Piranha Posted February 1, 2004 Share Posted February 1, 2004 Can anyone tell me about or what this is? ALTEC TUBE AMP Model 1570-B Thanks. Quote Link to comment Share on other sites More sharing options...
lynnm Posted February 1, 2004 Share Posted February 1, 2004 http://www.webace.com.au/~electron/tubes/Circuits/al1570b.gif They are monobloc designs rated in the 200 watt range. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted February 1, 2004 Share Posted February 1, 2004 It's a mono PP amp with 811a's for output tubes, from what little searching I did. Quote Link to comment Share on other sites More sharing options...
Piranha Posted February 1, 2004 Author Share Posted February 1, 2004 Hmmmm.....200W....I wonder if they would be any good? Quote Link to comment Share on other sites More sharing options...
johnellis Posted February 1, 2004 Share Posted February 1, 2004 Hi Piranha- If you go to audio asylum.... http://www.audioasylum.com/audio/index.html will will find alot of information about the 1570. Also, go to... http://www.high-endaudio.com/RC-Amplifiers.html This is another good site. Here is the information from high-endaudio. From what I understand, a stock 1570 sounds terrible. But, once they are modified, they are world class. Anyway, here is some information that might help. John ALTEC 1570/TUTAY MODIFICATION This "vintage" Altec is a fantastic amplifier. It could be the "dream" amplifier for many audiophiles. I didn't list it initially because of the many hurdles to get an optimized working pair, and the potential danger in using them. Let's discuss the sonics first, and then tackle the rest. This amplifier, after it is fully modified, can compete with virtually any push-pull amplifier in the world. It uses only two 811A direct heated triode output tubes, but it can still generate over 150 watts per channel. It has a very high quality power supply with chokes, tube rectification, separate input and output supplies etc. The end result is a combination of tremendous power along with a lot, but not all, of the purity and transparency of the single-ended designs. Other "high-power" tube amplifiers, that use multiple output tubes (8, 12, 16, or 20 per channel-especially pentodes) to create their power, can not compete with this simpler (and much less expensive) design. As usual, it is at its best with high-impedance loads, but it can still sound excellent in normal impedance loads as well, though it is not recommended with very low impedances. Now for the inevitable "hurdles": 1. The original Altec 1570 series of amplifiers were designed and built for "commercial" and "industrial" applications; The military, sports stadiums, factories, auditoriums etc. They are very reliable of course, and are also downright ugly in appearance. There may have been many made 40 years ago, but now they are difficult to find. Their sonics, stock, are horrible. They sound "dirty" and have no bass. So they must also be modified. 2. There are very few people who can modify these amplifiers. The person who has the most experience, and has achieved the finest results we've heard, is Tom Tutay, a talented engineer who lives and works in Florida (Go to "Links" section to contact him). So after a pair of these are found in good condition, they must be sent to Tutay for his (very extensive) update. I don't know the most recent cost, and there are some options, but it will cost at least $ 3,000, or more. Considering the enormous amount of work involved, this is a very fair price. The total cost, including the amplifiers themselves and all the shipping, will be in the $ 5,000 range, unless you can "score" on the Altecs. To put things in perspective, if such an amplifier were built in North America and marketed new in today's market, it would sell for a minimum of $ 10,000 and probably around $ 15,000 or more. 3. After all the above has been done, there is another important issue to ponder. The reason why these amplifiers can generate so much power with only two output tubes is simple; there is more than 900 volts DC on the plates. This voltage itself comes from the rare, high voltage power transformer, which has somewhat louder than average "mechanical noise". (The extra expense and difficulty in finding and utilizing very high voltage components is the primary reason why contemporary amplifier manufacturers haven't just copied this design.) Unfortunately, there is a potential danger to this design. The 811A output tube receives this high voltage from an (easily accessible) cap on the top of the tube, and not from the usual, inaccessible tube pins within the chassis. This means that anyone (or anything) who removes this cap while the amplifier is "on", or even "off" for a short period of time, and touches the internal metal part, can be electrocuted. I realize only a reckless fool or someone incredibly ignorant would do this, but I felt it should still be mentioned. The Altec came with a perforated, protective cover which made it impossible to reach the cap, but it may be missing, and some people may prefer not to use it because the 811A output tubes look "cool" when they are "on" and all "lit up". This is highly unadvisable. My advice is to do whatever it takes to make these plate caps inaccessible to others; a replacement cover, screen etc. Don't worry about "ruining" the appearance of this amplifier, it can't be made any worse than it already is. Once that is done, this amplifier is as safe as any other tube amplifier, and very reliable. One final concern also deals with the Altec's very high voltage. A reader has informed me that an electronics designer warned him that the amplifier can "emit high radiation levels". The designer's advice to an Altec owner is simple: "He will want to distance himself as much as possible from those amps..." This advice is also applicable with any other electronic device using high voltages; such as televisions, some older computer monitors and even "typical" tube amplifiers etc., so this information doesn't compromise the Altec 1570's recommendation except in very highly unusual circumstances. Tom Tutay, the modification expert and engineer, also feels the amplifier is "very safe". (20 or more of these Altec amplifiers were used in the Astrodome and they were on 24 hours a day. The engineers who worked in near proximity never had any problems with them.) 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jazman Posted February 1, 2004 Share Posted February 1, 2004 They are rated at 150WPC. If they are unmodified, usually people send them to Tom Tutay in Florida for an update, so count on that in their total cost to you. Tom is considered THE expert on these amps. Klipsch out. Quote Link to comment Share on other sites More sharing options...
