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I thought i would thank you all for helping finishing my projects. It started with PP RH EL34 project with outboard power supply. And now she has a SE companion, a RH6550 with 6J5 driver tube.
Sometimes questions about build problems don't seem to have any follow up or resolution and so i wanted to thank those that help resolve any problems that i encountered. Sometimes the suggestions were not the solution to the problems encountered but i found that communicating my issues helped me to troubleshoot with a more "open mind" and end up with a completed project.
The amps are PP RH6550; A PP stereo with EICO HF87 output trannys. The difference is it uses an input trans for phase splitting into a 6SL7. Each section of the 6SL7 drives the 6550 in class A instead of class AB.
The SE 6550 w/ 6J5 driver is the RH Universal circuit with the 6J5 driver tube instead of a 6SL7. This model is upgraded via Electra print OPT, 20watt with 3K secondary impedance. Just started listening to this bad puppy and i had stop writing just now cause my head was bobbing and the body was swaying too much with Bonnie Raitt.
The pulse behind the amps is the outboard power supply with twin rectifiers. LCLC or cLCLC switchable which delivers either 350 or 450v B+ when the 5UF "c" is switched out. 350vdc for SE and 450 for the PP amp. In the pics the power supply is on the left. I apologize for cheesy lp cover backdrop. Thanx again, best regards, Dak
Edits: 10/25/16Follow Ups:
Great work. I like the outboard power supply scheme.
How did you come to place the RCA input jacks in the middle of the amps like that?
Don't think I have seen that before.
dt 667
Thank you. It was a fun build. I have been doing the rca inputs close to the input tube just to keep the wiring short. The input wire is only 2 inches long and i use pure silver single strand with a loose fitting teflon tube for insulation. Seems to work fine and i get no noise pickup.
Aesthetically, having the rca cables in view is not as nice as it being hidden out the back but, i would rather go with performance with the silver input wire, over appearance. cheers.
Looks great, hope it sounds the same. Love your choice of records!!
"If you don't like what you're doing, you can always pick up your needle and move to another groove." Timothy Leary
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I have taken any of the new amp yet. The new amp has only been running for a few hours. I don't want to jinx it. cheers.
Hi DAK,
Looks very well built and well laid out. Kudos.. I like the corner brackets too.. Did you use K&K audio pcb's for the LL1544A? I have a pair myself in an old DAC with diy pcb's a friend made for me years ago. I want to re-use them in another app like yours one of these days but for SE as step ups.. Do they still have good bass response with a highish line level signal from a preamp? Thank you.
Regards....
hi Fred, and thank you for the kind words. The chassis is made from aluminum, probably home made, that i acquired with some Dynaco a450 outputs. The builder gave up on the project. I need to use the brackets to reinforce the rigidity which was poor since the sides of the amp were just bent and not welded. The corner braces made the chassis 10x stronger.
The input trans and the circuit board are from K&K and to me they perform invisibly. The only thing is the gain is halved which because of the preamp is not an issue. Although, this particular trans can be configured for more gain 2 or 3 times, but Kev suggested that since i am using a preamp for the best sound quality use it as straight split.
Since i based the amp on a SE circuit that i like to use, with each SE amp driving 1/2 of the split phase, i wanted to know what effect the cancelled 2nd order harmonics would have. I also wanted to know what is the "sound" of the phase splitter. I always felt that the tube phase splitter introduces some coloration since there is no perfect phase splitter. To me the sound from this amp is more coherent and very much like SE but "cleaner" with more subtleties coming through. cheers, Dak
Hi DAK,
Thanks for the detailed response, and sharing your thoughts on the Lundahl trafo as input phase splitter.. What type of preamp do you use with it?
Best regards...
It is an Audio Electronics AE3 made by Cary. It is a simple linestage preamp with SS rectification and 2 6sn7 for the tubes. Nice and neutral preamp.
Thanks DAK..
I remember Cary/AES 6SN7 preamps.. Iirc, one variation uses a 6CA4 series psu reg w/ ss rectifiers.
Regards..
Right. In fact the chassis has a hole for that but mine doesnt so it is covered.
I rebuilt an AE3 with a blown power trans, in which i used a potted transformer and i used a 6x5 rectifier tube. I think it sounded a little smoother than the SS rectified version.
Very nice, clean and neat! Love those AB pots, darn they're expensive now!
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Buy Chinese. Bury freedom.
I have a box full of the AB's, but they are all high value (5k+). Any way to use them?
The amps are the result of much that i have learned here on the asylum.
Nothing cheesy with Hendrix's Band of Gypsies, Joni Mitchell, and It's A Beautiful Day..
I like the chassis color, nice contrast on the Altec green on the iron and caps.. Congrats.
Nice work! And there's nothing cheesy about "It's a Beautiful Day." That's one of my favorites.
They had a unique sound, no doubt. But their troubles with their manager is really terrible. In essence the band doesn't get any money for the rights to their music.
I didn't know that about the manager. There's a little history on the Wikipedia page. I lost interest in them after Linda LaFlamme left the group since her vocals were an essential part of the sound in my opinion. That aside the Live album from Carnegie Hall in 1972 is an amazing recording even without Linda.
Belafonet at Carnegie Hall is another awesome album. Live albums can capture a spark that is missing in a studio record. cheers.
nt
Beautiful workmanship! Nothing cheesy about the backdrop either. Good stuff!
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Buy Chinese. Bury freedom.
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Have Fun and Enjoy the Music
"Still Working the Problem"
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