AudioCircle
Other Stuff => Archived Manufacturer Circles => Music Reference => Topic started by: Roger A. Modjeski on 1 Feb 2014, 01:47 am
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I have received several requests for a class in Amplifier Design. The course will cover basics circuit topologies and introduce how component values are determined. For those interested in doing complete designs a second level course will get into the rather simple mathematics of fine tuning circuit values, choosing voltage and current levels and specifying transformers and other components.
I am looking to enroll 12 students at $90 each for 10 lessons listed below. Hoping to start in late February. Test equipment is suggested for those who want to measure things but not at all necessary for the student who just wants to learn how these things work. If you do plan to build something a voltmeter will suffice and you can judge your results with your ears.
Enroll by sending me a personal message here and I will send payment instructions by Paypal, credit card or check. When I get 12 students we will start. Class will be held on Google Hangouts. You will view and hear me and there will be opportunities to ask questions during the lecture by typing them into the chat.
After the lecture I would like to try a discussion period among the participants which I will monitor and attempt to keep on track. The discussion will be about circuits and not about this or that brand of capacitor or wire or resistor.
If you have questions or suggestions about the course outline please ask them on this post. Be sure to vote on what you want.
Lectures and equipment suggestions
10 Lectures on tube amp design
1. Review ohms law, Thevenin’s theorem, volts, amps, watts, impedance, AC peak and RMS relationship to DC values
2. How to set up and bias a basic gain stage. Multi stage amplifiers.
3. Stage gain, input and output impedance, output voltage and current
4. Typical gain stage applications : common cathode, cathode follower, balanced,White follower
5. Line amps, phono RIAA EQ, MC/MM preamps
6. Power supplies: Choke input, capacitor input, hum reduction techniques
7. Intro to power amps: Push pull, single ended, OTL, SEPP, Ultralinear, Triode, Class A, Class AB1 and AB2
8. Power tube characteristics: Pentodes, tetrodes, triodes
9. Feedback: Effects on distortion, Frequency response, Damping Factor, Noise
10. Construction tips, Parts selection, transformer selection and ratings
1 hour to 1:15
10 Saturdays, 11 AM Pacific Time, so that you can try things out that same afternoon.
Suggested Test Equipment for the Experimenter, available on Ebay at low cost. HP is a bargain these days. Heathkit or Eico is less expensive but not as good or as stable.
Digital Voltmeter Fluke 70 series are very nice. Typical $35-50 used
Signal Generator HP 200 tube (Be careful of stiff turning dial, will need skillful lubrication) or later 204 solid state with large frequency dial are very accurate. $35-70
Oscilloscope dual trace, triggered sweep prefered, single trace ok. $50-$200. Hitachi V-152 or V-203 are great scopes, simple layout. Tektronix 422 (under $100) or 453 (under $200) great scopes though harder to fix if there is a problem. Get one that is guaranteed to work.
This is a great scope, looks like it was made by Hitachi
http://www.ebay.com/itm/BK-Precision-10-MHZ-Oscilloscope-1476A-/290839139744?pt=BI_Oscilloscopes&hash=item43b75d15a0
Stay away from the older black BK scopes, they are horrible.
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I am not seeing the 10 classes listed below. Are they still to come?
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I am not seeing the 10 classes listed below. Are they still to come?
Thanks, added to the original post now.
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SIGN ME UP!!!!!!! I've been waiting for this for years!
Will the classes be available for later viewing/reviewing? I would not be available at those days/times every other week as I watch my two sons while my wife works. I could view the class later that night after the kids are asleep. Any provision for recording the class at Google Hangouts?
This is really great of you Roger. I really appreciate that someone with your level of expertise is willing to share his knowledge with noobs.
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SIGN ME UP!!!!!!! I've been waiting for this for years!
Will the classes be available for later viewing/reviewing? I would not be available at those days/times every other week as I watch my two sons while my wife works. I could view the class later that night after the kids are asleep. Any provision for recording the class at Google Hangouts?
This is really great of you Roger. I really appreciate that someone with your level of expertise is willing to share his knowledge with noobs.
+1.
Best,
Anand.
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I'm in!
