Hello eveyone,
I hope that someone might be able to help me with a problem I have with my Akai M-8 Tube RR player. It plays fine from the R-R tape but when I connect my CD-player to the Line input using a home made RCA-PHONO connector, I'm getting really bad buzzing sound.
This happens on both channels. I tried the MIC input and it's the same. It's when I connect it to the PHONO PLAYBACK INPUT jack that I'm getting some sound out of it. However, It will distort badly if I turn the volum more than say 10%. What I don't get is when I play R-R tape, it sounds pretty good but using LINE in it's acting up on me. 
I would like to use the mono amps since I head that these 6bq5 amps are pretty good, but I don't know how to get it functioning properly.
TIA
Abmoggy
I hope that someone might be able to help me with a problem I have with my Akai M-8 Tube RR player. It plays fine from the R-R tape but when I connect my CD-player to the Line input using a home made RCA-PHONO connector, I'm getting really bad buzzing sound.
This happens on both channels. I tried the MIC input and it's the same. It's when I connect it to the PHONO PLAYBACK INPUT jack that I'm getting some sound out of it. However, It will distort badly if I turn the volum more than say 10%. What I don't get is when I play R-R tape, it sounds pretty good but using LINE in it's acting up on me. I would like to use the mono amps since I head that these 6bq5 amps are pretty good, but I don't know how to get it functioning properly. TIA
Abmoggy
You are probably overloading the input stage. generally both inputs cannot go bad the same way at the same time unless the power supply is faulty.
Forget the phono input. Drop your input signal using resistors and then try it out at the mic input. Mic inputs are in mV . Might be 2mV. CD player outputs are 1000 times higher.
try -----/\/\/\/\/\----|-------- to mic input
| 100K |
CD signal /
\ 100 ohms
/
|
|
GND
On each input.
Cheers.
My sketch comes out wonky. Thats a series 100Kresistor to the mic input and a 100 ohm resistor to ground from the mic input .
Forget the phono input. Drop your input signal using resistors and then try it out at the mic input. Mic inputs are in mV . Might be 2mV. CD player outputs are 1000 times higher.
try -----/\/\/\/\/\----|-------- to mic input
| 100K |
CD signal /
\ 100 ohms
/
|
|
GND
On each input.
Cheers.
My sketch comes out wonky. Thats a series 100Kresistor to the mic input and a 100 ohm resistor to ground from the mic input .
Ashok,
I modified my connector cable per your suggestion. The problem with the MIC and LINE Input are still flat, BUT the PHONO PLAYBACK Input is now listenable! I can use the volume control and there is no distortion. My question is is the LINE Input stage dead? 
On both sides? even when they are Mono amps? What should I check next?
Thanks for your help!
ABMOGGY
I modified my connector cable per your suggestion. The problem with the MIC and LINE Input are still flat,
BUT the PHONO PLAYBACK Input is now listenable! I can use the volume control and there is no distortion. My question is is the LINE Input stage dead? On both sides? even when they are Mono amps? What should I check next? Thanks for your help!
ABMOGGY
LINE IN
old thread but could not resist-
if you want the "line in" jacks to work properly on an Akai M8, you must put the deck in "record" mode. This allows the line in signal to pass through the amp, and output through the speaker jacks and headphone jack. The power output will be reduced from the nominal 6 WPC to around 3 WPC, but the unit will still perform excellent and sound stunning- while allowing you to still use the existing preamp built into the M8
if you want to use the phono in jacks, with something other than a phono, you will have to reduce the input signal, with an external preamp first- otherwise you are overloading the phono in jacks and that's why you get the distortion
If using the line in jacks (what I recommend for tape and CD), you can turn the drive motor "off" (the middle position on the switch), and also disengage the capstan by sliding the deck auto stop lever up to "off" (to avoid putting a permanent indention in your rubber pinchroller wheel)- the deck will then sit there in record mode, but without any spindles turning and without the motor running- you can then turn the motor back on if you want to run the fan to cool the unit- but I have run the M8 for 12 hours straight without the fan, in this mode, with no ill effects
using the M8 as a low-budget "SET tube amp" will give you sound equal and above modern tube amps costings $1500 and more new
I got my M8 for $10- it's been my main system amp now for 2 years. By comparison, I find SS now unlistenable and boring.
