Hello!
I just bought two ECC83 and now I'm looking for a schematic of a phono preamp for MC.
My humble demands are:
-I want to use one tube per channel.
-Oh, yeah and it mustn't contain an output transformer.
-It has to be for MC.
-It has to be RIAA, because it will be connected directly on an amp.
P.S.: It will be used on an Aleph5 or PPP using 2xEL84 per channel.
I really hope that someone has exactly what I'm looking for and will post schematic here.
I just bought two ECC83 and now I'm looking for a schematic of a phono preamp for MC.
My humble demands are:
-I want to use one tube per channel.
-Oh, yeah and it mustn't contain an output transformer.
-It has to be for MC.
-It has to be RIAA, because it will be connected directly on an amp.
P.S.: It will be used on an Aleph5 or PPP using 2xEL84 per channel.
I really hope that someone has exactly what I'm looking for and will post schematic here.
If you're talking about low output MC, you're going to have one hell of a tough time getting the noise acceptably low with a 12AX7 and no transformer. And you'll have barely enough gain. And to get that gain, you'll have to have a very high output impedance.
That's an odd list of restrictions you posted. There are much better ways to skin that cat.
That's an odd list of restrictions you posted. There are much better ways to skin that cat.
Mision Impossible.
Hi,
Yup, unless perhaps that MC is at MM output level or close you can pretty much forget it.
For MC's you need I/V conversion, this can be done with tubes but it ain't easy.
Usually a step-up xformer is used or a (usually FET based) conversion is used to feed the MM level preamp.
How about it?
Hi,
Yup, unless perhaps that MC is at MM output level or close you can pretty much forget it.
For MC's you need I/V conversion, this can be done with tubes but it ain't easy.
Usually a step-up xformer is used or a (usually FET based) conversion is used to feed the MM level preamp.
How about it?
Ditto SY and Frank. One tube/channel, and for MM you could use a modification of some of the classic NFB circuits like a 7C - Pooge or a PAS, but you'll still have insufficient SNR (I think even for decent MM) so you'll need an input transformer, and you'll have quite a high output impedance. The 12AX7 has a lot of gain, but isn't particularly quiet in itself. Having had a 7C, which was extensively modified over time, it's not that great sounding. I restored it and sold it.
You need to change your parameters to get a decent result, and in Eastern Europe, there are a ton of good tubes floating about like the 6C45 which would be a lot better.
You need to change your parameters to get a decent result, and in Eastern Europe, there are a ton of good tubes floating about like the 6C45 which would be a lot better.
Your humble demands aren't humble!
RIAA equalisation and amplification is one of the hardest analogue problems to solve well. People spend years tackling this problem. How many records do you have? Any investment on electronics/arm/cartridge/turntable only makes sense in the context of the number of records. If you have lots, it makes sense to do the job properly. You cannot possibly do the job properly with a single ECC83 per channel. It may just be possible to squeeze the required gain but it will sound terrible.
On the positive side. What is the cartridge, and what level do you need at the output of the pre-amplifier?
RIAA equalisation and amplification is one of the hardest analogue problems to solve well. People spend years tackling this problem. How many records do you have? Any investment on electronics/arm/cartridge/turntable only makes sense in the context of the number of records. If you have lots, it makes sense to do the job properly. You cannot possibly do the job properly with a single ECC83 per channel. It may just be possible to squeeze the required gain but it will sound terrible.
On the positive side. What is the cartridge, and what level do you need at the output of the pre-amplifier?
I'm not familiar with Dual ULM45s. Are you sure it's a moving coil? Sounds a lot like an Ortofon droop snoop to me. You really wouldn't want to let an ECC85 near audio. I've just had a quick look at the curves, and it will distort...
If your cartridge really is an MC, the 6C45 is an excellent valve for the front end.
If your cartridge really is an MC, the 6C45 is an excellent valve for the front end.
Beigebag
www.beigebag.com software have some RIAA amps on their web page.One of them is a single tube per channel ECC83 design. For an MC you still need to bring up the signal level to that of an MM. Alternatively you should use a FET with the input tube. Search the forum for that.
Cheers.
www.beigebag.com software have some RIAA amps on their web page.One of them is a single tube per channel ECC83 design. For an MC you still need to bring up the signal level to that of an MM. Alternatively you should use a FET with the input tube. Search the forum for that.
Cheers.
Swarf, and crystal cartridges.
Crystal cartridges don't need a pre-amplifier. They typically produce 250mV from a capacitance of a few nF, which is why they need a >1M load to produce bass. Because they are not velocity sensitive, they don't need RIAA equalisation, but the 318, 75 RIAA pairing is unequalised, so they have a step in their response at about 1kHz. They have huge tip mass and virtually no compliance. Before they were finally ousted, cartridges like the Connoisseur SCU1 was driven into the 47k load of an RIAA stage, and this was alleged to sound better. (The low resistance load gave a rising response which was then corrected by RIAA.)
Are you really sure you have a crystal cartridge? The giveaway is that the replacement stylus assembly clips into the cartridge and that there is a small soft plastic yoke into which the cantilever rests.
Crystal cartridges don't need a pre-amplifier. They typically produce 250mV from a capacitance of a few nF, which is why they need a >1M load to produce bass. Because they are not velocity sensitive, they don't need RIAA equalisation, but the 318, 75 RIAA pairing is unequalised, so they have a step in their response at about 1kHz. They have huge tip mass and virtually no compliance. Before they were finally ousted, cartridges like the Connoisseur SCU1 was driven into the 47k load of an RIAA stage, and this was alleged to sound better. (The low resistance load gave a rising response which was then corrected by RIAA.)
Are you really sure you have a crystal cartridge? The giveaway is that the replacement stylus assembly clips into the cartridge and that there is a small soft plastic yoke into which the cantilever rests.
OK, this morning I called my cousin and he said that I have MM cartidge. Yeah!!!
Probably that's why Paravinchini worked. So, now we are clear on the type of the cartidge. New set of characteristics:
-RIAA equlization
-MM cartidge
-one ECC83 per channel
That should put more schematics on the table... PLEASE!
Probably that's why Paravinchini worked. So, now we are clear on the type of the cartidge. New set of characteristics:
-RIAA equlization
-MM cartidge
-one ECC83 per channel
That should put more schematics on the table... PLEASE!
Just build the classic Dyna PAS-3 circuit. Trim up the RIAA to spec and it will sound just fine. You can find most of the old Dyna schematics buried somewhere over at www.triodeelectronics.com.
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