Remember the days before Dale Carnegie? Dynaco restoration suggestions?

[DizRotus]

I just bought a pair of Heresies and a Dyna SCA-35 on eBay to use in my office. They both work fine but I've gotten the tube bug and want to learn how to improve ths SCA-35 before moving on to PAS 3, ST-70, mono-blocks, etc.

As background, I built several Dynakits and Heathkits (all SS) in the 70's. I used a Dyna ST-400 to drive four Speakerlab SK-horns in a mobile DJ business. I had an open account with EV for the T-35 voice coils (then $11.00 as I recall) that got fried regularly. Therefore, I know how to read a schematic and solder, but I know nothing of tube gear.

My plan is to buy another SCA-35 to restore/modify and on which to begin the education. What tools/equipment would anyone(are you reading this Mobile Homeless?) suggest to add to my multimeter and soldering iron? I ordered the CD with Dyna schematics from Greg Kaufman.

For now, I'm not intereseted in Bottle Neck/Head/Whatever and the like. The sound levels from those four screaming SK-Horns did a job on my high frequency hearing. I just want to play with the Dyna tube gear and then listen to the music.

Any suggestions would be greatly appreciated.

Edited April 9, 2016 by DizRotus

[DizRotus]

Mdeneen,

Thanks for the reply. This is just the sort of advice I was looking for. Always love an excuse to get more tools.

After reading several tube-related posts, I see an EICO in my distant future. But, for now, I will experiment on the SCA-35. The only modification made to the current SCA-35 was a new three conductor power cord grounded to the chassis. As soon as I get another SCA-35, I will start by "restoring" it with upgraded parts. When it is in service, I will experiment on the existing SCA-35. As a prodigal kit builder, I enjoy the journey as much as, or more than, the arival.

Your offer of further advice is appreciated and will be accepted.

[NOSValves]

DizRotus

Your getting advise here from the best !!! Without MDeneen my HH Scott Amps wouldn't be the excellent amps that they are while they would work and sound better than most mid grade SS stuff they would have never reached there intended perfection.

On the EICO front I wouldn't get to over board on those ! I bought one in need of serious repair just to get one cheap. I find that the over all quality of the EICO's parts are sub par compared to my Scott's. I'm not saying that there not nice Amps all I'm saying is that they are starting to get priced way above there worth because partially the demand that has come from this forum. So the point I'm trying to make is there are better option's than the EICO HF-81.

Good luck and welcome a board

Craig

This message has been edited by NOS440 on 03-27-2002 at 02:06 PM

[mobile homeless]

Scott makes some great amps. Very nice and very well-made. They have an excellent reputation as well.

I have heard both the Scott 222/229 and the EICO integrateds. If looking at the wiring between the two, the Scott looks cleaner and with a better layout.

If listening to the Scott 200 series vs the Eico HF series on a purely sonic standpoint, the EICO is a more refined sounding amplifier. It is more transparent, open, and detailed, with a blacker background. At the same time, it remains very musical and is the closest to the openness of a Single-Ended design.

Although the Scotts have a very good reputation and are fine amps, I dont think they match the sonics. On the wiring front, I have to admit the EICO comes in second. On the circuit and transformer front, they have a sound that the Fishers and Scotts dont quite match.

Still, the Fisher, Scott, and EICO are all good vintage amplifiers, as well as the Dynaco, of course.

What to see some other interesting comments on the HF-81 (just to see that this forum is not the only place that loves these amps). Please take a note at the comparisons to the OTHER amps. One other thing, no one on this BBS has left any of these comments:

http://www.audioreview.com/PRD_115777_1583crx.aspx

kh

Phono Linn LP-12 Vahalla / Linn Basic Plus / Sumiko Blue Point

CD Player Rega Planet

Preamp Cary Audio SLP-70 w/Phono Modified

Amplifier Welborne Labs 2A3 Moondog Monoblocks

Cable DIYCable Superlative / Twisted Cross Connect

Speaker 1977 Klipsch Cornwall I w/Alnico & Type B Crossover

system one online / alternate components / Asylum Listing f>s>

This message has been edited by mobile homeless on 03-24-2002 at 02:01 PM

[mike stehr]

Have you had a chance to listen to your HF-81 yet,

Craig?

I like the reveiws, all 5 stars.

First reveiw compares the HF-81 to a Zen and Mac.

Mobile Homeless is one of many, many folks that praise

Eico and their 6BQ5 amplifiers.

Besides, don't you plan rewiring your HF-81, Craig?

