The Other Side: Tube HiFi Stereos

[KindaFuzzy]

I did a super simple stereo for my computer at work with old console parts. Plain single ended el84s, with each side of a 12au7 as an input, and a volume control. Here's a pic:

[img:500:375]http://farm4.static.flickr.com/3515/331 ... 84d3af.jpg[/img]

[DonMoose]

The way to overcome the relatively low power of these tube stereos is with hyperefficient speakers. In my stupid opinion, the Klipsch Legacy series (in particular the Heresy) are unbeatable.

[David Root]

bcmatt, yes the triodeel iron has a good reputation and the iron was by far the best part of the original. Dynaco had one of the top transformer designers of the time.

If you Google the web a bit you will find some informed and experienced opinion regarding the rest of the circuit. The PS caps for example, were too small. Also the screen resistors were too low power rating if I recall correctly.

[Teleguy61]

The way to overcome the relatively low power of these tube stereos is with hyperefficient speakers. In my stupid opinion, the Klipsch Legacy series (in particular the Heresy) are unbeatable.

Bingo Don.
That's how it's done. That's the reason for JBL and Altec and EV
speakers.
Could anyone need a stereo louder than a Twin Reverb through
2 JBLs?

To OP.
The Dynaco designs talked about are time tested and still sound great.
Good iron and upgrade components, you wouldn't be disappointed.
Just don't try to drive your modern low efficiency speakers with them.

[Zippy]

Could anyone need a stereo louder than a Twin Reverb through 2 JBLs?

Oh, yes...

[Lonely Raven]

Great looking equipment and artwork John!

[M Fowler]

Nice job on your amps guys, I want to build a stereo tube amp on one of my long cold winters.

KindaFuzzy I like that round amp

Mark

[Cygnus X1]

I did a super simple stereo for my computer at work with old console parts. Plain single ended el84s, with each side of a 12au7 as an input, and a volume control. Here's a pic:

[img:500:375]http://farm4.static.flickr.com/3515/331 ... 84d3af.jpg[/img]

Great!
Film can right?
Paint the trafo's to match now.


I, too have a vintage...knob.

[Teleguy61]

Could anyone need a stereo louder than a Twin Reverb through 2 JBLs?

Oh, yes...

Which is the member with the signature of,"Ears?
We don't need no stinkin' ears!"

[bcmatt]

The way to overcome the relatively low power of these tube stereos is with hyperefficient speakers. In my stupid opinion, the Klipsch Legacy series (in particular the Heresy) are unbeatable.

I inherited these speakers from my parents:
http://www.klipsch.com/kg-5-5
I was always in love with their sound. They were my instrument of choice in high school; long before I started playing guitar. Anyways, do you think they will work? It says the sensitivity rating is 98dB.

Of course, the first amp is for my parents and they are after very low profile when it comes to their living room stereo. They actually have some holes in their ceiling wired up ready for speakers that I think they would like to use, but I don't know if there make something suitable somewhere to make use of that. The in ceiling speakers I've checked out thus far are only in the high 80s decibel rating, which doesn't seem very efficient to me. They would be fine with some bookshelf speakers if there is no suitable in-ceiling models...

[img]http:600:400]http://cgim.audiogon.com/i/vs/s/f/1257218434.jpg[/img]

John! What sort of amp is that you are using in the bedroom? That's not the Dynaco ST-70, is it? Also, I got to say that you got a pretty classy home and furniture setup with those stereos and what they sit on. Some really nice and elegant wood all over the place. I want to be like you when I grow up.

I did a super simple stereo for my computer at work with old console parts. Plain single ended el84s, with each side of a 12au7 as an input, and a volume control. Here's a pic:

[img:500:375]http://farm4.static.flickr.com/3515/331 ... 84d3af.jpg[/img]

That thing's pretty sweet. You got some real innovation. I checked out your site too and already recommended your amps to a few young guys. I love the ammunition box idea!

bcmatt, yes the triodeel iron has a good reputation and the iron was by far the best part of the original. Dynaco had one of the top transformer designers of the time.

If you Google the web a bit you will find some informed and experienced opinion regarding the rest of the circuit. The PS caps for example, were too small. Also the screen resistors were too low power rating if I recall correctly.

So would you recommend getting a kit from Triode, or would I be better off trying to just get the Transformers and chassis from them? I see you can swap in Solen caps for an extra $20. I wonder if that bumps up their ratings too... or does Triode already beef up the components for their kits?

To OP.
The Dynaco designs talked about are time tested and still sound great.
Good iron and upgrade components, you wouldn't be disappointed.
Just don't try to drive your modern low efficiency speakers with them.

