Need advices, First DIY Project, Back Loaded Horn

[#60619]

Many thanks for the advice about another design of enclosure, but for me I think will be more straight forward follow exactly the Fostex enclosure plan for the full range driver FE208EZ and the super horn tweeter T900A, at least for this first project, I think if I continue to look for a lot of different drivers and enclosures, the project will never going to become a reality, the decision is already made 🙂

Yes, the dealer told me that the output impedance is 5k ohms

This is the amp:

ASTOR TO-EL34KG Push-pull Power amplifier | ホームオーディオ通販･下取･買取専門店エクスクルーシブ・オーディオEXCLUSIVE AUDIO

 

[planet10]

5k is not the outut impedance. If it is that makes the amp a current amp, and not suitable for these speakers at all without some impedance flattening of the speaker. Output impedance should be somewhere 0.1->1Ω

ie the dealer either has a language issue or does not know his product, a sign to stay away.

This speaker was designed for a high output impedance amplifier — from the driver designer himself when he met Scott in HK.

dave

 

[#60619]

Thanks, I will check this with the dealer... It's a store with good references I think, maybe is a communication issue, will try to get the correct info with him again...

 

[#60619]

Here's the dealear reply:

5K ohms is load resistance impedance of transformer. Please check out screen shot of data of output transformer from transformer manufacture. I am sorry I do not understand what your friend mentioned "Output impedance should be somewhere 0.1->1Ω". 0.1->1Ω is too small even for tweeter.

I explained to him that output impedance = damping factor

He also send me this data sheet bellow, I will get the complete data sheet with all others values besides the output transformers and post here soon.

An externally hosted image should be here but it was not working when we last tested it.

 

[#60619]

Here's the link with the data sheet:

Dropbox - data sheet.png - Simplify your life

 

[planet10]

That is what we deduced and it is not want we want to know.

5k is the impedance the output tubes see. What we want to know is what do the 4Ω (or 8 or 16) see.

dave

 

[#60619]

let me ask you, output impedance = damping factor right?
So I will ask him the damping factor data about the amp, correct?

 

[planet10]

This is the amp: ASTOR TO-EL34KG Push-pull Power amplifier

I had a look at the specs. SOmething is not right. PP EL34 should be about 40w in pentode, 30-35w in UL and about 20 w in triode.

They see this amp is 15 W UL.

These inexpensive Chinese tube amps i call pre-assemebed kits… it won’t likely stay stock long.

But for the speakers you ar ebuilding a SET would be a better match. Althou you could at least partially overcome that with highR skinny speaker cables.

If you have to buy from these same guys:
アストロ電子企画　AS-300BsB シングルパワーアンプ　 | ホームオーディオ通販･下取･買取専門店エクスクルーシブ・オーディオEXCLUSIVE AUDIO
アストロ電子企画　TO-2A3sKG 真空管パワーアンプ | ホームオーディオ通販･下取･買取専門店エクスクルーシブ・オーディオEXCLUSIVE AUDIO
アストロ電子企画　TO-2A3sKG 真空管パワーアンプ | ホームオーディオ通販･下取･買取専門店エクスクルーシブ・オーディオEXCLUSIVE AUDIO

The 1st has very unimpressive looking OPTs, the 2nd is better (but the parts described are for a completely different amp), the 3rd look best, and is probably cheapest, the OPTs are canned so who knows what is inside.

Here is something that is solid value from a known resource. Cheap, less so (and probably max bang for the buck), and probably amazing for the price. Even the baby one has enuff power for the speakers you are building.

Elekit TU-8100 PCL86 Integrated Amplifier Kit – diyAudio Store
Elekit TU-8200DX 6L6GC Integrated Amplifier / Headphone Amplifier Kit – diyAudio Store
https://diyaudiostore.com/collections/kits/products/elekit-tu-8600r

dave

 

[#60619]

by the way, I see that on the pictures of the amp, it have 4ohms / 8ohms / and 0 ohms??? speakers terminals..

see: ASTOR TO-EL34KG Push-pull Power amplifier | ホームオーディオ通販･下取･買取専門店エクスクルーシブ・オーディオEXCLUSIVE AUDIO

Anyway, I will try to get the damping factor spec with the dealer, will post soon

Already thank you very much for all the help guys

 

[planet10]

Damping factor is sort of the inverse of output impedance. You are looking for damping factor between 2 & 10 ohms.

dave

 

[#60619]

I had a look at the specs. SOmething is not right. PP EL34 should be about 40w in pentode, 30-35w in UL and about 20 w in triode. <snip>

Many thanks for this other options, I will take a look with more attention on this ones..