note- the record switch contacts on my M8 needed to be sprayed clean with CRC to get it to work right- and the linkage also adjusted to the record switch fully engaged. Another problem my deck had was the 1/4" jack grounds on input side were loose, which will cause the deck to not operate correctly in any mode- after resoldering them, it worked great.
old thread but could not resist-
if you want the "line in" jacks to work properly on an Akai M8, you must put the deck in "record" mode. This allows the line in signal to pass through the amp, and output through the speaker jacks and headphone jack. The power output will be reduced from the nominal 6 WPC to around 3 WPC, but the unit will still perform excellent and sound stunning- while allowing you to still use the existing preamp built into the M8
if you want to use the phono in jacks, with something other than a phono, you will have to reduce the input signal, with an external preamp first- otherwise you are overloading the phono in jacks and that's why you get the distortion
If using the line in jacks (what I recommend for tape and CD), you can turn the drive motor "off" (the middle position on the switch), and also disengage the capstan by sliding the deck auto stop lever up to "off" (to avoid putting a permanent indention in your rubber pinchroller wheel)- the deck will then sit there in record mode, but without any spindles turning and without the motor running- you can then turn the motor back on if you want to run the fan to cool the unit- but I have run the M8 for 12 hours straight without the fan, in this mode, with no ill effects
using the M8 as a low-budget "SET tube amp" will give you sound equal and above modern tube amps costings $1500 and more new
I got my M8 for $10- it's been my main system amp now for 2 years. By comparison, I find SS now unlistenable and boring.
note- the record switch contacts on my M8 needed to be sprayed clean with CRC to get it to work right- and the linkage also adjusted to the record switch fully engaged. Another problem my deck had was the 1/4" jack grounds on input side were loose, which will cause the deck to not operate correctly in any mode- after resoldering them, it worked great.
I have a friend with an M8. It always sounded very good.
I think it can compete with a lot of current day amplifiers.
Will see if they have a circuit diagram. I used to be their main repair guy ( for free ! ) until they moved to CD players and ss amps. I think it must still be around and see if they will sell it ( to me !).
Does anyone else have a circuit diagram ?
Cheers.
I think it can compete with a lot of current day amplifiers.
Will see if they have a circuit diagram. I used to be their main repair guy ( for free ! ) until they moved to CD players and ss amps. I think it must still be around and see if they will sell it ( to me !).
Does anyone else have a circuit diagram ?
Cheers.
Thanks for the info!
Thanks for the info Akai M8 It's been a while. I have subsequently sold my first M8 and thought that was it. Then I found a Roberts and another M8. The Roberts tape drive is shot, so I kept the two mono amps. The other M8 is in storage. Any recommendation as to hooking up the amps as stand alone. You're right, they're built better than modern gear and the OPT are huge for a tiny SE amp.
Thanks for the info Akai M8
It's been a while. I have subsequently sold my first M8 and thought that was it. Then I found a Roberts and another M8. The Roberts tape drive is shot, so I kept the two mono amps. The other M8 is in storage. Any recommendation as to hooking up the amps as stand alone. You're right, they're built better than modern gear and the OPT are huge for a tiny SE amp.yes, here is the circuit
http://i1.tinypic.com/muwg8z.gif
http://tinypic.com/view/?pic=muwg8z
above are the circuit diagrams for the Akai M8
Not only can the M8 compete with today's new expensive net market amps- it actually is superior to the new amps that are priced under $1000- I tried one, and sold it after the M8 cleanly trounced it in a back to back test
and the new amp was a $700 piece
a few small companies are actually making M8 copies now, using pentodes- or they have adopted the design and are running 2 monoblocks with triodes- but have copied the integrated design and dual volume controls of the M8
http://i1.tinypic.com/muwg8z.gif
http://tinypic.com/view/?pic=muwg8z
above are the circuit diagrams for the Akai M8
Not only can the M8 compete with today's new expensive net market amps- it actually is superior to the new amps that are priced under $1000- I tried one, and sold it after the M8 cleanly trounced it in a back to back test
and the new amp was a $700 piece
a few small companies are actually making M8 copies now, using pentodes- or they have adopted the design and are running 2 monoblocks with triodes- but have copied the integrated design and dual volume controls of the M8
hooking amp up stand alone- the monoblocks are removeable, from the wooden case of the reel deck
you could just cut the box in half, so only the bottom is left, and keep the monoblocks in there- the tape transport part does unplug internally from the monoblocks and power supply.
