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Old 23rd April 2013, 01:27 PM   #1
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Default RH84 Rev2 Build w/Premium parts

I had been looking to build a "real" SE after hearing the results of a Piccolo ECL86 SET I built years ago with old console parts. Last year I built a set of Markaudio 12.2P Pensils and wanted an amp to complement them. I looked at 300B, 2A3, etc. but the BOM cost was just too high. I ran across Alex's RH84 and have always loved the sound of the EL84. I contacted Alex and he was VERY helpful throughout the process and I come to find out he has a Rev.2 of the schematic with a zener to set the G2 voltage on the pentode and a constant current supply to bias the EL84.

I ordered all Obbligato film caps, Transcendar 10W OPT's, Riken carbon grid stoppers and Dale RN60 metal films. For tubes I am running a triple mica E81CC and a set of TAD EL84-STR's.

I decided to modify the power supply from Alex's design to utilize a TJ mesh plate 274b rectifier, so the first cap is a 4.7uf and the second is a 100uf, both Obbligato film.

To house all the loot, I chose the beautiful Hammond walnut chassis. The plan is to later build a line stage, phono stage and headphone amp on the same chassis for a matching quad of tube gear.

The build went without a hitch. All voltages checked out after plugging in junk tubes. I put the good tubes in and it played oh so sweet music!

The detail is incredible! Coupled with the Markaudio 12p's, it gives a level of detail and realism that truly makes the musicians sound like they are sharing the same room as me. ...but not to a fault! I have heard a Van Alstine true balanced system and it was incredibly detailed, but was like a cheese grater to my ears! The highs are crisp and clean, the midrange is as expected from any Class-A tube amp with female vocals to die for! The bass seemed a bit lacking at first, but I soon realized it was still there but a perceived loss as my old console SE had a more muddied bottom end making it seem louder. The other shocking phenomena was the almost complete lack of hum from the AC heaters. I left them floating and can hear only a slight hum at full volume once I get within 12" of the cones. At this point not even worth modification to try and reduce it since it is so benign.

While this amp is not a powerhouse by any stretch of the imagination, it is on of the most detailed and engaging amps I have heard. I found myself listening to tracks on CD's that I usually skip past because the never intrigued my interest. The only other system I found this "engaging" was an Audio Note kits demo using their complete top-of-the-line kits from CD transport, DAC, 300B transformer interstage mono blocks to their signature AN-E's. While my system is not as full an audible spectrum as the Audio Note system, mine also did not cost $100k! It will be a pleasure burning-in my ears to this new amp and rediscovering my music collection yet again!

Enough chatter ... now for what you really opened my thread for ... pictures:
Attached Images
File Type: jpg parts.jpg (212.1 KB, 221 views)
File Type: jpg guts.jpg (296.0 KB, 215 views)
File Type: jpg tubed.jpg (215.1 KB, 215 views)
File Type: jpg glow.jpg (250.6 KB, 210 views)
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Last edited by craigtone; 23rd April 2013 at 01:31 PM.
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Old 23rd April 2013, 09:33 PM   #2
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Great looking amp, congrats. I have two versions of the RH-84, 6BQ5 and 6V6.
The 6V6 kicks butt over the 6BQ5's. I'm just saying.
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Old 23rd April 2013, 09:45 PM   #3
tim614 is offline tim614  United States
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great job!
one of my first build was a RH84.
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Old 23rd April 2013, 11:33 PM   #4
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I may rebuild the 6BQ5 with the components on the underside of the PC board.
I would probably put a 12AX7 in place of the 12AT7 also. Notice the OPT's of the 6V6 are smaller than on the 6BQ5 and still it out performs the 6BQ5.
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File Type: jpg amp2.JPG (89.8 KB, 81 views)
File Type: jpg amp3.JPG (102.1 KB, 74 views)
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