Cube Audio Nenuphar Single Driver Speaker (10 inch) TQWT Enclosure

Would the Allnic T1500 integrated 300b SET Amp work well?

Key Features:

• 10 watts per channel of pure class A high power output. The T-1500 MK2 is a single ended, stereo integrated amplifier. Almost all other 300B amplifiers are under, and distortion, driven. This is a result of the use of conventional “Resister-Capacitor” circuits, which give only up to around a 70V swing voltage, with high distortion. This means that an already distorted signal of a lower than optimum swing voltage is directed to the deep biased 300B grid. Allnic’s powerful “Inductor Drive” circuit gives up to a 150V swing voltage, with very low distortion (about 0.3%). It is this drive delivered to the T-1500 MK2 that allows for a higher output (10w) with much less distortion than can be expected from standard 300B circuits.

• Real power drive. The drive tube, 6SN7 is a moderate-mu (about 20) twin triode. We use this to drive the 300B’s via a choke plate inductor. Our choke inductor (100% nickel permalloy PC core) has very low power loss and infinitely high load impedance. This configuration is an ideal drive stage for 300B SET. And as the first tube, a twin triode 6SL7, has a very high-mu (about 70), the T-1500 MK2 has a total gain of +35dB.

• Nickel alloy output transformer. Allnic uses sophisticated ratio mixed nickel permalloy PB cored output transformers. Because of their extremely high initial permeability, it is possible to use fewer turns on the primary winding while retaining very high ‘open circuit inductance”. That means a resulting very wide frequency range and low distortion bass response. This is another reason why the T-1500 MK2 excels over other 300B integrated amplifiers. Allnic also uses a very big nickel core, so as not to be magnetically saturated at a high current level of 100mA.

• Long life and trouble-free operation. Allnic employs a “soft start circuit” to protect the tubes and other parts. It applies the high B+ voltage only after tubes are fully warmed-up.

• Self-bias control grid.

• Analog Power Tube Current Monitors. Allnic uses analog current meters to display the condition of each channel’s power tube. The meters make it exceptionally easy to see the status of each tube at any time and offer a simple, unambiguous indication of each tube’s status compared to conventional LED bias monitors.

• Natural negative feedback. The T-1500 MK2 applies about -6dB of negative feedback. This is a very complimentary amount of negative feedback that differentiates the Allnic 300B single ended amplifier from the standard, which has a very coloured and weak speaker driving force. With this natural feedback, the T-1500 MK2 has a relatively high “damping factor’, very low distortion, and a higher S/N ratio, without losing the signature single ended natural sound quality.

• We use a NEW remote controlled high quality 41 step silver contact attenuator Ver.2 (all resistors non-inductive) instead of a carbon filmed slide potentiometer.

• Beautiful 20KHz square wave response.

Technical Specifications:

• Output Power: 10w + 10w (4, 8 or 16Ω load, at 1KHz)
• Distortion: 0.3% at 1KHz, 2.83V
• Frequency Response: 20Hz – 20KHz Flat
• S/N Ratio: -80dB (CCIR, 1KHz)
• Damping Factor: 10 at 8Ω load at 1KHz
• Voltage gain: +35dB
• Input Impedance: 10KΩ (single-ended, unbalanced)
• Input Sensitivity: 230mV for rated power
• Tubes: 300B X 2 (power triode), 6SL7(6N9P) x 1 (First tube), 6SN7 x 1 (Second tube)
• Fuses:   AC Mains – 3A / 250V (110W) (two supplied – one is a spare). Tubes -0.5A, 250V, 20mm glass type
• Dimensions: (W x D x H) 430mm x 380mm x 240mm (17 x 15 x 9.5 in)
• Weight: 22kg net. 26kg shipping weight.

 https://www.hammertoneaudio.com/product/t-1500-mk2http://

Opinion Poll

Hi all, I'm new to audiogon and new to this post.

It's been a very enjoyable read so far if not a little long winded and time consuming, but can now feel proud to have finally managed to make it through to the end.

Just wondering if those that have actually listened to both the Nenuphar 10 inch and 8 inch could give there preference just to see which one is ultimately the preferred choice.

Agree, I think the Allnics could be a good match. If/when ready we have both the 10 inch and 8 inch Nenuphar’s you can try at home. Let me know.

Thanks @toetapaudio and thanks for your previous comments and input, maybe after the lockdown ends.

@david_ten and @charles1dad

Thanks for your replies, very much appreciated.

@david_ten - Not decided yet, still trying to make my mind up and and save up some money OR more accurately have the confidence to spend the money in these uncertain times.

And also the confidence to spend a large amount of money on a speaker I haven’t actually heard/demo.

@stephendunn

Any suggestions would be appreciated.

Hi Stephen

I’m currently using an Allnic D5000 DHT dac which I’ve had for nearly three years now and have been very happy with it.

The original early models used to chew through tubes a bit but that was later rectified (pun intended) with an upgrade and the later models didn’t suffer with that problem.

It received a glowing review on Stereophile then managed to achieve the worst test results of any component ever tested in the lab which was later put down to a bad tube.

The review unit was sold on and it was never re-tested by Stereophile so it now has a dubious and mythical status.

As we all know some things can’t be tested in a lab.

There was also talk of a new unit coming out to replace it but as yet nothing has emerged from KS Park’s workshop.

Anyway, as I said I’ve been very happy with it and I have great synergy with a balanced connection to my Allnic T2000 integrated KT150 tube amp.

Would an 300B amplifier with the following specs be suitable for the Nenuphars?

10W per channel
Damping Factor 10 at 8Ω load at 1kHz
-6dB of negative feedback

@charles1dad 

Thanks for the quick and informed response, very much appreciated.

Yes it is a SET amp and as you pointed out slightly unusual with the -6dB, very small, and natural negative feedback, just for better bass.

@charles1dad 

Do you think an even lower watt amp would/might be even better? and do you have any suggestions?

Thanks again... 

@charles1dad

Another bonus is that it only uses 2 300b tubes. 

Thanks again Charles for all your help and advice.

@charles1dad

The amp is an Allnic T1500

http://allnicaudio.com/product/t-1500-mk2/

I think without going up to Kondo, Shindo, Tron, separates a secondhand integrated is about where my budget ends which is at around £3500 GBP - $5000 USD

Do you think this would be high enough quality?

Thanks david_ten, toetapaudio, charles1dad and cal3713.

I know the more expensive Allnic separates use point to point wiring but the integrated amps use a PCB.

There's an image of the inside of a T2000. 

https://www.stereonet.com/forums/uploads/monthly_2018_10/L9740204.thumb.JPG.cba63850ad0d73ed4e7a1eee...

KS Park told me that the T1500 also uses a PCB, so probably very similar.

I've been using an Allnic T2000 which uses 4x KT120 tubes at 50-100W (Pentode/Triode) which was OK but I think was maybe too powerful and has maybe been damping things a little.

I've been trying (just as an experiment) my old SS Olive Naim Nait 2 20w which doesn't actually do a bad job.

I know purity of signal path is very important with tube amps.

@david_ten - Thanks David.