Colin Posted October 2, 2002 Share Posted October 2, 2002 everything you wanted to know about the classic Dynaco ST-70 tube amps: http://www.enjoythemusic.com/magazine/manufacture/0902/index.html What we have is a typical vacuum tube amplifier with unlimited bandwidth input acceptance (DC coupled) but with limited bandwidth output transformers and small interstage coupling capacitors. The power supply is also limited bandwidth, being pretty feeble at both low and high frequencies. Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted October 2, 2002 Share Posted October 2, 2002 Man, you can really tell this article was written in 82. Some of the ideas are dated and it's interesting to see where changes have come; however, some others still ring true. Interesting. kh system(s) Quote Link to comment Share on other sites More sharing options...
BryanJ Posted October 2, 2002 Share Posted October 2, 2002 Mobile(Kelly), posted over at the tech questions but no answers. What is the best way to clean a record(vinyl)for play. On turntables, is the teres DIY turntable a decent player. What do you think? Bryan Quote Link to comment Share on other sites More sharing options...
edwardre Posted October 2, 2002 Share Posted October 2, 2002 I have almost finished performing this 'enhancement' to my ST-70. Despite the fact that the Rat Shack no longer has the items required, I did manage to aquire the lion's share of components locally except for the 1uf 400v coupling caps. I have Solen 'fast caps' on order from Welborne, should arrive soon as the order was placed early last week. In any event, for now I've substituted with .68uf's. Larger than the original .1's, but not quite up to the minimum spec of .8. After setting the bias to 1.56V (BTW - do not replace the 10K resistor with an 18K like the missive states, you probably won't get the bias to go lower than 2v. Leave the 10K in and try it first.), I've been running in this config for about 25 hours now. My initial impression is positive. First, the tubes definately burn brighter. Like little beacons even under the bright florescent lights of my garage. Hope this doesn't accelerate the life expectancy. Soundwise, the article pretty much nails it. Whereas in stock configuration the bass was overly 'boomy' 'loose' 'undefined', especially at decent sound levels, it is now much more taut and articulate. Overall throughout the freq range, there is a healthy robustness while retaining the original musical qualities. More importantly, the response is even across the amplitute range. It 'sounds' the same at low or high volumes now. Although this is a bandwidth limiting mod, I can detect no decrease in freq. response. In fact, if anything, the highs sound more 'airy'. Finally, there is a tremendous reduction in 'hum'. Used to be that I had to try different wall socket/extension cord/2-prong to 3-prong adapter combos to reduce this (like my KSW200 subwoofer). Now, it does not matter what I plug it into, it is dead quiet. This alone would be worth the few pennies it cost to enhance. All in all, for someone just breaking into the tube scene (like me) who has one of these and is a 'tinkerer', this is a nice little project that serves to familiarize you with your equipment beyond just the on/off switch. I recommend it for those with a (very) basic level of electronics exposure as well as a fundamental knowledge of how to use a soldering iron. Quote Link to comment Share on other sites More sharing options...
