ULTIMA Preamp - Part ３

A friend read my ULTIMA blog and emailed me, are you able to upgrade the preamp you built for me and also what do you think of preamp output transformers (OPT)?

That's interesting. I did not want to include a preamp OPT as it would be costly. Since this is a cost-no-object design, I say why not? Preamp OPT itself is a much more difficult design than a normal power OPT or capacitor. It's easier to design a good capacitor or power OPT but preamp OPT is another different story at all.

A very, very good and wide bandwidth will be needed to do this job. If that is used, benefits are plenty. Here are a few recommended preamp OPTs you can choose:

Sowter type 9650
http://www.sowter.co.uk/specs/9560.htm
Better than 10 Hz - 60 kHz, 7k5:600

FEATURES A very large core to ensure a high bandwidth and low output impedance. High grade grain oriented silicon iron (M6) core for minimal losses and harmonic distortion. Multi section winding ensures minimal leakage inductance for an exceptional bandwidth. Low copper resistance which permits an output impedance of 203 ohms when driven from a valve with rp = 3000 ohms and a secondary load of 600 ohms.

Hashimoto HL-10k-6
http://www.eifl.co.jp/index/export/hashimoto/hashimoto.html
20 Hz - 45 kHz, pri:sec = 10k : 600/150

Tamura A-4714
http://www.eifl.co.jp/index/export/export2.htm
5k/60mA: 600/6 Ohm

Some other excellent OPTs vendors are not mentioned, like Lundahl, Magnequest, Tango, AudioNote UK, and etc. You can select from them as well. You decide!

ULTIMA Preamp - Part 2

Alright boys, here comes the power supply!


It is a massive 4 choke supply. I believe many of the commercial tube preamps or even power amps don't even come close to this! Pseudo mono power supply is used to split the left and right channel B+ with chokes to reduce inter-channel crosstalk. Do remember this is a preamp and ripple on the B+ is highly undesirable, therefore the power supply has to be carefully designed. All the chokes have to be at least 20H 150mA for the 1st two, and 20H 80ma for the other 2. Since there is no output transformer used, the size and weight should still be bearable.

The filament supply for 5687 is AC and for 45, it is a special voltage-current regulated 2 stage DC supply. 5687 filament's supply is AC as it is indirectly heated. DC supply for 5687 is just an overkill. Some claim using DC as it reduces hum on indirectly heated tube, that's just plain BS as they do not know how to design a good power supply. As for directly heated tubes, this is another matter. For power amplifiers, AC heating on tubes like 300B (5Vac), 2A3 or 45 (2.5Vac) is still okay if users have medium efficiency speakers. For those with 94dB/w/m or above speakers, DC heating is a must to kill the AC hum. For preamps, DC is a must on directly heated triodes with whatever speakers.

Alright, that's all for PSU. Next, we're going to talk about parts... this is the interesting part... :)

ULTIMA Preamp - Part 1

ULTIMA design concept is determined. You do not need very complex circuitry and lots of components to make an amp sound good. Sometimes I just got so fed up looking at amps with such a complex design that are just simply an overkill, sound killer, noise generator, "body builder" and excuse for price increase, you know what I mean?!?! Simple is the key! Come on guys, not all audiophiles are stupid!

There shall be 2 flavors, 1 is for those with tube power amps, the other is for those with solid-state amps that desires more tube warmth and smoothness but also requires higher driving strength for the SS amp input stage.

Flavor 1 - two 5687 + two 45 + one 5U4G, 3 outputs preamp
Flavor 2 - two 5687 + 0ne 6X5, 2 outputs preamp


The 1st stage is a mu-stage, having a 5687 (other triodes are possible as well, like 6C45, 5842/WE417, 3A167M, etc) triode loaded with another triode that is configured as constant current source. The upper triode will act as a high impedance load for the lower triode. Such topology is much superior to simple resistor loaded or choke loaded types, with the cons of needing higher B+ and an additional tube in the circuit.

The 2nd stage is just a choke loaded gain stage with a direct-heated-triode like 45 or 2A3. Other choices could be 71A, 6B4G, 31, 01A, 801A and even the 300B! 45 is chosen as it fits nicey in to this application due to the sound character that is considered rather transparent and linear among the direct-heated-triodes. The current requirement to bias the 45 is just nice as well and not too taxing on the power design as very low ripple is needed to be used as preamps.

Some may ask why not just mu-stage the 45 as well? Of course you can! I'm not doing it as mu-staging the 45 will increase the power supply B+ voltage to over 500Vdc and there aren't many 500Vdc+ capacitors that sound that good compared to their normal 450Vdc/500Vdc brothers.

If you build the complete version, you shall get 3 outputs, 1 low and 2 medium output impedance outputs. The low output impedance channel can be used to drive subs as that is the worst sounding among the 3. The 2 medium output channels can be used to drive tube or SS power amps with input impedance of 25k or more, the higher the merrier. If your power amps just happen to have very low input impedance, then use the low output impedance channel, it is not as good as the other 2 but it is still a very good preamp output.

The frequency response of the preamp will be 5Hz - 100kHz @ 3dB. It also depends on the wiring methods and components used. One can copy the design but the results will differ depending on the skills of the builder. None is created equal. Don't blame if your version does not sound good. :)

The next article we shall talk more about ULTIMA in details.

The born of ULTIMA Preamp!

I've received a call yesterday while I was modifying a friend's Stranwood AV1 preamp. He said, "I want an ultimate, cost no object tube preamp. What can you come up with???". Immediately, I thought of the Ongaku class of gears... haha...

That kept me thinking for > 24 hours... My tube-stained blood is boiling hot! More and more ideas came up my mind and I just can't stop myself from painting the picture of what it could be... :) Nothing could be more exiciting than this!

