SE vs PP
I will first admit that I did not build this amp as spec'd so this is an already flawed review. That being said I built the 6HJ5/6GU5 version of the amp. First impressions, REALLY LOUD! No problem filling a BIG room with sound with this baby! I am using 2-way speakers (bass reflex) that I designed. Eminence Deltalite II 2510 + Ciare 1.38TW. The crossover is a highly refined 2nd order w/zobel & tweeter compensation. To me, the best loudspeakers that I have ever heard. I am biased as you might imagine. The sensitivity for these is about 97-98dB. This amp sounds very clean, no hum, no noise, very musical. However when I compare it to my single-ended KT88, only about 10 watts ultralinear, there is a distinct difference in sound quality. Don't get me wrong, the Millett amp sounds VERY, VERY good. The difference is in the detail. The SE amp excels many fold in bringing out detail such as the plucking of an acoustic guitar, the bow of a violin/cello/upright bass, the breath of the vocalist, the reed of woodwinds, the timbre of a concert piano, etc.
Maybe this is not the right forum for this review, but I am interested to find out what others have experienced with regards to SE vs PP.
MODS please move this post as required.
I will first admit that I did not build this amp as spec'd so this is an already flawed review. That being said I built the 6HJ5/6GU5 version of the amp. First impressions, REALLY LOUD! No problem filling a BIG room with sound with this baby! I am using 2-way speakers (bass reflex) that I designed. Eminence Deltalite II 2510 + Ciare 1.38TW. The crossover is a highly refined 2nd order w/zobel & tweeter compensation. To me, the best loudspeakers that I have ever heard. I am biased as you might imagine. The sensitivity for these is about 97-98dB. This amp sounds very clean, no hum, no noise, very musical. However when I compare it to my single-ended KT88, only about 10 watts ultralinear, there is a distinct difference in sound quality. Don't get me wrong, the Millett amp sounds VERY, VERY good. The difference is in the detail. The SE amp excels many fold in bringing out detail such as the plucking of an acoustic guitar, the bow of a violin/cello/upright bass, the breath of the vocalist, the reed of woodwinds, the timbre of a concert piano, etc.
Maybe this is not the right forum for this review, but I am interested to find out what others have experienced with regards to SE vs PP.
MODS please move this post as required.
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I have a red board built in a manner similar to yours. I have a Simple P-P with EL84's and another with 6CW5's. I have a SSE using KT88's and a TSE using 45's and another with 300B's.
The push pull amps all have the edge in punch and dynamics. The red board through 96 db speakers capable of eating 125 WPC is the clear winner of all my amps if the venue is "rock concert in the living room" As you move toward simpler more detailed music with less than ear bleeding volume the choice depends on personal taste and the type of music being played. The two Simple P-P's sound very similar and have the classic EL84 sound with great dynamics and good detail. I use one for daily listening when I don't want to heat up the room with the red board or risk ripping the cones out of low powered speakers.
I have a SSE with KT88's. As you have found out there are applications where an SE amp just can't be beat. The SSE is similar to your SE design except for the choice of driver tube and the CCS load on the driver. The CCS load does improve the detail, it's worth a try. There are also a few places where an EL34 sounds better than a KT88.
Now that you have found out about the "SE magic" you have only one choice.......Build a DHT SE amp. These are the ultimate in the detail department. The 45 tube is the clear willer if your speakers and music can deal with all of 2 WPC. If not, the 300B is close and a bit louder.
The push pull amps all have the edge in punch and dynamics. The red board through 96 db speakers capable of eating 125 WPC is the clear winner of all my amps if the venue is "rock concert in the living room" As you move toward simpler more detailed music with less than ear bleeding volume the choice depends on personal taste and the type of music being played. The two Simple P-P's sound very similar and have the classic EL84 sound with great dynamics and good detail. I use one for daily listening when I don't want to heat up the room with the red board or risk ripping the cones out of low powered speakers.
I have a SSE with KT88's. As you have found out there are applications where an SE amp just can't be beat. The SSE is similar to your SE design except for the choice of driver tube and the CCS load on the driver. The CCS load does improve the detail, it's worth a try. There are also a few places where an EL34 sounds better than a KT88.
Now that you have found out about the "SE magic" you have only one choice.......Build a DHT SE amp. These are the ultimate in the detail department. The 45 tube is the clear willer if your speakers and music can deal with all of 2 WPC. If not, the 300B is close and a bit louder.
I have to agree with you on the Millett PP listening to vinyl replica Dark Side of the Moon. Awesome dynamics. During the guitar solos, cymbal crashes, everything actually, the SE is the clear winner though. I have not tried LED cathode biasing for the preamp tube yet as I have been trying to steer clear of any solid state junctions. Boils down to semantics I suppose, as well as trying to avoid problems caused by incoming CMEs. 😀 No problem for my speakers to perform well with 2 watts. I suppose I'll have to bite the bullet and go for a DHT. Since you are guru of tubes, I guess there are no obscure DHTs that don't cost an arm and a leg? 😱
The only DHTs that fall into the category of not costing an arm and leg are the RF finals. However, those will require source follower drivers since they'll have to be run in Class A2, as most of these are high Rp, high-u, "zero bias" types designed for minimal bias to set a Q-Point, and for greater power sensitivity. Even then, prices for 811s and 812s have been creeping higher. A visit to a hamvention might turn up some goodies if you get there early before others snap up useful items.
