I recently got a Deliverance 60 II+, and overall, I’m really happy with it. However, I’ve noticed that it gets extremely hot. After about 30 minutes of playing, the back panel becomes so hot that I can’t keep my hand on it.
I’ve checked the ventilation holes on top, and nothing is blocking them. I’m using the amp with an attenuator, and the master volume is barely at 9 o’clock (around 25% or even less). The room temperature is normal, so I’m a bit surprised by how much heat it’s generating. I use the 8 ohms output.
This is my first amp that runs this hot, so I wanted to check if this is normal or if I should be concerned. Anyone else experienced this with the Deliverance 60 II+?
Sounds like you’re becoming acquainted with the way a real high power tube amp works, and the Deliverance model in particular.
First, the Deliverance amp uses 6550 power tubes and actually puts out 60 watts. A lot of two tube amps in the broader 50W class do 35W on average. Because 6550s are capable of producing much more output than a typical EL34 or 6L6, they can be biased hotter. That allows us to take advantage of the greater clarity and dynamic range of 6550s.
Secondly, on the Deliverance, setting the Master Volume to 9 o’clock sounds good doesn’t it? That’s because you’re pretty close to full output power. That may not be as apparent when you’re attenuating, but that is definitely what’s happening.
The Deliverance Master Volume has to be responsive when you are playing clean, which means you may often set it quite high. Conversely, when running high gain, you need to turn the MV way down. That’s just the way an amp with a lot of gain, and a lot of clean headroom works.
Now add attenuation, which makes cranking an amp more tolerable. You’re still pushing the amp very hard at 9:00 or more, so it will dissipate a lot more heat than a typical 50W amp.
So the short answer is, your amp is working just as its creator intended🔥
Hello Dave! thank you for your very complete answer, ok i knew the master volume was not supposed to be linear. I did notice that one of the power tube was very red in the center compared to the other one, is that normal? Here is a picture after just 5 minutes of playing :
That tube is defective and will need to be replaced. If you keep on using the amp an internal fuse will blow, so I suggest you turn it off until it can be replaced.
Did you buy this new? If so Fryette has 90 day warranty in tubes. Let me know, and we can start that process if applicable.
I bought the amp from a friend ( i have a sales agreement ), and he originally purchased it on December 20th 2024. That means the 90-day warranty expired just yesterday (91 days total)… Do you think you might be able to make an exception in this case? I have all documents available.
Actually, it may just need to have the bias adjusted down a bit. I know it looks horrendous in the photo, but iPhone pics tend to exaggerate contrast. If it turns out the tube is actually bad, sure, we’ll replace it.
To see if this is just a bias issue, I’d recommend you make contact with the distributor, they should be able to assist you with this inspection/maintainance and are local to you, so it will be easy to drop the amp off etc.
Thank you both for your super quick and detailed responses, I really appreciate it, top notch support.
As you recommended, I’ll check the bias first. If it turns out to be just a bias issue, then great—problem solved. But if the issue persists after adjusting it, I’ll get back to you for a replacement tube.
I do have one last question though, if the bias was ok, and therefore the tube was faulty, and you send me back a tube, will i need to rebias the amp again?
First of all, please accept my apologies for the late reply — I had a lot of work recently and didn’t have the time to get back to you earlier.
I wanted to update you: I replaced the tubes as the hot plate issue was definitely coming from one of them.
I received a matched pair of JJ 6550s (instead of Sovteks) with a measured plate current of 36mA and a Transconductance of 5820.
I didn’t rebias the amp yet, but it’s working perfectly fine, and the overall heat is now what I would expect from a normal tube amp — no more extreme overheating like before ( the tube that was hot plating had the paint completely cooked off by the heat…).
However, I noticed the amp seems a little less “punchy” than before, which could probably be due to the bias not being perfectly matched yet (especially since the previous tubes had a plate current of 56mA and i guess it was biased accordingly).
I have a question regarding this:
I know that you normally recommend having the bias set by a qualified technician, but honestly, I’ve done bias adjustments myself a couple of times in the past on 2 different amps ( hk triamp and 5150).
Also, I found photos of the Deliverance II+ PCB online, and it looks very straightforward: just measuring the value of the current sense resistor between TP1 and TP2 and adjusting the trim pot to reach 1.35VDC ( or the value printed as factory default on the PCB if mine is different).
Given how simple the process seems, would it be acceptable if I do the bias myself?
Taking the amp to a tech would cost me around 70€ + taxi fares, and it would take about 2–3 weeks… so if it’s easy enough to do it myself, I’d much prefer that. If there are other steps in the bias that are involved, then of course it would be preferable to send it to the technician
Thanks again so much for all your help and support!
That’s because you’re pretty close to full output power. That may not be as apparent when you’re attenuating, but that is definitely what’s happening.
