archangele

Joe's Dynaco ST70 should come tonight.Good! But,Craig said without a preamp I can't do much with it.BAD! I knew I wanted a preamp,but didn't know I HAD to have one. Hmmm. No one told you that the ST70 needs a preamp? Well, it does. That amp does not even have a volume control. But, it is a very fine power amp. The only negative is the use of the 7199 triode / pentode. The circuit is fantastic sounding but finding good 7199's is not always easy. I am assuming Craig will install his mod board. Anyway, you can opt for a modern preamp or have a vintage one like a Scott LC21 or Dynaco PAS rebuilt and use it. You can also buy a tube line stage preamp and then add one of those new small battery / AC operated phono stages as an outboard device. I have tried a couple and they are quiet, especially when running them with batteries. One preamp that is relatively cheap but sounds fairly good for a solid state is the Dynaco PAT5. There are several component upgrades and mods to enhance it's performance. Don't limit yourself to only tube preamps when dealing with a phono stage. There are several solid state preamps that can actually out perform tube phono stages in several areas. Most notable being the noise floor and hum pickup from the turntable's cartridge and wiring. Personally I switch between a PAS I rebuilt and a LC21 that I have also rebuilt. Both sound similar with the nod going to the Scott on the high end. There are a couple very minor mods I have made to the PAS but for the most part, it is stock with the big emphasis being on cleaning up the wiring and component upgrades. The Scott is totally stock but rebuilt with new capacitors and resistors. Bill B.

I don't know about Klipsch using Crown amps, but I have used their amplifiers in sound reinforcement applications and they are very fine amplifiers. I used a pair out of our sound system in my home for a while and the sound was quite good. I don't know of any crown amp that doesn't perform. They were considered the Rolls Royce of amps in the commercial audio world when I ran, serviced, and set up sound systems for bands and DJs. If you can find a pair of mono or a stereo power amp, chances are you will like it. If it is used in the house for your hi-fi system, it will most probably last a life time. I like these amps because the company builds stuff like I build amps. Tough both physically and electronically. Bill B.

Hi, For around $100 you can get a Grado Gold. I have one in a Technics SL-Q3 and it works great. I just happen to have an older Ortofon in another turntable and to me they both sound great but the Grado is quieter then then Ortofon. In a hybrid preamp I am designing using an FET phono stage, the hum and noise from both cartridges is the same. But using a tube preamp, both a PAS and Scott LC21, both of which I have rebuilt , the Ortofon has a higher level of AC hum then the Grado. As for tracking, both will go down to a little over 1 gram before they start sounding funny. As always, you will have to readjust overhang if you opt for a different cartridge to gain it's optimal tracking performance and sound. Bill B.

I was without a system for about 6 months while I lived in a rental house during a move. I finally gave in and unpacked a couple amps, a turntable and some speakers. I had just had it up to "here" with living out of boxes and set up a system. Two months is a drag. If I have to hang on to an amp that long, I let the owner know up front. I can't do that with commercial amps though. Those guys make their living with their amps. I have found that some peopel could care less how long it takes while others want the amp back as soon as possible. Still, when I work on an amps, I don't put any in the back room as it were and let them hang out for months. The local guitar shops where I used to live did that. They would rip an amp down, then there it would sit. Their tech would have several amps in different states of disrepair all over the shop. Some having been there for over a year. Amazing. Bill B. Audio design, building, and repair at: http://home.alltel.net/wbittle1 I went almost two years without my system. I was at the time (and again now) out of work. The only time I find myself playing it is when I'm happy. ----------------

Hi, How much are you asking for them? Thanks, Bill B.

Clean the filth outa you Zealot ears and get you needelneck to the Bose Store and ...... lordie !!!!!!!!!!!!!!!!! Ooookkkkaaaayyyyy, I think I can offer a reasonably good perspective on this issue since I own some Bose speakers as well as several others ranging from AR2A's to Mirage 190is. There are some rather nice sounding Bose speakers. My 301's sound quite nice, but placement is everything. I had a set of 901's which I personally felt sounded flat with artificial bass. But mids and the stereo sound stage were excellent. The big thing is that Bose speakers are very expensive relative to what you get. You pay a lot for that name. As for their newer gear and that wave radio, to me it sounds like typical band pass box technology. If you like thumping one note bass, then Bose bass is for you. If you like to be able to differentiate between an acoustic bass, electric bass, and a bass drum, then forget this acoustic wave or satellite / sub stuff and buy a set of Heresys. If a person feels a bose system sounds better then a pair of Paradigm monitors, then he or she has hearing issues. The bottom line is that Bose does get a lot of sound out of small cabinets and their stuff does not sound half bad. But it is not in the same league as Klipsch or Paradigm. Kind of like comparing a current production Realistic receiver to a vintage Marantz 2270. Just because a lot of people buy Bose does not mean it is good. It just means that they deliver reasonable bang for the buck and that they have good 'spin doctors'. Bill B.

the amp was completely rebuilt and upgraded (moded) by a very competant member of this forum (craig at NOS Valves) it is under a warranty as well thanks for the info Joe ---------------- If it keeps giving you problems you may want to let Craig have a look at it again. What mods were made to it? There is always the chance that one of the new components failed. This happens. Craig is a good tech. He will be able to figure it out. Bill B.

