Intact Audio

I've been using a pair of the 12 step, PCB mounted, AVCs with the added 3 position +/- switches for some years now. I recently changed my speakers from a pair of (100 db/1 watt) Lowther Fidelios to a pair of, back-horn-loaded, (105 db/1 watt!) Lowther TP1s with Lowther PM5A drivers. My lovely Yamamo...

Long story having tried a variety of driver and DHT power tubes. I'm now using a 2 stage SET with a triode-wired, grid battery biased, C3M with a Dave Slagle 49% nickel IT driving a Svetlana SV 811-10 DHT also grid battery biased ( to operate in class A1). I'm looking at building a new pair of, larg...

Hi Dave, I'm using your 49% Nickel ITs with triode-connected NOS Mullard E180Fs and various DHTs. the 205Ds are great on the micro dynamics but a (little) bit under powered even with my Big Fun Horns/DX4s. 300Bs are not quite as good at the micro but handle the macro dynamics very well. I've been of...

CCS gone and excess bass gone too.
Pure laziness not wanting to have to experiment with the right
resistor values to give the correct anode voltage and current.
Anyway 13.8K ohms gives me 10.5 mA and 185V dc on my D3As.
Amp still warming up but already liking what I'm hearing, Kevin.

Hi Dave, Removed the couplings caps and grid chokes and Installed the 49% nickel ITs. So each channel consists of battery grid bias (2.4V) on the triode wired D3A with cathode directly connected to ground without resistor or bypass cap. B+ is about 360Vdc and i have retained the CCS set to 11mA (whi...

Hi Dave, Thanks for the tubes advice. I'll be sure to try and get some 7788 (E280F) ? tubes. The designer of my DIY set amp suggested changing the D3A driver tubes from cathode bias to battery grid bias. I think the 'Troels Gravensen' grid bias is superior to 'conventional' capacitor/resistor cathod...

Hello Dave, Trying to decide on the best way to use the ITs I ordered. I've previously only built cap-coupled set amps. My amp uses fixed bias on the output tubes but i could re build it for cathode bias. Do you have any thoughts or 'bias' either way? Are the ITs bifilar wound as i understand the pr...

Hi Dave,
You read my mind concerning the ITs! but I thought i
should ask about the output TXs first.
I'd be very interested in trying a pair of ITs and
I'll contact you about costs and delivery etc.
Kevin.

Hi Dave, Your permalloy AVCs volume controls continue to do sterling work in my set up. My DIY set amp is designed to use a D3A with CCS set to 10mA, cap-coupled to a fixed bias 300B and grid chokes on the 300Bs. The fixed bias is set to 60mA and the 5K primary amorphous-Nickel output transformers a...

Hi, A D3A has a mu of 70 and was designed to give good performance as a pentode or high mu triode. I use D3As in a SET amp as an input/driver tube and yes they are available. Another similar pentode which can be used as a high mu (50) triode is the 7221 or E180F. I use Mullard NOS E180Fs in my LCR p...