mwhouston

From experience i found the Tripath more power full modules 150 and 180W into 8ohms sound better than lower powered modules.

The board above is about 40W into 8ohms?

Item: Portable Oatley K272C headphone amp in a can Location: Langwarrin - 3910 Price: $35 postage included. Item Condition: as new 9/10. Slight dint in can. Reason for selling: Have built another Payment Method: Pickup - Cash, Paypal, COD Only Extra Info: One of the original Oatley K272C kits ($40) with carbon resistors. Has seperate filament batteries (2X1.5V) and HT batteries (2X9V) and seperate battery health LEDs. The LEDs will indicate when batteries require a change (2 minute job). This model doubled the HT of earthier modules. Currently has a LM533 OPAMP but any equivalent can be rolled. Tubes are JNA6418 sub-miniature pentode. Very solid grounded sound. It can be operated in or out of the can and the cct. brd. is shock mounted (thick rubber grommets) to a varnish three ply plinth. There are volume/balance trimmers but no volume control. Use your source volume for control. http://retro-thermionic.blogspot.com/2013/04/oatley-k272c-headphone-amp-in-tin-can.html Photos:

For me and my system tubed preamp and Class D power amp is a killer combo. Had some Melbourne Audio Club members here a few nights back for a classical night and from one member (who also DIYs) his comment was best he had heard my system and I’m to stop changing it. He had not heard the tube pre/Class D/horns combo before and made a number of good comments. Probably one of the stranger combos; tubes/Ds/horns.

Which board was it you tweaked?

I won these Van den Hull interconnects at an audio demo. Soon after using them two of the RCAs fell off. I have since replaced them with Jaycar earth first better connectors. Unfortunately Jaycar no longer stocks these better RCAs.

Should add the differential PS is on the same piece of tiny cct. brd. as the amp. Also the Al foiled lining the amp is bituminised for resonance dampening.

Item: Compact light (160gms) and small portable headphone amp Location: Langwarrin 3910 Price: $20 plus postage $12 Item Condition: AS new 9.9/10. Rarely used Reason for selling: I have built two others Payment Method: Pickup - Cash, Paypal, COD Only Extra Info: Based on the famous CMoy OPAMP headphone amp this tiny pocket size HP amp can drive 32ohm phones well. At only 160gms with a single 9V battery it will go anywhere. Depending on battery quality (lithium batteries can be used) you will get up to 100hours of play. Two 3.5mm phone sockets at the front and on/off switch at the rear with a faint on red led. This is the improved version over the original two Kiwis being the "Kiwi SE" and uses upgraded parts, solid core copper hookup wire and silver solder throughout. The two tone ABS enclosure is lined with heavy Al foil for shielding. The OPAMP is a Burr Brown OPA2134 on a machined socket. Any equivalent chip can be rolled to further customise the sound and performance. No attenuator is included and volume is controlled from the source. Link to the original Kiwi; http://retro-thermionic.blogspot.com/2015/02/cmoy-knock-off-for-kiwi-friend.html

I think it’s obvious that tube pre and SS power amp is the more common hybrid setup. It could have gone the other way but I suspected this would be the most employed. To add just another combo yesterday I dropped in my DIY 1/3W 1920s tubed power amp. Because the amp uses a interstage Tranni on the input with no driver tube the input impedance is 400ohms. To drive this I used my DIY tube preamp with a SS headphone driver section. It’s happy to drive into 32ohms so 400 is easy. Above is a hybrid preamp with tube power amp. Now that’s mixing it up.

OMG just for a moment there I thought it was the wife!

For the low down on the low power; http://retro-thermionic.blogspot.com/2013/03/intermezzo-1920-ux-171-power-amp.html

My DIY Intermezzo 1/3W 1920s tubed (UX-171A nickel plate tubes) power amp with the rest of my system. Just enough volume to be listenable without noticeable distortion. System sensitivity is a bit better than 90db.

Horns with the 1/3W Intermezzo providing the grunt (lol).

In the next day or so I’m going to swap in my 300mW 1920s tubed “Intermezzo” power amp to drive the horns. The tubes are UX-171As and I have three pairs (getting harder to get). It uses a Hammond nickel core interstage transformer at the input with no driver tube. Originally I will just drop it in to drive my woofer\ horn combo. In the future going to use an electronic Xover to split the output from the preamp to drive the horns direct (110db sensitive) and the woofers with a Class D. 1/3W from Intermezzo should drive the horns to good volume and then the Class D drive the 90db efficient woofers hard and with adjustable bass balance and volume. http://retro-thermionic.blogspot.com/2013/03/intermezzo-1920-ux-171-power-amp.html

At one time I would have thought of nothing else except tubes to drive horns. But since I’ve been using a few DIY different Class D power amps I have to say I feel Class D amps, in my system in my room, sound the best. Add the speed and dynamics of horns to the clarity and drive of Ds it’s a dynamite combo. But it doesn’t stop me swapping in a few of my DIY tubers just for fun and a change. I do enjoy it but eventually I’m back on the Ds.