Re: Strictly Tubes...almost.
Would it be a better choice to subtitute the 6922 with the 6H30P,in term of quality and noise?
fdegrove said:Hi,
Maybe not but I can't help but wonder what this circuit would sound like with a really high gm tube such as the 6C45-P replacing the frontend....
With a Req 100R it has all the potential to come close to the 2SK170BL as far as noise goes, besides tube noise is far less obtrusive to my ears_if at all audible_ than semi-conductor noise.
Then of course there's always MC HAMMER if you're looking for an add-on headamp.
It's dead quiet, can take just about any MC, uses ordinary parts, looks deceptively simple and does not have the word "microphony" in its vocabulary....
All it needs to shine are two pairs of tightly selected 6922s, two matched low noise CCSs and you're done.
Cheers,
Would it be a better choice to subtitute the 6922 with the 6H30P,in term of quality and noise?
there are some realy good nuvistors out there, but they are hard to find. one of them is russian 6Н62Н (6n62n), almost 100% like 6Н9С (6n9s, 6SL7). though really trong constuction - not micraphonic at all. this tube is used in several tube tape players/recorders what USSR made in end of 60's. I got only one of then and think to make a small tube guitar drive fx for my setup.
Hello Franck,
I will try your mc-headamp.gif with my AT33PTG and DIY RCA tube preamplifier. It's simple and nice to try.
Have you some comment to do about this headamp ?
And do you think it's ok to use one transformer for both channels ?
Perhaps I will try with ecc88 and 6n23p because I have both
Thanks
Regards
Pascal
I will try your mc-headamp.gif with my AT33PTG and DIY RCA tube preamplifier. It's simple and nice to try.
Have you some comment to do about this headamp ?
And do you think it's ok to use one transformer for both channels ?
Perhaps I will try with ecc88 and 6n23p because I have both
Thanks
Regards
Pascal
Hi,
The main issue you'll need to be really careful about is the layout of the circuit.
As most headamps RF can be a PITA to keep out.
I recommend hardwiring so you can dress the wire harnesses for least noise and best channel separation.
For as long as the PT windings are properly isolated from eachother it's O.K to use a single xformer.
As for the ECC88's or 6N23P, both should work fine. Select them for low noise and pick whichever suits the blance of your system best.
Also make sure the CCS FETS are matched for noise and current.
They're quite sensitive to soldering iron abuse so take care not to overheat them.
Cheers,
The main issue you'll need to be really careful about is the layout of the circuit.
As most headamps RF can be a PITA to keep out.
I recommend hardwiring so you can dress the wire harnesses for least noise and best channel separation.
For as long as the PT windings are properly isolated from eachother it's O.K to use a single xformer.
As for the ECC88's or 6N23P, both should work fine. Select them for low noise and pick whichever suits the blance of your system best.
Also make sure the CCS FETS are matched for noise and current.
They're quite sensitive to soldering iron abuse so take care not to overheat them.
Cheers,
Hi,
Maybe not but I can't help but wonder what this circuit would sound like with a really high gm tube such as the 6C45-P replacing the frontend....
With a Req 100R it has all the potential to come close to the 2SK170BL as far as noise goes, besides tube noise is far less obtrusive to my ears_if at all audible_ than semi-conductor noise.
Then of course there's always MC HAMMER if you're looking for an add-on headamp.
It's dead quiet, can take just about any MC, uses ordinary parts, looks deceptively simple and does not have the word "microphony" in its vocabulary....
All it needs to shine are two pairs of tightly selected 6922s, two matched low noise CCSs and you're done.
Cheers,
Hi Frank,
Gain?
Equivalent or substitute transistors for CCS: BF244A & MPSA14?
TIA & Greetings
Felipe
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Last edited:
Hi,
Gain is roughly 20dB IIRC. It matched well with my preamp which used 1 x ECC83 per channel + a CF with only a tiny insertion loss (0.98, I think).
MPSA14 is used as a cap multiplier and should still be available. BF244A has been succeeded by BF245A (different pin out but of no consequence here).
The 78xx voltages regs are bolted to the chassis which doubles as a heatsink which is why the ground leads (central lead) have been clipped off.
MCs I used were Jan Allaerts MC One Boron (o.5 mV), Koetsu Rosewood, Talisman Alchemist IIIS (?), AT OC9 an OC7.
No problem whatsoever, no noise, just music.
The PSU could be revised but I wanted this to fit in a small box so it could be put close to the TT. It works great as is anyhow.
Should you need even lower noise then I'd recommend E188CC (or Cca) and a set of ultra deep pockets.....
Fins despres,
Gain is roughly 20dB IIRC. It matched well with my preamp which used 1 x ECC83 per channel + a CF with only a tiny insertion loss (0.98, I think).
