[mc whak]

As the subject states, I just ordered it. As soon as I found out that it was supposed to work well with Grados, I had to get it.

When I get it I will give a limited (I'm not good with those audiophile descriptions) comparison with a Creek OBH-11.

Just in case this hasen't been brought up. They are $329 (shipping included) until the end of the year. After that Divergent is raising the price to $369.

Now for the damned waiting game.

 

[Joe Lau]

NO need to wait for long time ! Will send first shipment to Canada by Air within 2 days. Divertech ship amps by sea if it is not urgent. He send this shipment of MG-HeadOTL by air. So I think it will arrived Canda arround 1 week.

 

[Mark Monroe]

Hey Joe,

Is this the "high end" OTL headphone amp that I have seen posts on or the OTL version of the MG Head?

Many thanks,

Mark

 

[dngl]

they are talking about the MG Head modified to OTL. The high end ASL amp is still in R&D.

 

[Kim Hardee]

I think I may have bad news for those of you who are hoping that the new MG Head OTL will work well with Grado phones. The 100mfd output capacitor will result in a bass rolloff at 50Hz if driving 32 ohm Grado headphones (do the math). This capacitor would have to be 250mfd to provide rolloff at 20Hz.

I called the distributor (Divergent Technologies) and they told me the new OTL amp will only work well with Grado phones when they are connected to the transformer output (non-OTL). I ordered the OTL amp because I have Sennheiser HD-600s.

I would like to know if the transformer output on the OTL amp is wired for low impedance or high impedance and if it is changeable by rewiring. If the same transformers are used as in the old amp, then this should be possible.

Maybe I'm missing something???

 

[Hardhead]

Quote:

I ordered the OTL amp because I have Sennheiser HD-600s.

What are the expected sonic improvements of the OLT Head compared to the current model?

Is the quoted increase in price for the base Head or the OLT version?

 

[Joe Lau]

Quote:

Originally posted by Kim Hardee I think I may have bad news for those of you who are hoping that the new MG Head OTL will work well with Grado phones. The 100mfd output capacitor will result in a bass rolloff at 50Hz if driving 32 ohm Grado headphones (do the math). This capacitor would have to be 250mfd to provide rolloff at 20Hz. I called the distributor (Divergent Technologies) and they told me the new OTL amp will only work well with Grado phones when they are connected to the transformer output (non-OTL). I ordered the OTL amp because I have Sennheiser HD-600s. I would like to know if the transformer output on the OTL amp is wired for low impedance or high impedance and if it is changeable by rewiring. If the same transformers are used as in the old amp, then this should be possible. Maybe I'm missing something???

No ! It is Fine in OTL mode for Grado 32 Ohm not only transformers output. I don't have a Grado 32 Ohm Headphone on hand but I had send a Proto type to Austrilia Acidware for testing. It have a very good comment on it when it work with Grado 32 Ohm. I had test it with a Victor 32 Ohm 107 db Headphone with good bass. May be our distributors still not know it can drive 32 Ohm.

 

[lextek]

So let me get this straight. The OTL version is available now? Do you have an idea when you'll have it in your hands?

Bob

 

[Kim Hardee]

I don't want to beat this bass rolloff issue to death but.....

I believe the equation for calculating the 3db down point is 1/(2XpiXRXC).

Therefore, the frquency response for R=32 and C=100mfd is 50Hz. This means the frquency response will begin rolling off at 100Hz and be 3db down at 50Hz. I think there would almost certainly be a noticeable loss of bass when listening to music with a lot of low bass content with Grado headphones if they are connected to the OTL ouput of this amp.
In general I believe the impedance of Grado phones is too low to work well with all-tube amps. They really need solid state or hybrid tube-SS to work well.

I guess we will just have to see what the OTL-Grado combination sounds like when the new amps arrive.

 

[Kubernetes]

Not so sure about your statement Kim...I have the Earmax Pro, which is all-tube OTL, and I hear no such loss of bass through Grados...of course I have no measurements to back me up, but I find it hard to believe that the combo is bass deficient.

 

[Kim Hardee]

I'm not saying that all OTL amps will have this issue. I am just questioning the use of a 100mfd output capacitor in the new ASL MG Head amp when driving Grado phones. It seems like it should be 250mfd. That's all. I'm not trying to criticize this new amp. In fact I have one on order (I use Sennheiser phones). I'm just saying I would be a little concerned about the bass response when using the OTL output on this particular amp with Grados.

 

[Joe Lau]

Quote:

Originally posted by Kim Hardee I'm not saying that all OTL amps will have this issue. I am just questioning the use of a 100mfd output capacitor in the new ASL MG Head amp when driving Grado phones. It seems like it should be 250mfd. That's all. I'm not trying to criticize this new amp. In fact I have one on order (I use Sennheiser phones). I'm just saying I would be a little concerned about the bass response when using the OTL output on this particular amp with Grados.

DOn't talk about -3db point but I'm sure it is better bass in OTL mode when use Grado. I had a Prototype send to Austrilia before production. It is a Replacement of a Damage MG-HeadDT (Damage by air parcel sending). It is a reviewer in Austrlia. They give me a good comment on New Amps. It have better bass compare with Old MG-HeadDT. It use same Transformers as MG-HeadDT but use the transformers as Plate Choke when work in OTL mode. We keep the High impedance tap of transformer but not wiring it ! It only use Low impedance out for transformers out. I consider to redesign the Output transformers to Lower impedance and omitted the Feed Back switch and High IMpedance tap in next shipment. Yes ! use 250Mfd Can made the
testing result in low frequency better but it seem to be no need when I test it by Ears. You still can modufy it to use higher value E-cap. I only consider it cost. I try to keep the price only increase very few dollars.

 

[Joe Lau]

Quote:

Originally posted by Kim Hardee I'm not saying that all OTL amps will have this issue. I am just questioning the use of a 100mfd output capacitor in the new ASL MG Head amp when driving Grado phones. It seems like it should be 250mfd. That's all. I'm not trying to criticize this new amp. In fact I have one on order (I use Sennheiser phones). I'm just saying I would be a little concerned about the bass response when using the OTL output on this particular amp with Grados.

DOn't talk about -3db point but I'm sure it is better bass in OTL mode when use Grado. I had a Prototype send to Austrilia before production. It is a Replacement of a Damage MG-HeadDT (Damage by air parcel sending). He is a reviewer in Austrlia. They give me a good comment on New Amps. It have better bass compare with Old MG-HeadDT. It use same Transformers as MG-HeadDT but use the transformers as Plate Choke when work in OTL mode. We keep the High impedance tap of transformer but not wiring it ! It only use Low impedance out for transformers out. I consider to redesign the Output transformers to Lower impedance and omitted the Feed Back switch and High IMpedance tap in next shipment. Yes ! use 250Mfd Can made the
testing result in low frequency better but it seem to be no need when I test it by Ears. You still can modufy it to use higher value E-cap. I only consider it cost. I try to keep the price only increase very few dollars.

 

[morphsci]

Why does this remind me of the RA-1 arguement. Oh yeah, because it is a discussion of how the amp should sound by someone who hasn't heard it and how it does sound by someone who has.

 

[discoman]

Any picture for OTL?
What are the colors for the front plate?