Get that thing going and listen to it.

Then if you don't like it, at least your judgement will have some viability.

THANX!

[NOSValves]

mike stehr

I'm holding my sonic Opinion for after I rewire it and see what it sounds like. In the state it was in when I received it you wouldn't want my opinion on the Sonics. The EICO is on my work bench right now getting ready to give it the once over. So it won't be to long and I'll have the Sonic opinion for you all.

I'm at this time talking about the Quality of the parts and engineering of the amps. The Scotts are by far superior to the EICO and that is a fact. Also the phono stage in the Scott's is to die for.

I wish I could get Mobile to listen to a fine tuned Scott and then I believe his Opinion would differ greatly. In fact I may be at the Lima gig this coming weekend and I think Mobile is attending. Wonder if there will be some speakers we could hook are 2 amps up to and compare and Vinyl would be a must.

The thing I fear about Mobile comparison is that the Scotts he has auditioned may not have been in good working order. The scotts have a much more complex layout. For instance my Scott 299 has 5 multi section Can Capacitors on the Top of the unit and the EICO has 1. There are like 45 Coupling Caps in a Scott and maybe 10 in a EICO. The problem is that to achieve the sound that the Scott is designed to give is hard unless the Unit is really been gone thru and brought back to the way HH Scott engineered it. If any of you have issue 12 or 13 of VTV mag read what he has to say about the Scotts they are his Absolute favorite vintage integrated Amps and for good reason.

Craig

This message has been edited by NOS440 on 03-27-2002 at 02:06 PM

[mobile homeless]

Craig States: The thing I fear about Mobile comparison is that the Scotts he has auditioned may not have been in good working order. The scotts have a much more complex layout. For instance my Scott 299 has 5 multi section Can Capacitors on the Top of the unit and the EICO has 1. There are like 45 Coupling Caps in a Scott and maybe 10 in a EICO.

Re-read that paragraph, put 2 + 2 together and then wonder why the EICO might sound more open and transparent than the Scott. Throw in the many switches and gadgets with the Scott as well. Then ponder it again.

I am not saying the Scott is a bad amplifier; indeed, I am saying I actually like some of the Scotts better than other units, notably the Dynaco SCA-35 and the Fisher X-100. But there is something that the Scott's just dont have on the EICO. It really has a more open and refined sounds with guts. As I said, it really comes closer to single-ended in this way than any other vintage integrated.

Now I will say this; in order to hear these things, you have to perhaps have some experience and a system with enough resolution to reveal the traits. The Scotts I have heard have been in great operating condition. They are just not as simple a circuit and even though they have more hefty transformers (and good ones at that), they dont match the EICO in this area.

Still, I love Scott amplifiers too. The little Fishers are great, probably coming in second to some of the Scotts depending. But once you insert both in a very tweaked system, the EICO takes it up a notch. Most that have heard both agree here.

Now Craig, you sound like you have your Scott running great and have done some very nice work to it. But after listening to quite a few tube amps of all sorts of circuits, including single-ended, ultralinear, Williamson, Class A, Class A/B, Zero Feedback, low feedback, and heavy feedback, I still say that little ugly duckling has it over all the vintage units I have tried.

When firing on all cylinders, it's a magical little beast.

kh

ps-There is a chance I will still make the show in Lima. IF I do get there, I'll drag the Moondogs and EICO along. No room for the CW, however. I'm sure Kevin will let us use his system as would the Chicago fiends next door with horns galore! Not sure if I can swing it but would be great if I could.

This message has been edited by mobile homeless on 03-24-2002 at 11:14 PM

[NOSValves]

Mobile

I hear what your saying and don't have the ability to say if your right or wrong. That is why I have refrained from stating anything about the Sonics of the EICO because frankly I don't know !!

The thing that makes me question that the EICO can best the sound of a Scott is pretty simple its almost impossible for a the EICO to ever fire on all its cylinders in stock form. It has no bias/balance adjustments to speak of at all now my 222c didn't either in its stock form (only balance). But that's not the case anymore and the sound difference from just being able to tweak the tubes into there perfect bias/balance state is incredible to say the least. The 299 comes with bias and balance adjustments stock.

