Frugel-Horn Mk3 Builds & Build Questions

frugal-phile™
Joined 2001
Paid Member
If the felt is of appropriate density, air passes right thru it. Low frequencies don't see it at all and HF get absorbed (as required)

Attached is a FH3 diagram with 1/2" lining. Magnet on the FE126 is slightly smaller than the cutout.

dave
 

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FH3 + MA CH*-70 + Amp for 4 ohm

I've been trawling though the site for information about a solid state or chip amplifier to complement the MA 4 ohm speakers. I've come up against many a resounding NO from various sections of the amplifier forum.

And then as you do on here came up with the solid state equivalent of a 300B, the Jean Hiraga Le Monstre Class A 8 watt and it's long thread stretching over a number of years. The amplifier will work into 2 to 20 ohms I read on there.

I put a question into the thread last week about 4 ohm speakers and as happens on this site many experts will devote time to a problem and Lineup is one of them.

What Lineup has done over the last three days is make alterations to the original Le Monstre to make it completely compatable with 4 ohm speakers and give out 21 watts, instead of 8. The thread can be picked up here: http://www.diyaudio.com/forums/solid-state/5462-hiraga-le-monstre-77.html on page 77.

The relevant circuit diagram is in post 767 with the components with altered values in red. I will be making one of these, it'll take me a couple of months but I will report back to this thread with the results.

I take this opportunity to again thank Lineup for his hard work.

This site would be as nothing without all the people like him who freely give their expertise.

I'm sure that in expressing my gratitude I speak for many others.

Warmest wishes - Jim

I removed the pillow stuffing from the front section of my FH3 and put 1/3 of it back stretched out thinly about 2/3 of the way down from the speaker result; even better bass.
 
Dear Dave,

I wouldn't want to mislead anyone, my FH works well and sounds great with my LM3875 GainClone.

But!! :) I heard Colins 300B drive his FH's and thats why I looked around for a 'benchmark' solid state amplifier. I hope it comes at least somewhere near to the 300B's.

Warm wishes - Jim
 
I've downloaded the TK2050 datasheet and am looking at it now.

Enjoy! There are significant board layout considerations with this chipset, so you very probably want to take a predesigned implementation ...

Maybe some of these prebuilt boards would work for you:
These by Helder-Hifi: TK2050 MKII - Helder-HiFi -EBay ( ebay store: Helder HiFi items - Get great deals on Electronic Components, DIY assembled PCB's items on eBay Stores! )

These by HifimeDiy: Hifimediy|Amplifiers.

Then 41Hz.com in Sweden sell very high quality unbuilt kits, e.g. 41Hz Audio:AMP11 kit (Standard 32V)
 
FH3 / CHP-70 and small tube amp?

Anybody have experience driving the FH3 with a small tube amp?

I might want to build a pair with CHP-70, to use in a small room with a small tube amp. I am however a little concerned about the driver sensitivity of 85dB, and the 4 ohm impedance.


The presumed natural warm, yet detailed sound of the CHP-70 may suit my ears better than the FH1 with Fostex did. The guy with a 300b amp who bought them off me was however very happy.

Svein
 
FH3 / CHP-70 and small tube amp?

Anybody have experience driving the FH3 with a small tube amp?

I might want to build a pair with CHP-70, to use in a small room with a small tube amp. I am however a little concerned about the driver sensitivity of 85dB, and the 4 ohm impedance.


The presumed natural warm, yet detailed sound of the CHP-70 may suit my ears better than the FH1 with Fostex did. The guy with a 300b amp who bought them off me was however very happy.

Svein


In brief , I think 5w and up would probably be fine for smaller rooms/moderate listening levels ( >300sq ft /90dB SPL). Of course all tube watts don't sound the same - I'm simply not that big a fan of most 300B SE *that I've heard - preferring a 2A3 or even EL84 pentode.

I've been quite happy with dual EL70 ( CSS kissin cousin to the CHP70) on less than 5W of EL84 classA P/P in a moderately large/open space, although 12W of pentode sister amp delivers even more authoritative bass and firm dynamics.



*mind you the Allen Wright DPA300 "P/P" amp (wow that was 8 yrs ago now ) was revelatory - but I dare say beyond the budget of any DIY contemplating a $100 pair of FR drivers in a design such as this
 
I went with Fostex drivers in my first pair of Mk3's so I could drive them with a Miniwatt ( 2.5 wpc ) which offers good sound and decent headroom in a 15X15 room playing small group jazz. They also match well with a Sure TK2050 ( with Meanwell PS ) but they sound much better when a tube preamp is added.

I'm thinking of springing for a Dared 2a3c ( 8 watts? ) which would hopefully offer the option of trying the CHP70 in the second set of Mk3's I've already built.
 
I have seen, scrolling through these pages, a lot of 'hard edged' enclosures.
This will give diffraction. Specifically as the enclosures get smaller.
Like is said in the "Fonken" website;
My favourite page in Olson's Acoustics is the one with the graphs that show the affect of box shape on diffraction and from this that a box with heavily champhered edges gets you most of the way with little effort.

The sound will clean up if BOTH the inside of the baffle and the outside edges of the enclosure are beveled, that is you just take a router with a 1/2 inch curve and just blast it off. It gives a lot more sound stage.
albert
 
frugal-phile™
Joined 2001
Paid Member
...has a rounded or beveled edge on de inside been considered?

It is a given. Driver cutouts are depicted as in the drawing snapshot attached and item 5 in the notes is standard boilerplate. Thanx for pointing out that it is missing. I really need to find some time to add to the drawings.

dave
 

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Back chamfer

Dear Triode-al and Dave

I used a little round rasp on the inside of my baffles and finished the chamfer off with some really coarse sand paper;
jkzk8l.jpg

Outside on a windy day and wearing a mask!

I am running mine in now, using Daves trick of a tuner played very quietly through them for a week or so, but do have the occasional sneaky listen for 5 mins or so. I only listen at low volume and they seem to need less power each time I do and as for the sound well, every time it gets so much better.

Warmest wishes - Jim
 
Helder or HifiMeDiy for 4 Ohms

Hi Jemraid,

I'd like to heartily agree with Kristliefur's recommendation about the Helder or HiFiMeDiy T3 boards for driving 4 ohms. Also to recommend the Virtue amps if your budget can afford them.

These examples of good Tripath implementations sound very close to a combination of really good tube SET coupled with the drive and control of monster solid-state amps. It's best described as "lively, juicy and powerfully extended with finesse AND slam"


I use this type of amp to drive the bass section my HolisticAudio H3's which run at about 3 Ohms, and the levels they attain are stunningly loud... and clean.

Just look for the Helder 2050MkII or the HifiMeDIY T3..... also Sure Electronics is selling similar units through Parts Express...

It won't cost you much to Try a pair and put your concerns to rest!

All the Best!