Thunderfunks vs ohms

You weren't kidding , you did scurry off to start a new thread!

Yup that was me.. I certainly did do it. Many , many times. Maybe 75 gigs in one year or so, The other gigs i used my GBE1200 into 2 ohms. I now run a shuttle in 4 ohms...

when i would run my TF550B into 2.76 ohms it was when i was playing with a fairly loud Texas guitar band. Strats thru twangy sounding twin reverbs.. LOUD!

So i would bring a 3rd Aguilar GS112 cab and run all 3 aggy GS112s each at 8 ohms. So you guys do the math. I just daisy chained them with 1/4 plugs after the first one going speakon from amp to cab.
I never had an issue.. yes the amp got hot, but i didn't feel it was much hotter than when it ran at 4 ohms.. And it sounded fine too.

It never shut down , but i dont think the TF 550B has shutdown feature .. Im not sure though... its either working or its a poof of smoke from what i gather..
But it always stayed on for me.. Maybe im just lucky.. knock on wood as they say
But I Never ran the 550B at two ohms..
I would like to hear others comments too... I never cared if it blew up, i would just send it in to get repaired and not do it again... Dave said it should do it so i was the stunt guy to try it out.

I used my gibson gb440 into an mline wizzy (4ohm) and an EV tl806 (8 ohm) a bunch of times. It got hot, but it gets hot running into my 8 ohm cab as well, so go figure. I dont push the amp hard AT ALL into 8 ohms and it gets hot.

Never shut down, no sonic issues. I stoped doing it since it seemed EVERYONE said you shouldnt, I like the amp, and cant afford to replace it with a tfunk.

EDIT: As some reference, at the time I was running a passive and/or active Jazz bass into the head, EQ flat except for -15db cut at 30hz and timbre knob usually ever so slightly clicked to left (bass) about 1 "notch". Gigged a few times with this setup, but rehearsed quite a lot like this. That was before we went IEM, so my rehearsal volume was on par with my gig volume, perhaps louder. It was about 11:00 on the pre and 12:00 on the master, maybe an "hour" later here or there, depending.

Yes I had it in a 3 space Gator rack bag.
It still got hot at 4 ohms. It seemed as hot at 2.6 as it did at 4 ohms .
Always had the fan running.. The amp really is a wonder and sounds so good.. I only wish there was alt least a true 1000 watt version.

Chef said:

I'd be fine with 2.67...
Was your 550 racked, and if so, in what?

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I have run mine the full night without any issues. I do play loud. I would boost 30hz to get my pants to feel the air a little bit.. You don't hear the 30hz as much as you feel it.. I think it may void any warranty if it were to fail or toast up.. But mine didnt.. Was I lucky? perhaps..

svtb15 said:

I have run mine the full night without any issues. I do play loud. I would boost 30hz to get my pants to feel the air a little bit.. You don't hear the 30hz as much as you feel it.. I think it may void any warranty if it were to fail or toast up.. But mine didnt.. Was I lucky? perhaps..

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Kirk, you are my hero. Crank it up, run it at 2ohms, and boost 30hz. THAT my friend is rock and roll If it fries, it fries

I dont know where you got that from. I never ran at 2 ohms

KJung said:

Kirk, you are my hero. Crank it up, run it at 2ohms, and boost 30hz. THAT my friend is rock and roll If it fries, it fries

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My friend worked for BGW power amps years ago.. They would test amps to see if they shut down properly by shorting the output with a screwdriver.. He said you could get the screwdriver to Glow Red.. SO he said....

sick bastard.. Those were my teachers when i was young.. No fear
.. And you wonder why I am the way I am..
He went on to win some amazing AES awards... The guy was an Audio genius. I Still love my crown /vintech /bagend rig though. Super clean and punchy... I have lead on an old API that Im looking at getting.. That would be killer..

I used to run my 90's GB440 (predecessor of TFB 420) on about 50 gigs with 2.67 Ohms.
No problems whatsoever. I have switched to 4 ohm HS410 since last year.

Hmmm... I'm running my TF550b with a pair of DB112s and I've been wishing I could add a third Might just give this a go!

Personally, I've never tried running any of my BH-420, GB-440 or TFB heads @ anything under 4 ohms. Just didn't want to take the risk. When a gig has called for more than one of my cabs (all my cabs are 4 ohm), I just run two heads. Just my way of doing things, as I'm not a risk taker with my gear, but to each their own...

Now what I've done to rectify this is to just buy a TFB-750A . They are supposed to be able to run 2 ohms safely, but honestly, I'll prob never even do it (or on very rare occasions), but it's sure nice to have the option.

Oh, anybody looking for a clean, low hours 550B (that's never been run @ below 4 ohms) with a Thunderfunk flight case? I'll cut ya a deal!

Be warned.. I dont think it is rated at that .. The only reason I did it is becasue Dave said he didn't mind me doing it and pushing the amp .. And if it did blow, he knew he would have to build a better amp.. I dont think he offers that sort or warranty to everyone... Just an FYI.. if you amps smokes, I would hate to see a thread saying KIRK SAID IT WAS OK..
Im just saying i did it without any problems... And i do have a vast knowledge of electronic gear incase anything did happen..
Please dont go haphazardly into this.. BUt for me it worked perfectly...

warwickhunt said:

Hmmm... I'm running my TF550b with a pair of DB112s and I've been wishing I could add a third Might just give this a go!