I have built Pete's "Engineer's Amp" (totally stock config.) as well as the Simple SE and Simple P-P from George's Tubelab. I agree with the other respondents that the "Red Board" has a lot of punch. However, the build I listen to most is the Simple P-P w/ EL84's. This little amp is amazing for what it cost me to assemble. Currently, I'm waiting for xfmrs to finish a pair of Pete's "Uniamp II" Monoblocks. I think it will be interesting to compare all these amps. Really, I don't think a tube diy'er would be disappointed with any of them.
So I think I've followed most modifications and then watch as they were 'unmodded' and the one area I am having difficulty following is the power side of the house.
My skills are average so...
I am looking to see if I can build a 75 to 125wpc amp so what should I be looking for in a power trafo? Do I follow the image in post 1087 or is better just to have a trafo wound that does the job of the two separate ones?
thanks
./e
My skills are average so...
I am looking to see if I can build a 75 to 125wpc amp so what should I be looking for in a power trafo? Do I follow the image in post 1087 or is better just to have a trafo wound that does the job of the two separate ones?
thanks
./e
The Anteks worked out great for my build. If you build the version using the 6HJ5s, just make sure you orient R8,9,10,11 correctly as the tube pinout is different than the original design. I used 470 ohm/2W. Also R29,30,31,47 need to be rated for a higher voltage, I used 220K/3W, and if you use C7,9,10,15, change to 2000V rating, or leave them out.
If you just want 75 watts, the best thing to do is do the 6hj5 mod, and pump 400v b+ into the red board with a single power supply, and use a 3.3k load.
the 125 watt model will require 300v b+ to the red board, and 300v b+ external power supply that will connect just to the output transformers. Its your choice but id suck up the 3db loss and go with the 75 watt version.
the 125 watt model will require 300v b+ to the red board, and 300v b+ external power supply that will connect just to the output transformers. Its your choice but id suck up the 3db loss and go with the 75 watt version.
If you mean C7,9,10,15, 820pF, the 2000V variety are only 42 cents each.
DEHR33D821KA3B Murata Ceramic Disc Capacitors
Hi all, just wanted to add that the board now works very well. Infact I cannot keep the volume at max from most of my sources unless I wish to have angry neighbours at my doorstep.
I had to play around with the driver tubes as I initially could not find a perfect balance.
Oh well, big thanks to the forum, the users and especially to Pmillet!
Alex
I had to play around with the driver tubes as I initially could not find a perfect balance.
Oh well, big thanks to the forum, the users and especially to Pmillet!
Alex
I am guessing as tubelab wrote, a faulty connection within the board. Maybe a mistake on my part soldering the components (temperature, contact time ecc) may have damaged the board splitting connections.
In any case the board now works very well and I am quite impressed by the volume! 🙂
In any case the board now works very well and I am quite impressed by the volume! 🙂
nightanole,
On the 75wpc build and the 400b+ did you use a 400-0-400 and then separate windings for the heaters, etc? a 3db loss for me isnt that big a deal, I'm running Klipsch that have a 96db rating so 75wpc will most likely chase me from the house or at the minimum a stern lecture from she who must be obeyed. At that point I should take a look and see if any caps have to be upgraded to a higher voltage...it's been awhile since I stared at the schematic could do me some good.
thanks
./e
On the 75wpc build and the 400b+ did you use a 400-0-400 and then separate windings for the heaters, etc? a 3db loss for me isnt that big a deal, I'm running Klipsch that have a 96db rating so 75wpc will most likely chase me from the house or at the minimum a stern lecture from she who must be obeyed. At that point I should take a look and see if any caps have to be upgraded to a higher voltage...it's been awhile since I stared at the schematic could do me some good.
thanks
./e
400v b+ is the limit of the stock caps, before you go ubber with 500v $$$ caps.
You can get your 400 from what ever you are comfortable with. My transformer didnt have a ct so i had to do a full bridge by soldering on 2 extra diodes. 300-0-300 is gonna give you about 400v b+ (stock is 280-0-280).
Man i hate edcor's new site layout. Um antek has a nice AN-2T300 that you would then need a bias transformer. Im not sure you can pull this off, but you could get the stock edcor, and then get a small 40 volt antek/edcor to boost the voltage. Just wire it in series before the diodes.
You can get your 400 from what ever you are comfortable with. My transformer didnt have a ct so i had to do a full bridge by soldering on 2 extra diodes. 300-0-300 is gonna give you about 400v b+ (stock is 280-0-280).
Man i hate edcor's new site layout. Um antek has a nice AN-2T300 that you would then need a bias transformer. Im not sure you can pull this off, but you could get the stock edcor, and then get a small 40 volt antek/edcor to boost the voltage. Just wire it in series before the diodes.
I was using an AN-4TK400, which has a couple of taps that can be used for bias. I don't see them on Antek's site anymore.
I believe you can still order "off the menu" transformers. Also the ones with taps are normally on ebay.
guys thanks for the info. This amp went from very cool to out of this world cool but make mongo's head hurt wid all de mods and back into the easy peazy realm.
awesome!
./e
awesome!
./e
Hi all, just curious: has anyone attempted to select different tubes for the output stages?
Would 6LB6 be suitable? (it looks like a high current capable beam pentode)
Would 6LB6 be suitable? (it looks like a high current capable beam pentode)