Bill,
Wow! You've been busy lately with this all out assault preamp project. I look forward to your listening impressions and how it compares to the TRL Dude you have used and admired for many years.
Audio Note, WE-91A, Rega, Ayon
1/20/12 -I built a 300b single ended triode amplifier based on Joe Robert's Western Electric 91A. Used all vintage caps and vintage resistors-Alen Bradley and Ohmite. These vintage parts came from Leeds Radio just a few subway stops from my apartment in Brooklyn. The coupling caps are .1uf V-Cap TFTF. Large motor run oils in the power supply. Sophia Electric 91-05 Opt transformers and Sophia Princess Mesh Tubes. Stancor PT's came from ebay.
3/2012: Replaced the Alps Potentiometer with a Goldpoint 50K stepped attenuator. More clarity and transparency through the entire frequency range.
Still not using a pre amp.
5/12- Replaced the oil capacitor C-3 biasing the 6C6 with a Black Gate.
6/6/12- Finished new chassis
7/12 - Added Rega P3-24 with Power Supply and Exact Cart. Will look at different cart options later
7/12 - Pulled the 24 gauge silver hookup wire used throughout the amp and installed 16 gauge pure copper wire. The 24 gauge wire gave the sound a weightless quality that I did not like.
The 16 gauge has been in for three weeks and I can report that the weight and depth has very pleasingly improved. Vocals have an added pleasing quality. Instruments throughout the entire frequency range have more depth and richness. The low end is more powerful. I can more easily perceive the stage that the players are performing on.
10/12 Pulled C-5 and didn't replace it. Pulling this capacitor has changed the sound of this amp. Clarity and detail throughout but especially in the lows thru the mid range. Much easier to detect decay and the accompanying reverb. Dynamics seem more unconstrained as well. It has decreased gain by around 20% but in my room with the AN-e's it does not matter.
1/2013- Replaced the 1k Allen Bradley 6C6 Cathode resistor with a Vishay TX2575. This resistor is very neutral...almost as though it has no sonic character of its own. Each instrument has its own accurate color and detail but not at the expense of the overall musical message. Took about 100 hours of break in time.
2/16/13--After a month with the TX2757 in the 6C6 cathode position, including bypassing them with Black Gate Caps I decided to pull these resistors. They did not provide the richness and room filling sound that the A-B's and the older AN Tantalum did. A few weeks ago I got two of the most recent production 1k An Tants from the Hi Fi Collective.
These new Tants are more closely akin to the A-B's than to the TX2575's. They are not as sonically accurate or pure as the TX's. But they do fill the room with rich satisfying music like the A-Bs but with more detail and without the extra noise or warmth or whatever it is with the A-B carbon comps. Still running the amp without the 6C6 bypass cap.
2/2013--Built a home brew phono pre amp using the Audio Note M3 schematic.
4/2013-Upgraded to the Rega White belt and Groovetracer Reference subplatter. Excellent sonic improvement.
5/2013- WE91a amp---Replaced the the screen cap (6C6) which was an oil with a 12uf Solen cap. Have about 50 hours on the Solen. Not sure I like it. Makes the amp sound a little cold and forward. Will live with it for a while.
Late 5/2013. The 12uf Solen has broken in and I like it better than the oil that it replaced. Warmth but with plenty of detail.
Mid 7/2013 (Audio Note DIY Phono pre) ---- Added Audio Note Tantalum resistors into the signal path. 7/27/13-took out the .047 and .33uf Solen caps in the signal path of the phono pre and added .047 Vcap TFTF and .33 Audio note copper caps.
8/11/13 (Audio Note DIY Phono pre) After two weeks with the Vcaps and AN copper caps in the phono circuit my vinyl rig is a lot fun to listen to. A more beautiful and open sound than with the Solen caps.
10/12/13 WE91a---
replaced the 15uf oil cap that was biasing the 300b tube with a polarized 22uf Black Gate. Will listen for a while and see if I like it.
11/1/13 WE91a
The Black Gate by itself is still fine.
I cleaned the resistor and Cap leads, tube sockets and tube pins with 99% alcohol. They have been in the cicuit for 2 years and were tarnished and very dirty. Once cleaned much more mid range clarity and cleaner bass.
11/20/13 Added Gold Lion GZ34 Rectifiers. Sound is open and airy. Very nice
12/28/13 Added Emission Labs 300bXLS.
2/17/14- Audio Note Home Brew Phono Pre-Finished new chassis for the Power supply.
Added 8 more Tantalum Resistors (4 per channel) to the Phono circuit. Now the circuit has a few A-B's and 6 Tantalums per channel. Phono pre sounds a lot better than it did with the PRP red resistors.