Now from my little understanding of these amps I believe that to get a EICO HF-81 to "fire on all cylinder" is nearly impossible in there stock form. The only way to do this would be to buy some real expensive matched quad of NOS output tubes (unless of coarse you are lucky enough to have bought one with all good matching originals) which after 40 years in not likely that they still match.

so your not rising to the LIMA challenge ?? I'm sure that you know someone that will be there to let us compare are amps sounds and even give us a outside opinion. I'm curious myself . My 81 is going to take some serious repairs and won't be even close to stock when its done. I would bring my 299 which is stock except for changing out the Cup caps to new of the exact same values. I guess if all else fails I could rent a hotel room and just bring my Heresy's and ksw-15 sub if your up for the comparo job (as long as its not raining I would have to bubble wrap and box my speakers and haul them in the back of my Silverado ?

Let me know

Craig

This message has been edited by NOS440 on 03-27-2002 at 02:08 PM

[mobile homeless]

This idea of fixed bias vs cathode bias is a sticky one. Both can bring GREAT sound. Yes, you can adjust the bias on the Scott when modified to run at your desired operating point. And the EICO is just as easy to do this. But cathode bias in a designed circuit is not a horror by any means. IT can be configured how you want it. By the way, as is, the EICO only needs matched pairs of EL-84, not a matched quad since it employs cathode bias resistors for each pair.

Did you actually READ the reviews in the link I posted above? Several go into the detail on the bias schemes.

Not sure if I can make it to the Lima event but am really going to try. As I said, if I do make it, I'm sure Kevin Haskins will let us use his HE10.1signature high efficiency monitors. He'll have them hooked up to the 300B SET monoblocks, but not 24 hours a day. Also, the Chicago freaks would let up do anything, even illegal!

kh

This message has been edited by mobile homeless on 03-25-2002 at 12:31 AM

[NOSValves]

Mark

That would be awesome I hope you can make it. Let me know if you are that would push me to the edge and make me go. I'm not trying to make this into a battle here. But I can tell you first hand I've bought 2 quads of recommended brand "matched tubes" from a well recommended dealer and found that they weren't even close and change by the day. So matching is a crock. They would have to run them for literally weeks to get them to settle in to there more or less permanent state and especially the newer tubes that most of us chump change people are forced to use.

So what I'm getting at is. In the current state of readily available tubes at affordable prices that we all have to suffer with any self biasing amp is running at less than optimum performance. The reason that Scott , EICO and others designed the self biasing and cathode biasing amps in the 50's and 60's was that you could run to any local drug store and buy top notch well matched Telefunken , Amperex's and USA branded tubes for next to nothing and it rendered bias not necessary or a frill that just added cost with little benefit(bean counter syndrome).

Also I will beg to differ with you on the only tubes needing to be close to matching being the outputs. What exactly do you figure the 12AX7's or 12AU7's would do to the sound if they are poorly or grossly mismatched ?? I'm not saying they have to be perfect but they should be relatively close for both channel to sound sonically the same wouldn't you say ?

Craig

Oh and I don't take reviews from people I don't know who they are or what they base there opinion on to seriuosly and also one of the guys is just pimping his schematic selling sight and one of the other modified the bias circuit. You never know what people are basing there opinion on until you get a chance to get to know them.

This message has been edited by NOS440 on 03-27-2002 at 02:08 PM

[NOSValves]

DizRotus

I think we got a little off topic in your thread Sorry !!!!

This message has been edited by NOS440 on 03-27-2002 at 02:09 PM

[DizRotus]

NOS440

That's OK. The passion is good for the hobby, so long as the discourse stays civil. I wish I could go to Lima.

[NOSValves]

Mdeneen

Very well said you walked on the top fence wire very gracefully

Craig

This message has been edited by NOS440 on 03-27-2002 at 02:15 PM

[mike stehr]

And this thread is why people don't get into Tube amplifiers.

[mobile homeless]

Indeed...depending on how you look at it, it very well could.

Obviously, just as in everywhere else, there are quite a lot of opinions on audio and what constitutes good sound and/or sound advice. Just within the tube camp, there are many different viewpoints and opinions on how to best go about achieving the ultimate music reproduction. Hell, in this one thread you see varying opinions.

It makes it both interesting and frustrating for those that want a simple answer. When it comes right down to it, you ultimately have to see, or should I say HEAR, for yourself.

kh

This message has been edited by mobile homeless on 03-25-2002 at 09:17 PM

[NOSValves]

mike stehr

Now exactly how do you figure that this thread is going to keep anyone from getting into tubes ??

Do you think that rants back and forth don't happen in the SS arena please !! This is the kind of thread that peaks peoples interest in what all the fuss is about !!!

Craig

This message has been edited by NOS440 on 03-26-2002 at 10:12 AM

[mike stehr]

Okay.

Somebody happens to get into Audio.

