Hi Victor - I've had the same issue: mine has blown the 2A fuse twice now. Would it be better to use the 4A fuse - or a 2A slow-blow fuse (or make no difference at all)?
A bit of an update. I ended up selecting a pair of Focal Aria 906b speakers after a local dealer kindly allowed me to try them out alongside a Dynaudio pair with my 8200 amp. They are simply phenomenal with both the 8200 and that much better with the 8900.
Even better, the dealer was using an Aurilac Altair G1 streamer / DAC for the demo. While certainly pricey - over 3000 USD new - he gave me a 30% discount for the demo model. It boosts the quality of the listening experience even more - let's say >20% - especially when streaming from high resolution sources such as Tidal or (in my case) Qobuz. The upshot is one of the two or three most astonishing listening experiences in my life - the other(s) with a very high-end installation of Macintosh monoblock amps and well matched speakers, a setup costing easily 30k USD or more.
Meaning the measurements as laid out under "Voltage check points and voltage references" on p. 25? Will be happy to try - but won't be able to get to it until returning from a trip on May 15. Many thanks in advance for your help!
Understood, and thanks in advance. In the meantime, will try the slow-blow 2A if the new fuse goes out.
Here is Mike's TU-8900 with Audio Note Siver cap + Brimar 6067/12AU7 + Cossor/LinLai E2A3 + Signal path with Audio Tantaulm Resistor 46 pcs
Mike's comment....
Quite happy with the amp. I’ve owned quite a few high end tube amps (Eddie Current Studio, ZDS, etc.), and I don’t feel the TU-8900 (as we have ours configured) is a step down, with the tube selection, etc, it’s a step up on many ways.
Mike
yes
it is custom made for using Audio Note Silver Caps
it includes 1x top acrylic plate and two spacers $38.00
it is custom made for using Audio Note Silver Caps
it includes 1x top acrylic plate and two spacers $38.00
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Having owned my 8900 for several months now, I feel compelled to write a follow up.
For comparison, I currently have the 8600S, a Luxman MQ-88uSE, an inexpensive modified Chinese single ended EL-34, and Levinson 536 monoblocs and pre, paired with 802D3s. Obviously a very diverse and different collection of gear with staggering price differences making a direct comparison moot. Each of these systems has their place, however for pure emotional involvement my 8900 (build detail in a prior post) suits my listening preferences best.
I don’t want to get too carried away with the descriptors. Sometimes too much hyperbole can diminish an experience (ever gone to a movie after listening to your friends Incessantly carry on about a particular line or scene? kind of takes the edge away from the movie). So best to leave the hyperbole to others and leave you to enjoy the experience for yourself.
By far my preferred configuration is with the 2A3s and 12Bh7s No negative feedback and highly efficient 10 inch full range drivers with speaker level connected REL subwoofers and the Denifrips terminator for a source. I tried several tube and speaker configurations including WE300Bs, NOS Amprex 7316 and others. For speakers I have also tried JBL 4367s. All sounded great but the magic for me was the 2A3 with zero NFB paired with a minimally reactive speaker load. With a slightly more reactive speaker load such as the JBLs The lower output impedance from the negative feedback gave slightly more control as did using the more powerful 300Bs
So, how does the 8900 compared to the 8600S? They are both wonderful. I will not be selling either. I would say the 8600s Has a slight edge in smooth and may be a better choice for slightly more reactive speaker loads, but still pairs best with full range drivers. The 8900 w 2a3 has a more defined “leading edge of a note” clarity. Don’t confuse clarity with sharp. They are not the same. Without listening side-by-side, unlikely you will notice a difference. Both stellar.
As a sidenote: With zero negative feedback, the gain while using 2V output from my Denafrips Terminator Is overwhelming. You will either need to lower the source output digitally through software such as Roon, or, as I did, add a voltage divider in front of the volume control.