3/16/14 WE91A. Because the EML300bXLS tubes are so well internally balanced, I was able to remove the Hum pots and still use AC heat. Now the 300b bias is going thru the center tap of the 5volt filament transformer. Without the hum pots, the sound is much freer and alive. I am liking this!
3/31/14-AN Phono Pre. Replaced several more PRP resistors that were on the plate of both the PS and circuit with Mills. Hopefully they will sound better than the PRP's
5/1/14 WE91a. Took out the Allen Bradley grid leak resistors and replaced with Shinkoh Tantalun resistors. took about two weeks to break in.
5/25/14 WE91a. Put the Allen Bradley grid leak resistors back in. The Shinkoh Tants made the amp have a glare that didn't go away even after the resistors were broken in.
Running the Amp at 425V B+ is sounding good with EML 300bXLS and GZ34's.
6/7/14 AN Home Brew Phono Pre-
Took out the last PRP resistors in the circuit and replaced with Allen Bradleys. Very nice change. Now the circuit has a good mix and Tants and Allen Bradleys. There are a few more PRP's in the power supply that I will replace very soon.
6/22/14 AN Home Brew Phono Pre- Took out the last of the PRP resistors in the power supply and replaced with Mills resistors
9/23/14 AN Home Brew Phono Pre - Installed Audio Note Copper Capacitors in the RIAA network. .0028uf and .0082uf in each channel
11/21/14 AN Home Brew Phono Pre - Replaced the six more Allen Bradley resistors (3 per channel) with Takman one watt resistors.
11/28/14 AN Home Brew Phono Pre - Tweeked the voltage in my phono pre. Very good results. Much more open and transparent sound. Orchestral strings sound really nice.
12/6/14 Rega P3-24. I added a Audio Note iQ3 cartridge. Needs about 100 hours of break in.
Rega Exact is a great cartridge but opportunity came up. We'll see which I prefer once the iQ3 is broken in.
12/13/14 WE91a. installed Duelund Copper Cast coupling caps. After two weeks more natural sounding than the V-cap Teflon
1/12/15-Duelund Copper CAST 630v coupler caps have a very natural, emotionally engaging musicality with a very rich and colorful tonal pallet. Keepers for sure!
3/1/15-WE91a - Experimenting with WIMA power supply caps. These are Metallized Polypropylene. C2 in my power supply is a 100uf oil. I have replaced it with a 50uf Wima. I think the 50uf is a better choice as it controls the woofer a bit better.
3/7/15- WE91a - Added new custom built power transformers by Heybour. 250mA. Also added another WIMA cap at C1- its a 15uf.
B+ went from 424 to 450. 375v across the 300b plate. 76mA. With all these changes the amp has better control over the woofer. Punchy bass.
3/25/15 WE91a. Took out the Wima at C1. Made the amp sound harsh. Put it a GE F97 oil.
3/30/15 WE91a. Took out the Solen 12uf Cap on the screen of the 6C6 driver tube and replaced it with a 22uf Black Gate VK cap. The Solen is muddy compared to the Black Gate. I didnt realize how important the cap on the 6C6 screen is to the sound of the amplifier.
4/15/15 WE91a - A friend has lent me four low DCR 2H chokes (two per channel) to try in place of the single 10H Hammond in each channel. PS is now 15uf/1.8H/15uf/2h/50uf. Amp sounds faster and more nimble. Nice.
5/14/15 WE91a. I have bypassed the Wima Cap at C2 in the power supply with four very low value film caps. Too soon to draw any conclusions about sound.
5/31/15 WE91a. New production Audio Note 50uf Kaisei Power supply capacitors have arrived and after a week of burning them in, I have installed them in place of the Wima 50uf and all of those bypass film caps. will see which I like better in a couple of weeks.
6/13/15 WE91a. The New production Audio Note 50uf Kaisei Power supply capacitors have been in my power supply for two weeks - about 100 hours or so of playing time. They have a purity, and a crystal clear clarity that no other cap in the power supply has had. I am going to replace the rest of the PS oils with these to see what happens. Maybe it will be too much- who knows. They dont have too much of a sonic signature. They just sound very free and open so adding a few more may be ok. If not I can put an oil back in.
7/10/15-WE91a. Installed Audio Note Ultra Hi B output transformers today. Will need a few weeks to come around.
9/1/15 - WE91a. The Audio Note Transformers and great with excellent depth and coherence. Added copper shrouds.
9/25/15 -Western Electric Speaker wire and interconnects. I like the speaker wire better than my Audio Note Lexus copper. More direct. They make the Lexus cable sound soft around the edges and diffuse. The WE Interconnects are very good too. But still learning about there sound.
10/11/15 - WE91a. Took out the 6C6 driver tubes and installed C3m drivers.