Thanks, I guess I'm asking you this question, what dB sensitivity rating do you think would be a minimum recommendation?
I get the impression that the Triode Kits are upgraded component versions. Would that be correct?
http://triodeelectronics.com/hifikits.html

[Cantplay]

bcmatt: I'm running MG20's with the Mk III's, 89dB

The amp is a Vaughn Audio Carina with MagnaQuest silver wound trafos. Speakers are Decware NFX with modified Fostex drivers.

Raven: http://www.vehicross.info/gallery/showg ... way=&date= if you want to see the rest.

John

[bcmatt]

So, I've been looking up In-Ceiling speakers and following the JBL/EV suggestions because of their sensitivity.

JBL doesn't seem to make anything too quality for this market.

EV has some interesting options, making me wonder how these sound:
http://www.electrovoice.com/sitefiles/d ... es-eds.pdf
8" model, 96 dB, 30 Watts, (80 - 16,000 Hz +-3dB)
Actually here is a youtube demo of one in open baffle:
http://youtu.be/1Ybq-GJY75A
I think I found a place that sells them online and they are about $100 each

What do you experienced guys think of them?

Altec has their own line too but I can't seem to find any for sale online anwhere:
http://www.altecpro.com/pdfs/CD408_SS.PDF
8" model, 98 dB, 32 Watts, (82 - 16,000 Hz +-5dB)

[David Root]

Xicon caps are not all that well regarded here by most, although one guy likes the Xicon MPP caps. If you go for the kit definitely get the Solen upgrade.

Can't tell from that pic about resistors, although they look like cheap Xicons too.

Buy your own tubes. JJs are very variable. Sovtek LPS is worth a try in 12AX7.

If you really want to get into the old Dynaco tone, dig around on the web and you'll find some pix and parts lists that show exactly what the originals used. I don't recall what brands of caps and resistors were used, but paper in oil caps are worth looking at for signal caps. Or old CDE "brown drops". Sounds rather unsavory but they are good caps. Not cheap these days. ARCO brown drops are worth a look too, look up "Difilm caps" on the web. More reasonably priced. Piher carbon film resistors were very nice too, you can still get them for reasonable prices NOS on EBay. Don't use those in the power supply though, use metal oxide 2W there.

I don't look upon the EL84 as a hifi tube either but the ST70 uses EL34s, which are good in both hifi and of course guitar amps too. Trouble with modern EL34s is they are a VERY mixed bunch, you would be better off with KT77s I think. The right NOS EL34 for this amp would be the Mullard Xf4, but a quad of those NOS properly matched at the operating plate voltage will run you about $500 to $550, ask me how I know this.

[bcmatt]

Xicon caps are not all that well regarded here by most, although one guy likes the Xicon MPP caps. If you go for the kit definitely get the Solen upgrade.

Can't tell from that pic about resistors, although they look like cheap Xicons too.

Buy your own tubes. JJs are very variable. Sovtek LPS is worth a try in 12AX7.

If you really want to get into the old Dynaco tone, dig around on the web and you'll find some pix and parts lists that show exactly what the originals used. I don't recall what brands of caps and resistors were used, but paper in oil caps are worth looking at for signal caps. Or old CDE "brown drops". Sounds rather unsavory but they are good caps. Not cheap these days. ARCO brown drops are worth a look too, look up "Difilm caps" on the web. More reasonably priced. Piher carbon film resistors were very nice too, you can still get them for reasonable prices NOS on EBay. Don't use those in the power supply though, use metal oxide 2W there.

I don't look upon the EL84 as a hifi tube either but the ST70 uses EL34s, which are good in both hifi and of course guitar amps too. Trouble with modern EL34s is they are a VERY mixed bunch, you would be better off with KT77s I think. The right NOS EL34 for this amp would be the Mullard Xf4, but a quad of those NOS properly matched at the operating plate voltage will run you about $500 to $550, ask me how I know this.

Thanks David! Very helpful! We had narrowed it down to an ST70 actually. But I will heed your advice on the Solens and look into your tube suggestions. So, some JJ KT-77s then? I have a couple of those in my JCM800 2204 clone. What do you think about their whole EF86 option? Seems like a sure-fire way to boost the cost, but is it worth it do you think? I do have a couple spare EF86s (1 JJ and 1 EH but neither as nice as the RFT currently in my DC30) I'd probably have to get 2 new the same and high quality. 6au6 tubes are so much more economical!
As far as other components go, I'm not too eager about scouring Ebay or other hard to find sources. If I could get decent resistors and caps for this sort of project at AES I'd be happy... I get overwhelmed by too many options from too many shipping locations.

[Aurora]

Just for the records , - I think there are several kits avalable for an ST70....
whether silver wound OTs are necesseary must be up to one's beliefs

As for the tubes, unfortunately some of the Ebay vendors seems to be trying to convince possible buyers that they are buying solid gold - or something similar.....prices are sometimes hyped up well beyond all reason,
fortunately there are exceptions, - as well as dependable regular E-shops......