Tall and narrow GRF style birch plywood cabinets

[Magna Audio]

The Cabinets I made for a pair of Tannoy HPD drivers could finally be collected after the lockdown easing.

The drivers were dropped off to me and I installed them during the day for afternoon collection.

The aftermarket crossovers are external hence dedicated boxes.
Nice components in the crossovers.

We also used high quality Janzen integral cable and gold plated Tannoy 4 pin plugs.

These are built using the Scandinavian birch plywood throughout and designed to be taller and narrower than the original Tannoy GRFs.
Modelled you have the same tuned backloaded horn path.
These also feature the bass cleaning up Tear drop baffle in the throat of the horn section.

Finished in English light oak.

The customer (a Dolby surround sound engineer) had the drivers in original chipboard Tannoy Berkeley cabinets.
Needless to say the cabinet material, construction and backloaded horn bass make these a very much improved Hi-fi experience.

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Driver installation

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[Swann36]

Forgive my lack of knowledge, if I was to buy from a pair of these narrow GRFs from you would I need to get the crossovers (Berkeley cabinets currently) altered to be tuned to the larger GRF cabinet ?

[Magna Audio]

Forgive my lack of knowledge, if I was to buy from a pair of these narrow GRFs from you would I need to get the crossovers (Berkeley cabinets currently) altered to be tuned to the larger GRF cabinet ?Hi,
The existing crossovers will work just fine.
The crossover point remains the same. 1000Hz.

The notch filter for the horn tweeter renains the same.

The energy settings on your crossovers give you the flexibility to essentially attenuate the bass some extent. Turn up the treble energy you turn down the overall volume = less bass.

I found my Berkeley drivers and crossovers worked very well in the GRF cabs.
I always had them set in the mid positions.
Average sized living room.

There are aftermarket crossovers which may improve clarity (higher quality components).
I've fitted quite a few.
Most customers stick with the standard crossovers.
I've also replaced the very old capacitors a few times.

The GRF bass is deeper, and it's more tuneful horn bass. Instrument mid bass and deeper bass subtleties become apparent.

Additions of the tear drop baffle to help block unwanted higher frequencies from the horn help too.

I make the cabinets so tuning of the bass horn damping can be achieved by the addition of more inner felt lining the horn.
Only found this to be necessary for small rooms.
Otherwise it's done as per the GRF drawings.

I use 21mm and 24mm premium birch plywood, the cabinets are of a superior faster/tighter sound.

Hope that helps.

[struth]

very nicely made steve.. very pretty too

[Swann36]

Hi,
The existing crossovers will work just fine.
The crossover point remains the same. 1000Hz.

The notch filter for the horn tweeter renains the same.

The energy settings on your crossovers give you the flexibility to essentially attenuate the bass some extent. Turn up the treble energy you turn down the overall volume = less bass.

I found my Berkeley drivers and crossovers worked very well in the GRF cabs.
I always had them set in the mid positions.
Average sized living room.

There are aftermarket crossovers which may improve clarity (higher quality components).
I've fitted quite a few.
Most customers stick with the standard crossovers.
I've also replaced the very old capacitors a few times.

The GRF bass is deeper, and it's more tuneful horn bass. Instrument mid bass and deeper bass subtleties become apparent.

Additions of the tear drop baffle to help block unwanted higher frequencies from the horn help too.

I make the cabinets so tuning of the bass horn damping can be achieved by the addition of more inner felt lining the horn.
Only found this to be necessary for small rooms.
Otherwise it's done as per the GRF drawings.

I use 21mm and 24mm premium birch plywood, the cabinets are of a superior faster/tighter sound.

Hope that helps.


It certainly does and thank you for taking the time to explain.

I’m contemplating moving up from the Berkeley cabs as I’m moving house soon (fingers crossed this year) and once settled in and see how all the bills work out plus room layout I plan on getting my last set of speakers and I’m really captured by yours as far as I can see only positive comments and I of course have the drivers 15 inch HPDs from 1976 which I’ve had recommended on another thread they should go to Paul at RFC for their surrounds renewing/ general fettling up and if budget allows his external crossovers too so your cabs might well complete the picture on the speakers front , well that’s where my heads at so far , Paul’s (RFC) Canterburys are stunning but well out of my price range even without the current inflation crisis.

Once again thanks for the reply I hope we can speak again before the year is out

Oh nearly forgot my further aspiration is to hear then perhaps save up for a Copper Amp like I’ve seen mentioned elsewhere on here

[walpurgis]

Very nice. I can almost feel the bass punch from here :), I know what big BLH speakers can do!

[Magna Audio]

It certainly does and thank you for taking the time to explain.

I’m contemplating moving up from the Berkeley cabs as I’m moving house soon (fingers crossed this year) and once settled in and see how all the bills work out plus room layout I plan on getting my last set of speakers and I’m really captured by yours as far as I can see only positive comments and I of course have the drivers 15 inch HPDs from 1976 which I’ve had recommended on another thread they should go to Paul at RFC for their surrounds renewing/ general fettling up and if budget allows his external crossovers too so your cabs might well complete the picture on the speakers front , well that’s where my heads at so far , Paul’s (RFC) Canterburys are stunning but well out of my price range even without the current inflation crisis.

Once again thanks for the reply I hope we can speak again before the year is out

Oh nearly forgot my further aspiration is to hear then perhaps save up for a Copper Amp like I’ve seen mentioned elsewhere on hereUncertain times, but we'll get through them.

Yes, it's Paul's X/Os I've fitted several times over the years.