Good point Spec.
my 300B SET project
- Thread starter Dave C
- Start date
Good point Spec.
Dave C
Super Member
I had the honor of a visit from SET12 Sunday afternoon. We had about a 4 hr listening session. He brought his Furman power filter along, I wouldn't have guessed clean power would make such a big difference. My house is on its own pole transformer. Hooking up the Furman unit really smoothed the amps out. I think I'll be putting one on my gotta have list. I always enjoy listening to artists that I am not familiar with. SET brought some really nice jazz and some soundtrack music. We had a nice time talking tech, our wives also enjoyed conversation. Thanks for stopping by SET!
TerryO
Super Member
Dave,
Very nice looking amps! Your layout seems logical and well thought out. Are you going to post some schematics soon?
Best Regards,
TerryO
SET12
Super Member
First off, I want to say thanks Dave to you and your wife for having me and my wife at your beautiful home.
I also want to say that for a first time Amplifier DIYer those amps are gorgeous. And they sound as good as they look.
In fact I was a little taken back by just how smooth they sounded with the Klipsch RF25's which are a perfect musical match
One can listen to them all day long and never become fatigued at all. They are just extremely musical.
I'd like to add that even though I'm a tube rectifier man, The SS Bridge rectification was superb in its smoothness.
The transformers that were picked out worked out great. The whole supply path is a mere 38 ohms of DCR including the 5H choke which resulted in excellent dynamic response.
The power Transformer at just 12 ohms of DCR with both secondaries paralleled http://www.antekinc.com/pdf/AN-3T325.pdf
And the 5H 26 ohm DCR choke http://angela.com/hammondchoke193p.aspx
I can't say enough about the 7193's very,very nice.
As to the Furman that was brought along. I have a thread here that details all its benefits which for the money I have found no equal.
http://newaudiosociety.com/cgi-bin/yabb2/YaBB.pl?num=1149518816
The Furman I use is their Power Factor Corrector which is able to source up to 45 amps of instantaneous power for ones amplifiers or any other component. The furman corrects for power line Inductance, meaning all the homes using the same pole power transformer may have loads of appliances running along with furnaces,washers, dryers and so on making the power inductive, therefore not the most responsive to musical peaks.
With the Furman Power Factor Corrector you can hear its benefits right away. It adds warmth to the music by sourcing the current to your systems needs. It also does treat noise as well and it has an extreme voltage shut down which has occurred twice in my home when the voltage exceeds 140VAC at the wall. A simple reset and your good to go. It has an LED voltage monitor as well.
I use three of them one on each power amp and one on my front end. One of these will handle 12 amps.
Congratulations Dave, on a great sounding pair of 300B Amplifiers :thmbsp:
SET12
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Dave C
Super Member
It's just a basic 300b schematic, very simple, low parts count. My change to most others is the power supply. I think it works very nicely and SET12 seems to agree with that. I worked in the 7193 drivers because people that have played with them seemed to really like them. Problem is that they were a specialty tube and haven't been made for years.
Dave C
Super Member
One year later ,,,,,,,
It's been a year now since I finished these amps. They have been a very worthy use of my time and money. I did a serious cross over upgrade on my speakers last month with such good results that I decided to up grade the coupling capacitors in my amps. You can read about the cross over upgrades here. http://www.audiokarma.org/forums/showthread.php?t=288022 I used Mundorf Supreme caps on the cross overs and while doing that research I had the idea of replacing the Solen coupling caps with Mundorf Silver / oils in the amps. I found this capacitor comparison http://www.humblehomemadehifi.com/Cap.html Every ones ears are different but this seemed like a very good guide to go by.
My thoughts on the Solen vs Mundorfs?