Mallette Posted October 2, 2002 Share Posted October 2, 2002 First, the Dyna. I've a recently "vanalstinized" ST70i and love it. Your statements work for me. Record cleaning: See latest $tereophile for review of latest LP cleaning miracle, "Premier" from www.microcare.com. I couldn't find the product on the site as given in the article, and I've emailed them with no answer yet. If it can be had and works as reviewed, it sound great. Otherwise, a few drops of Palmolive in lukewarm water, a gentle scrube along the grooves with a baby washcloth, a thorough rinse under running water, and a gentle dry with a recvac, chamois, or very soft lint free cloth does the job with available materials. Use distilled if you are super fidgety or your water has lots of junk in it. Dave Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted October 2, 2002 Share Posted October 2, 2002 See the links below on Record Cleaning and care. For general use, I use the Hunt/DECCA record brush and keep my stylus clean. Linn always believed in using the stylus to clean records as using a brush just pushes the dust deeper into the grooves. I tend to do a mixture of both. But when it comes right down to it, if you are gong to amass a large collection of vinyl, a quality record vacuum/cleaning machine PAYS for itself many times over. I have a VPI 16.5 cleaning machine that works EXCELLENT. I clean each record when I first get it, whether new or used, put it in a NEW sleeve, write the date of cleaning on the sleeve, get a plastic jacket cover for the album, make sure the sleeve open side is facing up as well as the vinyl jacket cover, and store them as vertical as possible. Most of what I do happens to be in the link below, actually. http://www.gcaudio.com/Archives/recordcleaning.htm I try not to overclean my records. But the VPI 16.5 is a great machine and works amazingly well. As for the solution, there are many theories here. I try to err on the gentle side of things. There are a lot of combinations available on the net; do a search and see what comes up. The store bought stuff is WAY too expensive - it's better to "roll your own." EDWARDE - I am really surprised you went with Solen Fast Caps as coupling caps. Man, I dont mind some Solens in the power supply in certain areas but these metalized caps can be QUITE unforgiving in a coupling position. You RARELY if ever see them used here. There are just too strident. AS I remember, there were quite a few answers to the coupling cap questions and I have not seen anyone recommend Solens in this position. Did you consider any other options? kh systems Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted October 2, 2002 Share Posted October 2, 2002 edwardre, remind me again, which ST-70 mod did you do, was it the Van Alstine mod? or was it a parts upgrade rather than a mod? -C&S Quote Link to comment Share on other sites More sharing options...
BryanJ Posted October 2, 2002 Share Posted October 2, 2002 Thanks MH Will look into it. Bryan Quote Link to comment Share on other sites More sharing options...
edwardre Posted October 2, 2002 Share Posted October 2, 2002 MH - Aw man.....I told you all I don't know beans from beef jerky about this tube stuff! Looking for a decent 1uf/400v cap, I read on several websites (other than Solen's!) that the 'fast cap' was ideally suited for use as either a network cap or a coupling cap. Just like I read about the orange drops. Jeepers. I guess I should 'mine' for answers more thoroughly in the future. So....guess I will try the fast caps to see what the sound is like, as they were only a buck or so apiece, I'm not out too much and I can at the same time, preview. C&S - The mod I was referring to was the Van Alstine one detailed in the 1982 Audio Basics, the one Colin provided a link to at the top of this thread. Additionally, I've replaced the other old fading caps with Sprague 'orange drops'. As several have (since) mentioned, they lend a rather 'harsh' sound, but so far not too much for my taste as I'm hoping that they will 'break-in' to a more mellower eventual sound. They do provide a lot of clarity as compared to the originals. I figure that caps are relatively inexpensive and since I like to tinker, this tube thing is right up my alley. Thanks for all your suggestions. Quote Link to comment Share on other sites More sharing options...
kjohnsonhp Posted October 2, 2002 Share Posted October 2, 2002 I've often thought about being more attentive to my records but for now here is the reality of what I do. I bought the Disc Doctor's "Miracle Record Cleaner" and brushes over a year ago. I use it on old dirty records but I've grown tired of cleaning, rinsing, drying and repeating on the other side. I mostly just use a discwasher brush and fluid but I can't keep the dust off. I could probably use an anit-static gun. I too store my lps in jackets/bags from bags unlimited--open side up--record vertical. I don't like pressure on the bottom from too much of an angle which can warp the lip on one side. I don't use new inner sleeves or upgraded after market sleeves although many of my used lps have them and they are certainly better. In general I've simply been playing them just like I have done since the 70's....I just have more of them. I'd like to get a cleaning machine someday. Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted October 2, 2002 Share Posted October 2, 2002 colin, what is that amp in your avatar photo? Is that a diy with some vintage trannies? what is the story, looks quite intriquing. -c&s Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted October 2, 2002 Share Posted October 2, 2002 That is the Bottlehead Paramour 2A3 monoblock, one of the least expensive monoblock SET amplifiers around and available in kit form. Damn, Clipped, ole Colin only mentions this amp two or three times a week! Where have you been? I dont think that is actually Colin's amplifier as I do believe there is a shot of this amp on Doc's site (then again, he may have got that very set). For a look at the kit with pics of the parts and interior, go here: http://www.bottlehead.com/et/adobespc/Paramour/paramour.htm This is basically a cost cutting design built to a price point but with excellent results. It uses PARAFEED transformers from MagneQuest but at a lower price point than Mike's other iron. Total cost of the kit is about $550. While the Bottlehead gear represents a certain take on the SET solution you cant argue with the excellent FORUM over there with GREAT help if one ever decides to tackle one of the Bottlehead kits, whether it be any of the amps, Foreplay preamp, or Straight 8 Speakers. kh systems Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted October 3, 2002 Share Posted October 3, 2002 What is with the patina on the transformers in the avatar photo, they look like they are rusty etc. Is this a designer option? -c7s Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted October 3, 2002 Share Posted October 3, 2002 Well, if you went to the link I posted about the Paramours, it explains all about this option and how they got it, going into great detail (in short answer, yes...it is a designer option that you can do on your own). That page is worth going to to see how easy this amp really is to make. It would take a stock beginner not that long to get these amps made once you got the soldering down. Bottlehead DOES have great instructions too. Yes, there are better SET amps around, for sure. But this is a neat little kit. ps- This amp does not have the same extension as other offerings and I dont think it's as sweet or a black a background, but this is based on this design type in general and not from having the Paramour in my own home. Quote Link to comment Share on other sites More sharing options...