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This is a great idea. PM sent. Also, does the Google option offer the capability to record the lesson by either the instructor or student? It would be nice for those of us with limited memory capacity left to have some permanent documentation :)
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There are many capture screen and convert to video programs. Camtasia is a well regarded old school product. One may also check out open source freeware at sourceforge.net among or elsewhere.
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SIGN ME UP!!!!!!! I've been waiting for this for years!
Will the classes be available for later viewing/reviewing? I would not be available at those days/times every other week as I watch my two sons while my wife works. I could view the class later that night after the kids are asleep. Any provision for recording the class at Google Hangouts?
This is really great of you Roger. I really appreciate that someone with your level of expertise is willing to share his knowledge with noobs.
Yessir! I would love to take classes for tube electronics. I tried and there was a class given years ago in the San Francisco area but it was not an internet course, you had to be in the Bay area to take it.
I have a similar problem as Ericus Rex in that I cannot attend at that time due to work, in my case. But if it can be recorded then I'm in. I realize this takes the live chat Q & A out of the equation but maybe email would fill the gap. Although it would slow things down a bit and may not be feasible for Roger so I'm just thinking out loud. I also suffer the vagaries of becoming "senior" thus having hard copies of class material would help refresh my feeble memory when needed.
Thanks!
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PM sent!
Clio and Jake, I fully appreciate your memory predicament! Some way to record or otherwise have documentation would be a boon.
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I wish I could attend. Moving cross country though, and I am amazed how many things can go wrong at the same time. Hopefully, there will be another class.
Steve
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UPDATE: So far we have about 5 people. We need 5 more to get this to happen. Tell your friends.
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quite interested but like a few others I will
have time conflicts. I would need to know
if I can listen easily ...time shifted... with out
much difficulty.
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Yes, that time is very difficult for the East Coast. Smack in the middle of the day.
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Yes, that time is very difficult for the East Coast. Smack in the middle of the day.
It is on Saturday, however I could make it later or earlier. Let's hear from those who need a different time.
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Must have missed this announcement before.
PM sent - would love to participate.
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PM sent yesterday. Early Saturday would not be a problem, I'm in Central time.
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RE - the possibility of somehow 'capturing' the videos for non-live viewing; Roger. Would it be at all possible to film the lesson as well and offer a complete DVD of it to participants? I know I would be willing to pay you for your time/trouble to do this. As mentioned above, I'd probably have to miss the live sessions of half of these classes and would love to be able to pick up what I missed at a later time.
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I would also be in. But need to confirm that the time works.
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RE - the possibility of somehow 'capturing' the videos for non-live viewing; Roger. Would it be at all possible to film the lesson as well and offer a complete DVD of it to participants? I know I would be willing to pay you for your time/trouble to do this. As mentioned above, I'd probably have to miss the live sessions of half of these classes and would love to be able to pick up what I missed at a later time.
Same here. I'd be willing to pay extra for DVDs or for RM's efforts to post his lectures on youtube or similar. Hard start times would be very difficult for me, likely unworkable. I have all the gear save the 'scope but I need to buy one anyway.
I hope people understand what a highly regarded figure RM is within the audio field and what an unusual opportunity this is-.
If I can make the timing work I'm in with both feet.
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EDS_ posted, "I hope people understand what a highly regarded figure RM is within the audio field and what an unusual opportunity this is-."
[Imagine my replying with a timid smile and total embarrassment.] Um. Well. I had to Google his name to find out who he is. :oops: This just goes to show how fresh off the boat I am in the audiophile world. Half the time I see this or that poster's name, I simply don't recognize who he/she is. It's almost as though I had lived in another world until recently. :wink:
Mr. Modjeski, I would be honored to learn from you whatever you can teach me about amplifiers. I will try to be a good student. :thumb:
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RAM - this is a very thoughtful and highly cool endeavor you are proposing. I would love to participate, but dedicating 10 Saturday mornings isn't going to work with my calendar at all.
Now if you were to record these 10 sessions and offer them out to people for a fee so they could view them at their leisure I would be the first to sign up. In fact, I bet you would likely get 5x the number of interested people subscribing, which should easily cover the cost of filming and hosting the vid's.
Just a thought. Thanks for offering to broaden our knowledge of the design and build aspects of this hobby.
Bob
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As I'm in Australia I definitely endorse what Bob said. Please consider recording lectures as I'm sure there are many like myself who would be happy to pay for such a service.