The Solen caps I think are very nice caps, the Mundorfs though have by comparison a much larger sound stage. With only an hour of 2 on the Mundorfs they are hardly broke in but man do they sound nice! Price difference was about $3.00 each for the Solens and just under $30.00 each for the Mundorfs. (BTW, The value on these caps is .22uf.) The sound from the Solen caps is very honest, the sound from the Mundorfs is elegant. They seem to put polish on notes that the Solen's made a little harsh. At this time I think the Mundorfs are a tiny bit noisier when the amps are quiet, but even with the smallest instrument sound they can't be heard. I use John Denver's "Whispering Jessie" for one of my reference CDs. That song now encompasses the whole room! I can hear the entire string section way off to my left side, well beyond the speaker. If you think capacitors don't make much difference either your ears are shot or you've never tried rolling caps. :yes::thmbsp:
It's been a year now since I finished these amps. They have been a very worthy use of my time and money. I did a serious cross over upgrade on my speakers last month with such good results that I decided to up grade the coupling capacitors in my amps. You can read about the cross over upgrades here. http://www.audiokarma.org/forums/showthread.php?t=288022 I used Mundorf Supreme caps on the cross overs and while doing that research I had the idea of replacing the Solen coupling caps with Mundorf Silver / oils in the amps. I found this capacitor comparison http://www.humblehomemadehifi.com/Cap.html Every ones ears are different but this seemed like a very good guide to go by.
My thoughts on the Solen vs Mundorfs?
The Solen caps I think are very nice caps, the Mundorfs though have by comparison a much larger sound stage. With only an hour of 2 on the Mundorfs they are hardly broke in but man do they sound nice! Price difference was about $3.00 each for the Solens and just under $30.00 each for the Mundorfs. (BTW, The value on these caps is .22uf.) The sound from the Solen caps is very honest, the sound from the Mundorfs is elegant. They seem to put polish on notes that the Solen's made a little harsh. At this time I think the Mundorfs are a tiny bit noisier when the amps are quiet, but even with the smallest instrument sound they can't be heard. I use John Denver's "Whispering Jessie" for one of my reference CDs. That song now encompasses the whole room! I can hear the entire string section way off to my left side, well beyond the speaker. If you think capacitors don't make much difference either your ears are shot or you've never tried rolling caps. :yes::thmbsp:
Dave C
Super Member
I've got a month of listening on the Mundorf silver/oil coupling caps now. I will use these on on any future projects I build. I had an hour of listening tonight, Cowboy Junkies Trinity revisited. This is a very well recorded CD and with my amps and speakers it simply makes you feel like you are standing there with the band. This whole DIY thing has really worked out well for me. My goal was never to assemble a bunch of stuff from old systems but to carefully purchase and build using the best stuff I could afford at the build time. I'm thinking the OPT's will be the next upgrade.
vincei
aka MasterControlMedia
No variac, I just made sure everything was wired ok and let her rip. No problems. I have since rewired the amp from first power on.
I will update my thread too with listening impressions and design changes I made....
Dave C
Super Member
Vincei, I'll keep watching your thread, please keep an eye on mine. I think I'm done until next winter, I've got so many other projects right now. I would like to buy some Sophia mesh plates and see what they sound like. I think the very first upgrade though will be some new OPTs. I'd like to try some plitrons.
vincei
aka MasterControlMedia
The bad thing about 300B's is the cost to roll them....:tears: Those upgrades you have in mind sound very interesting...I would be interested to hear your results!
Dave C
Super Member
The thing I've learned from this project is that the capacitors are probably a more effective thing to roll than the tubes. You are right though those 300bs aren't cheap!
Dave C
Super Member
Thanks! As I've stated, this has turned out to be a very worthy project. If I had to start again I would build them the same way. The power supplies really rock, never come up short.
Dave C
Super Member
I spent an hour or so listening to Renee Fleming's Dark Hope CD today. http://www.reneefleming.com/darkhope/index.php The frequency response of this amp / speaker combination clearly stands her in the room with you, very little imagination needed.
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Dave C
Super Member
I did a conversion to passive shunt volume control on these amps over Christmas. You can find information about this at http://www.audiokarma.org/forums/showthread.php?t=338214 for all the details. I am posting it here also to keep all the information of my 300B amps in one place. If you decide to build one of these you should plan for this update. These are very clean sounding amps but the passive volume can be installed by adding a 51K resistor and rewiring the 100K volume pot so the cost is very minimal and worth the results. This mod and the Mundorf silver coupling cap I mentioned earlier are mods that get results.
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Dave C
Super Member
I feed the CD player directly into it, if I play records I have a Onkyo pre that I use with a B&O turntable. At this point I play CDs 95% of the time.