posted by kesando View Post

I like this model more as the bass boost can be turned on or off and it only a couple bucks more. You also have to be careful when boosting a ported sub as well

http://www.parts-express.com/pe/showdetl.cfm?partnumber=300-803

You may have to build a spacer plate onto the sub box for it to fit

Agree that Dayton looks like a good option. With luck it appears to be near exact fit into existing cut out.
Another VTF-2 (MK2) owner on part-express.com said it fit his perfectly, but I don't think I have MK2 version so we'll see. Anyways its hard to look any further than this Dayton as it seems to be a good fit. The one things looks funny is the BASE BOOST button seems to be in a funny place behind the main control panel where it may interfere with installation.
Bernie7's Avatar Bernie7 10:57 AM 03-12-2013
This might help someone with a similar fault. My VTF-2 Mk I developed a low frequency noise. I changed some capacitors in the amp board and now it is fine!

Here are the caps I changed:
47uf 25v 1pc
100uf 16v 3pcs
10uf 50v 2pcs
These were replaced as they were an inferior brand that seemed most likely to fail. For a dollar worth of parts and some effort the bet paid off.
Saints's Avatar Saints 05:33 PM 03-12-2013
Quote:
Originally Posted by Bernie7 View Post

This might help someone with a similar fault. My VTF-2 Mk I developed a low frequency noise. I changed some capacitors in the amp board and now it is fine!

Here are the caps I changed:
47uf 25v 1pc
100uf 16v 3pcs
10uf 50v 2pcs
These were replaced as they were an inferior brand that seemed most likely to fail. For a dollar worth of parts and some effort the bet paid off.
Great advice. I did the same with a Samsung LCD TV that I have in my bedroom and it has been flawless ever since and it only cost me a few bucks. I had never done anything like that before, but it was a simple fix for something that most people would have spent hundreds of dollars for or even junk the TV altogether. Google is a wonderful thing! Now that I know what to look for on things like that I'm confident that I can repair a lot more of my electronics. I also fixed a broken PS3.
Max5150's Avatar Max5150 11:30 AM 03-14-2013
Updating my previous post. Bought the SA-240 and installed in my VTF-2. The amplifier worked for a few minutes then failed. Called Parts Express and did a RMA and received another one. Installed it and now it works great with a little more power than OEM!! The amp was an exact fit. Thanks again for the info.
Saints's Avatar Saints 07:39 PM 03-14-2013
Quote:
Originally Posted by Max5150 View Post

Updating my previous post. Bought the SA-240 and installed in my VTF-2. The amplifier worked for a few minutes then failed. Called Parts Express and did a RMA and received another one. Installed it and now it works great with a little more power than OEM!! The amp was an exact fit. Thanks again for the info.
Awesome man it's good to hear everything worked out and now people will have an option in the future if they run into a similar problem.
HDTBill's Avatar HDTBill 11:35 PM 03-27-2013
Quote:
Originally Posted by Bernie7 View Post

This might help someone with a similar fault. My VTF-2 Mk I developed a low frequency noise. I changed some capacitors in the amp board and now it is fine!

Here are the caps I changed:
47uf 25v 1pc
100uf 16v 3pcs
10uf 50v 2pcs
These were replaced as they were an inferior brand that seemed most likely to fail. For a dollar worth of parts and some effort the bet paid off.

Thank for the post...what cap brand do you think is inferior
Bernie7's Avatar Bernie7 06:37 PM 04-30-2013
Sorry for late reply, just logged back on. Suspect electrolytic cap brands imo are anything that's not a well regarded major brand such as Nichicon, Rubycon, Panasonic, Sanyo etc. I'm also suspicious of CapXon used on the board.
Bernie7's Avatar Bernie7 07:00 PM 04-30-2013
My Mk 1 sub has since developed another fault - no sound at all even though the power light is On.
Problem was traced to the relay circuit - it did not connect the amp output to the speaker. There is a relay and two npn transistors (C945) in the circuit.

Without replacement parts on hand, a quick fix is to bypass this relay circuit but then there will be a switch on thump (relay keeps this from being heard). Bypass can be done by soldering a link between the relevant relay (normally open) leg to the speaker connection. Check the relay (812H-1C) connections by googling for the datasheet.

I changed both the relay and transistors and everything's working as new. Parts cost less than $2.

Seems the plate amp is otherwise quite dependable and there's no need to replace it entirely, apart from changing the caps I mentioned earlier and the relay/transistors.
daMaster's Avatar daMaster 01:03 AM 07-28-2013
Quote:
Originally Posted by Bernie7 View Post

This might help someone with a similar fault. My VTF-2 Mk I developed a low frequency noise. I changed some capacitors in the amp board and now it is fine!

Here are the caps I changed:
47uf 25v 1pc
100uf 16v 3pcs
10uf 50v 2pcs
These were replaced as they were an inferior brand that seemed most likely to fail. For a dollar worth of parts and some effort the bet paid off.