This will be the perfect match for my upcoming 300B amp, with the plan of upgrading that to an extreme version as well, named "EXTREMA"! Instead of letting those brain energy go into waste, I shall record it down in this blog. My projects so far are always cost constrained as I and most of my audio buddies live in a real world. :( "Cost no object" phrase always pops up in our mind but none of us could dive into it with our hard earned money. I've been waiting for this call for ages and now it is realized. Way to go mate!

The preamp would be called, "ULTIMA"!

ULTIMA shall have the following features or specifications:

• High input impedances
• Medium + low output impedance outputs
• Ultra wide bandwidth
  
• Tube based preamp - triodes!
  
• Tube rectification
• Silver + amorphous transformers
• Cryo-ed parts and chassis
• High quality premium components

Design
An ultimate preamp starts with a good design. You can't go very far the design is crippled in the beginning. Since ULTIMA are designed to drive EXTREMA as well as other power amplifiers, it has to have tonnes of tone but yet not loosing a slightest bit on transparency and neutrality. Sounds difficult isn't it? Well, no worries, Kendo is here to help. :) Let's start cooking!

• Triodes on constant current load - linearity
• Tube rectification - warmth + tone
• Silver transformers + silver wires - extended + smooth highs
• Teflon tube sockets - minimal noise and coloration
  
• Capacitor instead of transformer coupled - widest bandwidth
• Cryo-ed parts - detail recovery + lower noise floor
  
• Aluminum, solid and rigid chassis - lower noise floor and vibrations
• Oil + high quality film caps - tone and lower noise floor
• Hand matched components - imaging + soundstaging
• Mains cleaner employment - lower noise floor + dark background
  
• Amorhpous choke loaded power supply - lower noise floor + detail recovery
  
• Stepped volume control - imaging + soundstaging
• Input transformer - lower noise floor and detail recovery
• High quality chassis components - minimal coloration and tone pollution
• CMC filtering - lowering noise floor
  

I'll be posting a concept schematic pretty soon, stay tuned!

Conned by unscrupulous eB*y seller selling Tannoy SRM12B (Super Red Monitor)

Buyers beware!

Let me share with you my bad experience on eB*y USA. :( I seldom buy stuffs from eB*y USA as the shipping cost a bom but I got no choice as there weren't many Tannoy audiophiles in Malaysia. Those who are seldom wanted to part with their belowed Tannoy speakers.

I saw a pair of Tannoy Darking SL35 (198x model, huge bookshelf with 10" Dual-Concentric with rubber surrounds) posted at an local (Malaysia) online site today (4OCT2008) selling used hifi gears. They were snatched within hours. I saw it in the morning and it was sold in the afternoon. Now that's call hot cake! :)

Do you guys have any bad experiences as well? Share with me please.

Picture taken while it was at my good friend's place in USA.

I bidded for a pair of supposedly good condition Tannoy SRM12B. SRM12B uses DCC-3149, 12" Dual-Concentric driver with pleated-rubberized cloth surround and paper cone with a dustcap. They're made in the 80's. The picture below looks fine right? It turned out to be nightmare for me. The claimed condition was excellent without any cosmetic flaws but I got more than what I bidded for.


Both the drivers have cracked surrounds that had to be replaced. One of the speakers had the spider damaged due to over-driving. The other speaker had the tweeter damaged due to moisture. The total reconing (*2 woofers) and tweeter replacements cost was U$550 for a pair of U$800 bidded price. That was not fun at all.

Luckily the nightmare ended here after the repair. Cathy at www.speakerex.com is a gem. I got the drivers refurbished with original cones and tweeters from Tannoy and now they're in mint condition. They work great and they've glorious sound! They're very efficient speakers boasting 95dB/w/m @ 8 Ohms. I've no problem blasting and watching movies with a 5W EL34 SET (DIY).

Guangzhou 2008 International Audio Video Show

I've the opportunity to visit Guangzhou IAVS 2008 while I was on business trip to Shenzhen + Taipei. I've taken some pictures with my cellphone. Check them out. Drop me a mail if you want to hear my opinion about the setups.

Setup: A.D.A.M speakers

Setup: Octave Electronics

Full set of MBL

Vienna Acoustics + Ayre

PMC + Audionet

Spendor + Classe Audio

Westlake + Jadis

Can't remember the name. :")

Can't remember here as well. :")

Dynaudio

Avalon + Jeff Roland

Wilson Audio

Full set of DCS!

Burmester from Germany

Wharfedale

Spectral Audio

Tannoy!!!!

Tannoy deserves another view!

Full set of Quad electronics

Marantz + B&W

PRC made speakers

Orgue single-driver full range speakers

Procella speakers.

Another PRC made speakers + amps.

ATC driven by AudioNote amps

My Audio Journey...

The story begins here...

My hifi fever started since I was in secondary school time when I began to appreciate music reproduction quality. My dad is an audiophile too, and he still is! He's still using ~20 year old gears that still sound pretty good. The old timers are built with quality and durability in mind.

I bought my 1st set of hifi back in university years, 1996 at Manchester, United Kingdom. They were Wharfedale speakers, Sony CDP-XE310 and Goodmans integrated amplifier. Those accompanied me for 2 years before I upgraded to a bigger Wharfedale speakers and Marantz PM50 integrated. Those were the years mates!

Now I'm into tube amplifiers, full range single drivers, Tannoy Dual-Concentrics, and building my own gears after the commercial on-the-shelf stuffs got too expensive, not to mention the quality-per-dollar ratio that went down the drain.

If you're interested at what I'm interested in, check out this blog regularly. I'll be update it as frequent as I can on all my audio thoughts, designs, experiments and experiences.

Till then!