Anybody ever do a stereo build?

[pinkphiloyd]

As in, for listening to music, not playing it? I've built several amps now, mainly AC-30 and Fender non-reverb variants, so I feel like I have a pretty good feel for things. I'm considering a stereo build for my next project. Just kicking around the idea. We listen to a lot of vinyl and have a quality turntable that we run through a Marantz 2230, but I'd love to get some tubes glowing to spin with. Ideally something integrated. Anybody undertaken anything like this? Any advice, anything I need to know? I know there are other boards but I just wanted to get the perspective of guitar oriented people which is where I come from. I know I'll probably have to do a rectified, regulated filament supply. What else that might seem foreign?

[martin manning]

Recent thread on this here: http://ampgarage.com/forum/viewtopic.ph ... mp&start=0

[Meat&Beer]

I also have a Marantz 2230, what a nice unit they are, huh? Good start for the phono preamp considerations mentioned in the link Martin provided. As far as the amp itself, I'd suggest researching the world renown Baby Huey that Gingertube developed. Good luck, have fun!

Never had problems with JJ EL84s.
BUT - I don't like self spit or common to both push pull sides bias schemes.

I have an EL84 Push Pull HiFi design which has been made into a Wiki here:
http://www.diyaudio.com/wiki/Baby_Huey_ ... _amplifier

Lots of these been made by folks all round the world. The forced balance scheme works really well and is the best sounding PP EL84 Amp I've ever built or heard.

The prototype of this amp was originally a Morgan Jones "Bevois Valley". Rebuilding to this scheme was a definite step up in performance.

The current source bias scheme is good BUT it has crap overdrive characteristics which make it an unsuitable circuit for a git amp.

There is a Baby Huey thread which includes some fixed bias variations.
What I'm now running at home is the schematics on posts #602 and #603 here:
http://www.diyaudio.com/forums/tubes-va ... ey-61.html
Post #604 schematic variation is something I tried for a while but eventually abandonned.

Hope these are of interest.
Cheers,
Ian

[ampfab]

I want to build a DYNACO ST-70

[pinkphiloyd]

Recent thread on this here: http://ampgarage.com/forum/viewtopic.ph ... mp&start=0

I did a search but apparently over looked this. Thanks.

[pinkphiloyd]

I also have a Marantz 2230, what a nice unit they are, huh?

Yep, wouldn't part with mine.

[Sone Aura]

I have built some clones: a pair of Marants model 9s, a Model 8, a Sansui, a Conrad Johnson restoration/mod. The Conrad Johnson is as good as the Marantz, but still different. I upgraded some of the caps in the Conrad Johnson. I just got some GE 6550As for it. WOW! Only real KT88s could be better. I mainly use an old Yamaha Natural Disaster receiver to run my electrostatics and a Marantz 1090 to drive some JBLs. It saves the tubes in my other amps, and they really do sound very good. I have plans to do a 120 watt per with these 60,000 hour Telefunken cinema & studio reference tubes. I already blew a $350 OT. It is/was some no name small shop tranny sold in the back of Vacuum Tube Valley magazine. These Telefunkens have a very large plate and a large plate resistance to go with it, so OTs are very hard to find. I have also repaired a lot of old tube stereos, mainly little 15 watt EL84, 6BM8, 6973, and other 9 pin mini power tube stuff. [img1800]http://i.imgur.com/jmVxL56.jpg[/img]

[Sone Aura]

This is a little old Martel, 15 watts per channel. This one was actually made by Roland, back before Roland started making studio gear, guitar effects, tape delays and other cool stuff. When Roland decided they were no longer going to be a contract stereo builder, Martel/Rotel stuff was made by Sanyo Japan instead, and later made in Taiwan. The Rotel name was a combination of Roland and Martel. Martel was just a huge import house on the west coast. This one uses 6BM8 power tubes, which have a cult following in Japan. I just did the front end of the tuner there. So, I do have the test gear to key in any AM FM broadcast frequency, and impose the 19KHz stereo modulation on the signal, and repair, or set up tuners and receivers, but I never really listen to the radio myself, so it is a moot point for me.. To this day, there is still a street named after Martel in Long Beach Ca. [img2250]http://i.imgur.com/GPfD2kq.jpg[/img]

[Sone Aura]

Dynacos are good units. I think there was also a Dynaco 150 that used 6550s. The ST70 boards and parts are all over the place, so they are a very good one to build.

[dcribbs1412]

Recent thread on this here: http://ampgarage.com/forum/viewtopic.ph ... mp&start=0

That build was a great leaning experience. I would liken it to a PCB 5E3 build for guitar amp. Granted Hi-Fi tube is a little different than guitar amps
but some component consideration is similar.
Some things to consider
Loudness... what volume do you listen at
Speakers ... efficiency matters
Expense ... budget vs mainstream Hi-Fi
Lots of good advise from the above thread
Good luck and post progress if possible

D

[TUBEDUDE]

Good looking stuff Sony Aura, magic eyE tubes make me firm. I have a modified dynaco FM3 with the EMM801? and a dynamo ST-70 that has the Alan Kimmel modded board installed. With Mullard xf2 EL34's. It sounds better than my friends $130K audiophool system. No doubt that spec wise, and clinically his system is far superior, but even he lusts after my amp.

[gingertube]

I also have a Marantz 2230, what a nice unit they are, huh? Good start for the phono preamp considerations mentioned in the link Martin provided. As far as the amp itself, I'd suggest researching the world renown Baby Huey that Gingertube developed. Good luck, have fun!

Never had problems with JJ EL84s.
BUT - I don't like self spit or common to both push pull sides bias schemes.

I have an EL84 Push Pull HiFi design which has been made into a Wiki here:
http://www.diyaudio.com/wiki/Baby_Huey_ ... _amplifier

Lots of these been made by folks all round the world. The forced balance scheme works really well and is the best sounding PP EL84 Amp I've ever built or heard.

The prototype of this amp was originally a Morgan Jones "Bevois Valley". Rebuilding to this scheme was a definite step up in performance.

The current source bias scheme is good BUT it has crap overdrive characteristics which make it an unsuitable circuit for a git amp.

There is a Baby Huey thread which includes some fixed bias variations.
What I'm now running at home is the schematics on posts #602 and #603 here:
http://www.diyaudio.com/forums/tubes-va ... ey-61.html
Post #604 schematic variation is something I tried for a while but eventually abandonned.

Hope these are of interest.
Cheers,
Ian

I'm now actually running the post #602 circuit using 6V6G push pull with 6SL7 front end, built into a MabelAudio Chassis which in hindsiight was a mistake, it was a real pain to shoehorn everything into that tiny space.

The Baby Huey design does give excellent results. I've built 9 of them.

Cheers,
Ian

Baby Picture: