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jeffs

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About jeffs

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    TO-39 Transistor

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  1. I tried this with a 10K pot on one channel, the other channel got full signal. I did not test for audio quality, etc.... I simply did a freq response test from 20Hz to 20KHz with a function generator connected directly to the amp, no preamp. Since a C-1 has 200ohm series output resistance, I included 220ohm in series between the func generator and the input on EACH channel, considering this a typical application. I ran 2 sweeps, one sweep with the pot all the way up, the other with the pot trimmed about 1/2 scale. Output level on the straight thru channel was about 3Vrms, input was at 100mVrms, dummy 8ohm loads on both channels. For the straight in channel, the gain was nominally 29.8dB with a variation of only 0.28dB. Set at full level, the channel with the pot was nominally 29.2dB with a variation of 0.27dB. The 220ohm and 10K pot make a voltage divider 10K/10220= 0.978. This would account for some of the difference. Note that the gain in this channel might be slightly less to begin with, I never went back to check without the pot. Set at about 1/2 level the attenuated channel was nominally 23.0dB, so about 6.2dB down from the full scale of 29.2dB. Makes sense as 1/2=6.02dB. Variation was a bit higher, 0.37dB, still excellent flatness over the audio range. So - from a freq response standpoint - this looks good. As mentioned, the grounding on these inputs is sensitive, your ears will tell you if the pot adds any noise due to ground loop or the like.
  2. Phil - I'm going to evaluate my current receiver over the next few days to see if I can get it to behave. If not, I'm going to kick it to the curb. I've come to the conclusion that I'm going to have to buy a unit with output amps. The processor/pres are just too expensive. Manufacturers clearly want us to buy a unit with amps, so I'm not going to fight it. My 5.1 speaker setup isn't expanding any time soon, so anything more than 7.2 is way in my future (I would need a new house even to get to 7 speakers). The Denon AVRX3500H at $500-600 seems to cover my needs and is on my short list if I have to buy something soon. I have no experience with this unit so if anyone does, it would be nice to hear about it.
  3. Just the pots. I got my dead amp up and running last night. I didn't look at the pots I have, but I think they are 10K based on an old Mouser order. I think 20-50K might be a better option, but as was previously mentioned, a pre-amp like the C-1 should not have much difficulty
  4. Great Karma. I'm out as I have a BillD for sale ....
  5. Yup - I have not used the Yamaha amps in years so I figured a pre-amp processor would be the ticket as I'd like to get more current on HDMI capabilities. I was shocked by the cost of these units. My Yamaha preamp output levels are somewhat lower than other units I've used in the past, but are sufficient for my needs.
  6. My Yamaha appears to be dying. Clicks and pops when it changes sources, noisy outputs when there is no source content. I need to check the cabling tonight, hopefully there is just a loose connection, otherwise it's days are numbered. The emotiva mc-700 has less features than the Outlaw, but it's $200 less and it looks to be able to change the displayed name. I had a chat with a guy from Outlaw and basically told him this issue would prevent me from spending $1K with his company .... big oversight. In the end, Outlaw does not seem to be what they say they are ........ I believe their unit is just a re-branded Chinese unit, not their own design ..... From their site: "Outlaw designs and manufactures its own brand of high performance audio/video components" Look at the Fortex DE4348 or the Sonodyne DE4348 next to the Outlaw 976 ....... they all look the same to me ... hmmmm..... I'm probably just going to buy another Yammy when my current unit becomes unbearable.
  7. I don't think it's that much trouble at all, at least to try. I was going down this path (for a m1.5t) and even bought some pots a while back .... changed gears and never followed thru. Pots are very small chassis mount ALPS units with indents. I think 20Kohm ... check when I get home. There's plenty of room to mount these internally on an l-bracket or similar, or even mount thru the back chassis if you don't mind drilling holes thru the nice diagrams on the back . I have a dead amp on my bench and Mouser parts expected to arrive today. After I get thru that, I have a m1.0t mkII and can give it a try for you with the pots I have? Let me know - might be a few days before I get to it ....... more than happy to try it out if you would like. 1 beer job, maybe 2 if I do a frequency response test (I used to spend time on some of the motorcycle forums and the HD guys timed a task by how many beers they would drink?) I have a project where I need a bit more amp gain (9dB or so) to drive a subwoofer. That's more of an issue as active components are involved. As a stop-gap I bought an external cheapo tube buffer with volume control for $31, maybe has maximum 15dB of gain. Works great, but in the end it's another rectangular box that I'd rather not have. When time permits, I will add a gain circuit internally to eliminate the extra box (once again it's a m1.5t).
  8. I'm cringing just thinking about it.
  9. I got pretty excited about the Outlaw and reviewed it in some detail (I read the manual). I don't know why in 2020 a unit would not have the ability to change the source name that ends up being displayed? The sources are defined as "cable/sat, disc, game, media, server, and aux". I don't have any of those (maybe DISC?, maybe media?) My Yamaha AV receiver is 10 years old and allows the names to be changed ... "Apple TV, Blu-ray, Roku, Firestick" are easily understandable. This simple oversight would be a non-starter for me, disappointing because the unit looks pretty good otherwise.
  10. The only unit I've worked on with a level pot would be the PM1.5. If you look at that configuration, there is input buffering, followed by a 20K pot, followed by the AC coupled amplifier input. The m1.0t basically starts at the AC coupled amplifier input right on the other side of the input RCA. My point being that if you wanted to do this in a similar manner, you would need to do it right at the input. You could maybe lift the input capacitor and put something in there to try it. One side of the pot to RCA input, one side to GND, and the pot wiper connected to the input capacitor. Whatever value pot you choose would be the load on your preamp. Can't see what possible harm this would cause, at least as a trial. Keep in mind that the input board has high voltage, and the components are sandwiched between the board and chassis. The grounding of the 1.0t is fairly sensitive, so be sure to get a baseline of idle noise level in the speakers before adding the pot, just to make sure you have not changed this with the pot addition. I believe it would be best to follow the pot with a buffer but that means more circuitry as well as tapping into the 12V supplies...
  11. Before legalizing weed, Massachusetts decriminalized it years ago. This more or less made small quantities legal because the penalty was $100. Most offenders did not pay as there was no repercussion for non-payment. LOL. Weed was legalized in 2016. It's been a slow roll-out. Taxes are in the neighborhood of 25-30%. The slow roll-out and high taxes have guaranteed one thing; the illegal market is thriving. End user costs on the black market are 1/2 of legal outlets. Everyone knows how to grow it. As long as the government keeps taxes high, people are going to find alternatives.
  12. @loner_t thanks for this link. I'm in the same boat as PhilDent so following this thread to see where it leads. Im going to look into the Outlaw in more detail. Pretty much exactly what I'm looking for ... need to review the detail.
  13. Thought about it but for my application it would have meant drilling the face. Couldn't figure out a way to make that look good. For your need it should be pretty straightforward. If youre worried about excessive loading, you could add a buffer stage. That means hanging an opamp off the +/-12V supplies which should be OK. The m1.0t has better 12V regulation than most.
  14. The other day I noticed your posts stopped on about 9/6. I've spent some time away myself, so I was not sure of the detail. Great to see you posting again. I've only been involved with this site for about a year myself, a significantly shorter time than you ..... however in that time I have met some incredibly warm, helpful and generous members (yourself included). I have the Carver bug, no doubt, but it's really the people that keep me coming back. In the scheme of the WWW, this is really a unique place. Your contributions to that uniqueness are significant.
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