• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Quantum Impex

I have a Quantum Minstel.

It is a hybrid integrated tube amp. The input stage is all mosfet electronics, and the output is push-pull tubes with large transformers. It came rated at 20wpc with 6L6 output tubes, but it can run at 40 wpc using EL34's. That would change the sound somewhat, but it's made to do it, or to use the milspec tubes, I forget the number but they are el34 compatible. .

If I recall correctly, the EL34 puts out 34 watts per channel with very low harmonic distortion, but since you can run tube amps with a lot more distortion "by the numbers" it will sound good up to 40 watts.

I think I bought mine in 1996, in St Louis MO from Flip's, and they had a stack of them. . . after hearing mine, 4 of my friends all bought them too. One had a cracked circuit board from being dropped but it was repaired. As far as I know, all 5 we bought are still in daily use.

Original retail price in 1996 was $1800.
Many thanks for the information Morst, I was starting to think I was the only person who had one of these excellent amps. I run mine through Lowthers or TDL studio2 transmission line speakers and it sounds superb through either. Mine has EL34's , but I may try changing for the 6L6 tubes you suggest. You dont have any info on the bias adjustment by any chance do you?
OK, I found some of the documentation. (I still need to find my glossy sales sheet) A very kind friend of mine gave me a matched quad of 6L6's for a "HOUSEWARMING" gift when I moved recently, and he included the data sheet for the amp. He marked it up a bit but I will scan it and make it available to those who wish to know. (splodgedog, I'll email it to you as soon as it's scanned.)

My friend specified that although the amp will work with other valves, the 6L6GC is the only one we should use.


2008-01-22 10:26 pm
I have one of these tube integrated amps less the tubes and hope to find biasing instructions. Found this site just now via Google and as a new member can't e-mail the two guys who chatted about it long ago.

If either of you are still here or anyone else knows, I'd really appreciate the input. It looks like the manufacturer is long out of business.
Let me try to attach the scan here, so anyone who needs it can find it. .

(good thing I have this board set to email me when there is a reply to the thread!)

Ok let's try posting it on imageshack.us.. .



note my friend's instructions in pen, we were told that milspec 5881 tubes could be used, but we're not sure if the biasing would be the same. Note that use of the 5881 tubes will increase the power output to approx 40w/ch and will change the charactaristic sound of the power stage compared to 6L6 tubes.


2010-07-29 5:11 pm
Hi - hope you are still getting alerts re the Minstrel amp - I have two of these - one with partridge transformers and another which I bought yesterday - I chose these over class A valve amps such as the puresound A30 and the quad II as they are a bit more punchy but still very much more open than solid state amps - but I know next to nothing about them and neither does my hifi delaer - one says "made in scotland" and the other "made in great britain". I tried to open your documents but no joy - any chance of you reloading them as jpegs ? Thanks


2012-04-05 6:35 pm
Hello Morst

Hope you are still monitoring this post. I too am looking for information on the Minstrel amplifier.

Ideally need circuit diagram / biasing info.

Cannot open either of the 2 links posted previously, could you possibly repost or send me an email please?



2010-01-15 6:42 pm
hi Morst

I too hope you are still monitoring this.

I have a Minstrel amp which I have had to put new valves in. I would like to check the bias current, there are two led's which I suspect are indicators of the correct level, but any information you have would be appreciated.

thanks. gary
if you are still paying attention, I applaud your patience. Here are the scans of my data sheet, with markings from my friend. It was originally folded, so we have two JPG's, one is page 1 & 4, the other was the inside of the booklet, pages 2 & 3

cheers! Happy 2015!


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