What would happen mechanically and sound wise if I switched the connection from 8 ohms to 4 or 16? Hi, Normally, if the amp is designed such that it's output transformer is of an optimal impedance for the output tubes, you loose efficiency and power when you use an output tap other then the one with the same impedance as the speakers. But speakers are dynamic devices which not only have a static resistance but an impedance that varies due to frequency and resonance peaks. The rating is an average, but not the one and only best value for all amplifiers. Although logic would suggest running 8 ohm speakers from the 8 ohm tap on the output transformer, many times one can actually get better performance by using something other then the 8 ohm connection for a speaker which is rated at 8 ohms. You just have to try and see what sounds best. 9 out of 10 times, an 8 ohm speaker sill sounds best on the 8 ohm connection. But there is always that amp which might perform better when the speakers are connected to 4 or 16 ohms on the amp. Now, in the case of a solid state amp, you run the risk of over heating the amp if you connect lower impedance speakers then the amp was designed to push. If you run too high an impedance, you loose a lot of power. Hope this helps. Bill B. (Wright 2A3's on Khorns) ----------------

What would happen mechanically and sound wise if I switched the connection from 8 ohms to 4 or 16? Hi, Normally, if the amp is designed such that it's output transformer is of an optimal impedance for the output tubes, you loose efficiency and power when you use an output tap other then the one with the same impedance as the speakers. But speakers are dynamic devices which not only have a static resistance but an impedance that varies due to frequency and resonance peaks. The rating is an average, but not the one and only best value for all amplifiers. Although logic would suggest running 8 ohm speakers from the 8 ohm tap on the output transformer, many times one can actually get better performance by using something other then the 8 ohm connection for a speaker which is rated at 8 ohms. You just have to try and see what sounds best. 9 out of 10 times, an 8 ohm speaker sill sounds best on the 8 ohm connection. But there is always that amp which might perform better when the speakers are connected to 4 or 16 ohms on the amp. Now, in the case of a solid state amp, you run the risk of over heating the amp if you connect lower impedance speakers then the amp was designed to push. If you run too high an impedance, you loose a lot of power. Hope this helps. Bill B. (Wright 2A3's on Khorns) ----------------

This is obviously a later Marshall. Marshall amps like the 50 and 100 watt heads of the 60's and 70's had their tubes mounted above the chassis and sat upright. Only later combo amps had sockets on the circuit board and were mounted upside down in the cabinet. Fender did this, but if you look at a Fender amp, the sockets are mounted to the chassis and the tag board is not directly over the sockets. I work on and restore vintage Fender, Ampeg, Gibson and Marshall amps and they last for may years. Most problems are due to the age of the components not poor design. Most all 30+ year old tube amps need to at least have their power supply capacitors changed and to have their coupling capacitors replaced. I also replace the plate feed resistors, bias power supply and all small electrolytic capacitors on the chassis as well as clean all controls and clean or replace input and speaker jacks as necessary. Your Marshall is nothing like the vintage Marshall amps made prior to 1980. I have a 1965 Fender Bandmaster which I have refurbished and still use to this day. It is rock solid and trouble free. The same was true for my 1973 Marshall 50 watt head, (which I sold a few years ago. Real dumb move. ) Bill B. Tube amps at: http://home.alltel.net/wbittle1

Thank you Thank you THANK YOU for posting that! Finally someone writes a good article which touches on the differences between a true pentode like the EL34 and the beam power tubes like the 6550 and 6L6. This totally reinforced my reasoning behind using the EL34 exclusively in both my hi-fi and guitar amps. Although not everyone's cup of tea, I personally find the EL34 and it's little brother, the EL84 to be the finest sounding output pentodes. No, they are not the most powerful, but if I need more power then I can get from a push pull pair, I can always do the push pull parallel thing. Great article with a lot of very good information. I also like the information about the unity coupled amps. It goes a long ways toward explaining why those great McIntosh amps have such a fine and unique sound. Bill B. Vacuum tube hi-fi and guitar amp repair, design and building at: http://home.alltel.net/wbittle1

Hi, A tube amp should not blow fuses just because it is a bit warm, or it is being played loud. Has this amp been rebuilt or does it still have all it's original coupling capacitors and bias power supply components? Any vintage tube amp must be completely gone through by a competent tube amp technician before it will be reliable. Things like the weakening over time of the selenium bias rectifier or the slight DC leakage through an old coupling capacitor can cause an over current condition which will blow the fuse. The number one reason for blowing fuses in amps like the Dynaco ST70 is the 5AR4 rectifier arcing. Chinese 5AR4's are notorious for this. Having your amp biased too hot (too much plate current) can cause the fuse to fail. A shorted output tube will certainly cause a fuse to blow. Do NOT use a larger fuse then the amp specifies!!!If it says to use a 3 amp fuse and it will not run long with a 3 amp fuse in the fuse holder, something is wrong with the amp. Installing a 4 amp fuse will only mask the problem and will most probably lead to a major problem. The next most common problem with a vintage tube amp is the main B+ power supply. Again, in the Dynaco ST70, the 'quad cap", that big 3" x 1.5" silver cylinder next to the 5AR4 rectifier tube can develop a mild short. It will still work, but it will get worse and worse till it loads the power transformer enough to cause the fuse to blow. It generally starts out by blowing a fuse every so often. Then as it gets worse, you find that you are replacing a fuse almost every time you use the amp. Anyway, these are a few of the problems you may have. But fear not, all this stuff can be repaired and is generally not fatal if taken care of before you see smoke. Bill B. Vacuum tube Hifi and Guitar amp repair, design and building at: http://home.alltel.net/wbittle1