Looking forward to the next Elekit design. 2A3/45??? 😁
For comparison, I currently have the 8600S, a Luxman MQ-88uSE, an inexpensive modified Chinese single ended EL-34, and Levinson 536 monoblocs and pre, paired with 802D3s. Obviously a very diverse and different collection of gear with staggering price differences making a direct comparison moot. Each of these systems has their place, however for pure emotional involvement my 8900 (build detail in a prior post) suits my listening preferences best.
I don’t want to get too carried away with the descriptors. Sometimes too much hyperbole can diminish an experience (ever gone to a movie after listening to your friends Incessantly carry on about a particular line or scene? kind of takes the edge away from the movie). So best to leave the hyperbole to others and leave you to enjoy the experience for yourself.
By far my preferred configuration is with the 2A3s and 12Bh7s No negative feedback and highly efficient 10 inch full range drivers with speaker level connected REL subwoofers and the Denifrips terminator for a source. I tried several tube and speaker configurations including WE300Bs, NOS Amprex 7316 and others. For speakers I have also tried JBL 4367s. All sounded great but the magic for me was the 2A3 with zero NFB paired with a minimally reactive speaker load. With a slightly more reactive speaker load such as the JBLs The lower output impedance from the negative feedback gave slightly more control as did using the more powerful 300Bs
So, how does the 8900 compared to the 8600S? They are both wonderful. I will not be selling either. I would say the 8600s Has a slight edge in smooth and may be a better choice for slightly more reactive speaker loads, but still pairs best with full range drivers. The 8900 w 2a3 has a more defined “leading edge of a note” clarity. Don’t confuse clarity with sharp. They are not the same. Without listening side-by-side, unlikely you will notice a difference. Both stellar.
As a sidenote: With zero negative feedback, the gain while using 2V output from my Denafrips Terminator Is overwhelming. You will either need to lower the source output digitally through software such as Roon, or, as I did, add a voltage divider in front of the volume control.
Looking forward to the next Elekit design. 2A3/45??? 😁
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I've now received mine - many thanks! Quick question, though: I don't see on the photo where the spacers go - between the cover and the cabinet or over the cover - or? (It's likely obvious when installing it - but won't be home to play with it on my own for another five weeks.) Thanks in advance
Electrostatics are not a typical choice for a low powered DHT amp. Also 91dB efficiency is somewhat low. I do not know how reactive these speakers are, i.e. how smooth the impedance curve is or if there are any significant impedance dips or phase angle shifts. Also unknown is the use of negative feedback in his amplifiers and the impedance of the output transformers.
These factors have a tremendous influence on the sound of relatively low output impedance of SE class A amps—speakers with significant impedance dips and phase shift angles become more difficult for them to control. I’m not saying electrosattic speakers are a bad choice for this amplifier, I haven’t heard them. But conventional wisdom would say they are not the best match. However if this was all about conventional wisdom none of us would be listening to SE DHT amps.
Given the influence speakers have on these amps and the dramatic difference in our speaker choices, our listening experiences are probably quite different. I have tried several different speaker types, but to me nothing compares, with Class A SE amplifiers, to a full range drivers with no crossover circuits. By nature these Provide the very stable minimally reactive load that single ended amplifiers lIke. Yes, full range drivers have measurable limitations, but then again so do SE DHT tube amps. I find the combination sublime.
There were some similarities in our experiences, but I do not completely agree with his findings. Possibly due to our vastly different speaker choices. Some of the places he found the 2A3 lacking I did not. Same could be said for the 300B. Based on my choice of speaker, a highly efficient full range driver backed with speaker level REL subwoofers, The 2A3 with zero negative feedback equals or slightly bests the 300 B in all parameters with a clear edge in transient detail. In theory a more reactive speaker load might be better controlled by the more powerful 300 B with negative feedback applied. This seems to be the opposite of what the reviewer found. Speaker control is also affected by output impedance of the output transformer which the reviewer Stated were different between the amplifiers. Lots of moving parts here.
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