| pingfloid |
Hi,
I am planning to build this RIAA preamp with ECL86 from the Elektor magazine, but without the input transformer. What is your opinion about the circuit? Have some of you already tried it?
Cheers,
Manuel :) |
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| analog_sa |
Lots of similar and better circuits all over the net . I would rather avoid this one as the designer was clearly not into serious hifi - just have a look at the silly coulpling cap values - and elcos!
And, ha, ha, a coupling cap after the transformer. What a moron! |
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| pingfloid |
Mmmm :xeye: Yes, the input cap is weird.
I've already bought all the components. :Ouch: ¿any suggestion about how to re-use them?
Thanks |
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| GG |
| quote: | Originally posted by analog_sa
Lots of similar and better circuits all over the net . I would rather avoid this one as the designer was clearly not into serious hifi - just have a look at the silly coulpling cap values - and elcos!
And, ha, ha, a coupling cap after the transformer. What a moron! |
Can you share some links to these ECL86 RIAA preamps.
Regards,
Gio. |
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| analog_sa |
| quote: | | Can you share some links to these ECL86 RIAA preamps |
No, i have never noticed ECL86 preamps and see little reason one should force this tube for phono. |
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| analog_sa |
ECC83 is probably not the best sounding tube but is widely available and easy to use. I still have warm memories of Marantz 7C phono section and the link to 'Ohashi' or AR SP-3 presents a very similar circuit. Thanks to the CF and NFB output impedance is low and one can feed a pot/power amp directly.
EAR834 seems like another very good choice |
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| GG |
I have the iron and tubes for the RCA preamp and plan to try it out eventually. I think there is an error in the schematic in your link. Compare the capacitors marked * in your link with the link I have posted below.
See
http://www.diyaudio.com/forums/show...6366#post526366
for a scan of the schematic from the RCA book which shows a different value for the np capacitors.
Good luck and let us know how you make out. |
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| planet10 |
| quote: | Originally posted by GG
the RCA preamp |
The as built map for Chris' version....
dave |
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| planet10 |
| and the power supply (severe overkill on this) |
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| planet10 |
| And a picture... |
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| resident |
Very nice!!
Tubes are inside the chassis for better screening?
I'd like to build my own phono these days but I'm planning to place the tubes outside the chassis.
Do you believe that I'll have hum problems? |
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| planet10 |
| quote: | Originally posted by resident
Tubes are inside the chassis for better screening? |
No... because to do anything else with the circuit board would have been tricky...
dave |
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| resident |
hmmm....
you have right.
Thanks |
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| Alkis |
No, i have never noticed ECL86 preamps and see little reason one should force this tube for phono.
I have allready constructed a line preamplifier using ECL-86.Designed by the same author(Experience).
I was so disappointed by the results,that I had to disassemble the device at once,althow I had used high quality parts.
Neither ECL-86,either the designing approach of the author is so audiophile(f.e. in my case,they sugested a center tap of 12.6V which feeds the two fillamentes in series).
And the gain of the pentode section is totally useles.
Not to mention that this tube is available from Mullard and Chinese manufacturers.I don't know if you could get some pair NOS from Telefunken.
It is not my intention to judge others works(tut mir leid) but they must improve their design. |
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| martinab2 |
I have been using a version of the rca circuit for about a year now which is now sounding quite reasonable. The circuit as shown earlier really needs a buffer stage (ecc88 cathode follower or something) as it is fussy about loading and the top end will be seriously rolled off if you get it wrong.
My version uses NiCad batteries instead of cathode resistors / capacitors. Think the circuit was on here somewhere but will see if i still have a copy.
I liked the circuit because it's simple and doesn't use negative feedback. |
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| pingfloid |
| Grrr! :mad: I've should have made this question before buying the parts from Experience Electronics. I'll build it anyway, just for fun, and then I will go to try planet10's circuit. Thanks Dave! :) |
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| planet10 |
| quote: | Originally posted by pingfloid
Grrr! :mad: I've should have made this question before buying the parts from Experience Electronics. I'll build it anyway, just for fun |
Potentially most of the parts (except OPTs) for a nice little SE power amp -- or without OPTs for a headphone amp.
| quote: | | and then I will go to try planet10's circuit |
I take no credit for the design except the drawing (& the scan in the other thread). RCA had this pretty much sorted out when i was still in diapers.
dave |
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| reinhard |
Have made the math for planet 10´s circuit. The 22k in the Riaa network must be a 24K to get a correct 318 uS. 2 * 12 K in series will do.
Reinhard |
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| richwalters |
.....any design that uses an ECC83....would profit for a 7025 swap .....sim tube but better sounding ... that is if there are any NOS left around.
richj |
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| stalker |
Look for mu follower ecl86 preamp, can't remenber the name of the French magazine but i can remenber that someone reported good results in this forum. I may try it some day, have the tubes anyway.
Cheers, |
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