Hi, Unfortunately, it sounds like your Denon is in need of service. There are only a few reasons why most solid state amps go into protect and stay there. One is that your DC offset voltage is not 0 and your power amps are trying to produce straight DC at the speaker terminals. In many MArantz receivers, this will trigger the protect circuit. Another problem is a detected high current condition, usually caused by a shorted output transistor. FInally there are devices which cause a shut down due to heat via thermal sensors on the output stage's heat sink. The bottom line is that this unit should be put on a test bench and checked out. If it is as new as you said, it may still be under a manufacturer's warrantee. Check into that first and do NOT open the unit up until you have checked into the manufacturer's warantee. There is no reason any amp should go into permanent protect mode just because someone hit 'mute' then came back and deselected "Mute'. Bill B. Archangele Audio: Vacuum Tube Hifi and Guitar amplifier repair, design and building at: http://home.alltel.net/wbittle1

The LC21 is a very clean sounding preamp and worth the $300 price tag. It is one of the more simple preamps from the "Golden Age" and has a refreshingly clean sound. When properly refurbished, the preamp is quiet, stable and just plain sounds nice. Personally, this is my favorite tube preamp. For years I have been telling people on the H.H. Scott forum that this is the best preamp Scott has to offer with respect to overall sound quality. Ironically, it is their least expensive and was actually a Scott Kit. It's matching power amp is the excellent LK-150. I have had the opportunity to service LK-150 and LC21 systems and everytime I finish with the systems and am ready to box them up I find it incredibly hard to let go of them. I finally got an LC-21 for myself and I can tell you that in an AB comparison against other Scott preamps or the Dynaco PAS series, or even the Marantz 7, I still like the old LC-21. It will drive anything from a Scott LK150 to a Dynaco ST70. Like any vintage preamp that is over 40 years old as the LC21 is, the preamp should be completely refurbished. But the end result will be quite impressive. It is a full featured preamp with stereo / mono selector, Scratch filter, rumble filter, phono preamp eq settings for tape and mag cartridge, separate tone controls for each channel, and even a center channel out with a level control mounted concentrically on the balance control. It also has a tape loop for recording. Hope this helps, Bill B. Archangele Audio; Tube amp service, design and building at: http://home.alltel.net/wbittle1 looking at a scott lc-21 tube preamp, in very good condition working and cosmetics, and am trying to get a value cant seem to fina alot of info on this, also is this a good pre-amp as far as quality construction and sound quality, fella is asking 300.00 for the pre thanks for all the help Joe ----------------

Hi all, I'm Bill of Archangele Audio and I have only lived here in sunny Florida for the past couple years. I was living in the Baton Rouge Louisiana area for the past 10 years and prior to that I lived in upstate N.Y. on the Canadian / U.S. border near the Thousand Islands. As Craig said, I am old school with respect to audio. I just plain like the stuff and now that I am working at it full time I hope to get more and more business. I will work on pretty much anything in tube audio, but am most experienced with Dynaco, H.H. Scott, Bell, McIntosh, Fisher, Eico, and Marantz. I also like working on classic guitar amps and know most Fender, Sunn and Gibson wiring diagrams by heart. Ok, I also know many Scott, McIntosh and Dynaco wiring diagrams as well. I have rebuilt several vintage (pre 1965 vintage) Fender amps which have actually been used in studio recordings in the New Orleans and Baton Rouge areas. I have been reworking amps for around 40 years now. But, one time about 10 years ago I found a pretty tired old Scott 299C and decided to not just fix it but totally electronically restore it. The result was really great and one thing led to another. People started asking me over the internet if they could send me their amps and such to be rebuilt. I must admit that at first I thought it was kind of an odd idea what with shipping costs. But when I saw the kind of work some shops did and what they charged, I knew I could do better for the same price or some times even less. And that was including round trip shipping. I have also 'fixed' and actually had to totally rewire a few modern production tube amps. I was amazed that amps costing over $5,000 could have such silly mistakes and such sloppy wiring. I'm sure Craig has some horror stories and can relate. Craig is cool and one of the few people I have talked to who does not think I'm bonkers replacing all that I do and taking the time to match resistors and such. So, if anyone has tube audio that needs to be made right, feel free to contact me. Like I said, I work on guitar amps as well as hi-fi so if you have a dead H.H. Scott or a Fender, I work on them all and know them quite well. Bill B. Archangele Audio: http://home.alltel.net/wbittle1