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Thanks for your votes, responses and Personal messages for enrollment (which I will answer soon). We are close to having enough people so I hope to finalize enrollment soon. I am looking into a way of making the classes available to those who cannot attend live.
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Thanks for your votes, responses and Personal messages for enrollment (which I will answer soon). We are close to having enough people so I hope to finalize enrollment soon. I am looking into a way of making the classes available to those who cannot attend live.
Wonderful, if it is not too late I would also like to join.
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Its not too late, we are still taking students.
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Thank you :thumb:
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Please register me for your course. Let me know when you are accepting payment.
Lynn Davison
lynndav@comcast.net
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Roger,
Most of the students are novices and safety should be of primary concern. The supply voltage is in excess of 350Vdc and DIYers must take special precautions.
I recommend you include at least 1/2 the lesson on how to deal with high voltages e.g powering up, voltage measurements, etc.
BTW your idea of Amplifier Design classes is a good one.
Cheers.
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Count me in! I am also on the east coast so the earlier the better. :D
Martin
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Roger,
Most of the students are novices and safety should be of primary concern. The supply voltage is in excess of 350Vdc and DIYers must take special precautions.
I recommend you include at least 1/2 the lesson on how to deal with high voltages e.g powering up, voltage measurements, etc.
BTW your idea of Amplifier Design classes is a good one.
Cheers.
Agreed 100%.
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Roger,
Most of the students are novices and safety should be of primary concern. The supply voltage is in excess of 350Vdc and DIYers must take special precautions.
I recommend you include at least 1/2 the lesson on how to deal with high voltages e.g powering up, voltage measurements, etc.
BTW your idea of Amplifier Design classes is a good one.
Cheers.
sorry....DP
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PM Sent.
Thank you for this opportunity Roger, really cool!
Chuz,
Drew
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I would like to be in the class if its not to late.
Is the time still 11 PST?
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That is still the projected time. I hope to get classes started near the end of March. Thanks to everyone for their interest and votes.
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Hey Roger,
I will have a look at google hangouts to see if they can be recorded, being in Australia time zones issuea arrive as well.
Chuz,
Drew
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Is anyone familiar with what ted_b used to record his talk about computer playback? That might be an option.
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That is still the projected time. I hope to get classes started near the end of March. Thanks to everyone for their interest and votes.
Fantastic... I received my Signal Generator today.
(http://www.audiocircle.com/image.php?id=96004)
Next up is an oscilloscope.
Martin
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I see an HP 175A tubed oscilloscope for sale locally for $30 with some other goodies. Is this a good model or should I wait for the recommended hp 200 or newer?
Thx!
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I picked up this oscilloscope for $50.
(http://www.audiocircle.com/image.php?id=96005)
Will be testing the signal generator with the oscilloscope and vice-versa.
Martin
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I see an HP 175A tubed oscilloscope for sale locally for $30 with some other goodies. Is this a good model or should I wait for the recommended hp 200 or newer?
Thx!
I don't recommend any tube scopes as they are a lot of work to keep going, big and run hot. If someone gives you one for free and it works, then use it.
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Looks good Martin, but the top of the wave should be thinner. Try adjusting the focus and astigmatism.
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What do you folks think about this guy for an oscilloscope? I am not sure what a table pen is but it appears it can measure up to 500V. That is awesome!
http://www.ebay.com/itm/SainSmart-DDS120-PC-Based-USB-Digital-Storage-Oscilloscope-20MHz-Bandwidth-50M-S-/300992154516?_tf=121291949295&ssPageName=STRK:MESE:IT
How about these two signal generators?
http://www.ebay.com/itm/370987464242?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
http://www.ebay.com/itm/DDS-Function-Signal-Generator-Module-Sine-Triangle-Square-Wave-Servo-Signal-/281220887054?pt=LH_DefaultDomain_0&hash=item417a12320e
If anyone is interested I found one of Roger's suggestions for sale (HP 200CD).
http://www.ebay.com/itm/231175477292?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
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Hi Roger,
I am new to the forum. I hope I am not too late. Can I still register for the class?thank you
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Hello Folks,
Did the class already start? Thank you
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Ivardlr2011,
As far as I know it hasnt, send Roger a pm so he knows, running a business means he doesn't live on these forums...