Colin Posted October 4, 2002 Author Share Posted October 4, 2002 Thanks for the kinds words, mobile one, coming from you, that means a lot. YES, those are my babies! Indeed, I did snag the pair in the Bottlehead pictures. Here is the story. When Bottlehead said on their forum that they were going to release a new 2A3 design at a very low cost, I said I wanted an assembled pair. But I did not want to wait the weeks, and possibly months, it would take to get a set. They had a pair they had customized with their upgrade kits and painted especially for publicity photos. I bought them, they shipped them. Assembly adds $100, upgrades add $100 and custom paint job adds more. I got them for about $700 per the pair. I wrote about them for Secrets of Home Theater and they raised the price! The Bottlehead 2A3 Paramours are a pair of low-powered hobbyist tube amplifier kits. They have an attention to attack, detail and tone that rivals far more expensive solid-state amplifiers, if used with super or ultra-efficient loudspeakers rated at 95 or 100-dB/w/m. For tweaking audiophiles who know which end of the soldering iron to hold, the $549 kits provide the least expensive way to enjoy one of the audio industry's classic masters of tone and texture the Class A single ended 2A3 triode amp. In fact, at this low price, the Paramour kits compete with only a few other tube amplifiers, either assembled or in kit form. Most new amplifiers, and most used ones too, are more expensive than these. The parallel feed idea is not so unique. The idea is to reduce the cost of the large transformers. They do sound great with all loudspeakers, with a good attention to detail, a mid-range warmth and high sparkle that rivals the best amplifier I have ever heard (Pass solid silver block of 250 watts). They do not have the ooomp to power the low bass, therefore I do think they need some solid state support in the mid and deep bass regions. (Even though the Khorns with the Paramours do measure fairly fat down to about 30-Hz.) My initial impressions have not yellowed over the past two years. There are measurable things that SS amplifiers can accomplish with loudspeakers, especially cone driven ones. But not even the best rig I have heard in my home or in showrooms, compares to the ease, details, textures, tones and rightness for such a low price as these antediluvian amplifiers when cuopled the the largest of PWKs big old horns. Quote Link to comment Share on other sites More sharing options...
Dmitry Posted December 8, 2006 Share Posted December 8, 2006 I try not to overclean my records. kh systems What do you mean by "overclean"? Quote Link to comment Share on other sites More sharing options...
Mike Lindsey Posted December 8, 2006 Share Posted December 8, 2006 I doubt if you'll get a response from mobile, since he hasn't surfaced in a couple of years. To be honest, I'm not sure what he means by that either, but I only clean my records once on the machine, and then use a dry CF brush after that. Mike Quote Link to comment Share on other sites More sharing options...
NOSValves Posted December 8, 2006 Share Posted December 8, 2006 Mike, Actually he has popped in a few times and been a joy to chat with! I for one wish he would drop by more often. Craig Quote Link to comment Share on other sites More sharing options...
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