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svtb15 said:

Be warned.. I dont think it is rated at that .. The only reason I did it is becasue Dave said he didn't mind me doing it and pushing the amp .. And if it did blow, he knew he would have to build a better amp.. I dont think he offers that sort or warranty to everyone... Just an FYI.. if you amps smokes, I would hate to see a thread saying KIRK SAID IT WAS OK..
Im just saying i did it without any problems... And i do have a vast knowledge of electronic gear incase anything did happen..
Please dont go haphazardly into this.. BUt for me it worked perfectly...

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Reports are that the TFB750-A runs fine at 2 ohms. Heat is not the problem. Current, power, and reliability are. The 750 has 50-amps of output devices, and 2-ohm operation "only" requires 19 amps, so there's plenty of margin. The 2-ohm rating was accidently omitted from the webpage due to three people working on the page at the same time. Those who try to throw doubt in the buyers mind about our amp running "excessively hot" don't know what they're talking about, and would seem to have ulterior motives.

I've never heard ANYTHING about amps over-heating from people who ACTUALLY OWN ONE. There have been NO failures of 750's. Our overall power amp failure rate is below 1% over 5-years. You can count failures on one hand. Failures have never been caused by heat or power, but rather by lightning strikes, power surges, or intermittent speaker loads (bad speaker wiring). This amp has been in production since at least 1985, and is the EXACT same power amp as used by Eden, so there're thousands of them out there. It still amazes me that some people act like, "Dave's amp hasn't been proven yet." The reason I was hesitant about 2-ohms was there's increased distortion, which will probably just make it sound louder to you anyway.

Dave Nordschow lives 1-mile from me. Small world. Since he was fired from Eden we've been visiting. Since he built the same Russ Allee designed power amp that I do, and has more experience with it, he helped me understand it better. The amp has output current reduction and it can be adjusted. The problem is to find a nice balance of reliability, power, and distortion. I don't think you'd like an amp that said it could handle 2-ohms, but then tended to blow up.

Other amps have "cut-out" thermostats that kill the input signal to the power amp if the fan fails and the amp overheats. We don't have that, nor do we need it. Our chassis runs hot because it's more reliable that way. Our transistors are rated at 300 degrees. We use Boron Nitride insulating putty tape to mount our devices, the best material you can use. We have a fan that the BH-420 never had, plus three heatsinks added for convective cooling. We know how hot the amp runs. Why would anyone think we don't? Guess what. ALL Analog amps run hot. It's the efficiency "loss" that produces heat. The only question is where does the heat go? With ours, much of it goes into the chassis. It's not heat that kills transistors, but changes in temperature. Come to Detroit Sept 28th and see how hot Jauqo III-X gets using the TFB750-A and the TFB610a speaker with his fretted, fretless, and sub-contra basses. Yes, 17Hz.

svtb15 said:

I dont know where you got that from. I never ran at 2 ohms

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Um... it was a good natured joke I just remember a picture of your TF550 on a stack of 4 GS112's somewhere (stacked in a cube configuration). 2 ohms, 2.67 ohms... whatever! That just seemed 'rock and roll' to me!

Per Dave's comments above, it seems like this is just fine, especially with the 750. It seems those who were commenting on the extreme heat with the 750 when pushed at 2.67 or 2 ohms were 'worried about nothing'.

I know I got caught up in this with my old SWR900. It would get hot enough to fry eggs on when bridged into 8 ohms (much less 4ohms). It never failed, and I was told over and over again that it was 'designed to work that way'. That being said, it always just 'felt wrong' to me. Not rational, I know, but my god it ran hot.. burn your hand hot.

My TF550b... pushed all night at 4ohms HARD and it doesn't even get warm! That's a good thing!

I see the joke... Sorry Kjung... I apologize.

Oh that gig.. yeah... I wound up only running 2 of those cabs in the end.. and then tried using the TF as a Preamp to run a power amp so i could use all 4..
Just for the fun of it ..
The truck with all my gear was there and we had plenty of time to sound check, so I wanted my tech have some fun that day..He was wanting to try that for a while...
That gigs was at one of the Nokia Theaters.. Real nice room.. Great sound.. I only needed 2 cabs in the end since Clair Bros were doing sound and had great monitors.. It was a cajun creole sort of band....

KJung said:

Um... it was a good natured joke I just remember a picture of your TF550 on a stack of 4 GS112's somewhere (stacked in a cube configuration). 2 ohms, 2.67 ohms... whatever! That just seemed 'rock and roll' to me!

Per Dave's comments above, it seems like this is just fine, especially with the 750. It seems those who were commenting on the extreme heat with the 750 when pushed at 2.67 or 2 ohms were 'worried about nothing'.

I know I got caught up in this with my old SWR900. It would get hot enough to fry eggs on when bridged into 8 ohms (much less 4ohms). It never failed, and I was told over and over again that it was 'designed to work that way'. That being said, it always just 'felt wrong' to me. Not rational, I know, but my god it ran hot.. burn your hand hot.

My TF550b... pushed all night at 4ohms HARD and it doesn't even get warm! That's a good thing!

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svtb15 said:

I see the joke... Sorry Kjung... I apologize.

Oh that gig.. yeah... I wound up only running 2 of those cabs in the end.. and then tried using the TF as a Preamp to run a power amp so i could use all 4..
Just for the fun of it ..
The truck with all my gear was there and we had plenty of time to sound check, so I wanted my tech have some fun that day..He was wanting to try that for a while...
That gigs was at one of the Nokia Theaters.. Real nice room.. Great sound.. I only needed 2 cabs in the end since Clair Bros were doing sound and had great monitors.. It was a cajun creole sort of band....

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That's the picture I remember. That was a nice looking rig! I'd like to hear all four of those cranked with a 750. That would be the voice of 'you know who'.