Chuz,
Drew.
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Hi Drew,
Thanks for the response. I sent Roger a message I hope he will respond.
Thanks
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Hi:
About six weeks ago I threw my hat into the ring, but have received no response about the status of the class. Was this for real, or was it a simple poll to gauge interest? Please let me know what is going to happen with this great opportunity.
davisoly
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I am sure when Roger is ready he will let us know the details. He has taught these types of classes in an bricks and mortar academic environment so I am sure he would want to prepare a curriculum that can now be morphed into an online environment. Not necessarily the easiest thing to do given that we have a mix of people with varying degrees of knowledge.
Not to mention Roger also has a lot of other things going on and I am sure he would like to have a personal life so his time is limited as such.
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Many thanks. Now I know just to be patient.
Lynn
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Nicely written Clio09, am looking forward to it, still sorting a signal generator!
Tis not the easiest thing to sorting out info such as this.
Looking forward to some learning!
Chuz,
Drew.
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What's a 'chuz'? 'Cheers' with a British accent?
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Gday Ericus,
Close......
We have what we call Kiwi's in Australia, they are of course from New Zealand, they have a native race called the maoris, funny people mostly, thet have several sayings such as "beached as bro" and "chuz bro", which is cheers as you pointed out. I use it cause im a lazy typist, which probably stems from the aussie method of shortening all speech as much as possible but still talk quite fast, this is to reduce the number of flies one swallows......
Chuz,
Drew.
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To me, it says a lot of good things about a nation's people when they are willing to poke fun at themselves. When I consider the current state of Canada or Australia, I can't help but think that, even if we had lost the Revolutionary War, we (USA) would be a contented people as part of the Commonwealth. Of course the world would not have had our successful republican experiment to grow upon. Hey! What does this have to do with building amplifiers? Sorry.
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Thanks for the explanation, Drew. I will now read all your posts with a very heavy Bill Hunter-esque accent!
Be patient my friends! If Roger says it will happen then it will happen...though delays are quite common in these parts....
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I wanna learn to, I really really would like to attend your classes. I send guns, drugs and money you go MEGADETH. Had to look quote up! :D
kdutton#vreel.com
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Hello Roger ,please let me know when this class is going to happen
thanks
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Any updated ETA on when or if this class is going to be held?
Still interested :thumb:
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Just a WAG on my part...
but Roger has expressed an interest in having a school/shop/clinic/site the N-Cal Bay area Berkley.
Where amplifier design & speaker design could be mentored & perhaps some construction.
the online classes previously mentioned woulda been a logistical nightmare and fraught with
the opportunity to freeload.
imho....
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Looks like Roger will be taking over the Randall Museum classes in January so that would be the class format for interested students.
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Just a WAG on my part...
but Roger has expressed an interest in having a school/shop/clinic/site the N-Cal Bay area Berkley.
Where amplifier design & speaker design could be mentored & perhaps some construction.
the online classes previously mentioned woulda been a logistical nightmare and fraught with
the opportunity to freeload.
imho....
The help in getting the on-line thing going has not materialized. I would much rather teach in person. Perhaps when I get that going I can run some video and put it up.
You hit the nail square on the head about the Mentoring. Although it will be a considerable bother to move to the Bay Area I know I will enjoy the people there and will have a much better chance of finding a special few who want to carry on this work. There is no high-end audio in Santa Barbara, no students, no interest. I am truly a fish out of water here.
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do you have any updates on your plans for Berkeley area workshop ?
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do you have any updates on your plans for Berkeley area workshop ?
We plan to offer the amp building class at the Randall Museum in January. Thanks for your interest.
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Roger, you may already know this, but the cost of living in the Bay Area in general, and San Francisco in particular, is insane. But then, Santa Barbara isn't cheap either!
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Roger, you may already know this, but the cost of living in the Bay Area in general, and San Francisco in particular, is insane. But then, Santa Barbara isn't cheap either!
Thanks, I have looked into it and found the cost in Berkeley to be very close to Santa Barbara, with more selection.
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It's an interesting city, bohemian mixed with politics. Lots of street energy, great audiences for live music (I used to play at Keystone Berkeley, San Francisco, and Palo Alto occasionally). People even dance, though it's often Hippie style (we called it the "Sun Grope" :wink:).