 

[#60619]

By the way, if you see inside this amps, the construction is OUTSTANDING handmade craftsmanship..

 

[#60619]

I had a look at the specs. SOmething is not right. PP EL34 should be about 40w in pentode, 30-35w in UL and about 20 w in triode. <snip>

Please, can you elaborate why this one:
アストロ電子企画　TO-2A3sKG 真空管パワーアンプ | ホームオーディオ通販･下取･買取専門店エクスクルーシブ・オーディオEXCLUSIVE AUDIO

It's better suited for my speakers, instead of this one:
アストロ電子企画　TO-EL34KG　プッシュプル・パワーアンプ | ホームオーディオ通販･下取･買取専門店エクスクルーシブ・オーディオEXCLUSIVE AUDIO

I think I not fully understood why....

Many thanks sir, If you can elaborate in a more simple way, (I'm not too versed on deep technical parameters) it will be a great help for me to understand)

By the way, it's still important to know the damping factor of the one from the first link?

 

[planet10]

1st, the specs on both of these are inconsistent and i can’t read the chnese parts. With just deductions from the pictures the 1st should have a more optimum output impedance (damping factor). It is the kind of amp these speakers are targeted at.

dave

 

[#60619]

Understood, I will post the damping factor spec of the first one soon.

Chinese parts you mean the tube? (because I think there's nothing chinese on the amp as far as I know, it's a handmade amp made in Japan) I will put a picture of the insides some time, is outstanding.

Thanks!

 

[#60619]

Here's the last reply from the dealer about the output impedance subject:

"The output impedance is already showing in the spec: 0. 4. 8 ohms

both amplifiers are same output impedance

these both:

ASTOR TO-EL34KG Push-pull Power amplifier | ホームオーディオ通販･下取･買取専門店エクスクルーシブ・オーディオEXCLUSIVE AUDIO
アストロ電子企画　TO-2A3sKG 真空管パワーアンプ | ホームオーディオ通販･下取･買取専門店エクスクルーシブ・オーディオEXCLUSIVE AUDIO

ASTOR does not check damping factor because the damping factor is not important for tube amplifier, but important is residual noise and distortion. Tube amplifier does not like transistor amplifier..and even transistor amp, damping factor is not important factor now. In fact there is quiet rare to show damping factor in the spec of amplifiers in any manufactures. The opinion of damping factor is coming from not only ASTOR, but also, other manufactures whom I asked advance. Of course, they considered relation of amplifier and speaker. It seems to be theoretical but not practical.

TO-2A3sKG is single power amp. It is not enough expression of bottom range than push-pull TO-EL34KG. If you want to enjoy Jazz, Hard-Bop, I assume push-pull amp is better choice. However your speaker design is backloaded horn, then it is possibly cover the lack of bass range.."

 

[Scottmoose]

Here's the last reply from the dealer about the output impedance subject:

"The output impedance is already showing in the spec: 0. 4. 8 ohms...

I'm afraid it isn't. Those are the nominal output taps, not the output impedance:

See: Amplifier Output Impedance Why It

ASTOR does not check damping factor because the damping factor is not important for tube amplifier...

Pardon? Damping factor is a factor, and personally I find the hard data it's derived from (output impedance) more useful when designing, but they're saying that they don't even calculate / check it? Claiming it is not important for a tube / valve amplifier is technical nonsense unfortunately. In point of fact, since most such amplifiers have quite a high output impedance (which translates into a low damping factor) compared to, say, the majority of solid state amplifiers, it is more, not less, important to know what it is for optimal system design and matching.

but important is residual noise and distortion

These are important, but hardly the only factors. I see that on the pages you link to, the former is mentioned, but the latter is not.

and even transistor amp, damping factor is not important factor now. In fact there is quiet rare to show damping factor in the spec of amplifiers in any manufactures

So rare that, for example, Pass Labs, McIntosh Labs, Musical Fidelity, Accuphase, Luxman and Audio Research (to mention only six rather well-known companies) all list it in their technical specs.

 

[#60619]

Thanks, I will check that with attention..

I would like to point that I can't get the output impedance of tube amps like Air Tight, Leben, Luxman, Yamamoto neither...

 

[#60619]

Doubt, Isn't common that the majority of tube amps already have a low damping factor?

 

[#60619]

Correction: Yes, Air Tight provides Damping Factor.