11/28/15 - WE91a. Added Regulation to the Screen of the C3m driver tubes. K&K CCS board and an OD3 glow tube that is puts out 150volts. The C3m driver tube and regulation is an excellent driver of a 300b output tube. Very fast and dynamic with lots of detail and musicality. I am very happy with the sound of this amp. Probably not making any more changes for quite a while.
1/1/16 - WE91a I still notice a bit of extra weight in the lower mids so I replaced the last oil cap in the power supply (c-1) with an Audio Note Kaisei 50uf cap.
2/1/16 -WE91a. After adding additional Audio Note Kaisei capacitor to the power supply, the voicing of this amplifier is complete. The power supply is 50uf/5h 30ohm choke/ 50uf and it sounds dynamic fast and clean. With all Kaisei caps in the power supply the lower mids are now more open and that weight I mentioned above is gone. Will rebuild the amp onto a new piece of wood and hide all of the hi voltage parts underneath. Will post pics of the new build as it progresses.
3/10/2016 - WE91a. New Chassis is finished. The new build features and extremely short signal path and a copper box known as a "faraday cage" which isolates the audio circuit from RF/AC, Cell phones, and other nasty's. The goal here is to eliminate the grid stopping resistors that are usually necessary on many tube grids. In a SET amplifier any extra part effects the sound especially a resistor in series with the grid. They are usually necessary on the C3m grid as well. Without a grid stopper the C3m tube can squeal and make all sorts of other very harmful noises but with my new chassis implementation I have not needed a grid stopper. If the C3m tubes continue to behave it would be a major step forward. The sound of the amp without a grid stopper is more open free and natural.
4/2/16 - Audio M3 Phono Pre- I had some copper left over from my amp build so I made a 8x6x2 copper box and put the phono circuit inside. Pics added.
5/16- Bought Kondo KSL-LP silver interconnects and am using them with Audio Note Lexus Bi Wire copper speaker cables. After trying various IC's like homebrew WE-16g and Ocellia silver reference and various Speaker cables like WE-16g and 10g and Kondo KSL-SPz, the Kondo KSL-LP silver interconnects with Audio Note Lexus Bi Wire copper speaker cables really bring something special to the table at least to my ears system and room.
9/20/16 Ayon CD07 - put in NOS Raytheon 5687 tubes and after a week of break in they sound tremendous. Transparent mids fast and clean lows and clean extended highs. Better than any tube thus far.
10/2016 WE91a - I removed the 91k bleeder resistor from the last cap in the power supply. I can't believe how much more open, free and transparent the sound is. It's like that bleeder had clamped down on PS and now without it there is more energy coming into the room. Any tonal warmth that had been left in this amp is now gone.
11/2016 WE91a - with the bleeder resistor removed I noticed a tinniness in they high frequencies so I removed the GE 12gauge wire from both the power supply b+ and ground and replaced it with vintage WE 16gauge wire and that tinniness is now completely gone. The WE vintage wire sounds very good just as others have reported.
1/2018 -WE91a. Replaced the Goldpoint 50k stepped attenuator with a Seiden Shunt stepped attenuator loaded with Audio Note tantalum resistors. Its been in for about a month and I am shocked at the change in sound. Extended highs and lows and more lively mids. Huge step up. The highs and mids are so open and beautiful. Powerful bass. A very worthwhile change.
3/2020- WE91a. Over the past year and one half, experimented with a .22UF Russian vintage cap in the coupling position in place of a duelund .1uf copper cap after growing tired of the accurate and analytical presentation of the Duelund. The Russian cap did not do anything that I liked even after a year of listening. It was kinda like all the instruments turned the color of grey. I’ve had some Audio Note copper .47uf caps sitting around for a few years so put them in around the first of 2020 so they now have three months on them.
The AN copper .47uf coupling caps after a two month an up and down ride stopped changing about a month ago. So I’ve been listening for a solid month after they finally settled in.
I perceive no less detail with them compared to the duelunds but the detail is integrated into a more musical and three dimensional presentation. There are real instruments playing in front of me. Much more texture and dimension. There may be just a bit of glue tying everything together but even with the glue, there is individual instrumental color and tone in spades. A bit more overall warmth and richness. Keeping in mind that my system has AUDIO NOTE output transformers, speakers, speaker cables, resistors and capacitors, kondo interconnects and an AN IQ lll Cartridge. So I would have thought adding an Audio Note coupling cap would have been to much, but it actually brought everything together in a very nice way.
I think they might be too much of a good thing in a system that already fills out a three dimensional space but for me they add something lovely and musical that was missing. This reminds me that there is no such thing as the best capacitor or best anything else....
Dimensions: 25’ × 12’ Medium
Ceiling: 9’