MPSA14 is used as a cap multiplier and should still be available. BF244A has been succeeded by BF245A (different pin out but of no consequence here).
The 78xx voltages regs are bolted to the chassis which doubles as a heatsink which is why the ground leads (central lead) have been clipped off.
MCs I used were Jan Allaerts MC One Boron (o.5 mV), Koetsu Rosewood, Talisman Alchemist IIIS (?), AT OC9 an OC7.
No problem whatsoever, no noise, just music.
The PSU could be revised but I wanted this to fit in a small box so it could be put close to the TT. It works great as is anyhow.
Should you need even lower noise then I'd recommend E188CC (or Cca) and a set of ultra deep pockets.....
Fins despres,
Last edited:
Hi Felipe, if you replace the 7812 to LM317 in the heater circuit, you will be positively surprised... Don't ask the reson.
Hi,
Much to my surprise the BF245A is obsolete as well.
Langrex UK still carry some stock of BF244A though.
Another option would be to pick a constant current diode such as the CR range from Vishay.
For the BF24xA VdS is 30V Max, Idss is 2 to 6.5mA Max.
Anyone know a good substitute for this BF245A J-Fet?
Ciao,
Langrex: Stocklist semi-conductors on the left hand side:
http://http://www.langrex.co.uk/stocklist.html
Much to my surprise the BF245A is obsolete as well.
Langrex UK still carry some stock of BF244A though.
Another option would be to pick a constant current diode such as the CR range from Vishay.
For the BF24xA VdS is 30V Max, Idss is 2 to 6.5mA Max.
Anyone know a good substitute for this BF245A J-Fet?
Ciao,
Langrex: Stocklist semi-conductors on the left hand side:
http://http://www.langrex.co.uk/stocklist.html
Hi,
Gain is roughly 20dB IIRC. It matched well with my preamp which used 1 x ECC83 per channel + a CF with only a tiny insertion loss (0.98, I think).
MPSA14 is used as a cap multiplier and should still be available. BF244A has been succeeded by BF245A (different pin out but of no consequence here).
The 78xx voltages regs are bolted to the chassis which doubles as a heatsink which is why the ground leads (central lead) have been clipped off.
MCs I used were Jan Allaerts MC One Boron (o.5 mV), Koetsu Rosewood, Talisman Alchemist IIIS (?), AT OC9 an OC7.
No problem whatsoever, no noise, just music.
The PSU could be revised but I wanted this to fit in a small box so it could be put close to the TT. It works great as is anyhow.
Should you need even lower noise then I'd recommend E188CC (or Cca) and a set of ultra deep pockets.....
Fins despres,
I guess gain is enough because I want to use with the Valve Itch old version 43dBs http://www.diyaudio.com/forums/analogue-source/140635-valve-itch-phono.html my cart is a modified Denon Dl103R without body but with brass isolator between the arm and the cart, the cart output is nominal 0.25mV.
Can be MPSA13G an equivalent Compre Transistores Darlington Transistor Darlington, MPSA13G, NPN 0.5A, 30V, HFE:5000, TO-92, 3 pines ON Semiconductor MPSA13G en RS Online y lo recibir en 24 horas.?
Hi,
Much to my surprise the BF245A is obsolete as well.
Langrex UK still carry some stock of BF244A though.
Another option would be to pick a constant current diode such as the CR range from Vishay.
For the BF24xA VdS is 30V Max, Idss is 2 to 6.5mA Max.
Anyone know a good substitute for this BF245A J-Fet?
Ciao,
Langrex: Stocklist semi-conductors on the left hand side:
http://http://www.langrex.co.uk/stocklist.html
I can get BF245A
Compre Transistores MOSFET N-channel JFET,BF245A 2mA 30V,BP ON Semiconductor BS170G en RS Online y lo recibir en 24 horas.
Hi,
I don't much about semi-conductors but surely the MPSA14 isn't obsolete as well?
Do you have Farnell in Spain? They should carry it.
And they do:
MPSA14 - MULTICOMP - DARLINGTON TRANSISTOR, TO-92 | Farnell España
MPSA13:
MPSA13 Datasheet pdf - Transistores De Darlington - Motorola
MPSA14:
MPSA14 Datasheet pdf - Transistor Pequeño Plomado Darlington De la Señal - Central Semiconductor
Ciao,
I don't much about semi-conductors but surely the MPSA14 isn't obsolete as well?
Do you have Farnell in Spain? They should carry it.
And they do:
MPSA14 - MULTICOMP - DARLINGTON TRANSISTOR, TO-92 | Farnell España
MPSA13:
MPSA13 Datasheet pdf - Transistores De Darlington - Motorola
MPSA14:
MPSA14 Datasheet pdf - Transistor Pequeño Plomado Darlington De la Señal - Central Semiconductor
Ciao,
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