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Santa Barbara has become a city for tourists and people who don't want to do anything. Film stars, producers, newly wealthy people have become the norm here. There is no Hi Fi here. In 25 years I have not walked into one home with a tube amp or Hi Fi of any note. It is not unusual for a person to spend 100-500K on a home theater or fully wired in-home music distribution system with in wall, in ceiling speakers and complete functionality in each room so each person can play whatever music they choose off the server. One system I saw being constructed was in two full 19 inch racks. That is their idea of a music system.
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Sounds very convenient but utterly boring. :sleep:
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It's an interesting city, bohemian mixed with politics. Lots of street energy, great audiences for live music (I used to play at Keystone Berkeley, San Francisco, and Palo Alto occasionally). People even dance, though it's often Hippie style (we called it the "Sun Grope" :wink:).
That is hilarious. We call it the "Contraceptive Dance". Once you see a woman dancing like that with lots of underarm hair your mind will shut off any and all interest in having a relationship with her.
Berkeley will welcome you with open arms. Welcome to the Bay Area.
Steve
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Berkeley will welcome you with open arms. Welcome to the Bay Area.
Steve
I hope so, it's a lot of effort to move there and I am doing it mainly to teach.
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Wait a minute, I didn't catch that you are moving to Berkeley. Just your family or everything, company too?
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That is hilarious. We call it the "Contraceptive Dance". Once you see a woman dancing like that with lots of underarm hair your mind will shut off any and all interest in having a relationship with her.
Berkeley will welcome you with open arms. Welcome to the Bay Area.
Steve
:lol: :lol: :lol::Great, great, great! It's amazing that the Hippie ethos has survived after all this time, but it's alive and well in NorCal. When I moved down from San Jose to LA in '79, I didn't see my old friends up there for quite awhile. When I did years later, I was amazed to see they were still smoking the special cigarettes. I didn't know ANYONE in SoCal that did, but EVERYONE I knew up North did and still does. Does the smell of female underarm hair go well with the smell of herb :wink:? And organic food :o?
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I hope so, it's a lot of effort to move there and I am doing it mainly to teach.
Great. Just when I finally get an MR amp (finally in two ways: Finally as in after all this time, and finally as in I plan on my RM200 being the amp in my Hi-Fi for the rest of my life. It will definitely outlive me), and am within driving distance of Roger, he up and moves North. Serves me right for not getting one sooner. By the way.....I really like the stainless steel transformer cover of the RM200 Mk.I. (the reflection of the tubes off of it in a darkened room is very cool looking). Is it removable from the amp's brushed aluminum top plate and put on an RM200 Mk.II in place of that amp's brushed cover? Is there a SS cover left over and available, or were they all used up?
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Great. Just when I finally get an MR amp (finally in two ways: Finally as in after all this time, and finally as in I plan on my RM200 being the amp in my Hi-Fi for the rest of my life. It will definitely outlive me), and am within driving distance of Roger, he up and moves North. Serves me right for not getting one sooner. By the way.....I really like the stainless steel transformer cover of the RM200 Mk.I. (the reflection of the tubes off of it in a darkened room is very cool looking). Is it removable from the amp's brushed aluminum top plate and put on an RM200 Mk.II in place of that amp's brushed cover? Is there a SS cover left over and available, or were they all used up?
I have few SS covers left. Write Ben tubeaudiostore@gmail.com
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Fantastic Roger, thanks. I guess they just bolt or screw onto the top plate?
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Everything I make is easy to work on. Just need a #2 Phillips screwdriver. Put the amp upside down on a towel, Take off the bottom and the cover comes off with 4 screws.
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I've just joined your site with the hope of getting into the amp class. Have any concrete plans been made yet for the classes? I live in Sacramento and would love to attend!
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I've just joined your site with the hope of getting into the amp class. Have any concrete plans been made yet for the classes? I live in Sacramento and would love to attend!
Did you see this post about the school? http://www.audiocircle.com/index.php?topic=127866.0
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Hi, New video on amplifier construction techniques at you tube.
https://www.youtube.com/watch?v=TuUiNhbMzjY&list=UUhBOdsRsM7YDnU2CHsgBG-g