what's nice about keeping it all together is, you can use the tape drive motor to cool it- it has a built in fan blade- so turn it on low speed and it cools the tubes
I'm sure you could also just built a nice wooden box for each monoblock as well- I was going to at one point, but nothing I could think up would be as efficient and worthwhile, over just leaving it in the reel deck.
I have since bought another M8 as a backup, for $96 delivered price. But this new one is mint.
you could just cut the box in half, so only the bottom is left, and keep the monoblocks in there- the tape transport part does unplug internally from the monoblocks and power supply.
what's nice about keeping it all together is, you can use the tape drive motor to cool it- it has a built in fan blade- so turn it on low speed and it cools the tubes
I'm sure you could also just built a nice wooden box for each monoblock as well- I was going to at one point, but nothing I could think up would be as efficient and worthwhile, over just leaving it in the reel deck.
I have since bought another M8 as a backup, for $96 delivered price. But this new one is mint.
Hi Akai M8,
I finally got an old M8. Not in very good condition but I plan to strip it for the tube amp. I will probably have to refurbish most caps and some resistors. I can't say how the tubes are. Any substitutes for the input tubes ?
I couldn't find your circuit diagrams on the URL you posted. Can you please repost it or email it to me.
Thanks in advance.
Cheers,
Ashok.
amadhavan(at)eth(dot)net.
Edit:
Akai M8 has not been around for a long time. Would anyone who downloaded the circuit diagram email me a copy ?
Thanks a ton.
I finally got an old M8. Not in very good condition but I plan to strip it for the tube amp. I will probably have to refurbish most caps and some resistors. I can't say how the tubes are. Any substitutes for the input tubes ?
I couldn't find your circuit diagrams on the URL you posted. Can you please repost it or email it to me.
Thanks in advance.
Cheers,
Ashok.
amadhavan(at)eth(dot)net.
Edit:
Akai M8 has not been around for a long time. Would anyone who downloaded the circuit diagram email me a copy ?
Thanks a ton.
Roberts 770x ss for preamps
I just bought a Roberts 770x SS for the preamps.
Here's what I know for sure: I like the sound of tube compression - that fat-grit, almost-distorting sound. But it doesn't distort and it doesn't break up. It's the coolest sound.
I've been looking a tube pre's on ebay for months and the prices, for something I have no way of trying out first, are ridiculous. I know I like the sound of tube decks so I picked up this deck for a reasonable price.
Aside from cutting the box in half, a suggestion I kind of like, is this (more or less) a plug&play operation or are mods necessary.
I mentioned what I know above. That means I have very little technical experience. I can solder but I wouldn't know the difference between ad resistor and a war protester.
Now here's the funny part. I WANT TO KNOW how to do this.
Where to start?
I just bought a Roberts 770x SS for the preamps.
Here's what I know for sure: I like the sound of tube compression - that fat-grit, almost-distorting sound. But it doesn't distort and it doesn't break up. It's the coolest sound.
I've been looking a tube pre's on ebay for months and the prices, for something I have no way of trying out first, are ridiculous. I know I like the sound of tube decks so I picked up this deck for a reasonable price.
Aside from cutting the box in half, a suggestion I kind of like, is this (more or less) a plug&play operation or are mods necessary.
I mentioned what I know above. That means I have very little technical experience. I can solder but I wouldn't know the difference between ad resistor and a war protester.
Now here's the funny part. I WANT TO KNOW how to do this.
Where to start?
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