[evilcthul]

Hey guys!

I've been talking with Joseph over the last few days regarding the latest ASL headphone amp. Please note that it won't be a son of MG Head or an MG Head plus, it will be a whole NEW design.

So what I'm asking is that you guys contribute ideas toward what YOU would like to see in this tube amplifier. So far it's based on the design Joseph said at:

http://www.head-fi.org/forums/showth...5&pagenumber=2

"Hey ! RGA ! Thanks for your buy of our products very much.
It is headache on packing. I'm try to improve it soon. Yes ! I start to test a New OTL Headphone amplifier. It will use 3 x 6DJ8/Channel. C4S load at cathode for 5 x 1/26DJ8 , remain 1/2 for gain stage. I hope it may be can drive down to 16 Ohm. It will be a seperated power supply. 5AR4 as rectifier , 12AX7 + KT88 as Regulator. A EI96 x 45 Power transformer. a Choke inside. 1/4" Headphone Jack x 2 . Hey ! I consider the power supply section can be siwtch to become a Power supply for Pre-amps. It will have 200V DC out to 280V DC Adjustable or 100V to 150V DC Adjustable. 6.3V x 4A for Filament. Hope it will retail at Lower than US$700. MG-Head Inside is too tighten and difficult to keep quality. We need to burn in 6BQ5 for around 48 Hours to test and select the tube. Cyber20 - I had look at his site. It outlook just like the reverse side of MG-Head. Use simuliar design as MG-Head.
12A series driver to 6BQ5. It just like a Image of MG-Head.
Also MG- series is build for Economic. So Buget is so tighten. Hey ! I had send a Headphone converter to Head-Fi for test. It will retail in very low cost , If it sound quality acceptable.
It can connect to your Integrated amps and it become a Ultra high quality transformers coupling Headphone amps. It will be less than US$100.
I'm not sure the quality of Cyber-20 but I only know when it retail in USA Price will be not cheap. "

So without any further ado please post your suggestions below. Joseph will be looking at this thread from time to time and he may accomodate your suggestion into the design. Please keep the suggestions serious and keep in mind that the price will be around $600-700USD.

 

[chych]

Few things of mine:

-Dual headphone jacks (already a go)
-Stepped Attenuator (a wish)
-Xfeed!!!!
-Silver finish or faceplate
-Preamp ability, or at least 2 switchable inputs

 

[dhwilkin]

I second xfeed and switchable inputs.

 

[morphsci]

Three switchable inputs or two + a tape loop or processor loop
Dual line outputs
Option for remote capability and stepped attenuator
Detachable power cord
Neutrik Headphone Connectors (perhaps as an option)
Cardas RCA Jacks (perhaps as an option)

If it had the above I would definitely audition and if the sound quality was good I would use it as the centerpiece of my headphone system.

 

[briantf27]

Many things come to mind, but for starters, how about point-to-point wiring?

Brian.

 

[bootman]

Quote:

Many things come to mind, but for starters, how about point-to-point wiring?

I would second that but can this be done at the $600-700 price point?

 

[briantf27]

Quote:

Originally posted by bootman I would second that but can this be done at the $600-700 price point?

Probably not. But this leads me to another suggestion: offer this amp with upgrades at incremental price points. I'd be willing to pay for p2p wiring, for one. AES and other companies do this with their amps.

Also, how about designing the thing around the 2A3 or 45 and dropping the 6BQ5s??

Brian.

 

[bootman]

Quote:

Also, how about designing the thing around the 2A3 or 45 and dropping the 6BQ5s??

drool! But then we will be talking something in the $1000 plus range.

$600-$700 sounds right.
I welcome some company to the likes of the MicroZ and earmax pro!

 

[rickcr42]

two or three inputs,headphone/mute/direct swith ,the direct would be from the input attenuator to rear RCA jacks which would allow use as a passive line stage direct to the power amps.But without the above mode switch you would have no way to mute the unused output,dual front panel headphone jacks like the MG-Head,keep it as small as possible-if you must enlarge it do so front to back rather than side to side,wood end panels as an option,choice of black or silver face plate,adjustable bias from the outside

 

[SumB]

It should drive low impedances without the addition of an output transformer.

 

[chych]

I believe it can drive down to 16 ohms, I think that is what he said...

 

[wasifazim]

Yeah, follow MSB's product strategy: an affordable base product in the same price range as the MGHDT with "premium" and "ultra" (and so on and so forth) versions..

 

[Number9]

To hell with 2A3, 300B or even 45 output tubes. This will drive up the cost like crazy.

For an OTL amp, the best output tube is the 6C33C-B .

It can withstand nuclear radiation and drive low ohm output. Plus, it sounds very good, is available, and not as expensive as the other options.

 

[Tomo]

Hello,

Please leave space for stepped attenuator in the place of pot. I understand standarizing steppers will considerably increase price.

I would like pretty good connectors and jacks. They can be generic but I would like them to be gold plated.

PSU. You should be able to get line filters for 5~10 USD each. You should use them. Solid state rectifiers are fine. Can you make the filament power regulated? Transformer should be outside of amp chasis to avoid hum. Shield the cable that supply the power to filaments.

Circuits. Gain should not be large so you should not use overly high gain tubes. Output tubes should be strong enough to drive headphones but should NOT be 6C33. These have massive quiescent current and require more expensive PSU. So NO! It should have pretty constant response whatever the headphone impedances are. So SRPP/mu stage may not be the best idea for output stage. However, it is good for gain stage; it will give you cleaner gain than simple tube gain. Note we do not like feedbacks. So try to avoid it whenever possible. But if necessary keep the feedback LOCAL. Good examples of our favorit gain tubes are 6922, 6CG7, 12AU7, 5842/417A, or 6C45P. Good examples of new output tubes are 6CG7, 6H30, ECC99, 6C19 (?). Many russian tubes are available now. You should be able to get them cheaply. You can also parallel multiple driver tubes like 6922. I have seen GlassAudio articles on 3 para 1 gain 2 X 6922 per channel amp. Capacitive coupling probably is necessary at output or input. But try to DC couple between stages. ... But then AC coupling btw stages are not known to be that bad as long as the caps are good. (generally tube DIYers can invest money anyhow (?) )

Please leave space for upgrades. However, you should not be obliged to add super large freedom for upgrades since you must keep the amp look good too. Some company have switchable choise between cascode designs and SRPP for their preamp. But I believe no users will flip switch very often. So it is pretty good idea to stick with one design and make it good. Switchable alternative is not necessary. (rather really superfluous.)

Thanks,

Tomo

 

[Joseph Lau]

Many thanks for all suggestion. I will consider most of it. I most interesting on 2A3 Headphone design. Is it possible to made a 2A3 Headphone in OTL mode. I think it should connect in cathode follower but How to coonnect the ground of Filament ? (It is direct heat tube. So cathode is same as Filament.) It may be too high output impedance when use plate load ! So I looking for some idea on it.