Vintage Stereo Tube Amp : Advice Wanted For First Time Purchase

tk1769

Member
OK, I know this has probably been asked a gazillion times (or as my kids say, a googolplex)...I have searched the previous forums but I can not seem to get the answer I am looking for (but please feel free to share a link if you know of one that addresses this).

I am looking to purchase my first stereo tube amp, and would like some advice as a good starting point (yeah, I went there, hope I'm not pissing anyone off...) :dunno:

My current system(s):
  • System 1
    • McIntosh MAC 4100
    • AKAI GX-270D
    • Pioneer CT-F9191
    • JBL L96
  • System 2
    • Nakamichi PA-5
    • Nakamichi CA-5
    • Nakamichi ST-5
    • Nakamichi CR-5A
    • JBL S38-II
I run a few different turntables (where my vintage bug was actually revived), and have not found a 'favorite' yet, but seem to keep coming back to a simple AR XB unit.

Here's my ultimate goal...to acquire a vintage tube amp/system at least up to the specs of what I currently have...what I do not know if that can be done fairly easily, or if I will have to spend some serious time accomplishing this. :music:

A secondary goal would be to utilize some of the gear I currently have, but if I need to 'start fresh', well, I've done it before and am not completely opposed to doing it again.

Thank you in advance for your insight, every time I post here I am both thankful and amazed at the wealth of knowledge available!
 
Here's my ultimate goal...to acquire a vintage tube amp/system at least up to the specs of what I currently have...what I do not know if that can be done fairly easily, or if I will have to spend some serious time accomplishing this. :music:


You standing, AK forum attempting to answer -


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You are right this question is also one of the more frequent ones. And like an open ended question such as this you will have many opinions. One of the main questions is budget ? How much are you willing to spend. Power requirements is also critical to achieve good synergy with your system. Next is care and maintenance. Do you have access to a tech or are you going to do repairs yourself? Patience. If you have your heart set on something that was only available in small numbers, then you will not likely find the piece without waiting. So, i suggest pick a output tube that you like, whether it is el84, 6l6, el34 7591, 6550, 300B, and their respective siblings, and maybe learn about the vintage amps available in that particular tube line. I love vintage tube gear, as once it is rebuilt it certainly can be an excellent audio reproducer.
 
It's a small listening space, I do not need a big wattage amplifier, 35 to 40 should suffice.
You should just post the specs you want. Otherwise you're going to have to wait for someone who wants to research it first for you, or have all the numbers from experience commited to memory or spec sheets. Start with power range you think is minimum necessary.

When I say "specs", I should have clarified I am more concerned about 'quality', opposed to 'power'. I rarely listen to my system(s) above 100db, it's nice to have the headroom, but not necessary for my purposes.

That said, I want to have 'at least the same quality sound' as my current system, when I delve into the wonderful world of 'tube amps'.

Thank you for your response, I hope this clarifies some of the particulars you addressed.
 
A fully-rehabbed, appropriately-modified Dynaco ST-70. Or, if you're technically-inclined a functional unit needing rehabilitation. Either way you'll have a fine tube amp to enjoy. Oh...and you'll need a preamp as well.
 
You are right this question is also one of the more frequent ones. And like an open ended question such as this you will have many opinions. One of the main questions is budget ? How much are you willing to spend. Power requirements is also critical to achieve good synergy with your system. Next is care and maintenance. Do you have access to a tech or are you going to do repairs yourself? Patience. If you have your heart set on something that was only available in small numbers, then you will not likely find the piece without waiting. So, i suggest pick a output tube that you like, whether it is el84, 6l6, el34 7591, 6550, 300B, and their respective siblings, and maybe learn about the vintage amps available in that particular tube line. I love vintage tube gear, as once it is rebuilt it certainly can be an excellent audio reproducer.

Budget is open-ended, I want to get something 'good', and if I need to save for awhile that is fine, just don't want to throw money around experimenting haphazardly.

Here would be my levels of advice wanted:
  • Budget (best bang for the buck, sleepers, etc...staying away from junk, hopefully)
  • Mid-to-High Grade (something known, I would consider the aforementioned MC240 amp in this range)
  • Uber High End (probably don't need this level, I won't get past the MC240 range as a starter)
No need for high power, small listening space, rarely over 100db.
I do not have access to a good tech, living in the mountains, but I am capable of basic maintenence (although I am not looking to rebuild).

