[Rossliew]

And how does it sound ?

 

[gibosi]

And how does it sound ?

I listened to the 1817 for only an hour today, so I can't say much in detail. But I can say that in my experience the sound of the 1817 is similar to that of double triodes and other rectifiers manufactured in Eindhoven. To my mind the most notable characteristic of the Eindhoven house-sound is a slightly forward mid-range with a bit of lushness. For those who have experience with Heerlen-made tubes, I would say on average the Eindhoven sound is not quite as lush as Heerlen.

Unfortunately, the only 5-volt Eindhoven-made rectifier I am aware of is the very expensive metal-based GZ34. And since I have yet to win the lottery, I don't have one for comparison purposes. But I do have a number of 4-volt Eindhoven-made rectifiers - 1815. 1817, 1861, AZ4 and AZ50. To my ears, the 1861 and AZ50 approach the lushness of the Heerlen sound, the AZ4 and the newer, more compact 1815 and 1817 are not quiet as lush, and the older 1815 and 1817 are even less so.

In short, I am a big fan of the Holland sound, Heerlen and Eindhoven, and to my ears the old 1815 and 1817 are wonderful rectifiers.

 

[Rossliew]

Many thanks for the impressions, Ken. Always a pleasure to read your notes on the tubes and their historical relevance

Btw, a bit off topic but do you reckon one of these 4 volt rectifiers may work safely in the Dragon Inspire IHA-1 amp?

 

[gibosi]

Many thanks for the impressions, Ken. Always a pleasure to read your notes on the tubes and their historical relevance

Btw, a bit off topic but do you reckon one of these 4 volt rectifiers may work safely in the Dragon Inspire IHA-1 amp?

Of course, some of them will work in that amplifier. But a bit of detective work is necessary in order to determine which ones are adequate and safe.

In my experience, the two key rectifier specifications are heater current and output DC mA.

The amp is shipped with a Sovtek 5Y3GT and from the data sheet, this rectifier can provide up to 133 mA with a 2.0 A heater. So this tells us that any 4V rectifier that can provide at least 133 mA is adequate. But many rectifier heaters draw more than 2.0 A, so this is a concern. But I see that the RCA 5U4GTB is listed as an optional rectifier and this rectifier draws 3.0 A. But still, a number of these 4V rectifiers draw more than 3.0 A.

So I would suggest that you contact the manufacturer and ask for the maximum heater current that amp can provide. You probably should not tell them that you plan to run 4V rectifiers, as they will likely freak out and just say NO! lol. But asking if it is safe to use a 5AW4, which draws 3.7 A, would be a reasonable question.

If the manufacturer is unable or unwilling to provide you with this information, then more detective work on your part will be required. If you can get a list of 5V rectifiers that have been found to be safe for use in the IHA-1, you can check the datasheets for these rectifiers to see which one has the highest heater current, and use that number as your maximum.

Obviously, determining the maximum heater current in this fashion may not be perfectly accurate, but it is safe. And this is important. If a rectifier requires more heater current than your amp is designed to provide, the amp may be damaged, perhaps fatally, so I encourage you to be very careful in this regard.

If it turns out that 3.0 A is the maximum, of those that I have personal experience with, you would not be able to run an 1817, as this tube requires 4.0 A. Others you would not be able to run are the NU12 and U18, which require 3.75 A, the 45IU, 3.5 A, and the PV 200/600, 3.4 A.

But this still leaves a good variety: FW4-500, U18/20, AZ50, 1861, 1815, RGN2504, AZ12, AZ4, UU7 and UU8. Further, since the IHA-1 requires no more than 133 mA to operate, there are plenty more out there, such as U12, UU5, 43IU, RGN2004, FW4-800 and many others, which are not powerful enough to use in the Glenn, but perfectly suitable for the IHA-1.

Hope this is helpful....

 

[Neogeo333]

I thought I'll never say this but I think Im sick of eating pizza. I get to eat all this at work anytime.

 

[gibosi]

And I get to eat frozen pizza all the time.... lol

 

[rnros]

You have my attention. Can you send me two of each?
They. Look. Incredible.
Toppings are great, but the crust looks... perfect!

Yeah, I'm hungry... You're not helping.

 

[Rossliew]

Of course, some of them will work in that amplifier. But a bit of detective work is necessary in order to determine which ones are adequate and safe.

In my experience, the two key rectifier specifications are heater current and output DC mA.