I have a VTF-3 MK2 that has just failed me: amp is not putting out enough output. I took the whole amp plate out and see a lot of caps on there. Did you just replace the largest caps? Never replaced caps before so this will be a first for me as well...
Korki Buchek's Avatar Korki Buchek 10:29 AM 03-12-2014
Hi Bernie,
Thanks for all of the great advice. My subs been out of commission for over a year. I'm Retired, so cant afford a new one as Somethng always seem to take precedence.. I bought the replacement caps you recommeded. However not being repair adept I dont know which to replace. I have 3 pics attached as JPG's. If you get a chance pls review and advise.
Hsu1.jpg 683k .jpg file
Hsu4.jpg 804k .jpg file
Hsu6.jpg 1265k .jpg file

Other opinions I have seen:
http://www.advrider.com/forums/showthread.php?t=521149

Thank You Bernie.
John
]
Attached: Hsu1.jpg (682.8 KB)  Hsu4.jpg (804.0 KB)  Hsu6.jpg (1.23 MB) 
shadyJ's Avatar shadyJ 11:16 AM 03-12-2014
Bernie hasn't been around since January, according to his profile. I would ask Hsu's tech support.
tinkinHD's Avatar tinkinHD 04:50 PM 08-22-2014
Bit late of a response, but in case any others are still in this situation, the Dayton Audio SPA250 fits perfectly into the VTF-2 MK1 without any necessary modifications.

$140 shipped from Amazon:

http://www.amazon.com/Dayton-Audio-S.../dp/B0070Z81MW

Can't complain about the extra 100 watts either. 8^)

I think the 6db boost at 35hz is their version of the extension/output switch on the original amp. Just pick one and stick with it though since the switch is not accessible after you install the new amp.
menagh's Avatar menagh 11:19 PM 08-25-2014
Quote:
Originally Posted by tinkinHD View Post

Can't complain about the extra 100 watts either. 8^)

I think the 6db boost at 35hz is their version of the extension/output switch on the original amp. Just pick one and stick with it though since the switch is not accessible after you install the new amp.
I just ordered one from Amazon last night for my VTF2.

Does the 6db boost set to ON represent the 1 port open, or 2 ports open option on the original?

Also, can you please comment on the difference you experience due to the extra power? Does it have more authority / extension than the original? I'm not sure what to expect with it but would hope it could fill the room more than the original since my room is larger than ideal for this sub size.

Thanks!
tinkinHD's Avatar tinkinHD 07:08 AM 08-26-2014
Quote:
Originally Posted by menagh View Post
I just ordered one from Amazon last night for my VTF2.

Does the 6db boost set to ON represent the 1 port open, or 2 ports open option on the original?

Also, can you please comment on the difference you experience due to the extra power? Does it have more authority / extension than the original? I'm not sure what to expect with it but would hope it could fill the room more than the original since my room is larger than ideal for this sub size.

Thanks!
The boost should correspond to running in extension mode with one port open. Presumably the 6db at 35hz rolls off enough to lower the extension down to 25hz. I'm not sure if that's exactly how the original amp worked. Sounds like you might be better off running in max output mode in a larger room?

I'd say it has more authority and headroom in general. I can now turn the volume up to 11 o'clock rather than 8 o'clock on the original. Adding a piece of carpet underneath seems to have helped as well.

After you unscrew the amp, removing the driver screws and pushing up on the driver can help to remove the old wires and then install the new ones. Also, you may want to stick with the original screws since they will fit into the original holes better than the smaller ones provided.
menagh's Avatar menagh 09:09 PM 08-26-2014
Thanks for the clarifications tinkinHD - I'll post my results after the amp replacement!
menagh's Avatar menagh 10:25 AM 08-28-2014
The new amp went in without any problems and I reused the original screws. For the record, you need to remove the woofer to reach the connected power leads - should be obvious but if this thread lives for a long time it could be useful to point out. Volume seems to be 11 o'clock now as previously indicated instead of 8 o'clock.

I didn't notice much difference in the sound quality or overall output - perhaps I'd need to really push the volume up higher to see any difference. I did set the bass boost to on and am running with one plug in (25 Hz extension).

I picked up another used VTF2 (original) very recently (plan to set it up for someone else) and have been running it for a few days while mine was down. I figured it would be a great way to compare the two, but after moving the second VTF2 around its amp started acting up, making buzzing and hissing noises with volume inconsistencies. Looks like I'll be doing another amp replacement...

This is currently out of stock at Parts Express, but Amazon had a few remaining in stock (but shipped from Parts Express - not sure how that works) for a little more money. Hopefully Dayton Audio will continue to make these amps as they will make a solid option in fixing these HSU VTF2 units, which are still great subs despite being old.
tinkinHD's Avatar tinkinHD 04:00 PM 09-14-2014
You're welcome menagh. As an addendum to this, I started noticing that my sub was making a rattling sound after installing the new amp while testing pink noise at reference level with an SPL meter. I almost went nuts trying to pinpoint the problem.

The distance between the installation screw holes on the DPA250 is not the same as on the OEM amp. Of the 12 screws, the ones in the middle should all line up, but the outermost screws on each side are slightly closer to the center. So you're left with 2 extra holes along each side of the enclosure and the air pressure running thru those, at least when running in extension mode, can cause a rattling sound.

Fill those old holes with Gorilla Glue or some such and you should be good to go.
menagh's Avatar menagh 10:25 PM 09-19-2014
I replaced the amp in my second VTF-2 as well, and all I can say is they both play with more authority/headroom than before. I've pushed the volume up quite a bit and have tested with both subs running, and it is quite impressive. I bought the second one for a relative, but haven't delivered it yet... I admit I'm tempted to keep both as running two evens out the bass much better than just one.

I also had a chance to demo a VTF2-MK4 in my home, and it was a remarkable experience... though I had it turned up way louder than needed but didn't mind a bit I really liked the extra depth of 18 Hz vs 25 for movies, and it plays with more authority than the original model.

tinkinHD - I'll keep my ears tuned for a rattling or similar sound - you passed along some great guidance!
Tags: Hsu Vtf2 Mk4
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