There isn't any real difference between designing a headphone amp and anything else. You can think of it as a very powerful preamp, or a very weak power amp, but the circuits are the same. Whether you can do it from parts from an Akai 1710 depends on what parts it has. Post some specs and someone can probably tell you whether they will work or not.
spec
If we're talking about this machine
Akai 1710
Then this is pretty good base for a small stereo amp. I think you will probably find a power transformer with 250V secondary (without center tap) which should be rated at least 90-100mA and 6.3V heater secondary @2.5A
The output transformers will probably handle 5W (or less).
If you planning a mono amp you may use EL84 output for some 4.5W, but for stereo I'm not sure the power tranny will have enough muscle for two 84's, you may want to use two "weaker" tubes like the ECL82 originally used in the circuit - or other triode-pentodes - ECL86, whatever.
The other idea for stereo is to use, say, two 6V6's and two 12AX7's (not 12AT7's) to save some current. Even if 6V6's + 12AX7's will require a bit more from the 250V secondary, you wil load the 6.3V heater secondary less so the tranny may handle this.
If we're talking about this machine
Akai 1710
Then this is pretty good base for a small stereo amp. I think you will probably find a power transformer with 250V secondary (without center tap) which should be rated at least 90-100mA and 6.3V heater secondary @2.5A
The output transformers will probably handle 5W (or less).
If you planning a mono amp you may use EL84 output for some 4.5W, but for stereo I'm not sure the power tranny will have enough muscle for two 84's, you may want to use two "weaker" tubes like the ECL82 originally used in the circuit - or other triode-pentodes - ECL86, whatever.
The other idea for stereo is to use, say, two 6V6's and two 12AX7's (not 12AT7's) to save some current. Even if 6V6's + 12AX7's will require a bit more from the 250V secondary, you wil load the 6.3V heater secondary less so the tranny may handle this.
if I were you, I'd build a mu stage incorporating a pentode CCS. They seem to have promise and don't look too amazingly complicated, and have very very good linearity and PSRR. if you read through this article you might be convinced.
http://www7.taosnet.com/f10/mustage.html
http://www7.taosnet.com/f10/mustage.html
dear Bob,
I have parts from such AKAI Reel to Reel. Pls be assured that the parts are high quality, the power transformer is mil spec Orion you can use it with solid state rectifier or can use Tube doing ganz bridge, out put transformer is sure high quality.
One thing reg speaker amplifier or headphone amplifier pls try simple/basic circuits with good quality parts-this is all about tube circuit simple is the best. For further experiences you can try complicated circuits lateron.
Regards
I have parts from such AKAI Reel to Reel. Pls be assured that the parts are high quality, the power transformer is mil spec Orion you can use it with solid state rectifier or can use Tube doing ganz bridge, out put transformer is sure high quality.
One thing reg speaker amplifier or headphone amplifier pls try simple/basic circuits with good quality parts-this is all about tube circuit simple is the best. For further experiences you can try complicated circuits lateron.
Regards
The (2) output transformers are each labeled:
RO-203 with a red wire and brown from one side, black wire and white wire from the other side
The power transformer is labeled Orion P-107C:
Left side - 240v/220/200/120/110/100/0
Right side - 6.3-1.5A - 6.3-1.5A - 210V-0.1A-E-210v
Any existing schematics that these would work with using the original (2) 6BM8 tubes and (2) 12AT7's?
RO-203 with a red wire and brown from one side, black wire and white wire from the other side
The power transformer is labeled Orion P-107C:
Left side - 240v/220/200/120/110/100/0
Right side - 6.3-1.5A - 6.3-1.5A - 210V-0.1A-E-210v
Any existing schematics that these would work with using the original (2) 6BM8 tubes and (2) 12AT7's?
Dear Bob,
Tx wire code is different in different countries I personally do not rely on that. Pls measure DC resitance of both side higher resistance side is primary, connect red wire with B+ and brown wire with tube plate, for the secondary connect any to any check bass response and swap connection if needed.
Power Tx
Connect primary and check output from 0 to one 210 and another 210 if it is 210 volt for both cased then it is 210V ct Tx. But I feel E is for earthing the Tx.
Circuit
Usually I do not refer to others circuit for copying (if it is even for personal need) because one designers curcuit is best suited for his / her own taste/audio chain. But if it is for start only please check the net their are dozens of them.
Pls excuse me if I sound rough but there is no short cut to paradise.
Regards
Tx wire code is different in different countries I personally do not rely on that. Pls measure DC resitance of both side higher resistance side is primary, connect red wire with B+ and brown wire with tube plate, for the secondary connect any to any check bass response and swap connection if needed.
Power Tx
Connect primary and check output from 0 to one 210 and another 210 if it is 210 volt for both cased then it is 210V ct Tx. But I feel E is for earthing the Tx.
Circuit
Usually I do not refer to others circuit for copying (if it is even for personal need) because one designers curcuit is best suited for his / her own taste/audio chain. But if it is for start only please check the net their are dozens of them.
Pls excuse me if I sound rough but there is no short cut to paradise.
Regards
dsavitsk said:
True in some ways but....
The real problem with any tube o/p stage is to keep the noise down with close headphone coupling to ears. Unless one likes music really loud, most o/p stage tube circuits are hard pressed to get quieter than -70dB down. If you like classical tones with many quiet passages then -90dB is min requirement to avoid hearing background hiss. So I'm ruling out the standard true pentode output stage unless it's wrapped up with so much feedback to keep it quiet. Any power stage must have low gain with low noise and a triode config is better with the gain coming elsewhere.
One can at a last resort use o/p attenuators i.e series # shunt resistors but again one needs the voltage drive to do this.
In the end I was forced to use 10 x 5534 ic's in parallel to drive the lowest Z phones.
richj
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.