The amp is shipped with a Sovtek 5Y3GT and from the data sheet, this rectifier can provide up to 133 mA with a 2.0 A heater. So this tells us that any 4V rectifier that can provide at least 133 mA is adequate. But many rectifier heaters draw more than 2.0 A, so this is a concern. But I see that the RCA 5U4GTB is listed as an optional rectifier and this rectifier draws 3.0 A. But still, a number of these 4V rectifiers draw more than 3.0 A.

So I would suggest that you contact the manufacturer and ask for the maximum heater current that amp can provide. You probably should not tell them that you plan to run 4V rectifiers, as they will likely freak out and just say NO! lol. But asking if it is safe to use a 5AW4, which draws 3.7 A, would be a reasonable question.

If the manufacturer is unable or unwilling to provide you with this information, then more detective work on your part will be required. If you can get a list of 5V rectifiers that have been found to be safe for use in the IHA-1, you can check the datasheets for these rectifiers to see which one has the highest heater current, and use that number as your maximum.

Obviously, determining the maximum heater current in this fashion may not be perfectly accurate, but it is safe. And this is important. If a rectifier requires more heater current than your amp is designed to provide, the amp may be damaged, perhaps fatally, so I encourage you to be very careful in this regard.

If it turns out that 3.0 A is the maximum, of those that I have personal experience with, you would not be able to run an 1817, as this tube requires 4.0 A. Others you would not be able to run are the NU12 and U18, which require 3.75 A, the 45IU, 3.5 A, and the PV 200/600, 3.4 A.

But this still leaves a good variety: FW4-500, U18/20, AZ50, 1861, 1815, RGN2504, AZ12, AZ4, UU7 and UU8. Further, since the IHA-1 requires no more than 133 mA to operate, there are plenty more out there, such as U12, UU5, 43IU, RGN2004, FW4-800 and many others, which are not powerful enough to use in the Glenn, but perfectly suitable for the IHA-1.

Hope this is helpful....

Many thanks for your input, Ken. Most, most helpful!

One other thing, would I need to look at the current draw of the rectifier in totality with the other tubes used, which in this amp is a pair of 6sn7 ( which can also accept 6BX7/6BL7)?

 

[whirlwind]

Whoa George.

I would love to indulge into that pizza!

 

[2359glenn]

I thought I'll never say this but I think Im sick of eating pizza. I get to eat all this at work anytime.

George What
You are just mean!!
You know I am trapped in NC with what Pizza hut or Pappa Johns.
You just want to torture me.

 

[Neogeo333]

It's great in this place, brick dome oven and whole 9 yards. Glenn you have to swing by when you get back to Brooklyn.

 

[gibosi]

Many thanks for your input, Ken. Most, most helpful!

One other thing, would I need to look at the current draw of the rectifier in totality with the other tubes used, which in this amp is a pair of 6sn7 ( which can also accept 6BX7/6BL7)?

No. The rectifier is heated from a 5 volt winding which is completely separate from the 6.3 volt winding heating the two 6SN7. And it is the current capacity of that 5 volt winding that you need to find out.

 

[gibosi]

A Raytheon 5CU4 arrived today. Hope to have some time this evening to roll it in.

Sylvania 3DG4 to the left and 5CU4 to the right.

 

[Xcalibur255]

Many thanks for your input, Ken. Most, most helpful!

One other thing, would I need to look at the current draw of the rectifier in totality with the other tubes used, which in this amp is a pair of 6sn7 ( which can also accept 6BX7/6BL7)?

FYI feel free to direct these kinds of questions to me if you want to. I own one of these and I've spoken to the designer so I'm equipped to answer them.

The rectifier does have it's own tap on the power transformer, which is rated at 3A with a 10% safety overtolerance. I asked Dennis if he thought a 3.8A rectifier like a 5AU4 would be safe for the amp and he seemed to think the transformer would tolerate it because the other tap is underutilized so the total heat dissipation should still be safe enough, but my personal opinion is that it isn't worth risking. The B+ requirement of the Inspire IHA-1 is very modest. Even a low capacity tube like a 5Y3 has a pretty easy job in this amp. The only advantage to big honking rectifiers in the Inspire is to shave a few volts off your drop voltage for a slightly different sound.

My personal opinion is that this amp likes 5R4GY tubes a LOT. The Philips version in particular absolutely stomps 5U4G and 5Y3 tubes in resolution and refinement.

 

[Xcalibur255]

Did you guys look at the front page article about the Toolshed Audio Euphoria 45? Wow what a beautiful amp. I don't even want to know it cost, but it sure has presence.