Piranha Posted February 1, 2004 Author Share Posted February 1, 2004 Sounds like something Smilin would be interested in. Tube amps with 150W output. Quote Link to comment Share on other sites More sharing options...
Guy Landau Posted February 2, 2004 Share Posted February 2, 2004 the modification cost is $3k alone. Quote Link to comment Share on other sites More sharing options...
Piranha Posted February 2, 2004 Author Share Posted February 2, 2004 Smilin may be up for that? He needs the power and extra bass slam Quote Link to comment Share on other sites More sharing options...
capt.khz Posted May 22, 2009 Share Posted May 22, 2009 I would not be so fast to mods these 1570B's, very good amplifiers stock! Only the 70 hz. filter need be removed from the front end 12AX7. The 1570B freq. response with inverse feedback removed for the test is flat fron 15Hz. to 30,000 HZ. With feedback as original, frequency response is flat 15 hz. to well up to 100,000 hz. Frequency response must not be confused with POWER RESPONSE, and indeed these amplifiers deliver rated power at 70 hz and less at 30 hz (approx 65 watts.) This is not an issue under most normal musical demands. The minimilist approach Altec built in these units is very clever, no better way to achieve a rugged, musical high power tube rig than the 1570B. Forget the fussy multiple 6550/KT88 amplifiers that are not half as reliable as these Altec units. . These are a high inverse feedback unit and feedback can be lowered some to improve low freq. stability as well. Approx. $200 for mods is all that is needed. Any tube amplifier has danger with voltages. This is a rule with any tube gear. Capt.khz (retired broadcast radio E.) Quote Link to comment Share on other sites More sharing options...
Tarheel Posted May 22, 2009 Share Posted May 22, 2009 Welcome aboard Capt.khz. Make yourself comfortable[] Quote Link to comment Share on other sites More sharing options...
VacuumTube1954 Posted May 22, 2009 Share Posted May 22, 2009 I have heard a pair of these amps. I was at Tom Tutay's house and listened to his personal pair. I would have to say that in my 55 years on this planet they are some if not the finest amps I have had the pleasure of listening to. Tom calls them "gentle giants". Quiet and powerful. Whether listening to analog or digital sources they excell at all. Oh those glowing 811 tubes ! I hope one day when the economy gets better to own a pair. Quote Link to comment Share on other sites More sharing options...
Tarheel Posted May 22, 2009 Share Posted May 22, 2009 And welcome to you as well Vacuum Tube 1954. Thanks for posting[] Quote Link to comment Share on other sites More sharing options...
VacuumTube1954 Posted May 22, 2009 Share Posted May 22, 2009 Thank you Tarheel. I appreciate that. Quote Link to comment Share on other sites More sharing options...
djk Posted May 22, 2009 Share Posted May 22, 2009 The output transformer is a bit small for real bass, and it lacks the taps for lower impedance speakers. 170W. Quote Link to comment Share on other sites More sharing options...
capt.khz Posted May 22, 2009 Share Posted May 22, 2009 You have to understand how power response measurements work. A graph is created as the amplifier is tested to clip into a resistive load at different frequencies. The 1570 delivers 165 watts from 70 hz. to 16,000 hz. and 65 watts from 30 hz to 25,000hz. this can be misleading and has nothing to do with frequency response and also does not mean this is only a 65 watt amplifier, plenty of real bass here. The output transformer bass rolloff is in power response, not frequency response. This smaller peerless 16492 output transformer is one of the reasons this amplifier sounds good....less primary inductance and less leakage inductance with broader bandpass at high frequencies than a very large high inductance transformer. BTW the amplifier has enough reserve to drive most 4 ohm speakers using the 8 ohm tap, unless your speakers are very low eff....not on this site!...Klipsch, anyone? Quote Link to comment Share on other sites More sharing options...
djk Posted May 22, 2009 Share Posted May 22, 2009 I've worked on them, I've owned them, I got rid of mine. Quote Link to comment Share on other sites More sharing options...
capt.khz Posted May 23, 2009 Share Posted May 23, 2009 Whatever turns your crank....better be careful working on those...hazards...hazards...hazards....leave to the professionals......ouch. Quote Link to comment Share on other sites More sharing options...
capt.khz Posted May 23, 2009 Share Posted May 23, 2009 My impressions exactly, and much like the McIntosh MI-200, as I had the pleasure to A-B these two classics, The 1570 achieves with less complexity, output tube expense, fewer feedback loops and all one one chassis. Quote Link to comment Share on other sites More sharing options...
djk Posted May 24, 2009 Share Posted May 24, 2009 " Whatever turns your crank....better be careful working on those...hazards...hazards...hazards....leave to the professionals......ouch." Be careful if you defeat the cover safety interlock There is close to 1KV exposed, about 1.5KV peak on the input side of the filter choke. Quote Link to comment Share on other sites More sharing options...
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