They start roaming the net. It's a cheap way to learn about the subject, and soon find out Audio forums are pretty helpful.

Now this Newbie discovers on the internet that there is more to offer than Solid State, and notices that there is big raves on Tube Amplifiers.

Curious, they start searching and find out there is many offerings in designs and price points.

Now the average Newbie discovers that most new factory wired units are exspensive.

And may not have the experience to build a kit, or simply understands that the cheaper kits compromise on design.

So the next choice is Vintage, so one reads up on it, and sees that vintage Tube design still holds it's own pretty well even today.

So they ask questions about Vintage gear.

No offense to Mark, and I understand DizRotus is into it for Tools of the trade and the fun factor of doing it.

But if one reads that they have to purchase a scope, a Function generator, A low Distortion Oscillator, a Distortion analyzer, and a Multimeter, the average joe will read this and just walk away from vintage altogether.

I know that Mark was answering Diz's questions pertaining to the tools needed for proper restoration and rebuilding, testing, etc..

I have no disagreement here, this is the way it is.

(Boy! I wish I had all that stuff!)

But for the average person to read this thread with even some interest in vintage Valve amps, they will be scared away from the idea for sure.

No offense to anyone here.

I's good to know what you are getting into when you purchase vintage, by asking questions to the seller, reviewing the design you may be getting, understanding that those Caps and resistors and possibly transformers are out of tolerance.

This will scare the Newbie away also.

I think I made my point.

I apologize Craig, my rant is out of Envy.

I'm pretty much in the same boat here, I have a pair of HF-12's that do not match as far as resistors and caps are concerned,(Different Brands) and one has a higher gain driver tube.

The one with the 12AU7 tube was wired BAD, real BAD.

Other than maybe save a couple of carbon resistors or a wirewound,(which is pointless, anyway) they need to be completly rebuilt to match each other.

But I'm into it now, I ain't walkin' away.

Keep posting your progress about the HF-81, I Kinda have the same circuit pretty much.

There is a lot to learn in this path into Audio Thermionic design, and there is always more to learn.

THANX!

[NOSValves]

Mike

In my Opinion if the newbie doesn't have the Ability/Equipment to check a vintage unit out or they are not willing to pay someone a few hundred to bring it up to good operating condition. Then I for one hope they do get scared away from vintage rather then see them operate a amp out of spec and in danger of destroying it to the point of beyond repair.

There is no reason for anyone to expect a electronic peice of equipment after 40+ years not to need some attention. If they do there just fooling themselves.

Its simple people that are not willing to give the equipment proper respect should either by New tube gear, Professionally restored vintage or Solid State.

Craig

Oh and out of respect for the originator of this thread I started one just to post my progress as I go.

This message has been edited by NOS440 on 03-26-2002 at 03:59 PM

[mobile homeless]

I personally dont agree with Mark on this matter and we have discussed it in the past. We just have different viewpoints on most things audio but I believe we both like tube amplifiers (just dont always agree on which, why, what, and where). We also both like music. I think the different viewpoints are healthy when they spur good discussion. IT allows the reader several vantage points.

I personally think you can be into vintage audio and not have to own half that equipment. In fact, I have gotten by (as have my friends) with a good VOM and the proper soldering gear and tools. OF course, it helps to have the other gear - some go out and build a power supply etc. I added a tube tester and a variac that my friend and I share. I personally dont think you need all this to fix problems with vintage equipment. Of course, Mark was asked to figure in the equipment in ADDITION to a meter and soldering iron so he did. But for those that just want to keep your vintage gear running as designed, or do some simple upgrades, you can actually get by with the basics and not be swimming in quicksand.

Of course, this is NOT to say that equipment is not helpful; indeed, it can REALLY help, especially if modifying circuits. But for the poor souls out there that want to purchase a soldering iron, tools, a good VOM, and some books, you are WELL on your way and past most people with gear.

kh

This message has been edited by mobile homeless on 03-26-2002 at 04:31 PM

[NOSValves]

Mobile

I agree with you completely. Its not neccesary at all to have a scope and function generator. All that is really needed for keeping your stuff at least operating in a "safe for the equipment manor" is a multi meter and cheap Iron and of coarse some clue as to what your doing.

What Mark means when he suggest a scope and sound generator is if you want your Amp to be really perfect this is required. To me this is pretty obviously the truth because just about every service manual I have read has instructions that include a scope and sound generator as required eqiupment to service the product.

Craig

This message has been edited by NOS440 on 03-26-2002 at 06:44 PM