As far as 'picking an amp I want', that is (was) my main question to the group...from your response it looks like I have some research to do on my own, thank you for educating me. :thumbsup:
 
A fully-rehabbed, appropriately-modified Dynaco ST-70. Or, if you're technically-inclined a functional unit needing rehabilitation. Either way you'll have a fine tube amp to enjoy. Oh...and you'll need a preamp as well.

I've looked at the Dynaco, seems like a great place to start...what pre would you suggest to match up to it?
 
You'll find plusses and minuses galore, but I'd match it up with a PAS-3 or PAS-4. Dynaco, of course. Again there are plenty of mods out there from simple to essentially remanufacturing, A bit of research will reveal much to know.
 
You'll find plusses and minuses galore, but I'd match it up with a PAS-3 or PAS-4. Dynaco, of course. Again there are plenty of mods out there from simple to essentially remanufacturing, A bit of research will reveal much to know.

cool, thank you for the advice!
 
A carefully purchased refurbed Dyna ST-70 / PAS combo might run ca $1000+$1200. A refurbed MC240/C22 ca 4X that.
 
A very good thing about the ST-70 is there were so damn many built...either kit or factory built. Kit builds can range from "Yeez!" to "This looks factory". Factory-built is just that: factory. They're a very simple design, easy to work on. A couple of years ago I rebuilt an ST-70 for a good friend. It had been sitting in the bottom of a closet for about 35 years. I replaced the filter caps (instead of installing a new multi-section can I secreted individual caps of the correct value under the chassis), rebuilt the bias supply with new caps and a silicon rectifier instead of the stock selenium, and, as per Frank VanAlstine's advice ( a true Dynaco guru) increased the value of the coupling caps by a factor of 10 and built a nifty little input filter he designed to limit low frequency response and improve overall performance. Tubewise, my buddy's originals tested fine but he opted for a matched quad from Tube Depot and a new 5AR4 rectifier. The 7199 driver tubes are lightly-stressed and enjoy a long life...which is good, since they're long out of production and NOS examples are expensive. 6GH8s can be substituted easily by purchasing a couple of adapters on eBay....and 6GH8s were used in nearly every 60s color TV and are cheap.
 
Scott 299C integrated amplifiers are still reasonable and sound very good. I'd take that over the Dynaco Stereo 70 ( I have owned both ) and better looking than the ST-70 by a good mile or so imo.

For new stuff, the Line Magnetic amps are very well done and won't require the kind of maintenance a vintage tube amp might require. For example (No affiliation): http://www.whetstoneaudio.com/product/line-magnetic-211ia-integrated-vacuum-tube-amplifier/
 
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If you have intentions on jumping into tube separates, maybe just start with a tube preamp with th Nak power amp and see what you think. I'd say there is a majority here that agree you will get more of the tube magic from the preamp vs the power portion. You can always add the tube amp later. Just a thought.
 
If you have intentions on jumping into tube separates, maybe just start with a tube preamp with th Nak power amp and see what you think. I'd say there is a majority here that agree you will get more of the tube magic from the preamp vs the power portion. You can always add the tube amp later. Just a thought.

Not a bad idea! Fits in with budgeting purposes, also...i also have a PA-7II amp I could use in this scenario! :music:
 
I had a Scott 299C many years ago, and remember it sounding theatrically "tubey" compared to whatever else I was using, I think a Hafler DH200 driven by a Voorhis last PAS.
It's been mentioned that most of the "sound" is the preamp, and the Sound of the 299C may well have been mostly it's preamp section. For that reason I try to avoid using an active preamp if at all possible as I'd prefer the system sound as much like the input content as possible, without an overall sound characteristic. Finding an affordable transparent active line stage preamp is really difficult, and few if any of the stock vintage tube preamps qualify. Power amps also can have a sound signature, but usually less that the preamp. I'd think that an upgraded ST-70 or any unity coupled Tube McIntosh amp to be reasonably sonically neutral, there may be others worthy of recommendation, but any of the refurbished unity coupled Mac amps (of which the MC240 is one, and fairly common) would be a solid recommendation on which to base a fairly neutral sounding system competitive or better than the Nak.
As far as the preamp goes, less is generally more for transparent neutrality, but most folks want versatility and tone controls that may be countrary to that goal.
So, what are your priorities?
 
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