Croft RIAA Gain

[gerlando]

Hello there.

I recently bought a second hand Croft RIAA for matching it with a high output MC cartridge (Hana EH), since not long ago Glenn (Croft) told me that the RIAA has a slightly higher gain (44 db) than average standard MM phono stages (about 40/41 db), so it is a good match with the HOMC's.

While waiting for the Hana to arrive, yesterday I tried the RIAA with my AT-VM95ML (in as new condition, max 20 hours), which if I'm not mistaken has an output of 3.5 mv respect to the 2 mv of the Hana, but the output level seemed quite low, maybe even lower than the Graham Slee Gram Amp 2SE I had before.

Do you think it may depend on the type of tubes used (ECC83 Harma Cryo), or there may be other parameters affecting the gain?

I tried to write to Glenn but he still hasn't answered me.

The RIAA however sounds great and it's very musical.

Thank you.
Mauro

[Firebottle]

If you are using ECC88 valves that is the reason for the low gain.
AFAIK every Croft RIAA should use ECC83, which are much higher gain than the '88.

[fiddlemaker]

If you are using ECC88 valves that is the reason for the low gain.
AFAIK every Croft RIAA should use ECC83, which are much higher gain than the '88.

Yes, always ECC83. Maybe the previous owner misread the "8" as a "3". Or gain reduction for compatibility with the rest of his gear? Or just a tinkerer?
It'll sound much better with the correct valves.

[gerlando]

If you are using ECC88 valves that is the reason for the low gain.
AFAIK every Croft RIAA should use ECC83, which are much higher gain than the '88.

Sorry, my mistake, it's a pair of ECC83 HARMA Retro CRYO

[Firebottle]

The gain of the Croft is generally on the high side as most phono stages offer about 40dB.

However even with more gain than that the signal level will be way down when compared to a typical CD player or Dac output.

[gerlando]

The gain of the Croft is generally on the high side as most phono stages offer about 40dB.

However even with more gain than that the signal level will be way down when compared to a typical CD player or Dac output.

My old Graham Slee Gram Amp 2 SE claimed at 41 db seems to have a higher output.

[Lawrence001]

I know Glenn makes lower gain line preamps to order. Is it possible he also made lower gain RIAA stages?

Sent from my BKL-L09 using Tapatalk

[fiddlemaker]

Hello there.


I tried to write to Glenn but he still hasn't answered me.

.
Mauro

I don't know if anyone else has found this, but there is something about Glenn's email address that triggers the spam filter on my email.
So might be worth looking in your spam/junk folder. I had to specifically add him to my contacts to stop this from happening. Just an idea.

[gerlando]

I don't know if anyone else has found this, but there is something about Glenn's email address that triggers the spam filter on my email.
So might be worth looking in your spam/junk folder. I had to specifically add him to my contacts to stop this from happening. Just an idea.

Than you for your suggestion.

Unfortunately no email in my spam folder.

[gerlando]

After receiving Glenn's reply, I understood the reasons for my Croft RIAA low gain:

"the gain of the RIAA depends on the input impedance of the amp it is driving - 100k ohms is the ideal value - anything lower will reduce the gain."

So if I understand correctly the RIAA would interface better with a tube amp.

My solid state integrated amplifier (Exposure 2010S) has a declared input impedance of> 14k ohms, so it's probably not the ideal match (my headphone amp has a declared input impedance of 47k ohms instead, and in fact connecting it directly at the RIAA the gain is significantly higher).

Wanting to keep my current integrated amp, do you think a solid state phono preamp (Trichord Dino, Lehmann BC, Dynavector P75, Graham Slee etc.) would pair better with my Exposure?

Thank you.
Mauro